Problem with 300turbo engine - Advice?

Just got my car back from the mechanic. Dealer found in 3 hours what original mechanic didn't find in three months, but that's another story...
Turns out that I have zero compression in the number 5 cylinder. 1 & 2
are good, 3&4 are ok but 5 is not even registering. Car had been running very well, one day it was extremely hard to start, shaking, uneven. The mechanic, who I trusted at the time, claimed that my injectors were worn out, and replaced all 5 of them. The engine has ~175,000 miles on it. He also said that he replaced a broken engine mount. When I got the car back it was not shaking but was still running very unevenly. I'm trying to decide how much more to throw at this car. If it's just a head gasket, I'll probably try fixing it. If the cylinder is toasted, I'm not sure. I know that these older (1983) engines are pretty bulletproof. I seem to have seen a fair bit of discussion about blown head gaskets though. Is this a common problem with the 300 turbos? How likely is it that this is the culprit?
I hate to ditch the car since the body is in wonderful shape, but I'm just not ready to drop another couple of grand on it to rebuild the engine either since I just dropped it in about four years ago and only have about 15000 miles on it since then.
Any suggestions gratefully accepted.
Rochelle
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Bah. Renew the head gasket and it'll do another 300K miles. Or part it out and buy another one. What color is the interior ? :-)
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Interior is brown, exterior is cream/lt. yellow. Mostly original paint, in very good condition. Trunk has been repainted where some #@%&* jerk took a hammer to it while it was at the mechanics.
Interior is in excellent shape. No tears, just repadded the front seat cushions and new skin on the seat of the drivers where a broken spring had poked through, replaced the frame too. All levers have new handles.
Car has never been wrecked. My dad bought it new, then gave it to me 12/95 when he bought E300D.
Rochelle
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I wonder if it is Weizengelb (wheat yellow) or the 'taxi cream'...
DAS
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I've owned one of these for 25 years. If this were my car I'd:
Find another mechanic.
1. Is there any coolant loss? Coolant in the oil? (head gasket symptom) Or oil in the coolant? (head gasket symptom) Any leaking around #5 injector nozzle? (cracked prechamber)
2. ask the shop to remove the valve cover and check and adjust #5 cylinder's valves. It COULD be that a valve is so tight that the valve isn't closing or that its valve spring broke, or rocker is stuck or broke etc etc. This is a benign inquiry that won't cost much and is also en route to 3, if that's needed. If nothing found under the valve cover I'd consider having the #5 prechamber removed and checked, as a last gasp possibility before removing the cylinder head. They might be able to inspect the cylinder and valves through the prechamber cavity using a boroscope. If it shows a horrible mess of smashed valves and piston, stop work and find another engine. 3. Have the timing chain's stretch checked BEFORE the cylinder head is removed so they'll KNOW the chain is either OK or ought to be replaced upon reassembly. 4. Have the cylinder head removed. The head gasket will be revealed in all its gore or glory and the valves exposed. One may be burned - have a piece burned out of it (in which case you should be thankful that the whole valve head didn't break off and smash everything to hell in there.)
If this motor was running well and suddenly fell into this state it can be repaired without an overhaul. IMHO it's very doubtful that the piston or the cylinder liner is affected, rather the problem is in the top - gasket - valves - etc.
These ARE very tough and durable engines; they typically just wear out with the rest of the car and RIP. One owner had a valve head break off but it made a hell of racket each time the piston smashed it into the head but that's the only one I know of.
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Ditto on the valve part... it is extrememly if not impossible to have one cylinder with zero compression... do a valve adjustment first.
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Very good advice! If you don't hear a bunch of metal parts beating against each other I'd certainly investigate further. Also, if the rebuilt engine has only 15k on it and it was done properly I'd think twice before starting over with another car.

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Just simple common sense. Something some people are remarkably short of, however. When it comes to things mechanical, I'm a firm believer that sounds of metal on metal are a REALLY BAD THING. Luckily, I have not heard any of these.
The engine was not rebuilt when I dropped it into my car, but I did have valves adjusted, timing checked, etc. It only had about 175K miles on it, and I've only put about 15K miles on it since then.
Right now the weather is not conducive to outdoor auto work, so I'll spend some time reading up on this particular engine and its' quirks. Then when the temperature gets somewhere that I consider marginally civilized, I'll know where to start poking. I truly hope that it is something as simple as a head gasket. I do really like the car, but was getting ready to throw in the towel after dropping just under a grand at the mechanic and having it come back running like a paint shaker.
Many thanks to all the folks who have written with suggestions and advice. I'll let you all know how this turns out.
Rochelle
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The party doing the compression test should have found the source of the compression leak. Don't make any decisions untill that is known. I would seek out another opinion and certainly another source other than a dealer (unless you have found the truly rare one) to do the work.
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I will check for oil in coolant and vice versa. I had had some coolant loss last summer, but I assumed that it was just getting hot and boiling off and there was no recovery tank, which I soon rectified.
I truly think that the first mechanic was jerking me around. He did do a nice job on the engine swap, but he took WAAAAAAY too much time. Every time he had my car it was a minimum of a month....You don't want to know the longest amount of time.
The valves were adjusted at the dealer, they found minor mis adjustments, but nothing major. Nothing stuck or broken.
The car was driven less than 50 miles since it started acting up. I really didn't want to make anything worse than it already was, on the theory that the less damage done, the easier the repair.
It is not making any self destructive type noises, i.e. nothing sounds as if it is either eating parts, or going to come shooting out of the hood. It is just running unevenly.
I have the printout of the compression test that they did at the dealer. Cylinders 1&2 show about 26 bars, 3&4, about 23 bars and 5 doesn't even register. The guy who did the compression test said he had never seen one that low. He said that he could not be sure whether it was a toasted head gasket or a scarred up cylinder wall.
I normally don't use the dealer for repairs $ince they tend to be expen$ive. But when I have a real head scratcher, I will use them for diagnosis. I have never used the service department at this dealer before, but the parts guys have always been great, more than helpful. Frequently giving me helpful information, and sometimes even a break on prices <G>.
There are not too many mechanics in my area who work on diesel cars. The ones who work on the diesel trucks, Ford, Dodge, etc. are usually the dealers for those, so I don't see any benefit switching from one dealer to another.
I may just wait for warmer weather, then start poking around a little. I tend to only do emergency work when the temp is below freezing and I can't get the car in the garage.
Thanks for the info!!!
Rochelle
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Any decent technician should be able to find the exact cause of the compression leak. If he cannot be sure, take it to some one who will be.
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22 - 24 BAR is the compression specification for this engine so your 1, 2, 3 & 4 cylinders are in great shape so fixing #5 will put you back on the road with a good motor.
Unless you find evidence of a broken head gasket I suspect a burned valve given this added information.
Since you're not in a rush to have it repaired perhaps you could make a deal with the M-B dealer - to undertake this repair as "pick-up" work at a reduced labor rate. Never hurts to ask.
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Surely a leak down test would reveal the cause of the the lack of compression
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I once had a guy take 3 years to rebuild a set of calipers. Maybe he knows your guy?
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I'm sure they know each other. It was 13 months on the engine swap, and at that I had to keep prodding him with a sharp stick.
Lesson #1--NEVER tell a mechanic"I'm not in a hurry".
Rochelle
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