coolant leak (non Buick)

[DCVING 6]

Have a tech question, non Buick related, hope its ok if it goes here.

1992 Chevy S-10 blazer. 4x4, 4.3L, is leaking coolant. It is coming from the radiator on the drivers side near the petcock.

Wierd thing is, it only does it after the car has been warm and is shut off. I let it idle in the driveway and get up to running temp, never leaked a drop. I held it at maybe 2200 rpm for 20 seconds, let off, no leak. Shut the car off, 30 seconds later there is a very small puddle under the car. When I say small, the circle is no more than 4-5 inches wide. I can't actually see it coming from the radiator because of the fan shroud, but it is pooling on a splash guard under the radiator.

What would cause it to only leak a little bit... only when the car is shut off?

 

[twin 93 svt]

Get a coolant pressure tester from pep boys, It's free!, It could be a hair line crack in radiator!

 

[DCVING 6]

Hey twin,
actually I forgot to mention that I did use the pressure tester on it. I pumped it up to 15, it slowly went down to maybe 10 and stayed on 10

 

[klrv6]

Water pump?

Check the water pump just to be safe. The weap hole will start to leak before the whole unit goes out. Our Suburban did this 60 some dollars for the parts. The coolant would run down the hoses and collect in the radiator support.

 

[DCVING 6]

Re: Water pump?

Originally posted by klrv6
Check the water pump just to be safe. The weap hole will start to leak before the whole unit goes out. Our Suburban did this 60 some dollars for the parts. The coolant would run down the hoses and collect in the radiator support.

Did the water pump about 6 months ago.

The thing I can't really understand is if it is the radiator does have a crack in it, why doesn't it leake when the car is just sitting there or driving? It only leaks out after the key has been shut off.

 

[AZ Vic]

The cooling system is under the most pressure after you have shut the vehicle off and things are no longer being cooled.

Your engine, heads, exhaust and other stuff operates at a higher temperature then your coolant. When you stop the fans and the water pump everything kind of sits there and bakes for a little while. Causing the temperature to rise which in turn, causes the pressure to increase - hence the leak after you shut your engine off.

Double check your hose clamps and valve to make sure they are tight. Then, I would take the shroud off if I still could not see where it was coming from and trace it back to the source.

Maybe some of that GM cooling sealant they use in the newer vehicles?


Good luck,

Vic

 

[PHANTASM]

PETCOCK

ALOT OF TIMES THE O-RING ON THE PETCOCK WILL LEAK.

check the petcock out and make sure it is tight, sometimes if you loosen it up and re-tighten it , it will stop seeping.

hope this helps.

 

[Dan Buick Man]

exactly what AZ VIC said. If there is a Coolant hose or clamp anywhere near the leak, check that first. Hoses are the first thing to leak in a cooling system, but they can be deceiving. Engine temps and pressure rise when coolant is not being pumped through it.