only overheats with a/c on

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m1bttltnkr

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I have a 2005 ls v8....it only overheats when and leaks out of the weep hole on the water pump when the a/c is on. The rest of the time the fan just runs like a scalded dog. If I don't run the a/c then I never have to add water. This familiar to anyone?
 
m1bttltnkr said:
I have a 2005 ls v8....it only overheats when and leaks out of the weep hole on the water pump when the a/c is on. The rest of the time the fan just runs like a scalded dog. If I don't run the a/c then I never have to add water. This familiar to anyone?
Click to expand...

Sounds like the water pump is leaking.
 
Any coolant coming out of the water pump weep hole at any time indicates a failed water pump.
Any coolant venting anywhere other than the degas bottle fill cap pressure relief at any time indicates a leak that must be fixed.
(Any coolant venting out of the degas bottle cap pressure relief indicates a system problem or the system is overfilled.)
 
Ok so water pump, thermostat, thermo housing, coolant cross pipe, radiator hoses all replaced. And now that all of that has been sealed a leak somewhere in the back of the engine bay is leaking profusely....but only with the a/c on. It is middle rear seems kinda toward the passenger side. The dccv is by the radiator right? The heater hoses are good. What is back there that can leak like this?
 
Could be degas. (It needs to be replaced if you didn't just replace it!)

It sounds like it is the 45 degree pipe that is below and behind the crossover pipe. You have to remove or at least loosen the intake manifold to change it. You should also replace the throttle body heater hose that goes down there while you have the manifold off.

Yes, this part is at the front of the engine, but when it leaks, the coolant pours under the intake manifold and comes out at the back of the engine.
 
That pipe was also replaced with oem seal as well as permatex. Using permatex has been the only way I've gotten everything to reseal. Meaning the pipe from water pump to crossover pipe. Whoever had this car before me was a hardcore stopleak believer. I've. Replaced everything up front besides the radiator
 
m1bttltnkr said:
Whoever had this car before me was a hardcore stopleak believer.
Click to expand...

Using that will just clog up the system causing high pressure build up and one heck of a mess......my wife had a car that someone also believed in that stuff.

After one hell of a tear down I was able to fix/flush most out to get it to correct again.
 
m1bttltnkr said:
That pipe was also replaced with oem seal as well as permatex. Using permatex has been the only way I've gotten everything to reseal. Meaning the pipe from water pump to crossover pipe. Whoever had this car before me was a hardcore stopleak believer. I've. Replaced everything up front besides the radiator
Click to expand...

Does everything include the Degas? With the OEM Degas?
 
I did a pressure/leakdown test @ 16psi with engine off and all was good. Boggles my mind that it will only leak with a/c on. When I get back home I'm gonna check the degas bottle. Where does the degas hose run from? The top degas hose was also replaced. I'm just trying to minimize my time leaned over under the hood cuz I got a messed up back.
 
The degas itself is ok but not replaced. Where does the bottom degas hose run from? I did a pressure/leakdown test @ 16psi and it was ok. This thing is boggling my mind. Also this is all been done with a system bleed per the factory service manual.
 
m1bttltnkr said:
Also I can see under the intake mani is bone dry.
Click to expand...

If that's really true (it's very hard to see under there where the coolant runs across), then that leaves the degas bottle, the heater cores, and a little bit of pluming (related to the heater and the degas) on the firewall.
 
found a crack in the metal line running to the degas bottle. gonna have to redneck it a bit with a hose bandaid over the pipe
 
While you are at it take the cover plate off the rad and see if the rad has gotten plugged up.
If so you can blow it out with a waterhose.
 
yup, when I went to do my whole cooling system over haul with the Jag thermo upgrade, I found a muddy caked on old plastic shopping bag (what was left of it) in between the trans cooler and Radiator. Was all hardened up and had to poke at it and run the hose on it for a while. Amazing what you pick up during a winters drive. Never lead to any overheating issues but it was not meant to be there so it had to go.
 
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