602 Problem: Runs like Sh**! HELP!! - PeachParts Mercedes-Benz Forum

350SL4spd · #1 08-19-2004, 04:20 PM

Hey all I'm back as the nightmare continues.
Object of hatred: 91 300D 2.5T
Issue: Runs like Sh**. Engine threw oil pump chain and was driven until seized. Rebuilt/reinstalled. It runs but acts like it is in a "limp" mode. If you hold it at about 1000rpms it idles ok (a little smoke...) but if you let it go the idle wll dive to almost nil and then something kicks in and pulls the idle up to avoid a stall, then it lets go and the idle dives and then it kicks in, etc... Everything should be mechanically ok... (and it starts really hard..as if the glow plugs are non-existant, but they tested out ok;voltage ok, plugs ok, burn like crazy!) I still need to try and time the injection pump, but it idles a little too good at 1000rpms for me to blame that and it shouldn't have been able to jump time as the timing chain never came off...
I guess my question is, when the motor locked up (and presumably just about EVERY sensor in the car totally sh** itself and freaked out) could it have blown up some part of the computer or some resistor or sensor or....SOMETHING?
And if NOT what else could be the issue??
I really want this thing GONE, I want to be done w/ it. (Three things not to do w/ friends: lend $, mess w/ their girl, promise to fix their car!)
Thakns guys,
-Matt-

TX76513 · #2 08-19-2004, 04:50 PM

Matt,

A diesel engine miss results from one or more cylinders not burning fuel properly. This is caused by an injection system problems which include
Faulty injectors
Clogged Fuel Filters
Incorrect injection timing
Low engine compression

Injection system leaks
Faulty Injection pump

You said it seized up - did you rebuild or is this a drop in?

RunningTooHot · #3 08-19-2004, 05:11 PM

You said “rebuilt/reinstalled”. Then you said: “the timing chain never came off”. A rhetorical question: how do you rebuild an engine without taking the timing chain off?

gsxr · #4 08-19-2004, 05:20 PM

Starts hard AND runs like crap? You need to:

1) Pull valve cover and verify timing chain stretch (should be zero to 4 degrees). Timing chain inspection procedure is at this PDF file.

2) Check IP timing (start of delivery)

My money is on #2. Especially if you had removed, then re-installed, the injection pump. Wouldn't hurt to crack one injector line at a time at idle, see if any 1 particular cylinder is causing the problem.

350SL4spd · #5 08-19-2004, 06:20 PM

TX76513:
Brand new fuel filters, all injectors are functional, new rings so comp is tops, and I am praying that the IP is not sticking somewhere from lack of oil.....I do need to get the timing checked out, that's my next step. It was rebuilt.

And I mis-spoke...the head came off, so the cam gear came off, but the chain stayed in, meaning that the IP gear shouldn't have been able to jump a cog btw it and the crank, so the pump timing shouldn't have changed in relation to the crank (right?).

gsxr:
Chain has no slop in it...188kmi, but it's still tight. The injection pump never came off...It was left on the side of the motor, so I was hoping timing would not have changed. All injectors are spraying.....
I guess Pump timing needs to be confirmed before i go further

Any other electrical bugs to watch out for?

Thanks all!
-M-

gsxr · #6 08-19-2004, 11:56 PM

From what you describe, it is pretty likely that cam timing is one tooth off, and/or your IP timing is *way* off (maybe 15-18 degrees, about 1 'tooth', and requires pump R&R to correct.) I've done this job and I know how easy it is for the cam, crank, and IP timing to get out of sync. If you didn't check this by rotating the engine multiple times when the head was installed, verifying cam timing first, and IP timing second... well... you'll see.

Electrical problems, or internal IP issues, are MUCH less likely (IMO). That is unless you fiddled with IP delivery valve seals or something, but it doesn't sound like it - I got the impression the IP went to a diesel shop and came back 'fixed', and you just popped it in place. (And that's exactly when the timing got off...)

AusMBtech · #7 08-20-2004, 06:34 AM

Just a thought.............I've seen a 603 timing pump reinstalled 360deg out (180deg at the pump) I don't know how it ran, but it would rev with HEAPS of smoke but wouldn't go below 1200rpm....................just a thought

TX76513 · #8 08-20-2004, 08:14 AM

WDBA -

Engine threw oil pump chain and was driven until seized

This happened to my 300D while idling in the driveway. I did a PM's overhaul but my timing was off -probably from the force of the engine comming to an abrupt halt. I would be very suspicious of timing

gsxr · #9 08-20-2004, 11:27 AM

Quote:

Originally Posted by AusMBtech

Just a thought.............I've seen a 603 timing pump reinstalled 360deg out (180deg at the pump) I don't know how it ran, but it would rev with HEAPS of smoke but wouldn't go below 1200rpm....................just a thought

Good point. I heard of an OM617 that got 4 or 5 different IP's trying to fix the smoking & awful running problem. Turns out it was installed 180 degrees out - basically with the crank in the right position, but the camshaft 180 degrees out relative to the crank. The cam & IP need to be on the same cycle. All goes back to what I was saying, I think the IP timing is WAY off (assuming the cam & crank are properly in synch - which I'm not convinced of either...).