I have owned a 89 300se for about a year. The car has never overheated or ran the slightest bit hot. I replaced the radiator and fans about 11 months ago, (I hit a deer not due to high temp).
In the past week I noticed I was using a quart of oil in 500 miles. It has always had a slight leak from the front seal. But this was more like a quart every 2k. I checked the coolant and found the mayonaise looking stuff in there drained it and flushed it, but after another 400 miles it is back.
There is no water in the oil, plugs look absolutely perfect, no smoke or steam at the exhaust. But on the back of the engine passenger side oil is leaking down onto the trans.
I have never had a head gasket fail so I am not sure how oil would get in the water but not vice versa. Also what would cause the gasket to fail? Did replacing the cooling components increase the pressure enough to blow the gasket? When I searched this it seems to have happened when the system was weak but my cooling system was fine before.
I drive the car 1k a week and it has 254k on it.
Thanks for any insight into this.

It's the head gasket. Near #5 cylinder there is a water passage in very close proximity to an oil passage. Since the oil pressure is higher than the water pressure, the oil will get into the cooling system.

Thanks for the reply.
Man that sucks, if I had any indication that something was wrong and I let it slide I could expect that, but I guess with this kind of mileage things are going to happen.

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“Fundamentally, sustainable development is a notion of discipline. It means humanity must ensure that meeting present needs does not compromise the ability of future generations to meet their needs.”--- Gro Harlem Brundtland


1989 300se 250,000
1983 BMW 528e 100,000
1999 Olds Alero 80,000

These pretzels are making me thirsty.

Is there a "average" mileage that the head gaskets seem to go on the 3.0L I-6's? I am wondering, because I am considering a 91 300SE with 181K.

Thanks.

I'm at 200,000 and mine has never blown. More m103 people, please post.

It sounds like a leaking valve cover gasket, not a cylinder head gasket.

Clean the engine and look for fresh oil leaks.

I have a 1991 300e with over 245k miles and it continues to perform well, uses 1 qt every 3,000 to 3,500 miles now that I relaced the leaking upper timing chain cover gasket.

Don't rush into fixing something that isn't broken. Determine where the oil is going.

What weight oil do you use?

Haasman

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'93 190E 2.6-Wrecked
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'65 911 Coupe (#302580)