Need some advice. My 2006 w203 c180k estate experienced a sudden loss of coolant which unfortunately ended up in the oil sump. Apparently it's a fairly common problem on the m271 engine that a circular seal inside the thermostat housing dislocates and causes a leak. Lo and behold this is exactly what's happened on my car. The question is what is the best way to fix it? Can I just buy a new seal and put it back in the groove or is it more involved than that? Any tips will be much appreciated.
M271 water pump housing seal dislocated
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Thermostat seal or seal on the front cover where the water pump sits? Never seen a thermostat seal fail, seen lots of seals on front cover behind pump fail.
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Then it's a labour intensive job, you have to remove the timing chain cover, including all ancillary components. You will also have to remove crank pulley and cylinder head.
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That is what I feared... I changed the timing gears etc last year after the chain slipped so I got reasonably acquainted with the build up of the front of the engine then. In the mean time I've had a split compressor breatherhose the second failed MAF. Prior to that failing can magnets, oil in the wiring loom etc. I think the report card to mr Benz on this engine reads "must try harder"....
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A couple of observations that may be useful to anyone experiencing the same problem. From my observations coolant ending up in the sump can come from 4 potential sources:
1) The head gasket being blown.
2) The oil filter cooler.
3) The inner thermostat housing seal.
4) The inner water pump housing seal.
For 1 and 2 my understanding is that you would be likely to see oil in the coolant as well as coolant in the oil (which I didn't have). For 1 you could see compression loss, effect on engine running, vapors in the exhaust and contamination on sparc plugs (all good on mine). I believe for 2 you are also likely to see external leaks around the oil cooler.
I quickly narrowed the likely cause on mine down to 3 or 4 with 3 being the most likely culprit as I had to reseal it as part of my timing chain/gear repair a year and a half ago. I bought a coolant system pressure kit on Amazon for 50 quid, whipped the the timing cover off and pressurized the system to around 20psi. Shining a strong light and looking down the right (near side) of the cam chain casing (the path of the static timing chain guide) I could actually see coolant spraying out of the water pump housing. I took the water pump out and could feel the dislocated seal inside. I guess it's theoretically possible to push it back in but it was beyond me. I crafted a temporary fix by manufacturing a 32mm 4 inch long plastic pipe that fitted snugly within the water pump housing (bridging the the pump housing and engine block). I filled the seal grove and the length of the pipe with HT silicone. Not sure how long that fix will last but least I can drive the car until a figure what to do longer term.
1) The head gasket being blown.
2) The oil filter cooler.
3) The inner thermostat housing seal.
4) The inner water pump housing seal.
For 1 and 2 my understanding is that you would be likely to see oil in the coolant as well as coolant in the oil (which I didn't have). For 1 you could see compression loss, effect on engine running, vapors in the exhaust and contamination on sparc plugs (all good on mine). I believe for 2 you are also likely to see external leaks around the oil cooler.
I quickly narrowed the likely cause on mine down to 3 or 4 with 3 being the most likely culprit as I had to reseal it as part of my timing chain/gear repair a year and a half ago. I bought a coolant system pressure kit on Amazon for 50 quid, whipped the the timing cover off and pressurized the system to around 20psi. Shining a strong light and looking down the right (near side) of the cam chain casing (the path of the static timing chain guide) I could actually see coolant spraying out of the water pump housing. I took the water pump out and could feel the dislocated seal inside. I guess it's theoretically possible to push it back in but it was beyond me. I crafted a temporary fix by manufacturing a 32mm 4 inch long plastic pipe that fitted snugly within the water pump housing (bridging the the pump housing and engine block). I filled the seal grove and the length of the pipe with HT silicone. Not sure how long that fix will last but least I can drive the car until a figure what to do longer term.
Lesterthetester
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Hi oulrichs,
I know it's over 3 years since you made your "Genius" fix with the 32mm pipe, my question is did it last, did it work, i would really like to know as I don't fancy the big job of head off and front cover off?
Many thanks,
Lester.
I know it's over 3 years since you made your "Genius" fix with the 32mm pipe, my question is did it last, did it work, i would really like to know as I don't fancy the big job of head off and front cover off?
Many thanks,
Lester.
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