ok so i got a weird one I'm hoping the powers-that-be can assist me in figuring this out. I have a major coolant leak that at first appeared to be coming from the water pump so I have changed the water pump with a new gasket as well as the thermostat and a new gasket where the pipe connects to the engine block housing the thermostat. Every time I attempt to put in coolant in the radiator it will begin to be leaking from somewhere either behind the water pump or up near the thermostathousing but I cannot seem to find the source of the leak any ideas???

 

WHICH V8?

 

Welcome to the forum.

+1, please identify the vehicle and the engine.

 

Ha! I had the same trouble! I had left a bit of old gasket on the block. When I put it back together, a small leak. Pulled it off, D'oh!. Back together. Hmm... still leaking. took it back off. Tore a small bit out of the new gasket. Two more tries with RTV and I was done.

It was the longest water pump change ever! lol

 

Jeep grand cherokee 5.2 v8

 

at first i though it was a **** gasket too. but this is the 3rd thern gasket redo and the water pump gasket is not the source. when i cap the radiator and squeeze the upper hose i can see and hear a leak near the thermostat kind of. is there some hidden housing or hose near there that can crack?

 

also if i try to top off the radiator it will leak. but when i removed the thermistat the engine is holding fluid(im giessing this eliminates the pump being leaky i presume)

 

the cylinder heads have a small freeze out plug located in the front and rear, perhaps one is rotted through.........

 

That;s good to know. Thanks.

 

the circled area is where the freeze plugs are, also the timing case cover could be corroded and leaking as well, it is not pictured here

 

if it looks like it is coming from the top of the water pump or close to the head gasket surface , then I would suspect that the timing case cover gasket is leaking, or worse case the timing case cover is rotted/corroded (it is aluminum, and a common issue)

 

The heater core pipe that jams into the water pump has a small O-ring seal. That should be replaced w/ the correct part.

There is a large aluminum casting that holds the generator and A/C compressor.

That large casting conceals the parts that could be leaking.

Remove the belt, the generator, flop the attached compressor to the side and remove the large casting.

Clean the front of the engine of oil, dirt and crud.

Remove the radiator cap and replace w/ a manual pump pressurize fitting, like this one.

Pressurize the cooling system to locate the leak.