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Oil in coolant. No coolant in oil. It's possible?

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Old 11-29-2004, 06:14 AM
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Car: 1986 Pontiac Firebird Trans Am
Engine: 305 Tuned Port Injection
Transmission: The famous 700R4
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Oil in coolant. No coolant in oil. It's possible?

I'm curious if the oil can be mixed with the coolant into the radiator only, but not into the engine.

I check, check and check the oil and nothing! In every change the oil is clean and coolant free.


Any idea?

Thanks,

Denis V.
Old 11-29-2004, 06:53 PM
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Automatic transmission, right?

The radiator has an oil cooler for the transmission built into it. If the oil cooler starts to leak, you'll get oil in the coolant, but no water in the engine.
Old 11-29-2004, 10:23 PM
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Originally posted by five7kid
Automatic transmission, right?

The radiator has an oil cooler for the transmission built into it. If the oil cooler starts to leak, you'll get oil in the coolant, but no water in the engine.
AND, you will have water in the transmission. Better check the fluid there to be sure.
Old 11-29-2004, 10:30 PM
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Car: 87 Formula
Engine: 327
Transmission: 700r4
Axle/Gears: 3.23
If you have an engine oil cooler you can get engine oil into the coolant as well. Since oil pressure is greater then radiator cap pressure any leaks will go into the coolant.

It's possible to get some coolant back into the oil with this type of leak when the motors shut off and the oil pressure drops, but coolant pressure doesnt. This may not happen though if it takes say.. 30 psi to make it leak. The oil pressure is greater then that but water pressure is lower so it'd be all one way.
Old 11-29-2004, 10:39 PM
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Car: 1969 Z/28, 1983 Z/28
Engine: 350, 305 (L69)
Transmission: TKO-600, T5
Axle/Gears: 3.42, 3.73
Originally posted by chevymad
If you have an engine oil cooler you can get engine oil into the coolant as well. Since oil pressure is greater then radiator cap pressure any leaks will go into the coolant.
I suppose that if the block was cracked, you could also get the same results as you described.
Old 11-30-2004, 06:02 AM
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Car: 1986 Pontiac Firebird Trans Am
Engine: 305 Tuned Port Injection
Transmission: The famous 700R4
Axle/Gears: No idea
Oh, thanks guys for all replies!

1.- I'll check the trans fluid, but, since the radiator was replaced in 2001, I think all is good with this stuff.

2.- "Oil pressure is greater than coolant pressure". This is new for me. Until now, I thought the inverse. This is very possible. The last weekend I did a travel (about 500km/300 miles) and the oil was down and coolant was up a little.

3.- Block was cracked, welded and machined in 2001. Problem started this year.

Thanks every one for your help,

Denis V.
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