I've had a leaking head gasket for some time on my 1992 300E (with 103.983 engine), eating a bit of oil and oil on the garage floor.

While on a trip the upper radiator hose sprung a leak. I chopped and shortened it to temporarily fix it, and in doing so noticed the coolant seemed "muddy". Further investigation showed oil in the coolant -- a bubbly syrupy mess in the coolant tank.

I took it to the city's MB dealer who diagnosed it as a blown head gasket. So... $1750 later I had a new head gasket and upper/lower radiator hoses, a new coolant tank, and resumed my trip.

I checked the coolant after a couple hundred miles and it seemed ok upon casual inspection. Also the oil leak seemed to have stopped.

But... today I had the hood up after driving (engine still hot) and noticed the upper radiator hose was collapsed on itself. The lower radiator hose was also slightly collapsed. Opening the coolant tank cap allowed air to audibly rush in and re-expand the hose.

And... the coolant was the dreaded chocolate milk color again. Aaaagh. The coolant does not appear to be as gooey as it was before, but that may just be a matter of time.

Before I take it back in for service, I'm hoping for some wisdom from the forum about what is going on here.

Is vacuum in the cooling system normal after running the car, and the hose collapse is due to softening from oil?

Is what I am seeing in the coolant (see photo below) in fact oil, and is a blown head gasket the only thing that could cause oil in the coolant?

Attached Thumbnails

 

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1992 300E Sedan (Sold)
1999 E320 Wagon (Sold)
1995 E320 Sedan
1995 E320 Wagon

Note: I am now 600 miles from the dealer that performed the work. I plan to have it fixed (again) by an official Mercedes dealer and then try to get the first shop to reimburse the second, or something.

From previous reading here about head gaskets, I inquired whether the head might need machining to ensure it was not warped. He said it would be a waste of time and money as long as the engine hadn't overheated after the gasket blew (which it had not).

I also vaguely recalled reading here about additional work that should be done during a head gasket replacement as a preventitive measure. So I asked him to let me know if there was anything else that should be done while they had it opened up.

He did not get back to me with any additional work recommendation, but when I came home... sure enough I found recommendations on this forum to have a complete valve job done at the same time, as well as replacing the head bolts, and resealing the timing cover. Grr...

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1992 300E Sedan (Sold)
1999 E320 Wagon (Sold)
1995 E320 Sedan
1995 E320 Wagon

I think the coolant reservoir tank cap is supposed to vent on reverse pressure - maybe cap is bad? It also took several re-flushes with Tide by the shop to eliminate the brown goo. They did not charge for those return visits, and eventually the coolant was normal.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

Thanks! That pointed me in the right direction for the radiator hose. Apparently the coolant caps do have a vent that has been known to go bad (as in this thread). My cap seems like a likely culprit for that issue.

Do you recall if your coolant looked ok for a while, then got brown again? And did it look like mine in the photo above? It seems too brown to me to be just residual, although I confess I've never paid that much attention to it before now.

The dealer said he was ordering some special solvent to remove the oil, although I see on the invoice it just says "soap and water". Maybe a bunch of oil was hanging around in the heater core or something and they didn't do a very thorough job flushing?

Another thought... is the coolant vacuum harming anything, i.e. sucking contaminants into the coolant (like maybe some brown stuff )?

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1992 300E Sedan (Sold)
1999 E320 Wagon (Sold)
1995 E320 Sedan
1995 E320 Wagon

Benzwood, the dealer should have confirmed the head was perfectly flat before reinstalling it. As you mentioned, the dealer should have proposed installing new valve guides and/or seals. If it were me I'd have the cooling system flushed/cleaned to remove any remnants of oil which could affect the cooling system efficiency. From your description it appears the Service Department at the first dealer was marginally competent, at best.

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Fred Hoelzle

I had a similar problem myself with my old 300E. I had no oil leak though, so I'm thinking I may have had transmission fluid and coolant mixing.

Anyway, you can flush the system yourself easily enough by disconnecting a couple of hoses and running 'tide' or whatever through there and clean water with a garden hose, take as many hoses off as you can too and either replace, or throroughly clean them.
Then refill with MB or Zerex G05 coolant + water.

I did this and hey presto- no more brown goo!

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1993 320TE M104
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past:

1983 230E W123 M102
1994 E300D S124 OM606 (x2)
1967 250SE W108 M129
1972 280se 3.5 W108 M116
1980 280SE W116 M110
1980 350SE W116 M116
1992 300E W124 M103
1994 E280 W124 M104
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