Parts for M103 head gasket job?
 

What all do you need?

Head gasket set
14 new bolts
14 new washers
Valve cover gasket

Also do the valve stem seal kit while you're in there...

Loctite 5900 for the front/top cover seal.

I recently replaced the valve cover and related upper seals so those should be covered.

Anything else?

Make sure...
 

the bolt do not have washers already built-in. The newer style bolts do not need washers....Also, while you are removing the head, it may be a good chance to replace the fuel injector seals. They are cheap and most of the stuff around them has to be removed anyways. The little hose between the engine and the water pump and/or any rubber hose connected to the engine/head. They do get hard with age...

The head bolts do not have to be changed if they haven't been stretched over spec. The manual has the info to check the bolts.
Valve guides also are a problem on the M103. Replacements from Benz are made from a different material that lasts far longer than the originals.

Head bolts are so cheap, why risk it?

exactly :) I guess anything you buy now, i.e. Febi/Bilstein would be the "newer style" that wouldn't need the washers?

Well, there's a rubber seal at the rear that is really what's leaking anyway.

German valve cover gaskets are quite reusable, as this one is plastic.

What do you mean rubber seal? The M103 is known to leak oil to the external from the head gasket on the passenger side/rear, hence the newly reinforced Elring design.

I've only received two maybe three times R&R'ing a valve cover gasket on these MB motors. Again, if you're pulling the head... use all new parts. Chain tensioner, gaskets, bolts, seals, etc.

I don't see anything in your post about having a valve job done to the head while it is off. DON'T EVEN THINK ABOUT DOING ALL THIS WORK WITHOUT DOING A VALVE JOB!!!!!

Secondly, there is absolutely no need to replace the head bolts if they are not stretched beyond spec. They are usually good for at least two retorquings.

When putting the rocker arm cradles back in place, DO NOT tighten down any single bolt without touching the others. Get everything in place with bolts started and then tighten them evenly a turn at a time all over until they are all tight, otherwise you can strip the aluminum threads and it is even possible to break the cam.

When torquing the head bolts, read the procedure carefully and make sure that you understand it. Torque them all in sequence to 50 ft. lbs or whatever it is, then use a 1/2" breakover to angle torque them all in sequence. Either mark all the bolts after the initial torque, or pay close attention while doing the angle torqe sequence. An interruption could put you in a situation where you don't know which ones you have already torqued. You feel like you are going to break the bolts in half and you will be tired after doing it I don't care what kind of physical condition you are in.

Be careful when sliding the upper timing cover rearward. You must not move the bottom U gasket and you must use your thumbnail to carefully slide the oiled shaft seal over the camshaft end. Be careful not to "fold" the seal.

Also, remove the exhaust manifolds by disconnecting the header pipes first. Do NOT get the bright idea to use bolts instead of studs on the manifolds to make it easier. In an aluminum head use STUDS!

Good luck.

Thanks for the advice Larry. I have to do this on my 300SE too. It's leaking quite a bit of oil out the back of the head.

I agree, reuse the head bolts if they're within spec. That's what I did. No problems. I imagine the spec was written because it's so easy to lose track and stretch-torque bolts twice during a job. Measuring the bolt length will weed out these bolts.

Plus, if you understand the stress-strain behavior of bolts, you'll feel comfortable reusing these bolts.

If you have the M103 manual, refer to the following job:

05-2190 - Removing and installing rocker arm bearing bracket.

In it, it is recommended that you replace all the rocker arm bearing bracket bolts with 73 mm long ones (the current ones in your vehicle are 70mm long) to avoid stripping the threads (refer image below)

Also, per item number 01-4192 of the M103 manual, it is recommended that you install helicoils on all the rocker arm bearing bracket bolt holes in the cylinder head (size = M8x1.25). This will be cheap insurance against thread strippage when you are putting the head back together (refer attached pdf below)

Here is a thread discussing stripped rocker arm bearing bolt threads stripped: http://www.peachparts.com/shopforum/showthread.php?p=1291085#post1291085

1) Does anyone know the torque spec for the rocker arm cradle bolts? I don't have a service manual yet.

2) :eek: Does this whole stripping/ 73mm bolt change/ helicoil insertion issue apply to a '90 300E 3.0L SOHC engine as well? I did not run across any indication of stripped or weak feeling bolts when I removed the rocker arm cradles.......

3) Can someone tell me the correct torquing sequence for the 14 head bolts if it is something other than "X"-patterned from the inside out ?

4) I'm pretty sure this is just an old mechanics tale, but do new head bolts need to be soaked in oil before installation as the shop doing the head has told me?

Thanks.
Andy