E300TD - Oil leak into injector recess

[big_mike]

Hi Guys,
Looks like the honey moon period is over! Number 6 fuel injector recess is filled with engine oil, only thing I can think if is that the rocker cover gasket is leaking. Doesn't seem to be a common fault (had a search on here and the net) Does anyone have any alternative suggestion or come across this problem before? Tempted to nip the rocker cover down a bit tighter but a little wary as it is an ally head and don't really want to strip the thread (assuming previous owner hasn't already...)

 

[spock500]

It sounds like the 'O' ring on the injector trumpet or at least I think that's what they're called - each injector has a trumpet inside the rocker cover, these are sealed with two 'O' rings, one at the bottom and one at the top.

You could try nipping up the bolts on the cover, may help the top seal but if not it's am easy fix

 

[big_mike]

Many thanks, I don't suppose anyone has a schematic of the head and valve cover do they? Want to know what goes where!

I am working on getting hold of the manuals but it is taking much longer than anticipated to sort.

Interestingly the black gunk appears to be closer to tar than engine oil (polymerized engine oil?) with a very slight bubbling going on which is presumably either the o rings leaking or the injector itself (but I would imagine the pressures involved with the injector would make this unlikely?)

 

[Number_Cruncher]

It's much more likely to be leak off from the push on small diameter flexible pipes. I would renew these first.

 

[spock500]

Just a quick thought, if it's engine oil could be the oil breather from the sump - on the OM605 it's under the plastic cover not sure on the OM606 as I have yet to take mine to bits

Poke a cotton bud down to see if it's diesel or engine oil.

If you have oil and it's bubbling then the 'O' ring has gone, if it was just bubbling then it could be the injector heat shield/seal.

 

[big_mike]

Have renewed the leak off pipes and whilst doing that noticed that the PCV bits and bobs where very loose. Have applied temporary fix (read bodged) and will see if that helps (looks like an accumulation of black crud from the crank case which floated to the top when the recess filled with water from washing off the degreaser). How does everyone else clean the injector recesses? Seems a bit deep and tight!

The elbow that fits into the rocker cover feels like hard plastic and is a crap fit, I am guessing it should be soft and pliable and a snug fit? How does it attach to the rocker cover? Will I need to whip the rocker cover off to replace it?

Sorry for all the questions!

 

[Number_Cruncher]

Yes, you're right, the crankcase breather tubing should be compliant. The elbow which goes into the rocker cover is a push fit; you may be better deliberately cutting it with something very sharp like a scalpel or Stanley blade, and then removing it bit by bit rather than trying to pull it out and risking part of it breaking off inside the cover.

If you also replace the rubber elbows on the inlet manifold, take care to ensure the drillings into the manifold aren't choked up - especially on the rearmost cylinders - the crankcase fumes are about the only lubrication the inlet valve seats get!

 

[big_mike]

Now that is interesting, my PCV vents into the inlet tract prior to the turbo (in exactly the same way as my Mitsubishi 4M40 engine did) are you saying that the PCV "fumes" should be venting closer to the inlet valves? or is that on the NA engine?

On the Mitsi engine I eventually decided to vent the crank case to atmosphere, I had excessive blow by and the extra pressure seemed to cause the turbo oil seals to fail (and I wasn't particularly happy about having oil mist hitting the turbine blades at 150,000+ rpm), certainly stopped the engine from turning turbo's into expensive scrap...

How serious a problem is valve seat wear on these? Presumably the main effect is loss of compression and / or slight cam timing effects?

 

[Smiley]

Valve seat wear will show up as poor running / idle when cold, as the head temperature rises (after a few minutes - does not take long) the valve seat closes fully - and there will be a reduction in compression of course - esp when cold.

 

[Number_Cruncher]

Now that is interesting, my PCV vents into the inlet tract prior to the turbo (in exactly the same way as my Mitsubishi 4M40 engine did) are you saying that the PCV "fumes" should be venting closer to the inlet valves? or is that on the NA engine?

Sorry, yes, on the NA engine fumes go into the manifold, on the turbo, they go in just before the turbo, and hence should be reasonably well distributed between cylinders, whereas on the NA engine if one of the small drillings into the manifold block, that valve seat gets no lubrication.

I wouldn't re-route the crankcase ventilation - the OM606 does suffer inlet valve seat recession.