1999 GMC Suburban Water Temp Gage

KENNYROYJOHN

MEMBER
1999 GMC SUBURBAN
V8
4WD
AUTOMATIC
120,000 MILES

If the coolant is compromised with the addition of an oily substance, would this cause vehicle to eventually over heat? After I keep draining, back flushing the rad & eng, the vehicle does not even approach the halfway mark on the temp gage when up to operating range. With all the oil mixed in with coolant, I am driving vehicle just a few miles every day until I can figure out what is wrong, but vehicle seems to run just fine.

1 Reply

MERLIN2021

MECHANIC
17,250 POSTS

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From: kennyroyjohn
To: merlin2021
Posted: Tue Feb 02, 2010 2:12 am
Subject: Oil in Radiator
Hi I have drained the radiator after running with cleaner in system, drained & filled with clean water & ran again for about 20 minutes or so & then drained, refilled and back flushed cooling system for 15 - 30 minutes. I then filled up system with anti-freeze & water. Ran for a day & Oil appeared in cooling system again. Repeated whole procedure again next day. Again there appears to be oil in cooling system. When system 's hot radiator content appears creamy yellowish & thick when this oily substance mixes with coolant. When system is cold, the oil appears to be in form of large yellowish globules when it separates from anti-freeze. There is no apparent water in engine, I checked the dipstick & fluid on it does not appear milky, just oil. I do not think the head gaskets are blown, but could they be bad and be letting engine or tranny fluid somehow get into the radiator? I am stumped. Is there a way for leaks into radiator from any gaskets or seals from oil pump, transmission cooler, etc? Kenn
If the tranny cooler lines attach to the radiator, the cooling tank for it may have cracked internally, check the tranny fluid as weel as engine oil. See if it's also mixing in the tranny. If not, a pressure test is needed, and maybe a compression test of the motor.