Dennis did the oil cooler repair and drove it. The engine was seizing. When he took it apart the damage was extensive. I did not have any luck finding a good used engine or a rebuilt that I trusted. Dennis had a 350 engine from one of his cars that he used the crank and some other parts from. The head is new. The injection pump was still good.

__________________
1991 350SD (updated rods)
Biodiesel B100 when I can find it.
Dino when really cold outside

I don't know if he can describe the difference. He spent considerable time researching the rod bending issue after I told him about it. He had not seen the problem before. The 350 is rare. If you are serious about putting in updated rods I suggest that you call him. There are few people who understand older Mercedes better than Dennis.

For those who would own a 350 diesel, my suggestion is that if you want to get something to burn WVO or thrash around until it dies, that you might be disappointed. Instead, if you want to own an exceptional rare diesel Mercedes, do the work you need to make it nice and go for it. If you looked at the pictures of Cignatta Motorworks you can see that you can spend a lot more money on a car if you want something good. (e.g. the BMW M1 turbo)

__________________
1991 350SD (updated rods)
Biodiesel B100 when I can find it.
Dino when really cold outside

Call them. I think they have the engine manual.

__________________
1991 350SD (updated rods)
Biodiesel B100 when I can find it.
Dino when really cold outside

Anthony,

Could you provide a procedure to remove and replace the head on the OM603? I understand there is a specific procedure to remove the camshaft to avoid damage. Is there a procedure for installing the pre-combustion chambers?

Thanks in advance.

Greg

Greg,

Yes, there is a specific procedure to remove the cam, it's in the FSM. There is also a procedure to remove the prechambers, but that is straightforward... remove injectors, lock rings, glow plugs, and then use the special tools to remove the prechamber from the head. Click here for photos of the prechamber tools (note that the 1990-up splined lock rings use this tool instead of the pin wrench.) Also, check your PM for info on the service manual.

__________________
Check out my website photos, documents, and movies!

I'm new to this S350 diesel engine problem, I have an eye on one and want to buy it. Also I would like to convert it to veggie oil
Is a 1994 with 175k miles worth buying it? Or the whole thing is just not worth it?

If you buy it cheaply enough to put in a good used 3.0 liter motor, you are fine. Other than the engine the car is extremely high quality.

Tom W

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Read that there is 50% possibility that the engine may be ok...how can I acutally tell if there is a problem or not. Also what do you consider a cheap price (or worth buying it)? for a 175K miles 1994 S350
Thank you

The only immediate way is to know the oil consumption, in number of quarts per mile, using proper diesel-rated (Cx) oil. Most sellers will have no idea so this is often hard to find out. A good engine should use a quart in 4-6000 miles, or better. If it's using a quart ever 2000 miles, that's a bad sign. Every 1000 miles, you've got a rebuild or engine swap on your hands before too long. The only way to tell for sure if the rods (and cylinders) are good is to pull the head, and measure the piston protrusion, and cylinder bores. If you REALLY want a W140 diesel, this could be a great car, but just prepare yourself for the worst just in case.

__________________
Check out my website photos, documents, and movies!

Oil use is a warning sign but leaks and the turbo seals can cause oil use too. A bad compression test is a sign that you have to take the head off to see if the rods are bent.

My car was using oil, but I could see it under the car! It turned out to be the oil line to the turbo.

__________________
1991 350SD (updated rods)
Biodiesel B100 when I can find it.
Dino when really cold outside

Mine registered 420 - 450 psi across all cylinders, but is using a quart per 300 miles.

I think you have to assume the engine is a time bomb waiting to go off. The idea that there are some that are just "good" and some that are just "bad" does not wash for me.

What is a fair price? If it is really really clean take the nada book and deduct $3000 to $4,000 for a motor conversion to 3.0 liter, IMHO.

For myself the 140 is too big and way too complicated.

Tom W

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Exactly. This *could* be a head gasket issue but on a 3.5L it's the lesser probability.


But for other people the 140 is the perfect size, and although it's much more complicated than a 123, 124, or 126... it's far less complex than a 210, 211, or 220. You can still service a 140 yourself when armed with the FSM and/or WIS. I too think the 140 is a bit large for my taste, but on a long road trip with 4 people in the car, I'd take a 140 over a 124 any day. My sister has a 140 (S500) and it's an incredible vehicle, except for the 15mpg. The S350 offers the same experience but with roughly 50% more fuel efficiency, in exchange for less power. But anyway, it's always good to factor in at least $4k in fudge factor for when (not if) the 3.5L goes belly-up.

So I did get the engine in my 92 300SD back together.

Just to refresh everyones memeory, this is the one that blew the head gasket at the #1 cyclinder after going only 84Kmiles. The dealer mis-diagnosed the problem as a bad turbo, the owner gave me the car because he did not want to replace the engine at a cost of $14,000.

When we removed the #1 injector to see if oil was leaking there, 1 gallon of oil came out of the combustion chamber in 3 1/2 minutes at idle.

The exhaust system was flooded with oil. When I first ran it with the new head gasket the oil heated up and began to both burn and boil out of the exhaust. Hot oil vapor is white by the way. So white oil vapor poured out thicker than steam. I drained the oil out of the exhaust system by drilling holes in the low spots. 3 quarts of oil drained out of the resonator and muffler. MB dosen't publish the oil capacity of the exhaust system. It is about 7 quarts I think, on level ground.

So now I have a really nice 85K mile 1992 300SD. It is a wonderful car to drive. It is amazing that a car so big and heavy can handle so well. I have put about 500 miles on it since replacing the head gasket. It appears that oil consumption is about zero.

So in this case, the gasket broke in such a way that there was oil everywhere. All over the intake system, gallons flooded into the exhaust system. The #1 cylinder was acting as a piston pump, spraying oil everywhere inside the engine. There where large amounts of oil being sucked into the turbo and pumped into the intake manifold as carburated oil mist. over a gallon of oil had accumulated in the exhaust system. How did it get there? I can only imagine that oil was pumped into the #1 cylinder during the exhast stroke via the oil gallery in the head by #1 and then pushed into the exhaust manifold. Why didn't #1 hydrolock and bend? Becasue the gasket was broken and oil was pushed out into the chain case during compression and combustion.

Why no bent rods? Becasue the engine was not run much after the gasket failed.

I am lucky becasue the cylinder seal in this gasket broke wide open rather than developing a leak that could have leaked for many thousands of miles subjecting the engine to sporadic cylinder overloads of the type that would bend rods.

I ask a simple question that is very difficult to answer because it requires that careful observations would have to have been made that were probably not made, when each rod bender was repaired.

Are there any cases of bent rods in 3.5 engines that did not have leaking cylinder ring seals?

Please carefully read the question.

It may be very difficult to see this kind of leak unless you know exactly what to look for. It is easy for me to think that once the rods are bent and the symptoms are evident, the head gasket would not be given a careful examination. Bent rods and gradually increasing oil consupmtion are not the sysmptoms we would normally associate with a head gasket leak. Especially a leak that requires very high cylinder pressures to activate and is not present at normal and low pressures, like during a compression test.

If there is any case of a 3.5 liter 603 that has bent rods and no head gasket leak, the answer to the question would go something like this........." We carefully examined the gasket in the area of oil gallery by the #1 cylinder. All of the gasket material on both the head and block sides of the gasket was intact and not burned or degraded."


I still like the oil mist theory. It takes only one excess combustion event to bend a rod.

__________________
JMF

In the case of the engine I took apart, #6 had the same piston protrusion uneveness as #1. Obvious head gasket breach in #1, I found no traces of a breach in #6. That said, this was a -20- head on an early block so #6 could have been bent by an earlier gasket failure.

That reasoning still suggests poor or marginal rod design because the rest of the 60x family is subject to the same head gasket failures but not the subsequent lower end effects.

Sixto
87 300D