Coolant in oil! 1990 5.0


Aug 6, 2018
North Carolina
Today I was changing my valve cover gaskets and found coolant in the oil on the rockers and in the oil pan. I am guessing a intake or head gasket leak. Recently I installed a new water pump. Can anyone tell me if coolant could get into oil via a leaky water pump bolt? There is no white smoke or rough engine running and no external coolant leaks


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My dad had a bra
SN Certified Technician
Sep 5, 2001
Fort Knox, KY
Nope. Water pump sits on the outside of the timing chain cover. There's no oil out there. It looks strange to me to see coolant without the baby puke looking oil/coolant mixture I'm used to seeing when it's a head gasket. In any case, if coolant is in the oil, then I'd have to assume you're right. It's probably either the head gasket or the intake gasket. You can usually tell the point of the leak when you break the motor down.
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Reactions: General karthief


SN Certified Technician
Aug 27, 2012
In the garage
if you need to confirm... look in your radiator ... does it look like mikshake? Do you see oil on the top of the coolant? Run a coolant exhaust gas test, that will tell if the HG is bad or a bad intake gasket..


Mustang Master
May 15, 2018
Better drain your oil pan. If coolant comes out first you’ve got a problem.

Mike is right: the exhaust gas test is good to do. Super easy and widely available.
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Reactions: Shakerhood


Aug 6, 2018
North Carolina
You guys will probably laugh, but a mechanic friend of mine mentioned something that made me remember of something I did a few months back. I had put in a little bottle of UV dye in the oil pan to help find out where the oil leaks were coming from externally, so its not water in the oil. I have noticed coolant in oil before and this didn't have that milky residue.

I will probably do a coolant system pressure test just to make sure.

I appreciate your responses
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Reactions: Boostedpimp


Aug 6, 2018
North Carolina
and FYI...UV dye doesn't show up that well in oil, I think its because oil doesn't evaporate and doesn't leave the UV residue behind like coolant or AC refrigerant
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