I have a 95 Bonneville 3.8 liter I paid $400 for. Beautiful car cosmeticaly, practiclay stole it when I paid $400 for it. I think it was starting to get on the way of the guys' Mercedes in the garage. Anyway, all highway miles, 165,000...and I went to flush the radiator and found a milky, gunky rainbow looking stuff in there. I figured it was oil. It was also in the overflow bottle. either I did not flush it good, or it came back. Car does not run hot, normal oil pressure, good power...good everything. So whats up this stuff?
Oil in radiator, but not in engine. (??)
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Sounds like you found out why it was only $400.
Things need to be checked, like bad head gaskets or cracked heads.
Things need to be checked, like bad head gaskets or cracked heads.
There is a good chance it is trans fluid.
+1 check the transmission fluid for a pinky milky like appearance.
GM puts oil & trans cooler in rt. & left radiator side tanks and its not at all unusual to have one fail.
Oil pressures on either AT or engine will over dominate coolant pressures hence oil contaminates the coolant and not vice-versa.
Oil pressures on either AT or engine will over dominate coolant pressures hence oil contaminates the coolant and not vice-versa.
Hi,
willix - You said:
"Oil pressures on either AT or engine will over dominate coolant pressures hence oil contaminates the coolant and not vice-versa."
Nothing is absolute (except perhaps death) and in engines with liners for instance it is common for coolant to enter the sump as the engine cools down and sits. Anybody familiar with DD 2 cycle engines will be very familar with this - many other engine families will do this according to their design
willix - You said:
"Oil pressures on either AT or engine will over dominate coolant pressures hence oil contaminates the coolant and not vice-versa."
Nothing is absolute (except perhaps death) and in engines with liners for instance it is common for coolant to enter the sump as the engine cools down and sits. Anybody familiar with DD 2 cycle engines will be very familar with this - many other engine families will do this according to their design
Originally Posted By: Doug Hillary
Hi,
willix - You said:
"Oil pressures on either AT or engine will over dominate coolant pressures hence oil contaminates the coolant and not vice-versa."
Nothing is absolute (except perhaps death) and in engines with liners for instance it is common for coolant to enter the sump as the engine cools down and sits. Anybody familiar with DD 2 cycle engines will be very familar with this - many other engine families will do this according to their design
No denying that, if you shutdown the engine oil pressures drop out yet the cooling system can remain pressurized for a period of time even with a cracked cooling tank coil.
Hi,
willix - You said:
"Oil pressures on either AT or engine will over dominate coolant pressures hence oil contaminates the coolant and not vice-versa."
Nothing is absolute (except perhaps death) and in engines with liners for instance it is common for coolant to enter the sump as the engine cools down and sits. Anybody familiar with DD 2 cycle engines will be very familar with this - many other engine families will do this according to their design
No denying that, if you shutdown the engine oil pressures drop out yet the cooling system can remain pressurized for a period of time even with a cracked cooling tank coil.
My knee-jerk suspicion with that symptom is oil cooler.
Well, this was $400, 8 months ago. The car has been on several 300 mile round trips in this condition. We got our moneys worth if this thing goes tomorrow morning.
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Thanks for the posts...Honstly, we have driving the mess out of this car. I will check into the things you suggested....
I'd have to see it and smell it to know for sure. But this sounds to me like you have bad intake gaskets and/or a bad intake. It's ridiculously common on those engines.
Now some may object saying that intake gaskets are not exposed to oil pressure, and therefore can't allow oil in the coolant. Well they're right on the first count- wrong on the second. When a cooling system cools down, it will come under a bit of vacuum- which is how it sucks coolant back into the system out of that non-pressurized overflow tank. Now when you combine that suction with a leaking intake gasket (which necessarily has at least a film of oil laying against it on the side opposite the coolant), you can very well get oil into the cooling system- I've seen it plenty of times.
Doug Hillary is right. There is no universal, one-way rule for the mixing of fluids. Pressure varies according to temperatures and whether or not an engine is running. Leak paths can effectively be one-directional... or they can flow both ways. Depends on what is leaking and why.
In your case, I'd first try to determine whether that oil is engine oil or ATF. If you don't see any milky coolant contamination in the ATF and if the oil looks dark, then it's probably engine oil. If that's the case, then you probably have bad intake gaskets and/or a bad intake. But a leaking trans. cooler is a possibility that you need to rule out.
Or if you just want to get your money back... throw some GM stopleak pellets in the thing and sell it. I've seen those things work miracles.
Now some may object saying that intake gaskets are not exposed to oil pressure, and therefore can't allow oil in the coolant. Well they're right on the first count- wrong on the second. When a cooling system cools down, it will come under a bit of vacuum- which is how it sucks coolant back into the system out of that non-pressurized overflow tank. Now when you combine that suction with a leaking intake gasket (which necessarily has at least a film of oil laying against it on the side opposite the coolant), you can very well get oil into the cooling system- I've seen it plenty of times.
Doug Hillary is right. There is no universal, one-way rule for the mixing of fluids. Pressure varies according to temperatures and whether or not an engine is running. Leak paths can effectively be one-directional... or they can flow both ways. Depends on what is leaking and why.
In your case, I'd first try to determine whether that oil is engine oil or ATF. If you don't see any milky coolant contamination in the ATF and if the oil looks dark, then it's probably engine oil. If that's the case, then you probably have bad intake gaskets and/or a bad intake. But a leaking trans. cooler is a possibility that you need to rule out.
Or if you just want to get your money back... throw some GM stopleak pellets in the thing and sell it. I've seen those things work miracles.
You can either get an all new radiator on rockauto for $92 or an external transmission oil cooler for less. This will eliminate the ATF as a source.
That year 3.8 was pretty good about not mixing stuff but of course this old anything can happen.
That year 3.8 was pretty good about not mixing stuff but of course this old anything can happen.
Up untill a year ago I had only seen 2 bad oil or transmission coolers that were putting oil into the coolant. Then suddenly we had about 15 of them in about 6 months.
Well, push comes to shove, scrap iron is .09 cents a pound right now, so I can at leat get about $300 for it at the scrap yard....Im not putting major money into a car like this when I could put that towards a nice little hotrod or something more desirable anyway. Thanks folks....
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