I'll be inspecting a 1987 300D, with 191K miles, that I want to buy within the next 2 days.

I'm new to MB diesels and need tips, advice, and walk-throughs on inspecting one.

Since it'll have the OM603, what procedures can I do to test out its reliability? Let's limit it to things I can do on the spot. I barely remember something about checking the cast number for the head, doing something with the oil cap, and cold start pressure?

I need details on these and other tests please. Thanks in advance!

I have reluctantly come to the conclusion that it may be important to take these cars somewhere for a pre purchase inspection and pay for it.
Also it helps in my opinion to have someone along who really knows this model well. A superficial inspection can miss a lot of things that are important and expensive to rectify.
Nothing replaces having a good mercedes mechanic familiar with this model going over it. If he finds very little you have a good car on your hands. On the otherhand you may just want a beater. So much just depends.
The upside is problems found can sometimes be used as a leverage to reduce the vendors price. Some cars they should really pay you to take.
At 191 K the front seats should not be beat to death in my opinion. Do not buy a 400k example with a 191K odometer. They are out there in droves. The more of these older mercedes diesels I buy over time the more selective I become. The good ones are still out there but are getting harder to find. Hope yours is one of them. Just my opinions by the way.

mike - I just recently bought an 87 300D with a 603. I ran into trouble with the body, so I would make sure you perform a close inspection of the floors (in particular under the driver's seat, the rear subframe mounts, and the trunk floor. These are places that I have trouble, even if the rest of the car doesn't even have a bubble.

Mechanically, You'd be best advised to get a Benz specialist to check it out. For instance, if it doesn't have any 'go', that may not be a major problem. Doing a search here would be the best for that.

1 important check would be the head casting number which is on the head near the injectors. '14' series heads are the originals and they are prone to cracking (there is a poll going right now, and only 25% of people have had cracked heads....)

After all the reading I've done on here, I think the body is the most important part. Anything mechanical can be fixed, but rust is costly to repair.

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1987 300D, 212,000 miles
1997 Ranger, 300,000 kms
2004 Honda Civic Si - 110,000 kms. FOR SALE
2004 Mazda 3 Sport - GF's car, but it's my problem....

Montreal, Quebec - The Rust and pothole capital of North America!

I strongly agree. Rust in the body / underbody is difficult or impossible to completely remove, most anything mechanical is repairable/replaceable.

I'm not (yet) afraid of head cracking, I have two #14 head cars. Maintain them well.

Also regarding the abovementioned not having any "go". All three of my '87s (603 and 602) had little power, one had harsh and early shifts, simple vacuum and adjustment fixes in my case and in my opinion, most cases. Kind of nice to see that the car doesn't develop full power, longer life for the driveline.

__________________

Gone to the dark side

- Jeff

For now lets just say there's no mechanic involved. What are those little tests that I can perform to the engine to see it's health? I read about them but people don't often go into detail about it.

For checking the heads, what exactly am I looking for? Is there a picture available that shows the casting number and/or how to read it? I've never done that before so I wouldn't know what I'm looking for.

As I remember, the test for a cracked head is to look for oil in the coolant reservoir, and feel the upper radiator hose with the engine cold to see if it is pressurized (it should be squishy if the head is good).

The oil cap test is to check for blow-by. With the engine running, unscrew the cap and see if it flies off, or dances around a lot (not just normal vibration from the engine running). If either of these happens, you have blow-by, which is not such a great thing.

The '87 300D is faster than the older 123 models, since it has 6 cylinders, rather than 5. It takes a second or two for the turbo to spool up, but once the turbo hits, it should move down the road pretty quick. Mine is kind of a dog when the engine is cold though. It runs much better when fully warmed up. I'm not sure if that is common, or if mine has some problem.

That's all I can think of specific to this model. Good luck!

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1987 Mercedes 300D ~200K (Greasecar & Biodiesel)
1993 Ford F-250 7.3 IDI diesel 165K (Biodiesel)
1996 Thomas/International Bus with DT466 engine

Adjust the ALDA, it shouldn't be that way.

__________________

Gone to the dark side

- Jeff