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-   -   Never ending problem for the 13th engine rebuild (very long post)...... (http://forums.pelicanparts.com/911-engine-rebuilding-forum/902416-never-ending-problem-13th-engine-rebuild-very-long-post.html)

911pcars 07-29-2016 10:47 PM

Quote:

Originally Posted by Flat6pac (Post 9219543)
The 930 tensioner so are still expensive, then you need new oil lines and chain covers.
There shouldn't be any problem with the Carrera tensioners, I think Tony bought all the defective ones......
Bruce

There's a common misconception that "930 tensioners" are the same as "pressure-fed tensioners". Not so.

So-called 930 tensioners (930.105.053.00 or 04) are an improved version of the original chain tensioners with a self-contained reservoir of oil. They are standalone, only receiving add'l oil as needed from oil splash as occurs in the chain box area.
http://forums.pelicanparts.com/uploa...1469860864.jpg


Pressure-fed tensioners (930.105.058.03) are fed engine oil under pressure from the engine's lubrication system. The kit contains two of these tensioners along with accompanying external oil lines and chain box covers.
http://forums.pelicanparts.com/uploa...1469860886.jpg

Either choice is expensive. Hope this helps.

Sherwood

boyt911sc 07-30-2016 09:09 AM

You are correct.............
 
Quote:

Originally Posted by Flat6pac (Post 9219543)
The 930 tensioner so are still expensive, then you need new oil lines and chain covers.
There shouldn't be any problem with the Carrera tensioners, I think Tony bought all the defective ones......
Bruce



Bruce,

When I installed the newly purchased Carrera hydraulic tensioners, I thought it would be an easy cruise to victory lap. And I could almost smell the joy of success. But the euphoria was short lived. First, the newly installed tensioner at the right side bank exhibited failure or collapsed by just cranking the engine for oil lubrication. I was not even running the motor. Removed the tensioner and tested. Confirmed defective when I could compressed the piston by hand.

Replaced it with a used known good unit from another engine. Test cranking the engine produced no abnormal noise. Left side still has the newly purchased tensioner and right side has the a used tensioner. Repeated the cranking cycle several times and was satisfied with the result. Next is to run the engine and observe.

The first attempt was not good. Turned off the engine and took a deep breath. Why? Tried to start again the engine and the knocking and rattling noise was there again. Not another bad tensioner? Removed the chain housing cover and inspected the tensioner. It was not easy to tell if the tensioner was bad so I removed and tested it on the bench. The tensioner has also failed this time because I could compressed it by hand.

So I asked myself if it was really a bad tensioner that was causing this abnormally loud engine rattle (knock) noise generated when you start the engine? Cranking the engine with the FP and CDI disabled seemed to be OK but not when you run the engine.

Next, I installed a second good used tensioner at the left side. Both sides now have used tensioners which were tested and showed very hard resistance to compression. With two (2) good tensioners, everything should be OK (?). Turned the ignition switch and kept my ears close to the engine to hear anything. Result: loud engine noise or rattle.

Back to square one:
When you cranked the engine with the ignition disabled, no abnormal knocking sound. However, with the ignition ON and the engine starts running it produces this loud rattling noise.

As a side test, I installed a mechanical tensioner at the left side and left the used tensioner at the right side and run the engine for a couple of seconds. Same annoying loud noise. Maybe it was coincidental that the tensioner/s was bad and the root cause of the abnormal sound is still undetermined or unkown (?).

What do I do next? There is something evidently wrong in the engine and I do not know what to look for. So I am back again from the beginning of my search to diagnose the root cause of this problem.

Why does the engine sound normal when you crank the engine (ignition disabled)? The engine speed is much less without ignition compared to a running engine. What mechanical part/s of the engine is causing this noise? I need help and guidance to solve this nagging problem. Thanks to everyone.

Tony

Lapkritis 07-30-2016 10:58 AM

Combustion can cause piston rattles if the bore is out of spec... it won't show while cranking. Same for rod bearings as they're in the stack beneath the combustion loads.

Are you certain it's not something like bendix from the starter not retracting?

Sub8 07-30-2016 10:59 AM

Combustion pressure would tend to show wear in big and little ends that might not be evident just spinning the engine?

911 tweaks 07-30-2016 11:40 AM

tony... if you are wanting to get this on the road sooner than later, no offense intended here, take the eng on its stand to mark and let him listen to it... he does have a lot more yrs of porsche engine sounds that are good and bad than you I believe...
I understand you wanting to conquer this yourself, but, if you want the car on the road soon, get more experienced input and let us know how it goes...
I am hoping it is nothing requiring a teardown, but prepare for the worst and hope for the best... good luck...!!

boyt911sc 07-30-2016 12:02 PM

Making a list of probable culprit/s for the next tear down........
 
Things to test and verify:

---Connecting rods bearing (big & small ends).
---Cylinder bore (out of spec.)

Please continue to suggest and share your thoughts. I will consider each and everyone's suggestion without bias. I have plenty of time to digest these suggestions during my extended family vacation in Carmel, CA next week. After my return back home, the inevitable engine tear down has to be done. Thanks.

Tony

911pcars 07-30-2016 12:17 PM

Begin diagnosis with a compression/leak down test. If the engine runs w/o endangering further damage, run engine while shorting (disconnecting each spark plug wire) while listening to the engine. If noise reduces on a disconnected cylinder, suspect the rod bearing on that cylinder. If not, could be a main bearing, that's about it for active engine diagnosis. Thereafter, engine parts must be removed for further inspection. Ok thus far?

Remove the distributor and inspect. Remove valve and chain box covers and take a look. Check tightness of threaded fasteners, rotate engine manually while observing all moving parts.

Remove drivetrain and inspect clutch/flywheel area. Inspect cooling fan and alternator Remove flywheel and inspect. If all appears ok up to this point, engine comes apart while inspecting pieces. Eventually, it'll be apparent. The slippery slope is yours.

Sherwood

boyt911sc 07-30-2016 02:36 PM

Professional Porsche shops......
 
Quote:

Originally Posted by 911 tweaks (Post 9220244)
tony... if you are wanting to get this on the road sooner than later, no offense intended here, take the eng on its stand to mark and let him listen to it... he does have a lot more yrs of porsche engine sounds that are good and bad than you I believe...
I understand you wanting to conquer this yourself, but, if you want the car on the road soon, get more experienced input and let us know how it goes...
I am hoping it is nothing requiring a teardown, but prepare for the worst and hope for the best... good luck...!!




Tweaks,

I hear you and I know Mark B. personally for more than 20 years. His phone number and email are in my contact list. BTW, I don't want to conquer this problem by myself or I would not be in this forum seeking help and advise. There are several well respected shops near by and would consider them too. I will be leaving for CA in a few days and would be away for several weeks and will make some calls to these guys including Mark B. Thanks.

Tony

boyt911sc 07-30-2016 05:31 PM

Over-stretched timing chain........
 
I just noticed tonight that the Carrera hydraulic tensioner in bank 1-2-3 (for my problematic engine) has the piston almost out all the way. Preliminary measurements (roughly) showed just about 1 or 2 mm for full extension. Will take pictures tomorrow.

In the picture (7-19) in Wayne's Rebuild book, you could see the 'step' about half "in". And mine is out a lot. I need to remove the muffler to get a good picture and I am too exhausted and ready to go to bed. See you tomorrow.

Tony

Walt Fricke 07-30-2016 09:23 PM

I once noticed that the top of the idler arm, against which the chain tensioner piston presses, was about hitting the chain housing. Why, I wondered?

Chain stretch? Not that much, I thought. Sprocket wear? Couldn't make that much difference.

Took the idler off. It was cracked! And it's a forging, I am pretty sure. But cracked, which distorted it.

Not likely to be the cause of your issues, but the left side idler (if my mental picture is still correct)is up close to the top of the housing, and the chain jumps around quite a bit, good tensioners or not.

Walt

boyt911sc 07-31-2016 04:23 AM

Over stretched timing chain .........
 
Quote:

Originally Posted by Walt Fricke (Post 9220785)
I once noticed that the top of the idler arm, against which the chain tensioner piston presses, was about hitting the chain housing. Why, I wondered?

Chain stretch? Not that much, I thought. Sprocket wear? Couldn't make that much difference.

Took the idler off. It was cracked! And it's a forging, I am pretty sure. But cracked, which distorted it.

Not likely to be the cause of your issues, but the left side idler (if my mental picture is still correct)is up close to the top of the housing, and the chain jumps around quite a bit, good tensioners or not.

Walt


Walt,

While I could not ignore the connecting rods (big and small ends), the stretched timing chain has caught my attention too. At this point, I am not certain if the jumping motion of the idler gear/s is producing the loud and heavy rattle/knocking sound from the engine or not because the abnormal noise is only observed when the engine is running (higher RPM) compared to cranking the engine using the starter. I am trying my best to sort and identify these likely culprits before the engine tear down.

It the culprit/s could be determined or diagnosed correctly before an engine tear down would be ideal. It would be pitiful to find out that I could have done and discovered the root cause of this nagging problem without a complete engine tear down. And an engine tear down is mostly to happen if I failed to identify it sooner.

I will bring the engine installed on the engine test stand to a couple of professional Porsche shops to take a final look before tearing it apart. Anyone have an idea or suggestion please post it or PM me. Thanks.

Tony

Sub8 07-31-2016 05:47 AM

Can you run the engine with the timing covers removed?

VFR750 07-31-2016 07:46 AM

I'm kind of loosing track of what you reused or replaced, so here is my input relative to your last post:

Pictures from my rebuild should help you assess chain and sprocket wear effects.

This is the gap between the idler and the chain housing after rebuild:
http://forums.pelicanparts.com/uploa...1469978714.jpg

New Cam chains
New Intermediate shaft sprockets
New idler sprockets
New Cam Sprockets
New chain ramps
REUSED LHS idler
REUSED LHS tensioner

This is what my 135,000 mile engine looked like at teardown:
http://forums.pelicanparts.com/uploa...1469978342.jpg

It doesn't take more than a few moments before you see just how much different the position of the idler arms and extension of the SAME tensioner between new and old.

For Completeness this is the RHS after rebuild:

http://forums.pelicanparts.com/uploa...1469979147.jpg

New Cam chains
New Intermediate shaft sprockets
New Idler sprockets
New Cam sprockets
New chain ramps
NEW RHS idler
NEW RHS Tensioner


I had to replace the RHS idler arm because the bushings were worn too much and no one makes replacement bushings. I also had to replace the RHS tensioner after only 38 miles due to knocking sound on start up. I'd go away after some seconds, but obviously a bad thing.

I now use a heavy tie wrap to hold the chain tight when I swap between the mechanical adjuster and hydraulic tensioner. It prevents the deadly chain jump if the idler arm is allowed to drop.

Here is the 135,000 mile teardown:

http://forums.pelicanparts.com/uploa...1469979418.jpg


Also note: My observation is the shaft that the idler arm rides on must be absolutely smooth. Over time the worn copper gets stuck on the shaft. It will cause binding.

It must be polished smooth so that all evidence of copper is gone. I used 3000 grit wet polishing paper.

I also think, IMHO, that idler shaft binding is one of the prime reasons for tensioners not working properly. There is a lot of load on that shaft, and any material deposits on that shaft will defeat the oil layers ability to let the idler rotate smoothly.

For completeness
Cases were not machined
Cylinders replaced, but same height class
.25mm base gasket
Heads resurfaced .008".
Original cam towers

So I can say my cams were .008" closer to the crankshaft

boyt911sc 07-31-2016 09:24 AM

Chain housing removed.......
 
Quote:

Originally Posted by Sub8 (Post 9220936)
Can you run the engine with the timing covers removed?



James,

I have been cranking the engine without the chain housing covers repeatedly with the ignition disabled. But once I turned the engine with the ignition connected, the knocking/rattling noise was very alarming. And quickly stopped the engine.

Tony

boyt911sc 07-31-2016 09:27 AM

The pictures I needed.......
 
Mike,

Ignore my request in your other thread. I did not read this thread before reading your other post about cam timing. These are what I wanted to ask you. Thanks.

Tony

boyt911sc 07-31-2016 10:43 AM

What would you do?????
 
Mike,

Take a look at the pictures below.

http://forums.pelicanparts.com/uploa...1469988642.jpg

http://forums.pelicanparts.com/uploa...1469988664.jpg

In the first picture, you will see how close the idler gear arm to the chain house and the amount of the piston protruding. In the second picture is a fully released tensioner. A rough measurement gave me about 2 mm for the installed tensioner to full extension. The piston in your engine showed a much less exposed piston length.

The engine was delivered to my house in several boxes by the owner (PP member) after two (2) auto shops failed to finish the job. I accepted the job because I like the challenge of getting this engine running again. I knew this would be more difficult and challenging but never expected it to be a nightmare.

Would it be prudent to replace the old timing chains and sprockets now or start the inevitable engine tear down? And start all over again? What would you do if you were in my shoes? Thanks.

Tony

VFR750 07-31-2016 11:27 AM

I think the chains are stretched too much. More than mine.

As a former motorcycle rider, I would never use old sprockets with a new drive chain. So I would replace all of the sprockets.

911pcars 07-31-2016 11:28 AM

Quote:

Originally Posted by boyt911sc (Post 9221292)
Mike,

Take a look at the pictures below.

http://forums.pelicanparts.com/uploa...1469988642.jpg

http://forums.pelicanparts.com/uploa...1469988664.jpg

In the first picture, you will see how close the idler gear arm to the chain house and the amount of the piston protruding. In the second picture is a fully released tensioner. A rough measurement gave me about 2 mm for the installed tensioner to full extension. The piston in your engine showed a much less exposed piston length.

The engine was delivered to my house in several boxes by the owner (PP member) after two (2) auto shops failed to finish the job. I accepted the job because I like the challenge of getting this engine running again. I knew this would be more difficult and challenging but never expected it to be a nightmare.

Would it be prudent to replace the old timing chains and sprockets now or start the inevitable engine tear down? And start all over again? What would you do if you were in my shoes? Thanks.

Tony

If the noise is caused by an overextended tensioner (driver side), the idler arm might be too close to the chain box/housing. Look for signs of the idler arm hitting the housing.

Chains don't actually "stretch". However the interconnecting links and pins can wear which results in a longer chain. If this is the case, chain sprockets will also show abnormal wear. Remove, inspect, measure and replace as needed.

As for the other chain parts (sprockets, idlers, chain ramps, etc., inspect and compare with new and/or good components before shelling out more $$ for add'l good parts.

Do you have any engine history? Here's one possibility:
The builder could have machined the typical engine parts (including crankcase spigots, cylinders, cylinder heads) to a total amount that reduces the valve train "stack", the above parts between the camshaft and crankshaft encompassed by the chain. Remember that any machining of the above parts affects the stack as well as the position of the camshaft within the opening of the chain housing (it must remain centered). If significant material is removed, the chain housing mounting surface must also be machined an equivalent amount to re-center the cam, otherwise the cam seal will distort and leak at that location.

Back to the chain. In addition, since the stack is shorter due to removed material (narrower engine), the chain is now effectively longer, thus the extended stroke of the tensioner piston/rod to take up the slack. One strategy to mitigate this is to install a larger Idler gear to take up the excess. Bruce Anderson's Performance Handbook shows the opposite condition; a wider engine and thus the need to increase the effective chain length via a smaller idler sprocket (page 192).

During inspection, you or the builder will discover the issue and what is needed to correct it.

Hope this helps,
Sherwood

VFR750 07-31-2016 11:51 AM

Tony

Since I did have to make the call on my engine, I new that splitting the case meant I'd do the chain. After looking at the sprockets I decided I would just spend the money and replace all the sprockets. They were worn.

Overall I spent 2x more than I expected on the rebuild. I found many more parts worn out than I first guessed. If it bothered me it was replaced or repaired. Some stuff I inspected and found within limits and I reused then. The left hand idler was good. But the right hand wasn't hence I only did the RHS.

i would imagine a nearly fully extended tensioner is not working within its normal range. And may not be able to damp out the pulsations.

VFR750 07-31-2016 02:58 PM

Yes chains wear out with the sprockets and when you adjust the axel, it is as if the chain is longer. We call that a stretched chain.

Which supports the need to replace the sprockets with a new chain.

Alan L 07-31-2016 04:23 PM

Tony, Is it worth fitting your mechanical tensioners (seen them in earlier pics) and try running the engine briefly. You would need to catch the oil feed in a couple of small containers. I would tension the crap out of the chain, lock it in place, bolt the housing cover on and give it a shot. If the problem goes away you know you are on the right track.
Or have I missed something? I am presuming you can run the engine with those tensioners.
Regards
Alan

boyt911sc 07-31-2016 04:41 PM

Test run with mechanical tensioner installed......
 
Quote:

Originally Posted by Alan L (Post 9221662)
Tony, Is it worth fitting your mechanical tensioners (seen them in earlier pics) and try running the engine briefly. You would need to catch the oil feed in a couple of small containers. I would tension the crap out of the chain, lock it in place, bolt the housing cover on and give it a shot. If the problem goes away you know you are on the right track.
Or have I missed something? I am presuming you can run the engine with those tensioners.
Regards
Alan


Alan,

I did test the engine with the mechanical tensioners installed (left and right banks). With the ignition disabled, the engine turns very smoothly ang quiet. But once you connect the ignition (CDI), the knocking/rattling noise is quite scary.

I also performed disconnecting the spark for cylinder and run the engine. After doing cylinders 1-2-3, decided not to proceed to the other side. Too much noise and getting worse.

What I found out that you could run the engine without the chain covers but not too long because the oil is spilling out. If I have an extra chain housing covers, I would cut the upper section and the lower halves to run the engine (next project).

Tony

Walt Fricke 07-31-2016 04:50 PM

Unquestionably it is the best practice to replace the sprockets with the gears.

But I've skipped this several times with no obvious bad effects, at least in the short term.

Perhaps the simplest and most immediate thing to do is replacing the left side chain with the split link replacement to see if a) the tensioner piston and arm are more where they should be, and b) if the noise is gone. Could the noise be the piston hitting its stop repeatedly?

If this makes the noise go away, you can perhaps discuss with the owner - go with what you have got, since chain wear elongation is what caused the noise, or a complete teardown again to replace the IS sprockets? Or in between - replace the cam and idler sprockets. Hardly optimum, but I doubt anyone can quantify by how much this will shorten the reasonable street service life of this motor.

What if, even with a replacement chain, you still find the tensioner overextended and the idler arm too far up? First off, since it seems that only the left bank has this feature, that sort of rules out a narrowing of the case due to the mating surfaces having been shaved so that it could be line bored back to standard (plus that doesn't involve taking off enough to do this, does it?). If the case spigots were decked, or the heads decked, or both, that is going to increase the compression ratio. You could do a compression test to see of the left bank readings are higher than the right ones?

But bravo for being willing to take on this literal basket case. Lots of shops refuse to do this kind of thing because they don't have the knowledge gained by doing the tear down and the machine work etc.

My understanding of chain wear is that the pins wears a bit, as do the cylindrical pieces which pivot on the pins. Not much, but there are lots of them so it adds up. Of course, these chains lead a pampered life compared with motorcycle chains (and gears) out there exposed to dust and other abrasives. Or are MC chains nowadays encased and bathed continuously in oil?

And the wear I see on my sprockets is mostly on the sides and tips, and not down in the valley where the rollers go - although this is only from looking at them, not from careful measurement.

When my left side idler arm cracked, it was up even higher. But I found this when reassembling an engine which was apart for completely unrelated reasons. Lucky I caught it, but it hadn't been making the kind of racket you just can't ignore before I had the motor apart - a race motor, though, with a very noisy exhaust.

Alan L 07-31-2016 04:51 PM

So even with the chains fully tensioned, you till got knocking noise. I would suspect not the chains, altho they may have stretch. Hopefully some of the engine builders can confirm - but it sounds unlikely that chain slap would cause the noise with the mechanical tensioners tightened up. If it was chain slap you would expect to see some marks in the chain housing somewhere?
Regards
Alan

Alan L 07-31-2016 05:02 PM

FWIW, I replaced the chains on my SC when I split the case at around 220,000km. I am conscious of sprocket wear on motor cycles and usually replaced sprockets - but I did not replace the SC timing sprockets. I can only assume no discernable wear. Some 60,000km later I have no chain tension issues - I fitted the carrera tensioners at the time.
Alan

boyt911sc 07-31-2016 06:44 PM

Investigation.....
 
I spent the day cleaning my work area and pushing the engine test stand aside in preparation for my travel to CA in a couple of days. But I kept thinking about the culprit all this time and getting back to this forum more often. My wife was getting annoyed why I am spending too much time in this forum. I still have a couple more days before my departure and will look closely look at the idler gear arm.

The best way to describe the abnormal noise is 'hammering'. I will remove the chain housing cover for the nth time and look for any sign of metal to metal contact or abrasion. Will keep you guys posted.

Tony

Alan L 07-31-2016 07:44 PM

If the chains are causing the hammering, there HAS to be a mark somewhere. Can you feel it - if you put your finger on the chain case? That is why I like the long screw driver over the stethescope, sometimes. While the stethescope is very sensitive to the noises, the screwdriver will transmit vibrations very well. The closer you get to the source, the more you feel it. And hear it. I would put the screwdriver on the chain cases and the cylinders - if that produces nothing, then the engine case.
Alan

Sub8 08-01-2016 07:40 AM

There is also potentially the issue with a worn woodruff key mentioned by another poster in this thread.

With engine firing you have a pulsed torque going into the system from the pistons. With a starter you have continual torque applied to flywheel. This is why you get different effects. I think it's probably time for a complete tear down! The only other thing I might do first is the cylinder by cylinder spark disconnect allready mentioned and maybe a complete bank disconnect and observe effects. Good luck!

boyt911sc 08-23-2016 08:12 AM

August update........
 
Quote:

Originally Posted by Sub8 (Post 9222344)
There is also potentially the issue with a worn woodruff key mentioned by another poster in this thread.

With engine firing you have a pulsed torque going into the system from the pistons. With a starter you have continual torque applied to flywheel. This is why you get different effects. I think it's probably time for a complete tear down! The only other thing I might do first is the cylinder by cylinder spark disconnect allready mentioned and maybe a complete bank disconnect and observe effects. Good luck!



James,

I did the splug plug wire disconnect test for cylinders 1-2-3 and decided not to continue for cylinders 4-5-6. The noise was getting noticeable and discouraging. It has been almost a month since I worked on this problematic rebuild and concluded to do another engine teardown after my return from vacation.

On the eve before I left (about 14 hours before my scheduled flight), I decided to do another quick test. With the chain housing cover removed and a known hydraulic tensioner installed, I ran the engine for a couple of seconds. The idler gear arm was not coming in contact at all with chain housing. I repeated the test several times with a wooden tongue depressor placed in between the chain idler gear arm and the housing during a brief run. No contact on the wooden tongue depressor but the loud noise still persisted.

Final verdict: Perform a complete engine disassembly and investigate the root cause of the problem. I am coming back home after 4 weeks being away and begin another adventure. Thanks to everyone.

Tony

al lkosmal 08-23-2016 08:51 AM

tony,
Greetings. I think you came to the right conclusion...it is tear down time.

regards,
al

boyt911sc 10-14-2016 04:35 PM

Half way down.........another surprise.
 
Al,

I was doing the engine teardown when I noticed something that caught my attention. The cam shafts nuts were not properly torqued and that could be the reason why the cam timing drastically changed (?). Re-did the cam timing @1.26 mm for both sides. Put everything back including the whole CIS unit. Removed the mechanical tensioners and installed the new hydraulic tensioners from Pelican parts.

To my surprise, the new tensioners were soft and spongy. I could compress the piston with my bare hands (?). These are the second set of hydraulic tensioners in three months span. Tests show that I have another set of defective tensioners that just out from th box.

The plan is to test run the engine after setting the cam timing for the 3rd. time and will be using a borrowed set tensioners from another engine sitting nearby. If the noise is still present during the next start up, complete teardown to follow right away. So I am keeping my fingers crossed and hope for a break. Will keep you guys posted.

Tony

Mick_D 10-14-2016 05:42 PM

I get the feeling I am going to need your patience when I go about building my motor. Tony. You're a saint.

al lkosmal 10-14-2016 06:26 PM

tony,
good to hear from you. I think that the camshaft nuts would have to be very loose for the timing to change. .....loose enough for the sprocket pin that locks the sprocket/timing in place to come loose.... but the looseness may have caused the noise.....it's worth a try. I'm not a fan of the Carrera, oil pressure fed tensioners. More stuff to fail in my opinion. If it is a rebuild and my customer already has them installed, I test them to verify they are good and leave them on....but I don't use them when I build an engine from scratch. My preference is to use 930 tensioners (old-school ) with hydro-stops to ensure that, if there is a collapse, they cannot cause the chain to jump. They are simple and straightforward and I've only seen one or two failed ones.............used ones, not new ones and the hydro-stops prevented total collapse. I noticed in a recent post by Henry Schmidt (Supertek), whose engine builds I admire, the he uses the same old-school tensioner setup...see link below.
http://forums.pelicanparts.com/911-engine-rebuilding-forum/931573-68-soft-window-gets-new-heart.html

regards,
al

911pcars 10-14-2016 08:29 PM

Quote:

Originally Posted by boyt911sc (Post 9319669)
Al,

I was doing the engine teardown when I noticed something that caught my attention. The cam shafts nuts were not properly torqued and that could be the reason why the cam timing drastically changed (?). Re-did the cam timing @1.26 mm for both sides. Put everything back including the whole CIS unit. Removed the mechanical tensioners and installed the new hydraulic tensioners from Pelican parts.

To my surprise, the new tensioners were soft and spongy. I could compress the piston with my bare hands (?). These are the second set of hydraulic tensioners in three months span. Tests show that I have another set of defective tensioners that just out from th box.

The plan is to test run the engine after setting the cam timing for the 3rd. time and will be using a borrowed set tensioners from another engine sitting nearby. If the noise is still present during the next start up, complete teardown to follow right away. So I am keeping my fingers crossed and hope for a break. Will keep you guys posted.

Tony

Funny that both have failed to pressurize (both faulty out of the box?). Confirm they're both receiving engine oil by disconnecting an accessible feed line fitting, then crank the engine over until you see oil. If not, check for obstructions in the feed tube as well as at the banjo fitting outlet on the cam housings. In addition, inject a jolt of pressurized air into the tensioner oil inlet. This can sometimes dislodge a stubborn check ball to close as designed.

The archives contain more threads on pressurized chain tensioner issues.

Hope this helps,
Sherwood

boyt911sc 10-14-2016 09:30 PM

Faulty tensioners 4X.........
 
Quote:

Originally Posted by 911pcars (Post 9319896)
Funny that both have failed to pressurize (both faulty out of the box?). Confirm they're both receiving engine oil by disconnecting an accessible feed line fitting, then crank the engine over until you see oil. If not, check for obstructions in the feed tube as well as at the banjo fitting outlet on the cam housings. In addition, inject a jolt of pressurized air into the tensioner oil inlet. This can sometimes dislodge a stubborn check ball to close as designed.

The archives contain more threads on pressurized chain tensioner issues.

Hope this helps,
Sherwood



Sherwood,

I had four (4) brand new hydraulic tensioners fresh from the box that were defective. See my other post in the Technical Forum. The batch of hydraulic tensioners Pelican Parts is selling has a very high percentage of failure in my experience. Four out of four were bad. I will try your suggestion to blast the inlet with pressurized air and retest. Stay tuned.

Tony

boyt911sc 11-02-2016 08:19 PM

Update.........The End.
 
After many months of ups and down, the engine is now running well without the annoying rattle and knocking noises that were observed earlier. I like to express my gratitude to the many people who assisted, directed, encouraged, etc. me to pursue and solve the problem/s.

http://forums.pelicanparts.com/uploa...1478142428.jpg

The turning point started in the month of October 2016. After procrastinating and delaying corrective actions to solve the problem because of too many setbacks, I decided to go ahead and go for it. I started to do another engine teardown and investigate each part I removed. Half way through the teardown, something caught my attention and thought it could be the culprit(?). One way to find out was to re-assemble the engine again and do another start-up. Not worried or concerned about the result of another failed start-up, the result was what I have been waiting and expecting to see. To my surprise, it is running smoothly and no abnormal noises. Now, I could close this chapter and go on with my other rebuilds awaiting for their turn at engine test stand.

The moral of the story is to try your best and don't give up. Whether you succeed or not is measured by your 100% effort. End of story.

Tony

Tippy 11-02-2016 09:18 PM

So what was the problem?

billybek 11-03-2016 04:15 AM

Quote:

Originally Posted by Tippy (Post 9344119)
So what was the problem?

It could have been this...

I was doing the engine teardown when I noticed something that caught my attention. The cam shafts nuts were not properly torqued and that could be the reason why the cam timing drastically changed (?). Re-did the cam timing @1.26 mm for both sides. Put everything back including the whole CIS unit. Removed the mechanical tensioners and installed the new hydraulic tensioners from Pelican parts.

Tippy 11-03-2016 05:49 AM

Quote:

Originally Posted by billybek (Post 9344216)
It could have been this...

I was doing the engine teardown when I noticed something that caught my attention. The cam shafts nuts were not properly torqued and that could be the reason why the cam timing drastically changed (?). Re-did the cam timing @1.26 mm for both sides. Put everything back including the whole CIS unit. Removed the mechanical tensioners and installed the new hydraulic tensioners from Pelican parts.

That's not in the post above mine?

Tippy 11-03-2016 05:51 AM

Quote:

Originally Posted by boyt911sc (Post 9344061)

The turning point started in the month of October 2016. After procrastinating and delaying corrective actions to solve the problem because of too many setbacks, I decided to go ahead and go for it. I started to do another engine teardown and investigate each part I removed. Half way through the teardown, something caught my attention and thought it could be the culprit(?). One way to find out was to re-assemble the engine again and do another start-up.

Tony

??


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