C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

oil in engine coolant

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Old Apr 3, 2003 | 05:03 PM
  #1  
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Default oil in engine coolant

i have a 87 coupe. i have noticed quite a bit of oil sludge in the radiator overflow.

havent noticed coolant in the oil yet.

any ideas

Paul
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Old Apr 3, 2003 | 05:04 PM
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Default Re: oil in engine coolant (uralman)

Blown head gasket.

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Old Apr 3, 2003 | 05:06 PM
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Default Re: oil in engine coolant (Lone Ranger)

shouldnt i see coolant in the oil?

Paul
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Old Apr 3, 2003 | 05:13 PM
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Default Re: oil in engine coolant (uralman)

Blown head gasket.

If oil is in the coolant, then coolant must be in the oil.
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Old Apr 3, 2003 | 05:13 PM
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Default Re: oil in engine coolant (uralman)

id be looking at the oil cooler.. and it is possible that there would be no coolant in the oil if its bad. 50 or so psi oil pressure will easily overcome less than 20 psi in the cooling system.
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Old Apr 3, 2003 | 05:15 PM
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Default Re: oil in engine coolant (neverendingproject)

but , its possible that your only seeing stop leak in the resevoir... ( gm suplemental coolant additive). make sure before you go tearing your engine apart.
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Old Apr 3, 2003 | 05:18 PM
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Default Re: oil in engine coolant (neverendingproject)

the oil cooler is in the radiator i presume. are the lines close enough to leak into each other.

Also how can i tell if its the cooler or a head or manifold gasket without oulling it apart?

Paul
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Old Apr 3, 2003 | 05:22 PM
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Default Re: oil in engine coolant (neverendingproject)

what does this stop leak look like. the stuff in there is a dark slimmy stinky shi_. looks like oil but hard to tell. it sticks to the sides and top of the plastic overflow bottle

Paul

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Old Apr 3, 2003 | 05:27 PM
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Default Re: oil in engine coolant (uralman)

The oil cooler is not in the radiator, its the finned thing above the filter, if you even have one.
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Old Apr 3, 2003 | 05:28 PM
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Default Re: oil in engine coolant (uralman)

the oil cooler is sandwiched between the oil filter and block. go to autozone or wherever and get a cooling system pressure tester. pull your oil filter. pump the cooling system up to about 20psi & look for leaks.
from what your describing , it could be either. however , if your cooler is leaking, it'll usually pump your oil into your radiator & out the cap.
if your not losing coolant or oil, id haveta say its additive. a blown head gasket will usually blow your water out the cap due to compression in the cooling system and the oil cooler will do the same due to oil pressure in the cooling system.
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Old Apr 3, 2003 | 05:37 PM
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Default Re: oil in engine coolant (neverendingproject)

please explain to me how a leaking oil cooler can leak oil into the radiator

thanks,

paul :confused:
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Old Apr 3, 2003 | 05:42 PM
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Default Re: oil in engine coolant (uralman)

the oil cooler is a heat exchanger. oil runs thru one side, engine coolant runs thru the other..
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Old Apr 3, 2003 | 05:43 PM
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Default Re: oil in engine coolant (uralman)

IF THERE IS A HOLE OR LEAK IN THE COOLER, ITLL MIX THE COOLANT WITH THE OIL. When the coolant gets back to the radiator, youll have oil in the radiator.

YOU likely have a blown head gasket, but if you EVEN HAVE an oil cooler (its not standard equip) then you might want to check this first.

Either way, unless you managed to pour oil into your radiator, you DO have coolant in the oil.

And you better check it out fast.
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Old Apr 3, 2003 | 05:45 PM
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Default Re: oil in engine coolant (neverendingproject)

is this common.

paul
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Old Apr 3, 2003 | 05:46 PM
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Default Re: oil in engine coolant (uralman)

NO, this is why i think you have a blown head gasket.

Blown gaskets are not common, but are the most common cause of this problem.
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Old Apr 3, 2003 | 05:47 PM
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Default Re: oil in engine coolant (vader86)

i presume that it could also be a manifold gasket

Paul
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Old Apr 3, 2003 | 05:48 PM
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Default Re: oil in engine coolant (uralman)

Well, only way to check is to pull it all off and find out.
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Old Apr 3, 2003 | 05:49 PM
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Default Re: oil in engine coolant (vader86)

got it

thanks for the help

paul
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Old Apr 3, 2003 | 09:49 PM
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Default Re: oil in engine coolant (uralman)

What you're seeing may not be oil. It may be sludge build up from old coolant, if its light brownish-orange in color and particularly if it is on the bottom of the reservior sort of stuck to the bottom like pond scum.

Might be worth flushing your cooling system and cleaning out your reservior tank, refilling with fresh coolant, bleed out the air, and put some more miles on it then recheck a few times and see if the suspicious substance returns.

what does this stop leak look like. the stuff in there is a dark slimmy stinky shi_. looks like oil but hard to tell. it sticks to the sides and top of the plastic overflow bottle

Paul

[Modified by Lone Ranger, 8:59 PM 4/3/2003]
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