mystery coolant leak
Thread Starter
Racer
Joined: Aug 2006
Posts: 276
Likes: 1
From: Brentwood CA
mystery coolant leak
When I bought the '89 C4 in August I had to immediately replace the leaking water pump. I replaced most of the hoses too. However every few days the LOW COOLANT light turns on and sure enough she is thirsty. I can't see any leaks and I don't think it's getting in the oil, but how would I check?
How can I determine why I have to top off the radiator every few days?
Thanks!
How can I determine why I have to top off the radiator every few days?
Thanks!
Burning Brakes
Joined: Jan 2006
Posts: 847
Likes: 0
From: Colorado Springs CO
Make sure your oil looks like oil and not milky.
I'm betting on air in the system that needs to be burped.
Make sure you don't have any leaks.Check the hoses, radiator and the heater-core.
Good Luck!
I'm betting on air in the system that needs to be burped.
Make sure you don't have any leaks.Check the hoses, radiator and the heater-core.
Good Luck!
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
I'm betting on air in the system that needs to be burped.
When you have the radiator cap off and warm, reach over and crack the throttle a copla times, being careful to release it slowly so as to not chug coolant from the radiator.
Finally reach over and hold the throttle open while filling the radiator, hold it open while you tightly screw on the cap.
Or you can just keep filling it as called for as it seems to be burping itself.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
You can also borrow a pressure tester from AutoZone.
Remove the radiator cap and screw on the tester. Then you pump up the pressure to about 15 psi and watch the gauge.
If the gauge shows the pressure isn't holding you'll know there's a leak somewhere. If it's not leaking outside the engine, it could be internal.
One of the tell-tale symptoms is bubbles in the coolant with the engine idling and the radiator cap off. This could indicate a head gasket leak.
Milky colored oil could mean it's the intake manifold gasket.
Jake
Remove the radiator cap and screw on the tester. Then you pump up the pressure to about 15 psi and watch the gauge.
If the gauge shows the pressure isn't holding you'll know there's a leak somewhere. If it's not leaking outside the engine, it could be internal.
One of the tell-tale symptoms is bubbles in the coolant with the engine idling and the radiator cap off. This could indicate a head gasket leak.
Milky colored oil could mean it's the intake manifold gasket.
Jake
Burning Brakes
Joined: May 2006
Posts: 857
Likes: 1
From: Morrisonville Illinios
Really check around the intake if you oil is staying clean, years ago had intake leak where it would puddle under the plenum and bake off while running took a little bit to figure it out. If you can park on a clean dry spot after it is driven and up to temps to see if it dripping. if you have too set some cardboard under it.
Good Luck wro87
Good Luck wro87
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
It's most likely a head gasket leak.
What happens is the head gasket probably has failed at one of the cylinder bores which then sucks coolant into the combustion chamber and is burned with the air fuel mixture.
That's why you don't see any external coolant leaks and you have to top off the coolant every few days.
What happens is the head gasket probably has failed at one of the cylinder bores which then sucks coolant into the combustion chamber and is burned with the air fuel mixture.
That's why you don't see any external coolant leaks and you have to top off the coolant every few days.
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Racer
Joined: Apr 2001
Posts: 302
Likes: 0
From: South Haven Michigan
Lisle makes a "Combustion Leak Detector" you might want to get. Air inside the radiator is sucked through a fluid. If combustion gases are present (via a blown headgasket), the fluid changes color.
I used it on my 89 and it was fine, but I still had the "Low Coolant" light coming on with no visible leaks or anti-freeze smell. Turned out to be loose clamps on the hoses. What lead me to this was the overflow tank was filling up when it was hot (as it normally should), but the level wasn't going down when it was cold, so that told me the necessary vacuum wasn't being developed. Tightened all the hoses I could find and the problem was gone.
I used it on my 89 and it was fine, but I still had the "Low Coolant" light coming on with no visible leaks or anti-freeze smell. Turned out to be loose clamps on the hoses. What lead me to this was the overflow tank was filling up when it was hot (as it normally should), but the level wasn't going down when it was cold, so that told me the necessary vacuum wasn't being developed. Tightened all the hoses I could find and the problem was gone.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
leak
whoah!!!!!! slow down!!
replace the hose and clamps on the overflow tank for the radiator.
if the $2.50 hose is cracked or chafed, it will spit out water when hot, but won't draw it back in when cold.
Check the level in the overflow tank, and if it's high, change the hose or tighten the clamps
replace the hose and clamps on the overflow tank for the radiator.
if the $2.50 hose is cracked or chafed, it will spit out water when hot, but won't draw it back in when cold.
Check the level in the overflow tank, and if it's high, change the hose or tighten the clamps
