GPMotorsLLC

we recently aquired a 1987 928 s4 with 82000 miles on it that did not run. well i changed a relay and got it to turn over then it had no spark. So i changed the cps and the motor tried to start a couple of times and then it quit turning and now only clicks as the starter trys to turn the motor. i took the starter out thinking it was not working properly and bench tested it and it works fine. Then i tried to turn the motor from the flywheel and that was a no go woulld not turn at all.

Leon Speed

Maybe not randomly. First thing to check is if the belt is still on there and if cam timing is ok. Then try to turn the crank by hand by using a 27 mm socket on the crank bolt. Is the car an automatic or manual? Is it in gear? Otherwise no other option than to remove the engine and take it apart. Maybe first the heads and oil pan. Hopefully not the cylinders or bottom end.

GPMotorsLLC

the car has a manual trans. the timing belt appeared to be new but i will double check it tomorrow thanks for the input. i hope i dont gotta tear it totally down.

Leon Speed

Just thought about hydrolock, check if there is coolant in the cylinder(s).

928 at last

Might be carbon or TBF......no way of knowing until you check the crank endplay, and if that's ok, and the belt/cams check out, it's then a matter of pulling the heads and pan to see where the interference might be.

GPMotorsLLC

i took the plugs out that was the first thing i thought was wrong.

928 at last

That's possible too. Pull the plugs and check.

mickster

Manual. Probably not TBF (unless you mean Timing Belt Failure).

jcorenman

Ouch, sorry to hear that! As mentioned, 27mm socket on the front of the crank, rotation is clockwise facing the motor, should turn easily with plugs out.

Next step might be to remove the two upper timing-belt covers and make sure everything is OK there, then try to turn the crank backwards and see if it moves. Manually turning the engine backwards is verboten because of the possibility of the timing belt jumping a cog, but that's the least of the worries right now.

If it moves, figure out which piston just moved off of TDC and have a look with a borescope.

There have been a couple of reported cases of large flakes of built-up carbon falling off the ceiling and piling up, jamming the piston. It is rare but possible, would requires a lot of carbon buildup and maybe sitting for a while with some moisture??

Good hunting and good luck!

Imo000

Have a look at this post.http://reutterwerk.com/forums/showthread.php?t=37808

If we knew ahead of time it was only carbon, a can of Permatex Gasket Remover would have fixed it.

depami

That's a really long thread. Is this the post of which you refer?

http://reutterwerk.com/forums/showpo...6&postcount=41

Imo000

Yes but worth reading it to see if your issues are the same. If yes, no need to pull the head. We didn't know this at the time.

928 at last

Probably not...but....

69gaugeman

Next time I will do a better scope of ALL the cylinders. Imo000 is right. If it is carbon buildup it would be possible to fix the problem with some gasket cleaner and some patience.

This is only if the seizing has no known possible explanation for the inability to rotate. Pull the filter and cut it open and check the oil for metal fragments. If there are none scope the cylinders carefully for carbon. If there is lots of carbon you might get away with just using gasket remover to free it up and clean it out.

Landseer

Best of luck on this.

What is the engine code?