Jimmy/Envoy Coolant Leak

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mccaskd

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2000 Envoy (Jimmy style) and a coolant leak.

Intake manifold gasket was replaced in the summer, heater core flushed and regained heating back. Thermostat was also changed at same time. New radiator cap.

Now it's winter, the temperature gauge does not get off the 100 deg mark. Little heat coming into the vehicle.

Noticed today a stream of coolant coming out from underneath but could no replicate it once it stopped. I can't see any obvious place where the leak is. I am guessing it could be the weep hole in the water pump.

Oil is not milky and I can see no oil floating in the coolant mixture, so I am pretty sure it's not the intake gasket again.

Any ideas other than pressure testing to see where it leaks?

What would cause the temp gauge not to move, failed thermostat?

Any help appreciated.
 
mccaskd said:
2000 Envoy (Jimmy style) and a coolant leak.

Intake manifold gasket was replaced in the summer, heater core flushed and regained heating back. Thermostat was also changed at same time. New radiator cap.

Now it's winter, the temperature gauge does not get off the 100 deg mark. Little heat coming into the vehicle.

Noticed today a stream of coolant coming out from underneath but could no replicate it once it stopped. I can't see any obvious place where the leak is. I am guessing it could be the weep hole in the water pump.

Oil is not milky and I can see no oil floating in the coolant mixture, so I am pretty sure it's not the intake gasket again.

Any ideas other than pressure testing to see where it leaks?

What would cause the temp gauge not to move, failed thermostat?

Any help appreciated.
Click to expand...

Replace the thermostat, it's known to happen that the thermostat may get stuck open if the pins don't line up after it opens and closes. As for the leak, from what you have described. It's the water pump if there is a leak coming from that area only when the engine is running.

Good luck and keep us posted. ;)
 
I replaced thermostat and got the heat back. Temp gauge moved off the 100 mark to about 200 :)

As for the leak, I couldn't see anything tonight, so I shall keep an eye on the level and an eye on the water pump.

Thanks for the reply

David
 
Needs a water pump too. Is it hard to remove the fan/clutch assembly?
 
mccaskd said:
Needs a water pump too. Is it hard to remove the fan/clutch assembly?
Click to expand...

Removing the fan and clutch:

There is no need to separate the fan from the clutch. The whole thing threads on to the end of the water pump. Turning counterclockwise removes the fan, clockwise tightens it back on (from the point of view of standing at the front of the vehicle facing the engine compartment).

I can't remember the size wrench off the top of my head 1 3/8th" I think. Place the wrench on the nut and tap loose with a hammer. The tapping will break it loose, you have to tap it. If you just try to loosen it, the belt won't hold it and the whole thing will turn. After it breaks loose just spin it off.

Then break loose the bolts holding the pulley on the water pump, 4- 13 mm or 1/2" bolts. Just break them loose, don't remove them. Now remove the serpentine belt, and finish removing the bolts holding the pulley and remove the pulley. Next is just to remove the hoses.

Once you have removed the old water pump, clean the surface and make sure you remove all traces of the old gasket.

Installing the new pump:

Apply a bead of blue Permatex around the holes on both sides of the gaskets, put them on the pump and insert the bolts through the holes to hold the gaskets in place. Carefully lower the pump in to position. Thread the bolts into the block and snug them. Then remove the bolts one at a time, add the permatex to the threads, and then reinsert. (only do one at a time so that the pump doesn't shift and disturb the mating surfaces) Then tighten all the bolts.

There will be a lot of air trapped in the system, so after you fill it, get the engine to operating temperature, shut it off, let it cool, then add more. The air trapped in the system can cause your engine to over heat if left unattended. I suggest filling the system with water only and run it like that just to make sure there are no leaks. That way you don't waste your antifreeze if you have to do further repairs. ;)

Good luck and keep us posted.
 
Last edited:
Thanks for the info, I'II let you know now I get on. Not the nicest of weather here in IN for working on my wifes vehicle.
 
Water pump replaced after a bit of cursing and grazed knuckles but job completed and no more coolant loss. Thanks for the advice. Much appreciated.
 
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