Hi,
I am about to replace the head gasket on my 92 300E 2.6 with 176,000 miles on her, as it is leaking oil at the front of the head which I have found out is a very common problem on this engine.
While I am doing that I want to put new valve stem seals, timing chain, and oil pump chain on too. Are there any other parts I should replace while I have the head off?
I have done similar work on other cars but this is the first time I'm tackling a Mercedes. What I need to know are there any special tools I would have to get and what potential problems might I face during the job?
Thanks,
Colin.

you have to take the complete front cover to take the time oil pump chain off and if you do the timing chain you need a special tool to crimp the chain together, your best bet is to do the headgasket and repl vavle uid seals on the bench when you got the head off

A head gasket oil leak at the FRONT of the engine on a 2.6 is not very common. Normally, it would leak at the right rear side.
Are you sure the leak is not coming from the front engine cover????
Whith the head off, I would suggest you have a good lock at the valve guides too

I am currently replacing a h/gkt on about the 60th 300e .
There are a few things you need to know.

There is a fair description of proceedure on Alldata DIY for a fee.

You need...
Torx TX25.
12mm/13mm end wrenches.
13mm universal drive.
Long 3/4in drive extensions.
Wobble extensions.
5mm/3mm/12mm Allen keys.
Long 'L' fan boss lock tool.
10mm/12mm/13mm/17mm/19mm sockets.
Chain guide pin remover.
Crank socket and torque wrench...(300 Nm !)
Flywheel lock #601 589 02 40 00.
Guard plate for radiator..600 x 480 mm.
Single row chain riveter.
Screw driver.
Clamp driver.
Valve stem seal tool.
12mm multi socket cylinder head bolts.

Parts you need are...
Upper rad' hose...OE style, thin wall.
Bypass hose...OE tappered.
Chain...single row.
Master link.
Cam sprocket.
Upper engine gasket set.
Valve stem seals..(.not included with h/gskt set.)
Rotor.
Distributor cap.
S. plugs.
Valve cover gasket.
Coolant.
Thermostat.
Oil filter.
Oil.
Surp' belt.

Parts you might need....depending on wear...

Chain guides.
Chain tensioner.
Water pump.
Belt rollers.
Belt shockabsorber.
Belt tensioner.


If you change oil pump chain....which they never seem to need ...
Front crank seal.
Chain and master link.
Lower crank sprocket.

'Right Stuff' gasket maker.

Enjoy.........!

__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

I agree with Jackd. You likely have a leaky horseshoe gasket between the top front cover/distributor housring and the main front cover. It's a pretty quick and easy fix compared to pulling the head. I agree further that if you have the head off, have a full valve job done.

The timing chains in MB in-line engines don't have inflection points and tend to last much longer than the timing chains in MB V8s. You don't hear much about M103 chains breaking on well maintained engines. Heck, even on abused engines.

To add to dkveuro's list, if you have to raise the engine to work on the lower chain, consider new engine mounts and shocks (if W124s have separate engine shocks ).

Sixto
95 S420
87 300SDL

Colin, I agree that you should positively confirm that the head gasket is the source of your oil leak. I've had the timing chain cover on our 1992 300CE resealed twice for oil leaks ... fortunately both times were under warranty. Our indeoendent advised me that the timing chain covers are tricky to seal properly. He's had better success with a different sealant than MB recommends. The name of the sealant slips my mind right now, but I'll ask him if you determine the timing chain cover is leaking.

__________________
Fred Hoelzle

On the 91 300SE I used to have I used Toyota semi-drying sealant (used for oil pans with no gasket) in place of the MB recommended stuff, actually 2 stuffs, and it held fine for over a year until I sold the car.

If you replace the cam seal, I found it easier to put the seal in the cover then the cover in place than to fit the seal with the cover in place. I think the manual says to do it the first way. The point is, it's easier to put the cover in place without the seal but you'll realize you're in a bind with fitting the cam seal later. YMMV.

Sixto
95 S420
87 300SDL

Thanks for all the advice, guys. I had a closer look at the front of the motor and I suspect the problem may be the timing chain cover after all. It looks like someone has tried to seal it with red sealant of some kind without much success. I will tackle this area first to see if that cures my problem.Can anyone recommend a good sealant?
I was using as much as a quart of my precious Amsoil a day, just now I'm using regular oil (Maxlife 10/40W) which does not leak out as much. I changed the rocker cover gasket last week as the old one was hard and this seemed to help a little.
It would be great if this is the problem after all as I can't have the Merc off the road for long as it's my only transport at the moment on a 200 mile round trip daily commute to Atlanta,GA!
I will keep you all posted. Thanks again for the advice.
Colin

I agree that the U seal on the t-covers is probibly the leak. I have used Three bond 1211 on them and seen the cars years later with no leaks.

This sealer is made for sealing two troke engine cases and if they leak it blowes up.
I have used it many times and think its the best.

It can even seal a Subaru engine case so it won't leak!!!!!

When you go to places that sell stuff for two strokes they will try to sell you what they have but don't fall for that get the real deal. Can you tell I like this stuff?

I haven't bought any in a few years because I got 5 tubes last time and just did a serch to show you its out there and you may be able to get it localy not sure. I have bought it from Dennis Kirk in the past.

http://www.threebond.co.jp/en/product/series/sealants/1200list.html

http://www.vitosperformance.net/TRX250R.HTM#SEALANT

http://www.denniskirk.com/jsp/product_catalog/Product.jsp?store=Main&catId=513&leafCatId=51304

As far as what should you also do. Just do as many parts that are known to wear out as you can possible pay for if you have access to them while you are in there and maybe you won't have to take it back apart in a long time.

Like the water pump if it has more than 80k on it or has been expossed to the green coolant its less painfull to do it if you are already doing some work and would suck to do it 6 months after you get it all back together.

Good luck........Dave

You really want to read this thread:

http://www.peachparts.com/shopforum/showthread.php?t=102977

Use the MB sealant. Mine's leak free.

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.

Thanks again y'all. I'll get the parts together and tackle the job within the next couple of weeks. Keep you posted.
Colin

__________________
92 Mercedes 300E 2.6
86 Plymouth Conquest TSi
79 Chrysler Cordoba (without Corinthian Leather!)

DRIVE FAST TAKE CHANCES!

I finally got around to replacing the timing chain cover seal as suggested by some of you. It was indeed the source of the oil leak. I suspect someone had done this job before but was VERY skimpy with the sealant,there was hardly any on the cover. I replaced the seal which had dried out along with the recommended camshaft seal for good measure, then used a more generous amount of Threebond 1211 sealant (brilliant stuff!). I have driven over 800 miles this week and have not lost a drop of oil. I'll keep an eye on the oil level for another week just to be sure and then replace the dino oil with synthetic oil if all goes well.
Thanks again y'all!
Colin

__________________
92 Mercedes 300E 2.6
86 Plymouth Conquest TSi
79 Chrysler Cordoba (without Corinthian Leather!)

DRIVE FAST TAKE CHANCES!