2001 5.3L Suburban 1500 coolant leak

RenegadeT

RenegadeT

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I'm pretty sure the radiator is leaking, but I can't find the leak so I'm not 100% sure where the coolant is going. I've been losing coolant (1gal/100miles), and it appears to be around the radiator. Everything on the engine side looks dry, I only see coolant dripping from under the radiator mounting area. I borrowed a pressure tester from Advance Auto, hooked it up to the coolant bottle, pumped to 15psi like the cap says. After 2 hrs it was at 13.5psi and I found a 4" spot under the radiator. Still couldn't pinpoint where it came from, but I'm fairly sure its the radiator. Its an aluminum core with crimped plastic tanks...never had good luck with those lasting long. When I started the truck after this, it ran really rough for the first minute, but no signs of coolant coming out the exhaust.

History of this truck...I picked it up in Oct., supposed leaking heads (very common problem on these), drained 15qts oil/water from the engine, replaced the heads and head gasket, its been OK since then. Both my engine oil and tranny oil look coolant free.

One thing that bothers me is that the upper radiator doesn't seem to have any pressure. After a 20 min drive this morning, the temp gauge looked normal (200deg or so), but I parked and was able to squeeze the upper rad. hose, it seemed empty, and hot. I'm wondering if my t'stat might be stuck, but nothing really makes sense. I'll admit, I don't fully understand how these no-radiator cap systems (pressure bottle) work. And FWIW, my burb has the rear HVAC.
 
The tank is the highest spot in the coolant system and they bleed pretty easy. Not much different than any other cooling system.

Since you've already addressed the heads, I'd say you just need a radiator. Might as well change the thermostat while you're at it.
 
On my 03 Yukon I had a mysterious leak that took me forever to find end up being on the heater core fittings under the hood right up against the fire wall. The disconnect piece had an o-ring go bad. Leaked slowly enough that I never noticed it and residual moisture flashed and dried from the heat of the passenger side exhaust manifold.
 
@Croatan_Kid ,that's my thoughts exactly, not sure if I was missing something. FedEx should be arriving today with my RockAuto radiator, I'll grab a tstat along with a couple gallons of coolant.
 
I always wind up taking the plastic fittings off of the heater core and putting the hoses right on the heater core pipes.
 
Could always pressurize it with a hand pump and go looking for leaks...
 
He already did
 
REPLACE the cap on the remote tank, its still a pressure cap and they do go bad,

The cooling system works that same as any regular system, the recovery tank is part of the pressurized system,and is the highest point.

as stated before, check the fittings at the firewall as well ( you can remove the quick connects and use band clamps ) there are also the same fittings for the rear HVAC, check the lines along the passenger side inner rocker, they get rock damage, and corrode as well. the AC lines are a real joy to replace
 
Ha! Got this one.
Check and see if you have Castech 706 heads. Pull the valve covers, pressurize the cooling system and watch them leak.
Ask me how i know.....
:flipoff:
 
That was the issue when he bought it. Said he did head gaskets...didn't say about the heads themselves.
 
RenegadeT said:
History of this truck...I picked it up in Oct., supposed leaking heads (very common problem on these), drained 15qts oil/water from the engine, replaced the heads and head gasket, its been OK since then. Both my engine oil and tranny oil look coolant free.
Click to expand...

Croatan_Kid said:
That was the issue when he bought it. Said he did head gaskets...didn't say about the heads themselves.
Click to expand...

clarification
 
I know it said he replaced them, but not what they were replaced with. I read stuff :D
 
Replaced the Castech 706 heads with stock 862 heads, and of course new gaskets. I wish I pressurized the system during the tear down, that would've been neat to see.

Tonight, I swapped in a new radiator. I'll pressure test it, and my cap too.
 
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