Weird coolant system problem (fixed)
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Weird coolant system problem (fixed)
Hello all, I have a 97 Civic EX and I recently did a coolant flush and replace my coolant with 50/50 Prestone anti-freeze and I replace the radiator cap with an oem. After about two weeks I started to get a temperature fluctuation at idle it wouldn't get really hot but it would go above the halfway point. I went to go check on my coolant level and noticed that my reservoir tank was overflowing but the radiator was kind of low. So I took coolant out of the Overflow put it back in the radiator turn the car on and I put about a quarter gallon of antifreeze and it would not stop bubbling. So I figured it might have been the head gasket so I got an engine block tester from AutoZone and the coolant tested negative 5 times for hydrocarbons and after every test just to make sure the test solution worked I put the test on the exhaust pipe and it immediately turned yellow. So I replaced the cap and about a week and a half later today I was experiencing temperature fluctuations at idle again. Went to go check coolant level this time the Overflow was about halfway filled and the radiator was about 2 in below filled. Now I haven't seen any leaking overnight and my radiator fan is working. What else could it be?
Last edited by Dylan29; Oct 18, 2017 at 03:18 PM.
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Re: Weird coolant system problem
Does the cap to the coolant overflow bottle have a suction hose attached to it on the inside of the cap? If the hose is missing or has fallen into the bottle it will do what you describe in regard to the overflow filling and the radiator going lower. The hose should look something like this.
https://i.ytimg.com/vi/JeRy6wjF5ZE/maxresdefault.jpg
How sure are you that you are getting all the air purged out of the cooling system? Does the heater blow HOT?
https://i.ytimg.com/vi/JeRy6wjF5ZE/maxresdefault.jpg
How sure are you that you are getting all the air purged out of the cooling system? Does the heater blow HOT?
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Did you bleed the coolant system per the service manual?
Raise front of car on jackstands as high possible. Turn climate control to max heat and fan off. Radiator cap off and bleed until radiator fan cycles on twice.
Block test is not a definitive test for a breached head gasket unless it turns green or yellow..otherwise it does not disproof a possible breach.
Do a coolant system pressure test. Clean out reservoir, reservoir tubing, and hose leading from radiator to the reservoir to ensure good flow.
Small external leaks that are sometimes missed are:
Heater hose that attaches to cylinder head under the distributor
Bypass hoses that connect to throttle body and IACV
Raise front of car on jackstands as high possible. Turn climate control to max heat and fan off. Radiator cap off and bleed until radiator fan cycles on twice.
Block test is not a definitive test for a breached head gasket unless it turns green or yellow..otherwise it does not disproof a possible breach.
Do a coolant system pressure test. Clean out reservoir, reservoir tubing, and hose leading from radiator to the reservoir to ensure good flow.
Small external leaks that are sometimes missed are:
Heater hose that attaches to cylinder head under the distributor
Bypass hoses that connect to throttle body and IACV
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