How to lock flywheel on 92 300e
 

Hi, I have a 1992 300e, 2.6. Was wondering if there was a quick way to lock the flywheel in place without the ridiculously expensive flywheel lock tool that I have heard about. Previous owner started a head gasket job, and broke the timing chain guide trying to get the head off (didn't pull the pin), so now I have to fix that too. Now I'm stuck on getting this damn harmonic balancer off. Thanks. Also, anyone have a the head bolt torquing procedure for this engine?

On my 1993 400E, I was able to lock the crank by opening the access plate on the bottom of the torque converter (2 small bolts), then turn the crank clockwise (facing the engine from the front) until you see one of the three torque converter bolts. Pull one of the bolts out and replace it with a longer (3") hardened bolt and a 2 1/2" hex-shaped sleeve. You can get both from Ace Hardware (I think it is an 8mm, but get the hardest they have).

Once you tighten the bolt, the outer sleeve will keep the torque converter from turning as you unbolt the crank bolt (counterclockwise when facing the front of the engine), because the sleeve will hit the transmission housing. You may need to add some extra nuts along with the sleeve in order to compensate for the bolt's length. Here are some pictures in this string that may help, although your setup will obviously be different, this is how I locked the crank on my 400 without the expensive tool.

http://www.peachparts.com/shopforum/showthread.php?t=190442&highlight=560+water+pump



My crank bolt was so tight that I actually had to use a floor jack under a breaker bar to loosen it and it nearly lifted the engine off the mounts before it came loose. If you're going to disturb the crank bolt, you may want to think about replacing the front seal while you're at it. The seal is right behind the balancer and coupling. On my car, there is a special tool to pull the coupling that goes around the crank and another special tool to install the front seal. I think you could probably get away with the generic pullers and a big socket to install the seal, though.

However, if you are trying to lock it up for reasons other than loosening the front crank bolt (e.g., to keep the engine from turning when you pressurize the cylinders to replace valve seals), then I doubt the above method would work.

Head Torque
 

I replaced the head gasket on my '88 260e, which is the same M103 engine. My original head bolts had washers, the replacement bolts were the newer washerless flanged style.

First step is to clean out the bolt holes with a q-tip and get all the oil and coolant out of them. Try the bolts in the holes while the head is off to make sure they thread in okay. I was surprised amount of clearance (looseness) the bolts had (especially for a German car). If the bolt doesn't thread in smoothly, run a tap in the hole to clean it.

Lightly oil the bolts with clean motor oil. If you are using a washer, put oil between the bolt head and washer. Do NOT use oil on the bolt flange or washer that contacts the aluminum head.

The bolts are torqued in three stages: first to 52 ft-lbs, secondly 90 degrees (1/4 turn), and lastly another 90 degrees. You start with the center bolt between cyl 3 and 4, then the one across from it, then the one between cyl 2 and 3, and 4 and 5...basically working your way out from the center. One thing I was not sure of is if you should bring all the bolts right to 52 ft-lbs or proceed in steps up to 52. I decided to take the middle road and snug them all up to 10 ft-lbs before taking them to 52. At this point I used white-out to paint a mark on the firewall side of each bolt head for angle-torquing. The paint helps keep track of which bolts have been turned and how far. Do NOT rely on your memory because it is very easy to lose track and giving an extra 90 degrees might break something.

Try to turn each bolt in a smooth 90 degree sweep without stopping. The second 90 degrees is pretty tight. You will work up a sweat. I thought I smelled aluminum burning as I torqued the bolts.

My car went together well and no more coolant leak from the head gasket.

Good luck!