I could not find a thread that mirrored my problem so I started new. My CLK320 has 96482 miles on it and I was told it was in great shape. Recently, the "low coolant" warning came on, I added distlilled water to the reservoir and took it in to my indie mechanic who replaced the reservoir cap saying it was worn. The problem recurred, the mechanic pressure tested for leaks and found none but said the front shocks & upper control arms and the right front catalytic needed replacing - I did this (10/3/05) for $1235 assuming the coolant problem was resolved. It recurred however, but accompanied by rough running immediately after starting; apparently there was oil was in the coolant and water in the oil so the diagnosis was to replace the head gaskets, manifold gaskets, and of course spark plugs, filters & crankshaft pulley and have a machine shop do a valve job - all this cost $2996! Incidently, there was nothing explicitly stated about resurfacing the head.

I was miffed but glad the problem was resolved. I got the car back Nov 1 and the next morning experienced the same rough starting and found the coolant reservoir very low (no warning liught though) - topped it up with distilled water and took it back to the shop. They kept it for 2 days. They said there was some residual water in the engine probably, and there were traces of oil in the coolant - "difficult to flush out completely" - they flushed the system again. I was told to drive the car but not to add water to the coolant reservoir if the problem recurred. That evening the rough running occurrred again; I was furious and intent on taking the car back. However, the next morning the car started effortlessly and ran smoothly and has continuedb to behave normally. However, the coolant level has dropped (it's coolant not water) but there are no signs of a leak. The car runs warmer than I recall especially when you push it a bit. My concern is that the head gasket may still be faulty (where is the coolant going to?) and I'm concerned by the traces of oil I see in the coolant reservoir. I intend to continue to drive the car for another week or so, or until the coolant level drops to the point where the warning light comes on (assumming the sensor is still functioning.

Am I being paranoid? I would appreciate sound insights and/or advice as I dread a recurrence of the entire problem a couple of months from now when the warranty has expired.

Ed

Depending on when you check it, coolant level can vary a little bit. Coolant level will be higher in the bottle on a cool engine.
Occasionally the only way to fully "burp" a cooling system of all it's air bubbles is to drive it. It could be you have a combination of those two issues. Keep an eye on the coolant level and temp guage for the next few days.

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Fourings

84 Audi Coupe GT with Turbo engine, EFI (buh-bye CIS), Jamex seats, Koni's/H&R's, e-code lights. 210k and counting.
1992 Anthracite 400E, 161k, "Grey Ghost".
1986 VW Quantum Syncro, 192k, gone to the crusher in the sky.
1989 300TE 172k. (Was mine, now also Mom's car)
72 280SE 4.5 (Mom's car)

I always checked the coolant level on a cold engine, so I'm sure the level has dropped.
ed

I would say-

Resurfacing heads was probably not nessary. It's not common to do that seems like most MB 6 cylinders have headgasket failure like this...


Michael

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Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E