Engine was running and now is frozen
 

Hello people. I finish rebuilt 1977 2.7 911 engine. Install hydraulic tensioner kit, new pistons rings and used pistons with honning cylinders using grape flex hone, all gaskets and seals. I start the engine for more than 30 second until the oil pressure rise. Then I start a couple of time to set the ignition. When the ignition was setting the engine start and run. No smoke, sound good, no mechanical noise and like 20 second later the engine stopped. When I will try to start again, ir doesnt start. I pull out the spark plugs to release any compression to facillitate manually rotate the engine and nothing. It not rotated. The engine appears to be frozen. What I can do to resolve this problem?

Please help me...this problem is a real pain in the a$$.

Doesn't sound good. Perhaps some moving part didn't get lubrication, overheated and seized. Did you split the case and rebuild the bottom end; if so was the case line bored and squared up? No smoke - usually rebuilt engines burn off a lot of internal oil and lubricants making smoke on startup. Did you use assembly lube? Jim

I no open the case. Just pistons rings replacement, update tensioners. I use assembly lube on the camshafts, rocker arms, oil in the pistons rings and cylindres during the assembly. I really dont know what happend. Is the first time that happend this to me. That is not the first 911 engine that I repair.

Could be a couple of things. Did you rotate the engine by hand before starting, or for that matter during the rebuild process? Maybe a bearing was not seated correctly or your ring clearances were too tight. Did you clear the pistons of carbon before you set the rings in place?

The pistons was like new condition, no carbon deposits. The ring groves was cleaned before assebly the rings. The cylinders are in tolerances and looks like new. The rings fit perfectly, The engine rotate easely during the rebuilt and after the rebuilt, and after I installed in the car.

This is so kind of mystery.:eek:

Has something (like a backed out screw in pressure plate) come loose in the clutch/flywheel area and jamed the engine?

Maybe something to do with the timing chain. Could it have moved out of position? Was there any noise such as valves hitting the pistons?

Cam bolts that weren't torqued enough and released, then cams turned out out of phase and jammed valves/pistons?

I think the only way you are going to resolve this is by pulling the engine and tear it back down until you find out why the engine won't rotate. Sorry.

Out of curiosity, what kind of cylinders do you have?

I was trying to rotate the engine manually and it moves like 1/16". I think that the engine no was frozen at all. I will start to take the oil out of the engine and take a look to the camshafts housings to see if I found something abnormal.

I will stay in contact!!!

Thanks for the help guys!!!;)

The camshaft turns freely. So the problem is internal the case. Today I drop the engine and is ready on the engine stand waiting for a surgery down to the bones. I will try to open the case tomorrow.

Interesting problem. Keep us posted.

I would check the flywheel/clutch bolts, as stated above, before dismantling the engine. This is a known cause of what you described.
It may (hopefully) save you a lot of work. Good Luck!

My guess is that it is external to the case. Either something came loose and caught or wedged the flywheel/pressure plate, or a cam issue.
Try separating the engine and transmission, then go to the cam towers and timing chains. I bet you will not have to go much further.
good luck,

The problem is not in the clutch system and flywheel. Is not on the cams. The problem is internal. The intemediate shaft can froze and engine if some damage occur to it?

maybe something go into chain ?

do you have lost tool ?

Could be anything - you'll probably have to tear it down...

-Wayne

With both cams disconnected from the crankshaft, spark plugs out and transmission in neutral. (Does the clutch petal pressure feel correct?) I would attempt to turn the engine over by hand. First in the direction of normal rotation. If it doesn't move then in the other direction. If it moves in this direction then there is something "big" in one of the combustion chambers. (Usually a screw or nut will simply break the piston/cylinder and the engine will continue to rotate.

If that doesn't work then the problem is more likely in the clutch pressure -plate area as indicated above. I doubt that it is inside the case

;)

Sage advice. ;) ;)