Overheating problems

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Jul 9, 2018
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#1
Make
Chevy
Model
Malibu
Year
2005
Miles
123000
Engine
3.5
Started off after sitting all night engine would run rough for acouple of minutes then run smooth, then after a while started to lose coolant but I couldn't find the leak, now engine temp whent up to to the red pulled off the road and sit for a couple of minutes and restarted and temp went down to normal temp.. I have replaced thermostat but when I run the car it still gets hot and top raditor hose is cool like thermostat mot opening I can open the bleeder valve and air bleedes out and then thermostat will open. I am not getting any coolant in oil or smoke out tailpipe. I am afraid I know what is wrong but I am joping there could be something else.
 
Joined
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#2
"Started off after sitting all night engine would run rough for acouple of minutes then run smooth"

Sorry to say it, but sounds like a head gasket. Intake might leak coolant into a cylinder overnight also, but you would probably have a foggy tailpipe after the engine warmed up, and you are not seeing that.
 

nickb2

Wrench. Diagnostic Tech.
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#3
Yeah, head gasket probably blew on a water passage. You could rent a kit from autozone just to make sure. They call it a block tester.

Here is a link to their loan a tool program and what the kit looks like. If the blue liquid turns green, well you now know for sure you need to pull the heads.

It's a good thing no coolant went into the oil, nothing worse than coolant in oil for a future crank knocker.:eek::money:


https://www.autozone.com/loan-a-tools/block-tester
 
Last edited:

jd

Hero Member
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#4
Seems to me too, that it's blown a head gasket... Unless maybe a coolant passage in the intake manifold...?
Would a simple Compression Test indicate a problem, even which cylinder? Blow-Down Test even better, might hear the leak by listening to Intake or Exhaust.
Or are these tests inadequate for this type of leak?
I realize it must be "smallish" since the Malibu doesn't run too badly after a few minutes.
 

billr

wrench
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#5
Both the compression and leak-down might give additional (and different) clues. Sure, try them both if you have the equipment handy and plugs aren't too hard to get to. The "block test" with dye is probably more definitive in a case like this, but you do have to pay for the dye consumed.