Head gasket issue - Cylinder and oil passage breached? - PeachParts Mercedes-Benz Forum

ah-kay · #1 02-11-2012, 12:04 PM

Need the collective wisdom of the forum here. I suspect the HG is breached between 1 or/and 2 cylinder and the oil passage.

The symptoms I have with the SDL om603 engine are

1) Engine runs rough and shakes at idle. It drives OK at higher rpm.
2) Smoke coming out from the vent hole at the left back of engine. It indicates bad blow by.
3) Oil accumulates near head bolts ( bolt 1 and 2 ) nearest to radiator. It is definitely not from valve cover nor dripped from cross pipe. I noticed it for a while and, cleaned it and it always comes back.
4) Oil seems to normal color - no milk shake like color.
4) Engine does not overheat, no oil sheen in coolant.

Any ideas? Could it be the HG? What test I can do to confirm, compression test?

jt20 · #2 02-11-2012, 12:44 PM

1) Not really indicative of failed HG unless there is combustion smoke at tailpipe. More likely an IP / fuel supply issue.

2) The one on the VC? -Could just be normal blowby, but if it was due to the HG, one would imagine that you might see some oil in the coolant by that point. Noticeable blowby due to HG is pretty severe.

3) It comes up from below them? Hard to imagine, but certainly sounds like HG.

4) Oil analysis will provide much more info. It still SOUNDS like your HG is doing the job, but may have a minor breach (one where all fluids remain separate, but are not properly contained).

4.2) Oil analysis.

If a compression was worth identifying an HG issue, you would have some serious failure on your hands. Comp test might tell you something else, but not really worth a valid HG inspection. If you really want to, test the #1 cylinder, it might say something, but don't rely on it solely.

If your head is over 250k miles, it probably needs a rebuild.

Quote:

Originally Posted by ah-kay

1) Engine runs rough and shakes at idle. It drives OK at higher rpm.
2) Smoke coming out from the vent hole at the left back of engine. It indicates bad blow by.
3) Oil accumulates near head bolts ( bolt 1 and 2 ) nearest to radiator. It is definitely not from valve cover nor dripped from cross pipe. I noticed it for a while and, cleaned it and it always comes back.
4) Oil seems to normal color - no milk shake like color.
4) Engine does not overheat, no oil sheen in coolant.

Any ideas? Could it be the HG? What test I can do to confirm, compression test?

sixto · #3 02-11-2012, 02:18 PM

What jt20 said plus:

1) Sounds like a compression problem.

2) What vent hole? You might have an exhaust leak.

3) If it's oil it's from the crossover pipe or intake manifold. New gaskets or old gaskets with RTV should help. If it's not oil, it's fuel that's gotten grimy. It should still smell like fuel, though.

4) Look for mayonnaise under the oil filler cap.

4') Good for you

I don't know that a 603 head with 250K miles needs to be rebuilt but it very likely needs a new head gasket.

Is there any coolant loss? Is there residual pressure in the cooling system after the engine has sat overnight (radiator hose pinch test)?

Sixto
87 300D

NJ300sdl · #4 02-11-2012, 02:26 PM

1. I had a bad injection pump when rough idle happened one year after doing head gasket.

Remove the #1 injector and turn the engine over, may show if head gasket is bad. Had one spray lube oil ten feet when the head gasket was not sealing at forward oil passage. Easier test is to remove plug at #1 exhaust and see if oil is present.

Have done two 603 head gaskets. One was putting a little oil in the coolant for years and then started to run rough at low rpms. The other sent alot of oil into #1 cylinder and the coolant was clean.

ah-kay · #5 02-11-2012, 02:30 PM

Thanks for the info.

The car has 345K. Not sure the HG has been replaced before. I need to look up the record from previous owner. No coolant loss, top radiator hose is soft ( pinch test ) to touch in the morning, not rock hard. The vent hole is at the left back of the valve cover, the hole is small and is not supposed to be covered. More info.

When car is idling, it shakes and as if it is missing. Injectors replaced with new nozzles but not balanced yesterday as I first suspected fuel delivery. Do not help.

When smokes out of the vent hole at idle, I can see oil droplets squirting out. It lands on the exhaust and gives a burning smell. So the blow-by thru the vent hole is quite severe.

GregMN · #6 02-11-2012, 04:12 PM

Quote:

Originally Posted by ah-kay

1) Engine runs rough and shakes at idle. It drives OK at higher rpm.

My experience with the same symptoms on the same engine (not my car):
The low compression cylinder(s) does not fire at low rpm.
When you increase the rpm's the turbo adds enough extra air to compensate for the low compression and the cylinder fires. Most noticeable starting around 2300 rpm.

In this case it was carbon impacted rings. Nothing to do with the head gasket.

Crack the injector lines open at each injector, one at a time, to find the weak cylinder(s). Swap injectors with a good cylinder. If the weak cylinder remains the same, it is the cylinder. If it follows the injector, it's the injector.