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One more thing Bryce. I was going to suggest one more thing with this Engine before the leak down test, but I did not want to sound stupid as I am not a mechanical engineer, neither a mechanic. From the physics of the whole bottom Engine, I understand that one can do the leakdown test at different piston positions. The most common is TDC because that is close to the combustion but leak down tests can also be conducted in any position as long as all of the valves are closed for that cylinder.

Firstly, is this true, second, would multiple leakdown tests at different positions reveal this piston ring issue because we can show the signs of the uneven ring (and maybe even cylinder) wear.
 

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Hi Tuttebenne, this is a higher performance M104 Engine. I'm just an observer of this forum with the M103 Engine and a previous owner of the M104 engine.

I'm just surprised that no one else with a M104 Engine who has done the exact same thing is chiming in here. So why is this case a one off in this forum? It should be more common among same Engine class. Maybe a M104 valve only job is not that common? It is very common with M103 but M104 could be a very different matter all together. Basically, Mercedes has squeezed 25% more compared to a 2 valve old style engine in a 4 valve M104, even if with same material used, perhaps the wear patterns are different.
Ducolasi, Just my opinion, but I think all the M104 boys abandoned trying to help with this thread once they saw there was little progress being made and the responses were starting to sound unrealistic and bordering on comical. The main difference between an M104 and M103 is the number of valves and related valve gear. This means the number of guides through which oil can flow, the number of seals that can leak oil passed and the number of valves that could be worn, is DOUBLE that of an M103. A shoddy job on an M104 head has the potential to causse oil consumption that is more serious on an M103 vs an M104. I know the differences between the two of them but the block, rings, and cylinder wear characteristics could hardly be considered to be unique to the M104; its the head that is where all the action is at.

I know there are those who want to explore the esoteric nature of mid stroke ring leakage and ring wear and I would not deny this is very remotely possible if at all. However we are talking about an engine that:
- is burning a quart of oil every 500 miles,
- has enviable compression ring and cylinder wall performance
- had minimal oil consumption prior to the head rebuild,
- unfortunately has seen a significant increase in consumption shortly after having the head work performed.

The recent test result support the observations of many who have tried to help with this thread. The boxes of unused new valve stem seals is a compelling piece of information that should be followed up on before any other actions are taken.

I hope the OP can solve the problem he has because, after all, its his problem to solve. Those of us who have been contributing have been trying our best to reduce the pain and to shorten the process and I guess the intangible aspect of this problem is what prevents a straight path directly to the solution but most of us have been trying to stay away from the types of solutions that are extreme and unnecessary.

It is becoming painfully obvious that the OP either will have to accept the oil consumption and all the damage that will go with it, or invest in more serious diagnostics with either the head on the engine or off.
 

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Discussion Starter #83
Visited the mechanic to pull the valve cover off and check to see if the guides and seals are in place, which they are.

However, I showed him the results of the compression and leakdown tests. He's agreed to remove the head at no charge and send it back to the machine shop for evaluation.
 

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Visited the mechanic to pull the valve cover off and check to see if the guides and seals are in place, which they are.

However, I showed him the results of the compression and leakdown tests. He's agreed to remove the head at no charge and send it back to the machine shop for evaluation.
That's a big step. At least the leakdown test was not a complete waste afterall. Keep us posted Stradivari! Cheers!
 

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Discussion Starter #85 (Edited)
One thing I did bring up was if anything else *aside from* the engine proper could be causing the oil consumption. He once again brought up the matter of the PCV valve that he had replaced but then also pointed to a hose leading from the intake to an area behind the A/C compressor and steering pump, saying something about a filter that's in that area and something about "crankcase ventilation."

What are your thoughts about this and what is he referring to?

Our plan of action is to remove the head and send it back to the shop that did the rebuild. He doubts that the shop made any mistakes because of his long-running relationship with them, and I understand his level of trust, but when I showed him the leakdown results he conceded that even the best make mistakes. If the head is without fault, he will give me the option of reassembling everything, also at no charge or proceeding with the bottom end, and I made it known I would probably just have him put everything back together and accept the result of the evaluation. I did mention considerable regret at having opted for the complete rebuild of the head as opposed to just doing the gasket, saying that I wouldn't have done the former if I knew that this excessive oil consumption would be a potential sequela. Obviously I am hoping something is found, but if not, I suppose it is what it is. I like the 104 motor a lot and I figured it would be better to do everything on the top end while it was out of the car thinking that I would have a very nice running motor after all was said and done.

I should also mention that the shop that did the leakdown test called to follow up as well. I was pleasantly surprised by that bit of customer service.
 

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Strange that he brought up the PCV valve. Recall, that's the only other possible source of oil fumes getting into your intake and straight into the cylinders from there.

I wonder if that got messed up somehow. Did you ever ask him why he changed it? Anyway, he should make sure everything is OK with that PCV valve. Basically there are fumes going directly from there into the intake as I was reminded by H.D. I think the PCV valve helps to pass air and less of the oily fumes from under the valve cover.

Anyway it is a long shot but better check that out and see if the end that goes into the intake is oily. (not sure it that was done already)
 

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In my post 54 i did mention to ask the garage to check the crank case ventilation .holes , If the system is blocked in any way, then it will pressure the oil system .
 

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Great posts guys and I certainly agree that with low mileage and the only thing being done to the engine and THEN an oil burning issue it SHOULD be the head having a problem!

This is the problem with a 1000 mile diagnosis on Any vehicle...

I will await the outcome....

Bryce
 

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Discussion Starter #91 (Edited)
@tuttebenne:

I do have an update. The shop was too busy to take my car back in as of the last post, but the job was finally scheduled on the 13th. To make a long story short, the head was removed and no problem was found per the mechanic. I do have a number of pictures that he sent via phone that I can upload over the weekend. However, he said that there was considerable debris and muck in the intake manifold, as well as whatever it is that is responsible for crankcase ventilation in the bottom end of the motor, and something having to do with the valve cover. He replaced the intake manifold and valve cover. Said the car no longer smokes but I started it up yesterday to move it and there was a puff of white smoke. Less than before, but it was there. Additionally, the water and ABS lights were on after reassembly but systems appear functional (car even runs at a slightly lower temperature than before)

He said that's all he can do for me, so I'm just going to move on from it.

Now to add another layer to this and probably fodder for a new thread...
Some may recall that I mentioned a hunting idle and very occasional stalling issue--which I assume is unrelated--he replaced the OVP relay and the plug connector that attaches to the harness. He also swapped out the throttle actuator with one I had hanging around for testing purposes. The one that came with the car had a 2004 date code, this spare had a 1995 code and was therefore suspect.

Took the car out from the shop after he said he'd tested it for a full day and it promptly died on me within a mile. Had it towed back. Next day he said he'd reinstalled the 2004 actuator, so I came to collect the car. Wouldn't start. Had him take me to work, called at my lunch break, and said the car was ready.

Returned to collect the car. The idle was very high in neutral (~1500) and about 900 in gear (about 400-500 rpm higher than I was accustomed to). Other than that it ran very well. Drove a good 15 miles or so without incident. Shut the car off a couple of times too to ensure that it would restart. Third time, however, it would just start and die. I could barely put it into gear before being able to move it, so I had to leave the car in a local parking lot, have someone from work give me a ride back to the office and then return that evening to call AAA to have the car towed back home. Mechanic is calling leaving messages postulating that the fuel pump or actuator are at fault, which I don't dispute, but I've chosen a new shop after discussing my situation with the proprietor of said shop. He's willing to examine and feels he can give a definitive diagnosis without any willy-nilly pissing-in-the-wind postulating but cannot take my car for at least a week.

The car runs terribly now. Sputters, misses, if it doesn't stall altogether. Water light is still on, but ABS light is out. Check engine light intermittent as it has been.

For reference, MAF, ECU, starter harness, fuel pump relay, fuel pressure regulator, and engine harness have all been replaced on the car during the last 12-18 months.

So right now I'm beyond the oil burning issue because I can't even use the car without worrying that it will conk out at the foot of my driveway. When it stalled the first time after I picked it up end of last week, the only place I could manoeuvre it into was in front of a fire hydrant!
 

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Sorry to hear about your experience with this car. Unfortunately the only advice we can give you st this point is to look for another mechanic unless you are able to pull up some error codes from the built in diagnostics box and post them here.



Sent from my iPhone using Tapatalk
 

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Starivari, seems you nightmare has gotten even worse. I have now lost track. Did the same mechanic that worked on your head originally performed the second removal and check?
 

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Help yourself to acquire Hfmscan and a cable, so that you can find out why your engine is behaving as such. The problem is now not exactly related to the head gasket. Read my threads on Hfmscan to know how it can help you.

jftu105
 

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Strad -- Sorry to hear you still have a problem . I wish you all the best in getting the car up to normal healthy running .
Its such a worry when the car is problem , as it never lets you rest. Good luck ..
 

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Stradivari, I went back and read your entire thread again. Your car seems to be in a death spiral. Sorry.

My conclusion is that something happened to your PCV after the first rebuild. That caused oil burning as well as major gunk all over your intake.
And seems that also triggered other problems. Not sure if the problem is fixed now either. You did not mention if the car is still burning 1 quart/500 miles. Since you had the intake replaced did the mechanic give you the old intake for you to inspect for gunk yourself? I sure hope so.

But all this is past history now. You have to decide whether you want to resurrect this car or just get rid of it. My recommendation is that if you do want to keep the car you need to become a DIY person. Otherwise it will cost you a lot of money and also you will not be aware of things being done to your car.

There is plenty of good advice in this forum should you decide to become a DIY'er. That is what I've become and have fixed most of the issues with my car in the last year. But my situation is different, I'm resurrecting the very first new car I bought back in 1989, and it is a harder to find stick shift W201.

I wish you good luck with your decision making process.
 

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Thanks for the update. Sorry the second attempt at removal of the head didn't resolve the issue as hoped. It is a wise decision to move on to another mechanic and to leave the one who never fails to point at new causes at every opportunity. Keep us posted. I will have a little more patience now that you are working with a new shop. :)
 
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