Any data I need to collect for the gurus before dropping?

[sobamaflyer]

After reading "what's this sound" threads for several days I've got a really bad feeling I have thrown a bearing. I have a new "knock" seems to come from the middle of the block, distinctly different from the tap that's been coming from [I think] #5 for a bit (I can't get my valve cover off due to a header that's too close to it).

I've learned/decided I need to drain and check the oil to check for fragments and I need to drop the engine anyway to address that unable to adjust valves issue. Should I make a video of the sound or do/check anything else like compression while it's still in the car and running before I start down a path that I'm sure is going to lead to quite a while without my favorite toy?

As is my typical I'm on a tight budget, I know I haven't collected enough data to even ask what I could be looking at spending here. I've rebuilt 2 VW motors, will be doing everything but machine work myself. I really don't plan to try and increase performance, I'm not unhappy with it as it is.

I've even lightly investigated what I'm sure is considered the highest form of sacrilege around here but I think I'd rather have you all talk me down and pray this can be fixed for some reasonable amount of $.

Thank you
Travis

[E Sully]

Try just dropping the exhaust instead of an engine drop. Then you could remove the valve covers, adjust the valves, check for broken head studs, examine the rockers, make sure the rocker shafts are centered, check springs and camshaft lobes. With the exhaust removed you can also check the exhaust ports and valves visually.
You could get your oil analyzed for signs of bearing material, cut open and examine the oil filter.
Make sure to eliminate the alternator as a cause of the noise.
A compression and leak down test is always a good idea to get an idea of the condition of the ring and valve sealing.
Do you know much about the history of the engine?

[sobamaflyer]

Thanks for the suggestion. I ordered a leakdown tester earlier so I will do that and a compression test next weekend.

[Sboxin]

Yes, please make a video with good sound to put up on this thread - the more history you can capture the better. And, a good photo of your exhaust header clearance problem might be helpful too. The mechs on this Forum can help you with that too.

Regards,

[sobamaflyer]

For reference, not in my initial post:

1975 911 with a 78 (iirc) 3.0. Oil level is good (in the middle of the stick after warm), oil pressure is 30 on the gauge, warm temps never get above 200-220.

I purchased it a couple of years ago, had been sitting a while, failed restoration. I got it running and have driven it 1-3 times/week since until the last month or so. Totally unknown engine history. I've probably put 7-8k miles on it, have changed the oil 3 times, last about 6 months ago and at that time tried to adjust the valves and discovered I couldn't get the right valve cover off due to hitting the aftermarket header that's on the car.

Ok, videos:

Initial Start - Cold:


Taken when warm:



It seems my new "knock" comes on strong after a few seconds, it's steady with RPM, seems to be coming from the middle of the motor. There is a "tick" that I have undoubtedly identified to the middle right (5?!) cylinder with the long screwdriver method. All others are relatively quiet. I can't identify the exact location of my knock with the screwdriver.

Pictures:

This is the "diaper" under my car, haven't driven it in 3 weeks at all, as you can see it's not leaking but a drop here and there. She has never in my time consumed any oil to speak of:


Right Bank - shows my clearance issue w/ the header:


Right side showing cam cover:


Bottom of the engine:


Left Bank - this side clears the header


Left Cam:

[Sboxin]

Very good on the videos and photos!

Valve covers: looks like the right exhaust has to come off one way or another to inspect
the rockers and adjustment.

Knocks and taping : You will need to get a really good ear to listen to the video - Grady Clay, Henry Schmidt, Bruce Abbott(Flat6pac), etc. -- suggest PM them to get their attention... and cross post a link to this thread on "911 Technical"

My guess on the knock is like yours' -- rod bearing failure. If you drop the engine now
you can do a top end and check the rod bearings - if #5 looks like ours did then you will need to open the case and polish the crankshaft anyway.

It seems you are prepared to do what is necessary to keep this really nice Porsche running for yourself. It also appears some previous owner modified the car for a Hot Rod - and may have driven it too hard or run the engine hot at some time in the past. The main bearings seem to last forever but the rod bearings take a beating. Be prepared to replace a lot of parts you might not have thought about when you open this engine up -- and they ain't cheap. Be sure to get a machine shop to measure cylinders and everything you take apart...Porsche has very low tolerances (we found out the hard way - thought we could do rings and bearings, now looking at big $$$$-
BUT, we are also building a race engine- "since you are in there")

Wish you the best,

Regards,

[Sboxin]

Cross posted to 911 Technical with a very good Grady Gray response --


Cross Post - Another "what's this noise" thread

I hope you follow Grady's instructions...

Regards,

[sobamaflyer]

I fully intend on it, embarking on the path next weekend (this weekend's shot due to work and I want to do that leakdown test)

[boyt911sc]

Travis,

Have you tried to use a mechanic's stethoscope? It not easy to determine where and what was the noise from your videos. I have seen and worked on a motor that the owner thought was a bad motor. And it turned out to be an improperly adjusted intake and exhaust valves. Have a second opinion from someone familiar with 911 engines.

Tony

[sobamaflyer]

Thanks Tony, I'll keep every appendage I have crossed in hopes you are right! I know for a fact they are a bit out of adjustment. I will know more this weekend and will report back with my findings.

I don't have a mechanic's stethoscope but I did spend some time with the longest phillips head I have crammed in my ear

[sobamaflyer]

I've been updating my other thread but not getting a lot of direction out of it so I'd like to turn it back here since this has fully become an engine rebuild:

Posted 10/2/12:

Made a little more progress today (a little)

I have the top stripped down, chain covers off, cam nuts are both loose.

I continue to feel like this engine was rebuilt not terribly long before it was put away, everything inside is relatively spotless, seals are all fairly fresh.

I don't seem to have Carrera tensioners but they look odd (anodized collars on the top?), any hints as to why they look different than what I've seen in pictures?

I have the valve spring compressors on-hand but have yet to delve into exactly how to use them. I'm continuing to follow the book so...

[sobamaflyer]

Posted 10/14/12:

I'm looking for those in the know to comment on what I've found so far.

Clutch:
I'm in need of a new disc? Resurface the mating surface or can I clean it w/ a scotchbrite pad?




Cylinders:
All look like this, some carbon buildup on the crowns but the cylinders seem to be in nice smooth shape. Given my good leakdown and compression numbers I'm thinking about removing the pistons & cylinders as a unit (as described in the book). Not messing with them/the rings?





Heads:
Also (aside from dirty) appear to my untrained eye in decent shape (I may be corrected in this) the valves appear to seat but I need to look into this further. I also still need to take off the valve springs to check them and see if one is broken. I foolishly bought the 2 seperate tools when I needed the 1 big c-clamp one.


Studs:
I'm thrilled! Every single dad-blame nut came off without incident. Hoping someone can tell me what is here, they are not magnetic, they are black and slimmer in the middle than the threads.


I continue to hypothesize that this engine was rebuilt some time before it sat for at least a few years. I have no basis for judgement of the quality of the rebuild, what was done, what wasn't. I highly doubt this is a stock, original '78 3.0.

I still have a way to go, I plan to at least get all the way inside to find out if there is a bearing messed up causing that knock. (I will be at a loss if I find nothing amiss as I have so far)

Thoughts, opinions, tips, hold on moron what are you doing??(s)

Thanks, Travis

[sobamaflyer]

Posted 10/16/12:

I really thought I'd find something significant at this point......

Trying to capture the amount of play I found on the rods. This is indicative of all 8, I can wiggle them side to side less than a mm.



(pardon my shop helper in the background)

Pistons:
All look exactly the same, all rings visually appear clean, solid, ok. Surfacing is clean, mar free.















Dennis, I tested my rocker arms for play, when off the cam I can wiggle them maybe 0.25mm back and forth (all of them)

So where do I stand? Do I keep going since I'm this far? Do I finish taking it apart the case? Shouldn't a failed bearing have presented itself at this point? Or maybe that was never the cause of my disturbing knocking (and if not what was?)

Hoping someone will tell me check this or that or notice anything good or bad in my photos. I'm in too far to just put this back together without ensuring (to some measure) that I will get some significant mileage out of her before doing this again, but I also don't want to waste $ if it is fine.

[Flat6pac]

Compare your rod play between each other especially in and out of the engine because youre high on the pressure at the top of the stroke.
Someone has been in the top of the engine because you have 24 dilivar studs, there is no appearance of a broken vlave spring from hitting the piston.
I did about 20 years ago have an engine that sounded like piston slap and it turned out to be bad rockers..after I bought a set of pistons...
Youre far enough down you might as well reseal the case. That will tell you about the crank and reseal the center line of the case after cleaning everything up.
Youre already committed to a certain amount of expense and unless you look at everything youre shorting yourself as to know what you own..
Bruce

[sobamaflyer]

Thanks Bruce, you are the second to suggest I may have rocker issue. I was given the number of a machinist with old Porsche experience today to call today and after talking to him for a good while I'm taking my heads to him Monday. He is going to disassemble them and check everything for spec. Also taking him my p & c s tomeasure and check out.

I intend to finish opening up the case as I do want to know full well the state of everything and I'm this far...

I'm glad someone else thinks this engine has been into, the studs are my biggest clue, they look brand new, as do many reciprocating parts. My problem is I don't have a way to feel convinced what parts I don't need to replace. Hoping this machinist will help me in that evaluation. Can't afford to just summarily replace everything that is fine.

sent from my Galaxy S III

[Aurel]

Your head studs were already updated, so that is one less thing on the to do list. Did you try to adjust the valves before taking the engine appart? (Although I would agree it sounded more than just valvetrain noise...).

[sobamaflyer]

I had adjusted them about 6 months before the new noise. One of the several reasons I went ahead and pulled it was that I couldn't get the right lower valve cover off due to header clearance.

...I now know I can loosen said header enough to get it off while it's in the car. :-)

sent from my Galaxy S III

[Aurel]

Have you checked for any abnormal lateral play in the rods? A rod bearing failure might knock like that.

[sobamaflyer]

I'm going to open it up to be positive. But I have taken each one and tried to push and pull and don't have any play in and out in them at all.

sent from my Galaxy S III

[Flat6pac]

Your cylinders are alucil so there is nothing you can do with them, even measured, you have to keep everything together.
Bruce