OM602 nailing under 1300rpm -- IP timing? - PeachParts Mercedes-Benz Forum

cscmc1 · #1 11-30-2009, 02:45 PM

I'm trying to decide what my next repair step ought to be... replaced head gasket (after having the head checked and valve seals replaced), and now my engine is nailing hard at idle. Smokes, too (and smells like unburnt fuel, I think). Injectors were checked by bgkast, and cam timing is within spec.

Will bad IP timing manifest itself in this way? It smooths out considerably over 1300rpm, but under harder throttle, it will smoke quite a bit at higher revs.

I'm not seeing much that's rpm-specific in searching this topic; thanks in advance for any guidance. Hope I can get away with adjusting the IP timing and call it all good!

sasquatchgeoff · #2 11-30-2009, 02:59 PM

Quote:

Originally Posted by cscmc1

I'm trying to decide what my next repair step ought to be... replaced head gasket (after having the head checked and valve seals replaced), and now my engine is nailing hard at idle. Smokes, too (and smells like unburnt fuel, I think). Injectors were checked by bgkast, and cam timing is within spec.

Will bad IP timing manifest itself in this way? It smooths out considerably over 1300rpm, but under harder throttle, it will smoke quite a bit at higher revs.

I'm not seeing much that's rpm-specific in searching this topic; thanks in advance for any guidance. Hope I can get away with adjusting the IP timing and call it all good!

Just on principle, I would prosecute any air ingress in the fuel circuit. Then I would check the IP timing.

cscmc1 · #3 11-30-2009, 03:04 PM

Quote:

Originally Posted by sasquatchgeoff

Just on principle, I would prosecute any air ingress in the fuel circuit. Then I would check the IP timing.

I had two obvious leaks initially, and have been looking for signs of more to no avail. This is good advice, though. I'll keep checking. I also should note that I loosened each injector line individually and while the idle dropped a little with each, the nailing didn't go away. Thanks for the reply, BTW!

sasquatchgeoff · #4 11-30-2009, 03:11 PM

You are very welcome - My situation was a cracked secondary filter housing that was allowing air in at some point, then the air would accumulate in the filter canister, causing nailing, rough idle, startups, etc. Drove me buggy trying to get to the bottom of it. Ended up rebuilding every replaceable part in fuel delivery, of course I swapped the filter housing last, and it was what solved the problem. Folks tend to over torque banjo fittings (myself included) to try to squeeze new life out of crush washers.

cscmc1 · #5 11-30-2009, 03:14 PM

I found several of your threads during that fiasco in my searching; what a nightmare! Glad you got it sorted out, anyway!

cscmc1 · #6 11-30-2009, 07:56 PM

No obvious signs of air leaks... but I'm still looking. It's idling REALLY rough with smoke when cold, but once warmed up, it's just nailing at idle. Anything over 1100rpm or so is smooth as silk. Odd. I didn't see much smoke once warmed up tonight, either, but it was dusk, so it would have been harder to see. Need to do a daylight warm run and see if she's doing any better. Maybe it was just burning some of the oil out that I put in the cylinders before I put the head on. I suppose the turbo would suck that right out and keep running it through for a little while, and I'm sure there was oil left over in there from the head gasket failure (when it was smoking like a locomotive). Maybe that's all burning out. I still have the nailing at idle to deal with and the rough (uneven, like a miss) cold idle.