RADIATOR LEAKING SOMEWHERE?

10

Asked by Nov 29, 2014 at 09:09 AM about the 1995 GMC Sierra 1500 C1500 SL Standard Cab SB

Question type: Maintenance & Repair

I HAVE  95 SIERRA 5.7 V8 WITH 240K MILES AND THE RADIATOR DRAINS
EXTREMELY FAST BUT THE FLUID IS NOT DRAINING VISIBLY. I HAVE CHECKED
MY OIL AND IT IS OT DRAINING INTO THE MOTOR, I RECENTLY CHANGED MY
WATER PUMP AND THERMOSTAT BECAUSE OF OVERHEATING, BU NOW I CANT
FIND THIS LEAK. ANY SUGGESTIONS ON WHERE TO LOOK NEXT?

7 Answers

143,075

One way you can try is with one of these. They can be rented, pumps air in to radiator, do it cold, engine off. Fill radiator then pressurize and see if you can find leak

2 out of 2 people think this is helpful.
10,090

could be an intake manifold gasket.

7,250

Look around the thermostat. Some thermostats are under the engine and the leakage is hard to see. Did you fix the overheat problem?

10

I believe so. After replacing the thermo the truck didn't overheat until this morning about a week after replacing. I'll try the pressure tester this afternoon

10

Ok update. I can smell antifreeze through my vents very strong when I turn on my heater and there is a small leak coming from the heater box on my firewall. I guess the next step will be to check that out

1 out of 1 people think this is helpful.
10,090

you have a bad heater core.

2 out of 2 people think this is helpful.
143,075

With that additional information I agree with mikepriestlake. Text-Book symptoms. If/when you do the pressure test make sure heater core has coolant flow to it. i.e turn it on first, run for a few minutes, allow to cool (does not have to be stone-cold just don't pop a hot radiator cap)

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