RE: 1979 Mercedes Engine Dies - What could be the problem? (Full Version)

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RE: 1979 Mercedes Engine Dies - What could be the problem?

  

sfk -> RE: 1979 Mercedes Engine Dies - What could be the problem? (2/13/2007 9:20:55 AM)

Thanks,  I did put brand new bosh injectors in and still the same thing...  I also tried both fuel filters.   Hmmm.  I just ordered the compression check (to measure the compression on the cylinders).  That is the only other thing I can figure it could be.
Only other thing is if it is the actual injector pump on the side of the engine.  Does this ever go bad?  What is the sypmtoms when the pump goes bad.  I know they contain little pistons that pressurize the fuel to like 4,000 psi.  Is there any way to test the pump?

  
Charles Munn -> RE: 1979 Mercedes Engine Dies - What could be the problem? (2/13/2007 10:11:23 AM)

As I understand it, the injector pump rarely conks out, but it's mechanical so of course it does occasionally belly up. You might try loosening the fuel injector lines at the top of the fuel injectors and have someone crank the engine while you check for a healthy fuel flow. But I don't know how to check for the needed pressure... For all I know, even though you're getting what seems to be enough fuel from your tank and through your fuel filter, it may not be enough to feed the engine. There still may not be enough fuel pressure there to the IP to keep the engine running and, even though it gravity flows, it could still be partially blocked. The only true way to test that is by switching those incoming and outgoing fuel lines as I discribed in the first post. If you haven't done that, then, IMHO, you haven't yet eliminated that problem...

Theres a couple of very smart mechanics on this forum, such as forcedinduction,  who might know how to test the IP. If not, there's a dozen or more of really smart MB diesel mechanics at http://www.schumanautomotive.com  That's where I go when I really need help. Henry Schuman, who has been a MB diesel mechanic for decades, will even get you the best prices on new and used MB parts. Or others there may be willing to trade parts, etc.... In my book, some of those guys are genuis'es at tinkering....

sfk -> RE: 1979 Mercedes Engine Dies - What could be the problem? (2/13/2007 10:20:26 AM)

Charles,
Thanks for the tips. I will try that again.  I had replaced the fuel filters but will try that again.  What is still is wierd is this
Why would you get diesel spray/mist coming out of the exaust pipe, when I KNOW the glow plugs are working.
ALSO, the engine isn't cranking as easy as it use to. I had put a new battery in it and same thing.  It is like something is restricting the engine down.  Hopefully the compression check shows everything ok.  I am afraid of a blown head gasket.  I don't know what else it could be.

Do you know if air enters the Injector pump.  If so, is there a flap or something that would stop the air from mixing with the fuel.  I think the fuel just gets sprayed into the injector with no air.  Just not sure what the vacuum hoses are going to on top of the injector.  Do you know.

Charles Munn -> RE: 1979 Mercedes Engine Dies - What could be the problem? (2/13/2007 10:27:27 AM)

Maybe a broken or burnt piston? But probably not. It seems to me that it's usually something simple... Believe me, if those guys at schumanautomotive can't come up with some answers, no one can....

Charles Munn -> RE: 1979 Mercedes Engine Dies - What could be the problem? (2/13/2007 10:40:13 AM)

BTW, did you also replace the heat shields when you replaced the injectors? And were they put in with the right side up? Is it leaking fuel at the base of the injectors? Also, since you smelled raw diesel at the tail pipe it sounds like it's not firing... so I can see why you ordered the compression set....I don't remember if you tested the glow plugs....But since the engine is hard to crank... it's probably not a broken piston top....Maybe it still could be a burn't piston.... dieselgiant.com has a picture of a burnt piston in an old MB engine here: http://www.dieselgiant.com/mercedes617engineinternals.htm

AMGMercedes -> RE: 1979 Mercedes Engine Dies - What could be the problem? (2/13/2007 10:47:56 AM)

quote:

diesel fumes coming out of the exhaust pipe


Unburnt fuel may be the effect of a burnt piston. Still leaning towards bad glow plugs as well. When was the last time those have been changed?

Charles Munn -> RE: 1979 Mercedes Engine Dies - What could be the problem? (2/13/2007 11:20:17 AM)

quote:

ORIGINAL: sfk

ALSO, the engine isn't cranking as easy as it use to. I had put a new battery in it and same thing.  It is like something is restricting the engine down. 

A common problem is a corroded ground connection on the starter... In fact you need to go through all of the ground connections, from the battery to the relays, to the starter....

quote:

Do you know if air enters the Injector pump.  If so, is there a flap or something that would stop the air from mixing with the fuel.  I think the fuel just gets sprayed into the injector with no air.  Just not sure what the vacuum hoses are going to on top of the injector.  Do you know.

I can't see how those lines have anything to do with your problem/problems...That's for the vacuum engine cutoff. dieselgiant.com has a pictorial about that.... it's great... shows how to remove all vacuum lines, and brake line around the ALDA and then remove the ALDA so you can look into the pump in order to see how to connect the vacuum engine cutoff switch...

danzel -> RE: 1979 Mercedes Engine Dies - What could be the problem? (7/10/2007 5:45:57 PM)

check your engine harness as well..

sfk -> RE: 1979 Mercedes Engine Dies - What could be the problem? (1/8/2008 5:06:16 AM)

I am the one who posted this Question.

I took the engine apart and #2 piston rings were shot.  (I could move the piston slightly with one had.  I'll try to post a photo.  Thanks for your help.

sfk -> RE: 1979 Mercedes Engine Dies - What could be the problem? (1/10/2008 7:32:40 PM)

Just as a final follow up in case anyone else has this problems

It turned out to be the #2 cyclinder.  The rings broke, so when I took the head  off, you could move the piston back and forth a little.  I am now swapping engines.
Thanks for your help

  

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