[GeneL]

Hi,

I have a 91 dlx with the 22RE engine and automatic transmission. Completely stock Calif model with 185K miles. Recently I've been having cooling system problems. What I've done so far.

New gennie T-stat and radiator cap. Hoses replaced under the intake manifold and a small hose shaped like a question mark on top of the engine between the valve cover and intake manifold.

What the problem is the engine consumes lots of coolant, after looking in the coolant tank. I fill it usually twice a day, driving about 5 miles to work. What confuses me is that the rediator is always full, unless I let the level in the expansion tank drop too low.

I see no leaks when stopped, either running or not. I also see no white smoke when the engine is running.

I've pressure tested the cooling system, it passes. I've also done a compression test, it passes. The only thing that might be a problem is the oil, I let it go too long without changing it, but I changed it just before the problem got worse. From what I've heard, if there is a coolant leak into the oil, the oil will look milky. The oil is definately not milky, but in my opinion not the usual color. Also, the oil is high, but I'm not 100% sure I didn't make a mistake filling it. I'm going to change the oil again this weekend, and see what happens. Thanks for reading this this far, and any observations or advice is welcome.

 

[sdspeed]

Does the heater work properly? With the cap off and it idling is there cavitation, lots of air being introduced?
Might consider a Exhaust Gas Test to check the coolant.

 

[GeneL]

Thanks SD speed. With the cap off, no cavitation. The heater works, but if I have it on, my coolant temp gauge rises a bit. As for the exhaust gas test, I've done it., and it's a negative.

 

[DCM]

Any external wetness underneath after driving it?

 

[GeneL]

DCM, no, no leaking. The mystery deepens.

Thanks DCM and SD speed for the quick replies. Maybe Sherlock Holmes could figure it out.

 

[Handyman85383]

It is odd that the coolant temperature rises when you have the heater on. Usually when you add the heater core into the mix the coolant temperature goes down not up. If the truck passes a cooling system pressure test, exhaust gas test, and compression test and you are using coolant my guess would be a leaking head gasket or a cracked block or head that only leaks once it is heated up. The reason I say that is all tests are passing but the cooling system pressure test is not done hot and the same may be true of the compression test. You could connect a bypass hose between the heater core supply and return lines and eliminate the heater core from the variables. Then if your coolant consumption stops you know your heater core is the issue.