newbie needs advice on head 86 Mercedes 300sdl
 

I am a new Mercedes owner. Majorly enjoyed car for 2 weeks before the head gasket blew. This 86 Mercedes 300sdl is in great condition. Has 169,000 miles. Never overheaded. Records show amazing service and care has always been taken. Paid $5,500. I am a DIY'er so working on the car myself...a learn as you go endeavor! I finally found a manual and got down to the head...done a lot of reading from forums to hopefully not miss anything along the way. Carried head several miles to get head resurfaced...guy was clueless about aluminum heads so rescued it before he touched it...Trying another guy now that seems much more knowledgeable. The car was in 'storage' for a couple of years, just taken for a drive around the block and polished on occasionally. Could this 'time out' have cause the head problem? Also, is it worth keeping or will this thing be a money pit? I did a lot of research and the word was so great on these cars that I felt good about it...now I'm having serious doubts...any advice?: UPDATE: Head resurfaced 16,000th, guy says it looks good! Got to find 3 exhaust valves to send him...the part no. I have doesn't match the ones I find...does that mean anything if it says if fits this an 86 300sdl?

I don't know enough about it to comment specifically but, some of the early Diesel with Aluminum Head had issues with the Head design.

Search on #14 head to learn about the problems associated with the head design on an OM603.

http://en.wikipedia.org/wiki/Mercedes-Benz_OM603

Head gasket failures are not common on that OM603 engine, but the early cylinder head castings are known to be crack-prone if overheated. The replacement head castings (which went into production in approx 1988-89) do not have this problem. If the head is crack-free and straight, I'd bolt it back on with a new gasket. If there are any cracks, it's risky to have it welded, as it may crack again... better to located a used late-style head and install that. If the head surface is flat, it DOES NOT need to be resurfaced. If you do get it resurfaced, you will need to measure prechamber protrusion before installing, as described in FSM job # 01-410.

Make SURE you follow the procedure in the factory manual to the letter for the head R&R!! And before starting the engine afterwards, rotate the engine 2 revolutions by hand to verify the camshaft timing is correct (lining up the marks on the balancer, and on the cam tower).

Also read this buying guide, it's primarily for the 1987 300D/TD, but all the information about the engine applies to your 300SDL as well.

Have fun!

:stuart:

300SDL came with the large football shaped Trap ox on top of the turbo. if yours still has it, you may be able to get MB to repair the damage for free.

Good point! Forgot about that... photo below:

http://www.w124performance.com/image...p_oxidizer.jpg

:balloon2:

Got to love that Lifetime Warranty!
Just a word of caution...If a machine shop unfamiliar with MBZ diesels does the work, they may ruin your head or cost you considerable time and money fixing their mistake.
X2 what gsxr, kerry and vstech said

where o where are you?
 

Hi Jeff.

Welcome to the forum and the unique ownership club of the 300SDL.:D So, where are you located?

Some of us have owned a few.:eek: If you have any questions about these vehicles do an initial google search restricted to site:www.peachparts.com and see if you find anything. Most things have been addressed/answered a few times. This forum is the best one I've every found. If you don't find anything in your search, just ask.

Oh. We like to see pics!!! So, take some pics of your car and post them up.

Good Luck with the blown head gasket.

Replace word "may" with "most likely will".

Very few shops are qualified to work on these heads without causing more damage to them.

Here is one that it thoroughly tested and trusted:

Mercedes Rebuit Engines

You better check if it is allowable to remove 16 thousands. You might find there is a thicker head gasket available hopefully if needed.

Three thousands is the limit for the old cast iron heads I believe. Hope the guy that surfaced your head used the book that auto machine shops have. This tells them the allowance for material removal on all makes of automotive heads.

Maybe you are allowed 16 thousands I just do not know. You have to really check this out. This is a 169k engine? Should not need three exhaust valves since it has hydralic lifters. Maybe someone dropped a higher milage engine in this car at one time. Although there can be exceptions to the rule I suppose.

FSM job # 01-418 says 0.50mm can be shaved, and 0.016" is approx 0.41mm so that should be ok. Max unevenness is 0.08mm (0.003") in longitudinal direction only. The prechamber protrusion will need to be measured since 0.4mm was shaved off, if they stick out too far, they will need to be shimmed upward to compensate.

http://www.w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/Engine/602_603/01-418.pdf

:blink:

Brian I agree there are too many garbage shops in the auto machining/rebuilding business. It is up to the purchaser of this service to verify they really know what they are doing.

A busy mercedes independant shop or even a dealer that sends heads out may be a good refference source. They cannot tollerate all kinds of bad jobs coming back from them.

I only got stiffed the once. It was on a head for a gas car. I assumed and this is always dangerous that they knew what they were doing. It was a misteak as they took far too much material off. I only asked them to resurface the head. I of couse expected them to call if the removable allowance was going to be exceeded. When a shop messes up on the simplest of tasks. I have to wonder how bad their more complex issues turn out.

I do agree that things have gotten progressivly worse in the auto maching business over the years. Still are firms out there that know what they are doing though. Plus do it well. You just have to both find and verify them. Never assume just because the job is easy someone in that business cannot mess it up.

Glad he was under the material removal allowance. Nice of you to check the maximum as well.

This statement is much easier said than done.

The only way to "verify" what was done is to bring a complete set of measuring tools and check all the dimensions on the head prior to handing them any money. Of course, you'd need a place to do this work, in their shop.

Then, there is the issue of what to do when you find many items not to spec. Clearly, they are going to argue with you at that point.

No, my conclusion is that you cannot verify a machining shop by yourself, even if you have the capability to measure all the relevant dimensions. The only solution is to go with a shop that is independently known to be trustworthy.

The methology of resurfacing heads is to measure the overall thickness of the head before you start. Otherwise the head may have been resurfaced before and a new resurfacing will take it too far. That auto machinist guide book contains the original head thickness as well. . I just threw this in for general information.

If you are within a reasonable distance of Montreal, Canada. There is a shop there that is the best in Canada. They are extremely competant and where cheap the times I used them.

Since they also do most the automotive machining repairs for exotic car dealers across Canada I figured they just gave everyone the same prices. A lot of their work comes from other automotive machine shops as well.

From some work they did for me they must be pretty large as well. and extremely well equipped.

That said I have not used them in at least several years now. They really do all aspects of their business very well. Their rates where cheap enough that shipping was not a cost issue. Located six to seven hundred miles away from me. In their business it was safe to say they were the best available in Canada at that time.

I would not hesitate to use them again once I did a quick check that they were still at the top of the pile in Canada at least. They are also capable of doing the most complex things in their business well and we never in general have that need.

What I am driving at is if you want work at the quality level of the famous american automotive machine shop this could be the place. At least a price quote from them for the same job might prove intereresting by comparison. Not that the bulk of our members are cost concious.

For a Canadian in my location the american place is difficult to justify costwise. For example. Freightwise I can move something from Florida to the canadian border cheaper than the charge for the last two hundred miles to reach me. Plus customs matters have to be dealt with.

Brian is perfectly right though. I would seriously hesitate to use any of the four local companies except for the simplest of jobs. There is one good company fairly close though that does not take work off the street.

That can be gotten around by getting a dealer to send the head or whatever in usually. I can only surmise they do not like dealing with the general public. They have a fairly good reputation.