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Discussion Starter #41
Didn't check that. I'll try again.

I consulted with another shop this morning. Another specialist, very thorough and reasoned in manner. He doubted the usefulness of a leakdown test, but hearing the story also seemed to share the opinion of most on this forum--that the problem was indeed with the top end given the symptoms before and after the job, as well as the scope of work being performed. He felt that at the very least, the head should be removed and inspected by the person who did the work, regardless of where the problem may be originating from.
 

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Discussion Starter #42
Just tried it again. Had someone stand behind the car to watch. No oil spewing, just some white smoke. Tried putting my hand over the filler aperture as well and there is a slight vacuum.
 

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Thanks for the helpful comment H.D. The question remains though, if one artificially induces some vacuum under the valve cover and the car coughs up oil, is this a sign of anything or is it a sign that valve guides are shot and in normal conditions without this vacuum, oil may still get thru the valve guides?
I only let the engine idle for a minute, no more and there was a large oil stain under the exhaust pipe.
The only other time this (oil stain under the exhaust pipe) happens with my car is during warm after an overnight cool down.
That doesn’t necessarily imply that the valve guides / seals are bad or that there is excessive blow-by ...

Picture that strong vacuum under the valve cover, caused by that small rubber hose … plus picture normal blow-by which can only leave the crankcase via the oil return channels, which it does more hastily than without that strong vacuum ... entraining draining oil … What are the odds of no blow-by/oil mixture getting sucket through that small hose into the combustion chambers?

Of course, if you have, for instance, bad exhaust valve guides / seals, more exhaust gas is sucket through them by that strong vacuum too ... also entraining some oil ... which is also sucket into the combustion chambers through that small hose. But how can you tell from which spot under the valve cover the oil is sucket in? ... So, I wouldn't base my diagnosis on such a (unrecommendable) vacuum test.

H.D.
 

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That doesn’t necessarily imply that the valve guides / seals are bad or that there is excessive blow-by ...

Picture that strong vacuum under the valve cover, caused by that small rubber hose … plus picture normal blow-by which can only leave the crankcase via the oil return channels, which it does more hastily than without that strong vacuum ... entraining draining oil … What are the odds of no blow-by/oil mixture getting sucket through that small hose into the combustion chambers?

Of course, if you have, for instance, bad exhaust valve guides / seals, more exhaust gas is sucket through them by that strong vacuum too ... also entraining some oil ... which is also sucket into the combustion chambers through that small hose. But how can you tell from which spot under the valve cover the oil is sucket in? ... So, I wouldn't base my diagnosis on such a (unrecommendable) vacuum test.

H.D.
Sorry H.D., I'm not an expert in internal combustion engines. Just an electronics engineer. So please be patient with me if I'm making wrong assumptions.

How can more oil get into the combustion chamber when a moderate vacuum is created in the valve box by any means other then thru the valves?
What other path is there for the oil to get in there?

I do not see a scenario in which blow-by thru the piston rings has changed at all by this vacuum. Perhaps I do need a picture. Keep in mind that this is a M103 engine that does not have an EGR valve, so the only way oil gets into the combustion chamber is thru the intake or the valves or the piston rings. I do not think we effected anything but the valves here. Your insight would be appreciated.
 

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Not mine either. H.D. There is a direct hose connection from the crankcase to the valve cover. I suppose this it for the blow by gasses. So perhaps the vacuum created with the breather hose plugging is also applied to the crankcase assuming a one way check valve is not present. Not sure if a vacuum in the crankcase would push oil up the cylinders. I thought that would have the opposite effect if any at all in terms of pushing oil up the piston rings.
 

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... Perhaps I do need a picture. ...
Haha … yeah … usually when I explane stuff, I’m being watched and listened to while I create sketches … saves a LOT of time.

... How can more oil get into the combustion chamber when a moderate vacuum is created in the valve box by any means other then thru the valves?
What other path is there for the oil to get in there? ...
The vacuum in the valve box is created via that small, about half an inch thick, rubber hose next to the thicker breather hose. … And it’s not moderate when you block the regular breather hose opening, it’s significant !

And that small rubber hose is the path via which the oil gets into the combustion chambers.

... I do not see a scenario in which blow-by thru the piston rings has changed at all by this vacuum. ...
And I didn’t say that it changes, I talked about “normal blow-by”. … With that significant vacuum in the valve box it’s just sucket faster through the oil return channels, entraining oil.

... the only way oil gets into the combustion chamber is thru the intake or the valves or the piston rings. I do not think we effected anything but the valves here. ...
Don’t forget that small rubber hose ! :wink_2:
 

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But the rubber hose just goes into the valve cover, not into the intake. Valve cover is already full of oil.
Still confused....
 

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One end of it … yes. … But the other end of it goes into the intake. … Check what I said in post 37. :wink_2:
OK, I think I'm getting the picture. I thought it was going to the crank case, it actually goes to the intake.
I have an extra cylinder head, and I just checked, the two hoses are virtually connected under the valve cover like you say.

So when I blocked the breather hose and created a vacuum in the valve cover as well as the intake.

But I still do not understand why oil is being sucked into the intake when this happens. Seems a positive pressure could push the oil thru the small hose.

Can you once again explain why oil is flowing thru the small hose to the intake when there is a vacuum in under the valve cover?
If anything it should go the other way
 

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Thanks. Am following the M103 oil consumption thread above and the comparison of dealer versus independent rates have me wishing I'd gotten a quote from the dealer. Spent $2800 on the head work alone...and I supplied the gaskets.
Sorry to go off-topic, but I gotta say, that's too much. I did mine for less than $1280 with machining and parts including pistons, timing chain, seals, head gasket, and some other stuff excluding the valves, oil pump and the guides. All parts are non OEM originals from the manufacturers (if I get the right English choice of word here), valve stem seals are OEM, and pistons are some high quality Turkish made. If my mechanic goes to where you live he's gonna get rich in no time, and he's good.
 

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OK, I think I'm getting the picture. I thought it was going to the crank case, it actually goes to the intake.
I have an extra cylinder head, and I just checked, the two hoses are virtually connected under the valve cover like you say.
So when I blocked the breather hose and created a vacuum in the valve cover as well as the intake. ...
Bingo!

... But I still do not understand why oil is being sucked into the intake when this happens. Seems a positive pressure could push the oil thru the small hose.
Can you once again explain why oil is flowing thru the small hose to the intake when there is a vacuum in under the valve cover?
If anything it should go the other way
That vacuum is created by the engine’s downwards moving pistons via this small hose. … It’s the strongest in the combustion chambers … it’s a little weaker in the small hose … and still a little weaker under the valve cover. … In other words, the downwards moving pistons suck it through the small hose. :wink_2:
 

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I did tell you about the breather holes for gases to get sucked in to the engine you said the garage had looked in to them did you not
 

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Soooooo, to break this discussion down to what is relevant for the OP with the oil consumption problem, would it make sense to remove the small hose running from the cam cover to the intake manifold to check it for oil. And even if it is not a conclusive inspection, would it be worthwhile to make a small catch tank out of a rigid bottle of some sort and to run two hoses out of the top of it, one to the cam cover and the other to the intake manifold. This would replace the small elbow hose and not change the vacuum system but allow any oil that may be flowing out of the cam cover to be observed in the catch tank so this could be ruled out or in as the source of the oil that is being burned?
 

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Soooooo, to break this discussion down to what is relevant for the OP with the oil consumption problem, ...
Sorry ... I didn't want to distract attention from the OP's issue.

Two days ago I visited it for the first time when dolucasi wondered in post 32 (oldest post I’ve read) whether it’s normal that there is vacuum created under the valve cover when the breather hose opening is being blocked. … When a day later there was still no (correct) explanation from anybody, and dolucasi repeated his interest in one, I thought I should offer mine. :)

... would it make sense to remove the small hose running from the cam cover to the intake manifold to check it for oil. And even if it is not a conclusive inspection, would it be worthwhile to make a small catch tank out of a rigid bottle of some sort and to run two hoses out of the top of it, one to the cam cover and the other to the intake manifold. This would replace the small elbow hose and not change the vacuum system but allow any oil that may be flowing out of the cam cover to be observed in the catch tank so this could be ruled out or in as the source of the oil that is being burned?
I don’t say it is or is not “worthwhile” … but it might give you additional insight regarding the question whether oil consumption is caused by blow-by or by worn valve guides / seals ... however only at idle.

On the M104 it would, of course, have to be done in place of a different hose, due to the different crankcase ventilation system.

For higher revs it would have to be done in place of the normal breather hose between the valve cover and the air cleaner.

H.D.
 

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I don’t say it is or is not “worthwhile” … but it might give you additional insight regarding the question whether oil consumption is caused by blow-by or by worn valve guides / seals ... however only at idle.

On the M104 it would, of course, have to be done in place of a different hose, due to the different crankcase ventilation system.

For higher revs it would have to be done in place of the normal breather hose between the valve cover and the air cleaner.

H.D.
Thanks for your input. The reason why I was thinking more about the small hose is because the OP responded that there is no oil in the air flow meter chamber. Your point about the small hose being used more at idle is a good point. Since there is no oil in the AFM then is it plausible to eliminate the cam cover vent system as the source for the oil being burned in this M103?
 

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Let's close out the side discussion. On the M103 engine what I did was a no-no. Period...
I do not have an M104 engine any longer so I can not comment on the venting of the gasses for it.

Sorry for the confusion and the side discussion.

The OP already suggested there is no indication of vacuum or pressure build up under the valve cover.
He also observed no oil burning during warm-up which is indicative of bad valve guides/seals.

No-one here has a fool proof way of vindicating the bottom of the engine and also it had not been touched by the mechanic anyway. I still think a leak down test and compression test for $200 is worth the effort but that is up to the OP.

My suggestion is for OP to take the car to a trustworthy mechanic and tell them the whole story and get it fixed if it bothers him. My car has been living with the oil consumption for many years now....

I would start with the dealership for warranted work and pay a few hundred dollars extra if a trustworthy mechanic can not be found in SoCal.
 

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Discussion Starter #60
I am going to be taking the car in for a leakdown and compression test from a third party on Friday.

One thing I told one of the mechanics I visited, which prompted a good chuckle on his end, was that I supplied a number of parts and noted that something pertaining to the valves was returned to me. I said, "they come in these little inch square boxes, Corteco brand. I just assumed that they weren't comfortable using parts supplied by me and used their own." His response: those are the Mercedes parts, they could have forgotten to do the valve seals. It's possible, people make mistakes."
 
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