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... 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."
My $0.02
Put off any focus on the bottom end (leak down test, additional compression tests, etc) because there was no issue before you had the head done and you have observed there is no appreciable crank case pressure indicating ring issues.

Spend your money this Friday having the mechanic remove the parts necessary to allow an inspection of the upper end of the valves, guides and seals to take place. First step would be to see if the seals are there. Second step would be to wiggle the valve in the guide to see if the guide is worn. Third, he should be able to measure the valve stem to see if it is worn. Finally, he if nothing else is found, he can install the new seals that the other mechanic returned to you. This is money better spent than leakdowns and compression checks on a motor that has no indication there is a bottom end issue.
 

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The man said "Trust but verify". The mechanic claims the compression is perfect, 180 on each cylinder.
I would want to know if that is true. If they messed up the oil thing, they probably messed up that too.
Also, what if we are all mistaken and the guides/seals are just fine on this car.

I agree I would have them check a few of the guides/valves really quick when they do the leakdown test as that requires the valve cover to come off anyway.
And I believe they may need to pressurize the cylinders for the valve check anyway, this can be done during the leakdown test as the cylinders would be pressured already.

I would want to know my engine is in perfect condition except the oil burning. Or if it is not,I would want to know that too before I throw more money at the problem.
 

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The man said "Trust but verify". The mechanic claims the compression is perfect, 180 on each cylinder.
I would want to know if that is true. If they messed up the oil thing, they probably messed up that too.
Also, what if we are all mistaken and the guides/seals are just fine on this car.

I agree I would have them check a few of the guides/valves really quick when they do the leakdown test as that requires the valve cover to come off anyway.
And I believe they may need to pressurize the cylinders for the valve check anyway, this can be done during the leakdown test as the cylinders would be pressured already.

I would want to know my engine is in perfect condition except the oil burning. Or if it is not,I would want to know that too before I throw more money at the problem.
BTW, I'm going to do this (leakdown test and valve guide check) on my own engine once I get a compressor. Should be a good weekend project.

So I'm in agreement with you.
 

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Discussion Starter #64
Here are the results of the third-party test:

Compression
Cylinder
1: 210psi
2: 200psi
3: 200psi
4: 205psi
5: 208psi
6: 200psi

Leakdown
Cylinder
1: 80/78
2: 80/78
3: 80/78
4: 80/75
5: 80/77
6: 80/76
 

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Here are the results of the third-party test:

Compression
Cylinder
1: 210psi
2: 200psi
3: 200psi
4: 205psi
5: 208psi
6: 200psi

Leakdown
Cylinder
1: 80/78
2: 80/78
3: 80/78
4: 80/75
5: 80/77
6: 80/76
As many of us have said, the bottom end on these motors is stout. Your mechanic should be pulling the cams next and inspecting the seals, guides and valves. OR he should be simply pulling the head for deeper inspection. Also, you should be preparing your small claims court offensive position.
 

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Well stradivari, those numbers are perfect, so rings are good, valves are good.

Your valve guides do not appear to show the symptom of dripping oil in the the combustion chambers when after cool down either.

I assume the leak-down test did not include a cursory check of the valve guides but I'm guessing no mess up there either. Hopefully they did not forget to put the valve seals in.

We have also ruled out the blow-by gasses being a major issue.

Honesty, at this point, I'm not sure if I would go deeper into this and pull the head off again with a new mechanic.
Seems you have no other issues related to oil burning, meaning nothing else is getting effect by it. You mentioned some idle hunt, etc but those are not related to oil burning.

Unfortunately, in this state, it will only take a couple of years before you will have to change the Catalytic converter. Also, you will need to change your spark plugs once a year, because they will get dirty. My car burns the same mount and there are no issues with ignition or combustion after nearly one year after the last tune-up/spark plug change. Getting ready for a tune-up now.

My position remains unchanged, if I were you, I would take your car to the dealership and tell them what happened to date. Ask them if they can help you. Most likely they will say "yep, we can fix this, and it will cost you xxxx dollars". Remember they are there to make some money on car repairs but they want a happy customer in hopes to see you a new car some day. If you can stomach the xxxx dollars, go for it, because if it does not get fixed, you will have it all back, I truly believe that.

This has been my experience with the dealership here.

And the good news is you actually know more about your engine then they do now, after all the tests, so they are not going to be able to BS you in any way.
 

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This has been my experience with the dealership here.

And the good news is you actually know more about your engine then they do now, after all the tests, so they are not going to be able to BS you in any way.
You have a unique dealership that you work with. Most don't have techs who know 30 year old engines and also most don't repair assemblies, they replace them. I'm not saying the OP can't find a dealer who would want to methodically go through a cylinder head, I'm just saying its rare these days.
 

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Discussion Starter #68
The dealer here in town said essentially, "you might as well write us a blank check."

Same dealer basically said the same thing when I asked about the subframe recall on a 450sl I just bought.

They clearly don't want to be bothered with old cars.
 

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The dealer here in town said essentially, "you might as well write us a blank check."

Same dealer basically said the same thing when I asked about the subframe recall on a 450sl I just bought.

They clearly don't want to be bothered with old cars.
Well, at least you tried. Maybe my case was a little different in that even though the dealership has changed hands since I bought the car from their showroom back in '89, they claimed the mechanic that probably worked on my car is now the floor manager.
It was nothing personal either, I had not been there to buy a car or to the shop in the last 15 years for any of my cars.

Now you have to decide to fix it or just let it be. I'm just waiting to pull my head until I have to change the camshaft and the rockers as well as the head gasket. Everything on my 103 head is original. No oil leaks whatsoever other than the timing cover plate, which has a diaper on it so it does not make a mess.

In the meantime, the CAT gets replaced every couple of years with an aftermarket Walker ($250) with labor and a quart of oil is put in every other gas fill up. You have to watch out for your next emissions test though, with all that oil burning, you may not be able to pass it without some trouble. Mine was difficult.

Or... you find a shop that you can truly trust and go for it.
 

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Seen it too many times!!!

As the previous owner of a auto repair shop I have seen too many times that you rebild the head and it pulls oil UP past the rings and causes oil burning. Its a simple matter of vacuum. I guarantee that this is the issue, the leakdown test works because its positive pressure you are dealing with NEGATIVE pressure.
 

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Discussion Starter #71
As the previous owner of a auto repair shop I have seen too many times that you rebild the head and it pulls oil UP past the rings and causes oil burning. Its a simple matter of vacuum. I guarantee that this is the issue, the leakdown test works because its positive pressure you are dealing with NEGATIVE pressure.
Is this something that will, then, remedy over time as the top end wears?
 

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No the rings wear in an arch to the bottom so therefore the top of the ring is at a larger dynamiter than the bottom, its an angle so the only answer is to do the bottom end or at least the rings to solve the problem.... not a happy alternative....
 

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Discussion Starter #73
No the rings wear in an arch to the bottom so therefore the top of the ring is at a larger dynamiter than the bottom, its an angle so the only answer is to do the bottom end or at least the rings to solve the problem.... not a happy alternative....
In your opinion, is this a problem that can be foreseen prior to starting a job like this? If not, is it something that is customarily brought up as a potential risk?

After the engine was disassembled and the bottom end exposed, could anything have been done to assess the cylinders with the block in situ and alert the mechanic to a potential problem before the engine was reassembled?
 

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Very interesting that this does not show up in the leak-down test. I was pretty sure that your valve guides are not warn but this assertion at least fits the original assessment of the shop. Top and bottom ends not matching...Hmmm. Compression of >200PSI sounds high to me but that must be normal for a brand new valve job. I also have a couple of questions to you both:

(1) Is there a way to definitely prove this is the case?
(2) Stardivari, what type and viscocity oil are you using? I suspect synthetics would be worse for this but certainly a viscocity of 20W50 may help in your case. That is what I use in my M103, 20W50 conventional.
 

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Discussion Starter #75
Very interesting that this does not show up in the leak-down test. I was pretty sure that your valve guides are not warn but this assertion at least fits the original assessment of the shop. Top and bottom ends not matching...Hmmm. Compression of >200PSI sounds high to me but that must be normal for a brand new valve job. I also have a couple of questions to you both:

(1) Is there a way to definitely prove this is the case?
(2) Stardivari, what type and viscocity oil are you using? I suspect synthetics would be worse for this but certainly a viscocity of 20W50 may help in your case. That is what I use in my M103, 20W50 conventional.
The shop that did the work reported compression of ~180psi across all cylinders. The data obtained yesterday were from a third party shop, now approximately 300 miles since the plugs were changed. He said that when he pulled the plugs there was no sign of fouling but did note the white smoke from the tailpipe. He didn't rule out that the bottom end could be contributing to the matter but at the same time felt that the oil consumption was excessive given the test results.

The car was put on 5/30 synthetic when the rebuild was done. I tried switching to 20/50 conventional around 5000 miles and it doesn't seem to make much, if any, difference.

One observation I've noticed is that the rate of consumption doesn't seem to be consistent through the 500 mile period. It will surely burn a quart every 500 miles, but sometimes no consumption is seen for the first 2 or 300 miles (and every time I see that I think, "ooh, maybe it's stopped") and then the consumption progresses rapidly over the next couple of hundred miles.
 

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Brycemack thank you , for that bit of information about the bore .I never knew about the ark . Would this be due to the way the piston travels, in line with the crank or would the ark be the same all around the bottom of the cylinder.?
 

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Further to oil burning

In your opinion, is this a problem that can be foreseen prior to starting a job like this? If not, is it something that is customarily brought up as a potential risk?

After the engine was disassembled and the bottom end exposed, could anything have been done to assess the cylinders with the block in situ and alert the mechanic to a potential problem before the engine was reassembled?
Lets face it the reason the top end needed work was WEAR whether it be valves or guides. Unless it was an issue with a head gasket look at the mileage on the assembly.

Whenever we did top end work on a higher mileage vehicle we ALWAYS told the customer of the potential of lower end issues coming to light with the rebuilt top end.

Sounds like your oil burning issue is just a little smoke and a quart of oil too regularily but bottom line is drive your nice car and remember your not making huge monthly payments on a new plastic car.

LOL
Bryce
 

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Brycemack thank you , for that bit of information about the bore .I never knew about the ark . Would this be due to the way the piston travels, in line with the crank or would the ark be the same all around the bottom of the cylinder.?
It's more a matter of FORCES on the rings when the engine is under compression and fireing stroke the force is downward. This causes a really tight seal of the ring to the cylinder wall. However in all other stroke the ring is not under pressure and the ring kind of floats and contorts in the bore. therefore the top of the ring remains larger and the bottom and sides wear more (yes marginally) but at 2000+ rpm for thousands of miles it makes a difference!

Bryce
 

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As the previous owner of a auto repair shop I have seen too many times that you rebild the head and it pulls oil UP past the rings and causes oil burning. Its a simple matter of vacuum. I guarantee that this is the issue, the leakdown test works because its positive pressure you are dealing with NEGATIVE pressure.
This might be more applicable with a"lesser" marque but low mile (under 150k) M103 bottom ends are tight. I did heads on two of my M103s (one at 230k and the other at around 175k)and both resulted in oil consumption of less than a quart between changes (3000 miles). My experience is not unusual with these motors. A quart every 500 miles is excessive and unusual.
 

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This might be more applicable with a"lesser" marque but low mile (under 150k) M103 bottom ends are tight. I did heads on two of my M103s (one at 230k and the other at around 175k)and both resulted in oil consumption of less than a quart between changes (3000 miles). My experience is not unusual with these motors. A quart every 500 miles is excessive and unusual.
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.
 
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