Can't rotate crank on engine stand
 

On the engine strand, with all of the rockers off I can't rotate the crank. It stops just before #4 TDC.

I took the engine (1979 911SC) out to get the transmission re-built.
I then checked my valves while the engine was sitting on a motorcycle stand, no problem it rotated. Then I got a set of used SSI's while installing it one of the #3 exhaust studs broke while torquing it. I then decided to clean the engine up and have my cams re ground to 964 specs.

I purchased an engine yoke put it on the engine, I put on the rear engine mount and attached a chain to the ends, and then using a 2x4 to spread out the chain, I attached the other end around the engine yoke and lifted it up and put it on the engine stand. I have removed all of the rockers and the end cam covers and tried to rotate it to #1 TDC before I took out the cams, and it will not rotate.

Other than than I haven't done anything stupid that I know of? HELP!

Maybe the engine yoke is hitting the flywheel somewhere?

Maybe one of the timing chains is bunching up on one side. Make sure both chains are hang about the same length and motor is sitting level. My other guess, without seeing a photo is what 356RS said, flywheel catching on something as simple as a bolt holding the yoke in place. Maybe you can provide a few photos from different ends. Maybe we'll see something you don't. If for some reason you have one or all pistons removed, the con rods are catching at rotation points within the case.
Regards, R

The Flywheel is free. I haven't taken the heads off and the engine was running when drooped. The cam chains are still attached.

The problem seems to be #4 Piston can't get to the top, something is hitting on the right bank. I checked the valves to see it the were sticking out but that doesn't seem to be it.

Over the years we have seen engines that fit the symptoms you describe. They are generally engines that have been shipped or dropped.
What might be happening is carbon in the cylinder. It is common for carbon to form on the the chamber and when the engine is jarred the carbon come loose from the head and falls into the cylinder and when the piston moves up the carbon bits are compression and the engine stops. If you can turn the engine upside down you might free the carbon bits.

I tried that. Rotated the engine in all 4 axis and no go.

The engine supposivly was put together last year by a rogue porsche mechanic around Branford CT who had picked the car up after it had been sitting for 5 or so years. He said he split the case and freshened the engine. The leak down test was 3- 4% so I thought I had a good long block ?

I guess I'll have to call in professional help, I'm calling Rudtners this morning.

If carbon is not the issue I would suspect a foreign object. Just ask Aaron (Burn_bros) on this board. He just completed an engine install after finding a nut/or bolt in an engine.

Loose nuts can drive you nuts.

+1 On henrys advice, definately make sure there is not a foreign object in the cylinder. Trust me , there is not enough room for it.

Yup, Intake nuts are a Biotch!

If it were my engine, I'd just split the case and make sure what's wrong. My philosophy since I started dabbling with the 911 engine is, " IF YOU CAN'T "SEE" THE PROBLEM, THEN DIG IN AND FIND IT." Sure, narrow it down to something from experience, but when you still can't figure it out, time to get out the wrenchs and work from A to Z. Sometimes if you find one thing wrong it can affect something else, so finding one thing doesn't mean you have fixed everything. **Also, I diden't realize, if I'm hearing you correctly, if a novice, NON Porsche guy messed with the bottom end then I wouldn't think twice about redoing the short block completely. He may have reused all the rod bolts, which you should never do. Maybe one of those is wedged in on something, but like I said, better to know than guess. Too bad you are 3000 miles away, I would have been glad to help you in person. With removal and rockers out, you have about a 80% tear down already. Ther rest is the easy parts. Tear down cost nothing. I just got a quote today for 766. I can get everything for rebuild. Gasket set, Top and bottom, all bearings, ramps, intake hoses, head gaskets, exhaust gaskets. Heck you'd spend more if a shop did a tune up. See the start of my build in this same forum catogory " 3.0 SC Rattle found..... " I'm done with tear down and just power washed my case.
Glad to answer what I can for you. Just ask. RelaySwitcher.


http://forums.pelicanparts.com/uploa...1224558368.jpg
http://forums.pelicanparts.com/uploa...1224558407.jpg

You are all right. I've decided to pull the heads. I had got all of the intake nuts, but I'm thinking a washer may have droped down the #4 intake. No rattle when I rotate the engine on the stand but...

The guy I got the car from was a Porsche guy who ocassionaly re-builds engines for a big shop in Oxford CT but on stuff he sells he is also known as a Dr. Frankenstein using what ever he has available. I'm sure he put the engine together with minimum new parts.

I'm sure I'll have questions.... now maybe I'll get those 9.8:1 JE pistons?

Pulling the heads is a good decision! You absolutly must find out exactly the cause of this.

can you obtain a bore scope? if so, you can look in to each cylinder easily.

I've got a friend who works for the LIRR, he's away this week, maybe I'll ask him if he can borrow something.

you could probably rent one at a good rental business.

Are the spark plugs out?

I took them out when I started having problems.

I'm going to try the simple stuff first.
Take the engine off of the engine stand and put it back on the cycle lift and see if it turns.

Surprise, it turned. I put it on its side with 4,5,6 facing up and it turned completely as a fine oiled machine. I put it back on the horizontal and it turned. I'm thinking that it was the cam chain that was jamming. These are my cam chain tightners and they seem to be extended pretty far out. Should I be replacing my chain?http://forums.pelicanparts.com/uploa...1224869509.jpg
http://forums.pelicanparts.com/uploa...1224869548.jpg

Another question how do I separate my Alternator from the fan housing ?
http://forums.pelicanparts.com/uploa...1224869644.jpg

Hey there , #1,
Ah ha!....I guessed the chains were the problem.... I was right, that feels good. And good for you, too.

To get the alternator off. You'll need to back up a bit in your photo.
1. First, mark position of housing to the alternator for replacement later.
2. Put the six 10mm nuts back on. Hope you did the same for the air guide you removed from it.
**Also, you should have taken a photo of how wires hook up, too.
3. Then get a 6" puller like in my photo here and remove your 11 blade fan from the alternator by centering it to the threaded spindle arm protruding out of the alternator. 4. After fan is detached, remove the 10 mm nuts again from the back.
5. Then, still face down, use a rubber mallet to gently tap on the six thread stud ends sticking through the housing frame. The alternator should just drop down onto the towel underneath eventually... or you may have to prop it up off he table a bit to make room for it to fall. I suggest you put a soft towel underneath everything as you work.
Now you are ready to sandblast and paint as you need....not the alternator, or course. I'm painting my housing red, polishing and clear coating my fan, and the chrome strap will be "Mother" polished.

http://forums.pelicanparts.com/uploa...1224876654.jpg

You can get these 3 or 2 jawed pully sets, 4 pullies per set, at HarborFreightTools.com for under $30 or 3 pullies for under $20. By mail or go to the stores in NY..... they have 7 in your state. Albany, Rodchestor, Saracruz, Buffalo, etc. I bought my two long arm floor jacks there and my 2000 LB. engine stand. Go to the site for 'retail store" phone #s and addresses. Great place and prices are better.
Hope this has been helpful to you, RelaySwitcher / Josh

Oops, meant to say "photo of you air guide positioning, too."

Fact is, the alternator might be corroded into the housing. Probably is from the looks of it. The magnesium housing will have "expanded" a little bit and will make removal a serious pain.

Even pounding on the studs (they are really long bolts) as gently as possible, you may have to hit them hard enough that they will bend. That sucks, because replacement is next to impossible. I know, I tried. Once I got my alternator out, most of them were bent pretty badly.

I used this "opportunity" to install a rebuilt alternator...yup more costs.

I'm still not sure what it is.

I rotated the engine on all 4 axis on stand and then it stuck again just before #1 TDC, with 4,5,6 facing down. If I'm not mistaken # 1 and #4 reach top at same time. I put a magnet into the cylinder #4 but noting attached. I've tried to get a borescope but can't seem to find someone who has one. I rotated again with 4,5,6 up and if rotated. If it is an aluminum washer then it may have layed flat. I'm going to get a borescope from e-bay before I am convinced it is the chains.

The best way to separate the alternator from the fan ring is the "John Walker" method.

http://forums.pelicanparts.com/911-engine-rebuilding-forum/431994-how-do-you-seperate-alternator-fan-housing.html?highlight=alternator

Never had had problem with removing the alternator from the fan housing ever.... done it 5 or 6 times. I'm from sunny dry California near Palm Springs and I notice that most of your replies are from Denver due east. Most people in that part of the country deal with severe whether and moisture, etc.. So if you are worried about the studs ..... wire brush them and then just WD40 the heck out of them. Come back in an hour or so and use the RUBBER mallet on the studs. DO NOT use a metal hammer, that's how they break. ALso.... chains don't catch as much if at all with the engine level..... worse when turned on it's side. It's simple logic..... if I"m reading what you are doing correctly.

Again without seeing a photo, it seems to me if it turns off the stand and won't on the stand, something is blocking the rotation having to do with the yoke area. Send some photos of the engine yoke on stand area. Or did you say you removed the flywhl?

I never took it off of the engine stand, With it on the engine stand, I rotated the engine every 90 % and tried to rotate the engine. When I had cylinders #4,5,6 in the up position I was able to rotate the engine. I kept rotating the engine and on the horizontal it still turned, when 4,5,6 were facing down it got stuck again, but this time just before #1 TDC. I now know that it is not a problem with the engine stand. I put a magnet into each cylinder through the spark plug hole and nothing was there. My fear is it may be an aluminum washer. That is why I am asking around here for a borescope to look into the cylinders. Ebay has them for under $100, I may go that route if I can't get one anywhere else.

Dog,
I have a bore-scope you can borrow but I don't think you will see the cause of your problem. I had the same issue when my engine was on the stand and I panicked when it locked up. My problem was that the cam chain was bunched up inside the crankcase. When I turned the engine in reverse slightly and pulled on the chain, I felt the slack come off the inside of the crankcase and it rotated fine. I was relieved...

From your pictures, the right side (looking at the cam chains) tensioner is at the limit of its travel. Your chain is stretched or the sprockets have worn out. For example, look at the picture below and compare how much of the tensioner piston is showing to your tensioner.

http://forums.pelicanparts.com/uploa...1224990206.jpg

I think the left side looks OK. If you remove the right side cam, rockers, rocker shafts, and cam tower; then you are only out the cost of an o-ring and a gasket. Then you will be able to determine the reason for the fully extended cam chain tensioner. And, you may find that your engine is locked because of the valve train on the right side and not something inside the engine. Have you changed your cam timing accidentally or on purpose?

Having said all that, you may want the bore-scope on Ebay. I find uses for mine all the time, you may want your own.

PM me if you want to borrow my scope.

Good luck,
Mark

i had a problem almost the same thing what i found was the inner cam chain was worn and slipped off the sprocket just enough to jam against the case.this happen when i took the pressure off the tensioner. i could see the problem but could not repair until i split the case or get it loose.the chain was twisted and stretched.i hope this may help you.

Looking at the photos, I am a little alarmed by the amount of corrosion present in the engine. This engine has been sitting in storage a LONG time. I would really recommend this engine be disassembled. I agree with everyone the tensioner on one bank is over extended and the sprocket teeth may be worn.

You are right. The whole car had been sitting for a few years when the mechanic I purchased it from first got it. The mechanic has a good reputation if he is building an engine for a customer, but here he was freshining it for a quick sale. He said he split the case, and there are signs of that and it didn't leak oil when it was running. He had installed the Carrera Chain tensioners just before I picked it up.

I got a borescope off of Amazon and it was an aluminum washer in #4 cylinder. Just a little too big to come out through the spark plug hole.

I'm trying to loosen the big nut on the cam. I have the special tools for a 1979, and through trial and error I found that on the claws-foot (or crowsfoot what ever it is called) you have to mount you wrench on a 90% angle or else it slips off the nut real easy. BUT, I can't seem to break it loose, are there any tricks to this ?http://forums.pelicanparts.com/uploa...1225568480.jpg

There is a deep cold chisel mark on the nut, that is used to set it tight when installed, No? Should I be doing anything else to counter it?

That chisel mark should not be there. Looks like someone tightened it in the past without the proper tools!

You should be able to break it free. It does take quite a bit of effort. It helps if you can find someone to hold the cam while you try to loosen the nut - can be difficult to do both at same time.

I'd be wanting to replace the nut.

In which case you could do what I did with a damaged nut, drill through it and the cold chisel it open. Once its broken through it will be lose.

Be very careful doing this.

http://i164.photobucket.com/albums/u...n/DSCN0472.jpg

I was thinking of drilling some holes then connecting them with a cold chisel.

I had someone holding the cam, and then when I apply a lot of tension the claws-foot will slip off.

Craw-foot sucks. Make a proper tool from a 46mm socket. Weld on a handle and cut the end of the socket so you can slip a holder through. Or you can make some bends in an 46mm wrench so it will clear the chain housing.

With an impact wrench and compressed air it takes less than a minute to loosen these

take off the intake or exhaust then extract the washer through the port.

Harbor Fright has 3/4 socket sets on sale for 50 in both am std and metric size. I belive the nut is 46MM. I bought one from Aubuchon Hardware
@ HardwareStore.com for $20 + shipping.

Thanks, I've been looking, I got the cam nuts off, but they were a little mangled from the crow-foot sliping so they are getting replaced.

Now when you re-install the nut, how are you going to torque it down and hold the cam shaft steady? Of are you only using the 46mm socket to lossen it?

I was thinking of cutting off the top and welding it back on to the side with the socket head offset just like the crow-foot.

When I timed my cams I planed on holding the cam with the special cam holder and an torque wrench, but that proved difficult due to extremely poor quality of the cam holder socket (from Pelican).....

I then instead held the cam with a 17mm open wrench jammed on one of the chain housing studs, then tightened the 46 mm until my face turned blue.
I'm not sure if I should recommend that method... but it has held 4 now so I guess I'm on the safe side.