Overheating out of nowhere!

[Aloeffler97]

I was driving to autozone to get a replacement headlight and as I pulled into the parking lot, the temp was rising like crazy. I shut it off popped the hood and there weren't any leaks, I let it sit for 30 minutes and popped the cap and it was low on coolant, so I filled it up with dexcool. I got it back home and it was low again but I still can't find a leak, water pump is dry, oil is good and I can't smell any coolant. Anybody have any ideas? (Elbows were already replaced)
2005 Grand Prix GT


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[Fivefingerdeathpunch]

It must be eating the coolant through the intake gaskets.

If they are still the black plastic ones, you better change them ASAP.

[Aloeffler97]

They are the black plastic ones, I am also using quite a bit of oil, would replacing the gasket also fix that?


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[Fivefingerdeathpunch]

Likely not, but a new PCV valve could stop the issue.

[Aloeffler97]

How long/ how much does this usually cost?


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[SubwayGuy]

Smell your exhaust and see if it smells like burned coolant. If you are going through that much, your exhaust should smell pretty "sweet." If it does, as mentioned above, intake gaskets.

[Aloeffler97]

We smelled the exhaust and neither my dad nor I smelt any coolant being burnt


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[SubwayGuy]

Is it leaking in your oil?

[Aloeffler97]

I'm not sure, my dad said with dexcool it doesn't turn milky, but I go through about a quart or so in a 3 month period.


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[Fivefingerdeathpunch]

The thing is, if you can't see or hear the leak at all, the car is burning it.

Doing the repair yourself can take a few hours depending on your skills I guess. For me it's nothing special and maybe a 2 hour job taking my time. Costs arent that much, figure $150-175 if you bought all the gaskets and coolant/oil at the same time.

Most shops charge 600-800 bucks for everything. Mark up on parts and cost of labor at 100/hr for most places and it does call for around 4-5 hours I think.

[SubwayGuy]

It would still turn milky. Do your intake gaskets. It will more than likely solve your problem, and you can get a look at if your PCV valve is sucking all your oil. If your intake gaskets are miraculously not bad, metal ones are good assurance that you won't have future issues.

[Fivefingerdeathpunch]

Any coolant in any oil will turn the oil into a milkshake.

It does not matter if it's dexcool or green or universal. Water and oil always makes a milkshake.

[Aloeffler97]

Alright so they aren't mixing which is a positive, should I look at doing head gaskets along with upper and lower intake gaskets?


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[SubwayGuy]

Head gaskets rarely go bad on 3800's. Not needed. Just do upper and lower intake gaskets.

[SubwayGuy]

And change your PCV valve while you are at it. Also since you will have basically the top of the motor apart, change your valve cover gaskets if they haven't already been changed.