Can't rotate crank on engine stand

[Number1_dog]

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!

[356RS]

Maybe the engine yoke is hitting the flywheel somewhere?

[relayswitcher]

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

[Number1_dog]

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.

[Henry Schmidt]

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.

[Number1_dog]

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.

[Henry Schmidt]

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.

[fastfredracing]

+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.

[BURN-BROS]

Originally Posted by Henry Schmidt

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.

Yup, Intake nuts are a Biotch!

[relayswitcher]

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.

[Number1_dog]

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?

[burgundyben]

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

[kodioneill]

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

[Number1_dog]

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.

[kodioneill]

Originally Posted by Number1_dog

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.

[rbutts]

Are the spark plugs out?

[Number1_dog]

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.

[Number1_dog]

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?


Another question how do I separate my Alternator from the fan housing ?

[relayswitcher]

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.



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

[relayswitcher]

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