Siezed Crank pulley bolt - PeachParts Mercedes-Benz Forum

#1 05-30-2002, 05:26 PM

Trying to do the lower timing guiderails on my 1985 500SEC. The Crank pulley bolt is REALLY seized on tight. Got the 27mm 6-point deep socket and 4-foot breaker bar. Cannot budge without turning engine backwards (bad thing) Even tried the starter with the breaker bar wedged on the floor but the whole engine just shudders and acts like it is about to jump off its mounts. What is next? I don't have air for a pneumatic impact wrench and even with the radiator removed I think I will need a right angle electric impact wrench!? Does something lik this exist? Any other ideas out there about removing a stuck crank bolt? Thanks, Brant

mbdoc · #2 05-30-2002, 05:39 PM

That bolt torques to 225 ft lbs. May require twice that to break it loose.
WE use a flywheel lock on the ring gear to break it loose & to retorque the bolt as well.

csnow · #3 05-30-2002, 06:52 PM

These things are always a pain.
There is no way the starter can do the job.
I have had no luck using impact wrenches for this purpose either.
As MBDoc said, a flywheel lock is probably the right tool here, though I have never owned one. I presume you remove the starter to gain access to the flywheel ring gear, which is not always a desirable step, depending...

1) Is the pan off? You can usually put a block of wood between a connecting rod and the block to stop the motor from turning. This has been the most successful method for me, even when everything else failed.

2) A big strap wrench around the pulley worked once. It was designed just for this. Can be hard to find. I got mine at Harbor Freight. Has a V-belt, but works ok on serp belt pulleys too.

3) Before I had a strap wrench (which is gentler), or when the strap wrench is just not enough, I sometimes have success using a big chain-wrench for this. Now this thing gives you some serious counter-torque. It can damage the pulley surface, though it helps to put a rag or an old segment of belt under it. I got the chain wrench at Sears. I was able to wedge the chain wrench against the floor to stop the pulley from turning, then put a big pipe on the breaker bar, and presto...

4) In a pinch, I once used an old piece of serp belt and a pair of big visegrips. Wrapped the serp belt around the pulley, clamped on the vise grips real tight, and was able to stop the pulley from turning by tying the tails of the belt to something solid. That particular bolt was only torqued to 90lbs, though, so I doubt it would work here. Belt might break or slip first!

Good luck. I feel your pain...

mbdoc · #4 05-31-2002, 08:02 AM

On this engine there is a starter block-off plate on the left side of the engine, that is where the flywheel lock goes. Have seen people use a very large screwdriver to hold the flywheel as well.

mplafleur · #5 05-31-2002, 08:08 AM

Wedge a small block of wood between the drive plate and the housing where it bolts to the torque converter. This will stop the motor from turning.

Now get a long (6-8 foot) pipe to extend that cheater bar.

I had to put an 8 foot antenna mast over a 3/4" breaker bar with a block of wood between the piston and frame of my Harley to break loose the bolt on the compensation sprocket. I had someone sit on the back of the bike because it was lifting off the ground. That bolt was spec'ed at 325 ft-lbs.

Good luck.

#6 05-31-2002, 06:04 PM

Well I found a good way to remove the Crank-bolt. I already had the lower oil pan off so I just placed a metal bar straight up from the ground up to the first crank-throw. It worked perfectly. Just got a 27 mm wrench and gave it a few good raps with a 5 lb sledge and it lossened right up. YAHOO! I think the rest is downhill now. Thanks for all the other ideas and I'll let everyone know how my repair goes,..Brant