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Discussion Starter #1
1999 Suburban 1500/350.
Has a liquid discharge that does not appear to come from the AC Condenser on the firewall.
The liquid will stop if the truck is run with the heater on and driven for approximately three miles.
Problem is intermittent.
The liquid rolls down the block and comes off the Torque Converter housing or a little to the passenger side of the block.
Heater hoses are not leaking.
Truck became hot (210 degrees) a few days ago.
Original Radiator Cap.
Sometimes it discharges the fluid other times, no trace of a leak.

Any suggestions would be welcome.

Thanks

gary
 

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Welcome to the club Gary. First thing to do is try & determine if it's fresh water or anti freeze/coolant.
 

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Welcome to the club, Gary. What stepan said, start there first.
 

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Discussion Starter #4
Thanks

Welcome to the club, Gary. What stepan said, start there first.
The cooling system is mostly water right now.
Lost coolant, got hot.
What I don't understand is why the leak is intermittent.
If it is the manifold gasket needs replacement I'm going to do the rear heater hose at the same time.
I understand that there is a "fitting" in the rear of the engine that's problematic as well.
As
ny advice on where to find do it yourself instructions, mechanic is not doable.
Thanks for your replies and knowledge.
Look forward to hearing your ideas on how to proceed.

Only the Best to You Guys

gary
 

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Gary, since this is intermittant I don't think it's engine coolant. I don't think a coolant leak would repair itself. I think since this is intermittant that it is water condensation in the air box, & when you run the heater for a few miles it dries it up. Also, besides making this water condensation when the ac is on, it can also make "water" with the heater on if you're in the "defrost" mode because the CC runs the ac to mix cool & warm air during defrost to reduce the fogging effect on the windshield.
If you still think you have a coolant leak there is some dye that you can put in the cooling system to check just to make sure. You could also get a rad pressure tester & try that, but since it's intermittant, chances are it might show a good test 50% of the time.
Also 210 degrees F isn't really overheating. Most run 195 degree thermostats or higher now days so I don't think you have any damage from that temp.
 

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Discussion Starter #6 (Edited)
AIr Box

HI

Thanks for the info.
Where is the air box located?
It is losing coolant regularly now.
The leaking is now consistant, large drops, puddling under truck,
No milky oil.

Thanks

gary





Gary, since this is intermittant I don't think it's engine coolant. I don't think a coolant leak would repair itself. I think since this is intermittant that it is water condensation in the air box, & when you run the heater for a few miles it dries it up. Also, besides making this water condensation when the ac is on, it can also make "water" with the heater on if you're in the "defrost" mode because the CC runs the ac to mix cool & warm air during defrost to reduce the fogging effect on the windshield.
If you still think you have a coolant leak there is some dye that you can put in the cooling system to check just to make sure. You could also get a rad pressure tester & try that, but since it's intermittant, chances are it might show a good test 50% of the time.
Also 210 degrees F isn't really overheating. Most run 195 degree thermostats or higher now days so I don't think you have any damage from that temp.
 

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The air box is behind the dash & houses the AC evaporator & the heater core, but if you're losing coolant then disregard the ac condensation possibility. I would get a radiator pressure test pump & pump it up to about 15 psi & look for your leak. Autozone & a few other auto parts suppliers loan tools if you leave a small $$ deposit so you don't need to buy one. Since it's leaking all the time now, it should be fairly easy to locate with the pressure test
 

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Discussion Starter #8
Pressure Test

Thanks, I'll do it.

Only the Best to You

gary





The air box is behind the dash & houses the AC evaporator & the heater core, but if you're losing coolant then disregard the ac condensation possibility. I would get a radiator pressure test pump & pump it up to about 15 psi & look for your leak. Autozone & a few other auto parts suppliers loan tools if you leave a small $$ deposit so you don't need to buy one. Since it's leaking all the time now, it should be fairly easy to locate with the pressure test
 

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Gary, just had a simalar problem with my 99 C2500, the intake manifold was leaking. I have a 7.4L Vortec (454Ci) in my truck, it is not a really difficult job, only thing I had issues with was the distributer timing, be sure to mark it well before disassembly, I'm a former Chevy dealer mechanic and I have done it plenty of times before but this new stuff really gave me a hard time.
Where are you located?
 

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Discussion Starter #10
Leak

What tools would be neede? A torque wrench is mandatory, van you recommend a brand, I have Ceaftsman. Is a breaker bar necessary?
I'm in Austin, TX.

Thanks

gary.




Gary, just had a simalar problem with my 99 C2500, the intake manifold was leaking. I have a 7.4L Vortec (454Ci) in my truck, it is not a really difficult job, only thing I had issues with was the distributer timing, be sure to mark it well before disassembly, I'm a former Chevy dealer mechanic and I have done it plenty of times before but this new stuff really gave me a hard time.
Where are you located?
 
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