M112 Engine E280 V6 Oil in cooling system woes
05-02-2014, 06:28 PM
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2006 W203 C200K, 1998 W210 E280 (totalled), 1993 W124 200E (sold)
M112 Engine E280 V6 Oil in cooling system woes
Hi, removed right hand cylinder head on M112 E280 V6 today because of suspected head gasket failure. In between cylinders in water jacket I found a broken O-ring, presumably made from silicon (see attached pictures). Gasket showed no signs of failure but left hand cylinder head is still to be removed. Cooling system was severely oil contaminated - 3 liters of oil was consumed (lost in water channel??? 
) over a distance of 120 km which I consider to be very excessive for the distance even with a blown cylinder head gasket. I just wonder whether the O-ring could be responsible for oil reaching into the cooling system but I have no idea where it came from. Any ideas??
Attached photos show the muck in thermostat housing, the O-ring seal in cylinder head and as show-off the O-ring next to my home-made camshaft alignment tools 
. The O-ring dimensions are approximately 48mm OD, 38mm ID and 6mm thick.Suggestions highly appreciated
01-31-2018, 12:55 AM
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1999 W210 - AMG E55 - Euro Spec.
Did you ever figure out the source of your contamination?
Sorry to revive a long dead post but the circumstances or so dang similar and still unresolved. I have a 1999 CLK320 with the M112 and I'm pumping water to the oil and not the other way around. This is not the product of short trip condensation and my 112 does not have the cooler built off of the oil filter housing.
I had milkshake in the motor but no oil in the coolant. I pulled the heads and found at least one potential source of burning coolant, had the heads milled, and then put it all back together. The codes cleared up; car runs well; but I'm definitely still contaminating.
Fluid is mixing in one direction only; high pressure coolant to low pressure oil. I also found that specific gasket wedged between the same cylinders.
Anyone?
I had milkshake in the motor but no oil in the coolant. I pulled the heads and found at least one potential source of burning coolant, had the heads milled, and then put it all back together. The codes cleared up; car runs well; but I'm definitely still contaminating.
Fluid is mixing in one direction only; high pressure coolant to low pressure oil. I also found that specific gasket wedged between the same cylinders.
Anyone?
02-02-2018, 04:56 PM
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2006 W203 C200K, 1998 W210 E280 (totalled), 1993 W124 200E (sold)
Sorry to revive a long dead post but the circumstances or so dang similar and still unresolved. I have a 1999 CLK320 with the M112 and I'm pumping water to the oil and not the other way around. This is not the product of short trip condensation and my 112 does not have the cooler built off of the oil filter housing.
I had milkshake in the motor but no oil in the coolant. I pulled the heads and found at least one potential source of burning coolant, had the heads milled, and then put it all back together. The codes cleared up; car runs well; but I'm definitely still contaminating.
Fluid is mixing in one direction only; high pressure coolant to low pressure oil. I also found that specific gasket wedged between the same cylinders.
Anyone?
I had milkshake in the motor but no oil in the coolant. I pulled the heads and found at least one potential source of burning coolant, had the heads milled, and then put it all back together. The codes cleared up; car runs well; but I'm definitely still contaminating.
Fluid is mixing in one direction only; high pressure coolant to low pressure oil. I also found that specific gasket wedged between the same cylinders.
Anyone?
My problem was eventually resolved when I replaced the oil cooler which is fitted next to filler cap. I did a fair amount of mileage which included towing a caravan for 1100 km on a single stretch with no further problems. What I have done were:
1. Heads were skimmed - I believe this was unnecessary
2. The 2 o-rings behind the cam gears/chain were replaced.
3. Head gaskets were replaced twice because I damaged the 1st replacement set when I found the origin of the 2 O-rings.
4. Water pump gasket was replaced.
I just had my faith restored in my car and then I totalled it in an unfortunate incident
Regards Andre
02-02-2018, 09:11 PM
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1999 W210 - AMG E55 - Euro Spec.
Hmmm
Hi there.
My problem was eventually resolved when I replaced the oil cooler which is fitted next to filler cap. What I have done were:
1. Heads were skimmed - I believe this was unnecessary
2. The 2 o-rings behind the cam gears/chain were replaced.
3. Head gaskets were replaced twice because I damaged the 1st replacement set when I found the origin of the 2 O-rings.
4. Water pump gasket was replaced.
I just had my faith restored in my car and then I totalled it in an unfortunate incident
Regards Andre
My problem was eventually resolved when I replaced the oil cooler which is fitted next to filler cap. What I have done were:
1. Heads were skimmed - I believe this was unnecessary
2. The 2 o-rings behind the cam gears/chain were replaced.
3. Head gaskets were replaced twice because I damaged the 1st replacement set when I found the origin of the 2 O-rings.
4. Water pump gasket was replaced.
I just had my faith restored in my car and then I totalled it in an unfortunate incident
Regards Andre
Were those Orings on the cams a source of water? I don’t have a cooler and my radiator is clean but obviously I’m pumping a lot of water over. The cooler was my first guess until o saw I didn’t have one. Not sure if the milling helped me or not, same as you.
that gasket wedged gives me pause. So does the water pump.
when you had the water pump off did you notice if there were any oil ports there?
02-03-2018, 04:27 AM
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2006 W203 C200K, 1998 W210 E280 (totalled), 1993 W124 200E (sold)
Photomonkey,
The 2 water channels from the engine block (1 from each bank left and right) run through the timing gear/chain cover. The 2 O-rings are the seals between the engine block and the timing cover which has to be removed to get to the O-rings. there are no oil ports behind the water pump as far as I remember. Please note that you get 2 types of gaskets for the water pump, a rubber/silicon type and one that looks like a proper gasket. Make sure you get the same one as originally fitted if you do replace it, so keep your sample.
It is quite a job to replace the 2 O-rings. The following needs to done:
Refitting the cam housing was to me very difficult with the cylinder heads in place. I damaged the (new) head gaskets in my efforts to do so hence the reason for replacing them twice.
Keep track of signs for oil in your radiator. Mine became so contaminated with an oil/water sludge that it had to be replaced *** well.
I had to rack my brains to remember what the exact procedures are as quite some time went past since I did it. If I think of anything else I will advise.
Good luck with your efforts.
Andre
The 2 water channels from the engine block (1 from each bank left and right) run through the timing gear/chain cover. The 2 O-rings are the seals between the engine block and the timing cover which has to be removed to get to the O-rings. there are no oil ports behind the water pump as far as I remember. Please note that you get 2 types of gaskets for the water pump, a rubber/silicon type and one that looks like a proper gasket. Make sure you get the same one as originally fitted if you do replace it, so keep your sample.
It is quite a job to replace the 2 O-rings. The following needs to done:
- Radiator, fan, belt and tensioner , power steering pump to be removed
- The water pump must be removed to get to all bolt.
- The main crank pulley must be removed.
- Timing chain and the 2 gears to be removed. The gears are bank specific.
- The front section of the oil sump must be removed to get to the oil pump.
- Oil pump to be removed.
- Finally the cam cover/housing. The 2 O-ring positions will be visible.
Refitting the cam housing was to me very difficult with the cylinder heads in place. I damaged the (new) head gaskets in my efforts to do so hence the reason for replacing them twice.
Keep track of signs for oil in your radiator. Mine became so contaminated with an oil/water sludge that it had to be replaced *** well.
I had to rack my brains to remember what the exact procedures are as quite some time went past since I did it. If I think of anything else I will advise.
Good luck with your efforts.
Andre
02-03-2018, 07:36 AM
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1999 W210 - AMG E55 - Euro Spec.
Oh man....
Photomonkey,
The 2 water channels from the engine block (1 from each bank left and right) run through the timing gear/chain cover. The 2 O-rings are the seals between the engine block and the timing cover which has to be removed to get to the O-rings.
It is quite a job to replace the 2 O-rings. The following needs to done:
The 2 water channels from the engine block (1 from each bank left and right) run through the timing gear/chain cover. The 2 O-rings are the seals between the engine block and the timing cover which has to be removed to get to the O-rings.
It is quite a job to replace the 2 O-rings. The following needs to done:
- Radiator, fan, belt and tensioner , power steering pump to be removed
- The water pump must be removed to get to all bolt.
- The main crank pulley must be removed.
- Timing chain and the 2 gears to be removed. The gears are bank specific.
- The front section of the oil sump must be removed to get to the oil pump.
- Oil pump to be removed.
- Finally the cam cover/housing. The 2 O-ring positions will be visible.
with your understanding of the ports....
if i I blew out those two gaskets would water be able to transfer to the oil? That sounds like the likely culprit to me.
If you confirm that could be a source of contanmination the next decision is if it’s worth the headache.... ugh...
thanks!
02-05-2018, 04:48 AM
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2006 W203 C200K, 1998 W210 E280 (totalled), 1993 W124 200E (sold)
Photomonkey,
The O-rings are between the engine block (the V-section) and the timing gear housing. The cooling system side is certainly a high pressure area there as heat is built up in the water channels of the block. The timing gears is on a low pressure area of oil the lubrication system as oils flows back into the oil sump. From your post you do not get oil in the water so yes, I do believe that is a possible cause of your problem. The fact that you found the O-ring (or both) between the cylinder sleeves certainly tells on that there is a problem. I certainly cannot guarantee that is Other causes could be cracked or warped cylinder head/s or head gaskets.
I am by no means a motor mechanic but I do my own repair/maintenance work where possible for most of my life as I do not trust the stealerships. I apply logic when confronted with a problem and will systematically work till I solve it as labour does not cost me anything - it only takes a bit longer and give ma an excuse to to buy tools
I certainly know what I would do if I was confronted with your problem.
I hope I was of help to you as I personally got no assistance from members in this and another forum to guide me in the right direction apart from one member of the Mercedes-Benz forum how remember that the older V8 engines had those O-rings and reckoned the later V-6 would most probably the same - he was right.
Good luck and happy
Andre
The O-rings are between the engine block (the V-section) and the timing gear housing. The cooling system side is certainly a high pressure area there as heat is built up in the water channels of the block. The timing gears is on a low pressure area of oil the lubrication system as oils flows back into the oil sump. From your post you do not get oil in the water so yes, I do believe that is a possible cause of your problem. The fact that you found the O-ring (or both) between the cylinder sleeves certainly tells on that there is a problem. I certainly cannot guarantee that is Other causes could be cracked or warped cylinder head/s or head gaskets.
I am by no means a motor mechanic but I do my own repair/maintenance work where possible for most of my life as I do not trust the stealerships. I apply logic when confronted with a problem and will systematically work till I solve it as labour does not cost me anything - it only takes a bit longer and give ma an excuse to to buy tools
I certainly know what I would do if I was confronted with your problem.
I hope I was of help to you as I personally got no assistance from members in this and another forum to guide me in the right direction apart from one member of the Mercedes-Benz forum how remember that the older V8 engines had those O-rings and reckoned the later V-6 would most probably the same - he was right.
Good luck and happy
Andre
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02-05-2018, 07:42 AM
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1999 W210 - AMG E55 - Euro Spec.
Photomonkey,
I hope I was of help to you as I personally got no assistance from members in this and another forum to guide me in the right direction apart from one member of the Mercedes-Benz forum how remember that the older V8 engines had those O-rings and reckoned the later V-6 would most probably the same - he was right.
Good luck and happy
Andre
I hope I was of help to you as I personally got no assistance from members in this and another forum to guide me in the right direction apart from one member of the Mercedes-Benz forum how remember that the older V8 engines had those O-rings and reckoned the later V-6 would most probably the same - he was right.
Good luck and happy
Andre
Your replies have been very helpful. When I first did the heads on the motor I read this thread a few times and was frustrated for you. It’s pretty clear, in my case anyway, that there is positive flow of water to oil that is WAY beyond condensation. The O-ring was an obvious clue that was being ignored when I was trying to diagnose on the first go too.
i really appreciate the time and effort to reply. You’ve helped clarify a lot of what needs done. Now the only decision is whether it’s worth all the work for what amounts to a car that’s already like a 6/10.
thanks a bunch!
08-19-2018, 09:49 AM
#9
I had this same issue on my c32. It ran like a champ but coolant was flowing into the crankcase. I pulled the motor in anticipation of headgaskets. When I removed the timing covers one of the ORINGS was missing!!!!! I think this is a common thing on m112. Often gets misdiaged as head gaskets. If it were a head gasket I believe I would of had rough starts due to coolant in combustion chamber.
01-14-2023, 08:10 PM
#10
M112 v6
Photomonkey,
The O-rings are between the engine block (the V-section) and the timing gear housing. The cooling system side is certainly a high pressure area there as heat is built up in the water channels of the block. The timing gears is on a low pressure area of oil the lubrication system as oils flows back into the oil sump. From your post you do not get oil in the water so yes, I do believe that is a possible cause of your problem. The fact that you found the O-ring (or both) between the cylinder sleeves certainly tells on that there is a problem. I certainly cannot guarantee that is Other causes could be cracked or warped cylinder head/s or head gaskets.
I am by no means a motor mechanic but I do my own repair/maintenance work where possible for most of my life as I do not trust the stealerships. I apply logic when confronted with a problem and will systematically work till I solve it as labour does not cost me anything - it only takes a bit longer and give ma an excuse to to buy tools
I certainly know what I would do if I was confronted with your problem.
I hope I was of help to you as I personally got no assistance from members in this and another forum to guide me in the right direction apart from one member of the Mercedes-Benz forum how remember that the older V8 engines had those O-rings and reckoned the later V-6 would most probably the same - he was right.
Good luck and happy
Andre
The O-rings are between the engine block (the V-section) and the timing gear housing. The cooling system side is certainly a high pressure area there as heat is built up in the water channels of the block. The timing gears is on a low pressure area of oil the lubrication system as oils flows back into the oil sump. From your post you do not get oil in the water so yes, I do believe that is a possible cause of your problem. The fact that you found the O-ring (or both) between the cylinder sleeves certainly tells on that there is a problem. I certainly cannot guarantee that is Other causes could be cracked or warped cylinder head/s or head gaskets.
I am by no means a motor mechanic but I do my own repair/maintenance work where possible for most of my life as I do not trust the stealerships. I apply logic when confronted with a problem and will systematically work till I solve it as labour does not cost me anything - it only takes a bit longer and give ma an excuse to to buy tools
I certainly know what I would do if I was confronted with your problem.
I hope I was of help to you as I personally got no assistance from members in this and another forum to guide me in the right direction apart from one member of the Mercedes-Benz forum how remember that the older V8 engines had those O-rings and reckoned the later V-6 would most probably the same - he was right.
Good luck and happy
Andre
