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Losing coolant, overheating, but engine block test is negative?

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Dec 21, 2021, 10:16 PM

Post #1 of 3 (459 views)
Losing coolant, overheating, but engine block test is negative? Sign In

Late 90's Acura v6.

My car overheated and died a few weeks back. Thought it was my alternator, but after recognizing the engine was smoking after being pulled over (it was late at night) realized the car had somehow overheated and apparently redlined. Unfortunately I never paid close attention to the temp gauge as it's never been an issue in the past.

Interior heater was also blowing cold air.

So didn't drive it and filled with OEM Acura coolant last week as the reservoir was low and barely any was visible in the radiator port. Warm air back and car was normal temp after a long drive....for awhile.

Now the temp gause is back to slowly creeping up over the halfway point after warming up. Only way to keep the temp in check is to keep the car in motion (makes sense...air rushing into the radiator).
Checked coolant...low again. Checked under car...appears to be coolant on the pan on the drivers side (opposite of oil pan).

White smoke blows out of exhaust, making me suspect head gasket blown.

Purchased a head gasket test kit (one with the fluid and suction mechanism). Performed the test exactly as directed. Fluid stayed dark blue and never changed.

I'm stumped. Could I have been getting a false reading? Or is there a possibility the head gasket leak is so minute that it won't test positive?

A few things:

- both upper and lower radiator hoses replaced and fine
- currently no misfires, and the car 'appears' to run and drive very smoothly without issue, aside from the overheating
- both radiator fans do not turn on even after engine has been running awhile. ac condenser fan doesn't even engage when ac is turned on. need to check this out and test both independently with 12v source
- replaced ECT module after a cel code. it hasn't returned. however, I checked the new ect today and there's no fluid on the bottom of it, indicating that the coolant level is so low it's probably not even getting a reading
- no traces of coolant or anything odd in the oil or under the oil cap

I'm lost. What should be my next steps here aside from the cooling fans? Is it possible to still blow some white smoke out the tailpipe without a head gasket issue?

At worst, I was going to use a sealant product as a last ditch effort, but want to eliminate all possibilities before I go that route.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 22, 2021, 1:11 AM

Post #2 of 3 (449 views)
Re: Losing coolant, overheating, but engine block test is negative? Sign In

Pressure test it, this should be obvious. Those "block tests" are not dependable so no surprise there.
It's wildly using coolant so if it was some other item (hose, gasket not head's) it probably is now. Expect it.
BTW the sensors in coolant are going to misbehave if in just air even hot air/vapor will be slow or inaccurate.

Plan on the whole job and make sure head(s) are checked out for damage or it will just fail again right away,

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 22, 2021, 4:37 AM

Post #3 of 3 (439 views)
Re: Losing coolant, overheating, but engine block test is negative? Sign In

Yep, white smoke is dead giveaway. Blown head gasket. Those chemical tests are totally useless.

It could have done a lot of damage so the heads have to be sent out to the machine shop for testing.

Once it is repaired you will have to look for the original leak that started the whole process in the first place.


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