Mechanics

COOLANT LEAK

1998 GMC Truck • V8 4WD Automatic • 105,000 miles

I smell coolant all the time but can't find the leak. Sometimes I have a puddle under the truck (still can't find the leak) and sometimes there is no puddle under the truck. The puddle is a foot in diameter so I'm loosing fluid some where and can't find it please help getting very frustrated. Everything is supprisingly clean an dry. Found a few leaks(but of oil)and fixed those hoses that came from the radiator, still have coolant leak.
Avatar
Cologuy
January 14, 2011.



Would help to know where puddle is located under truck. Front, back, P-side, Drivers side? Have you checked ALL the hoses that run coolant? Is the water pump making a strange sound of late? Do you have a cream colored foam on the underside of your oil cap? Have you checked to see if the overflow tank is cracked, or the attaching hose leaking?

Ford Man in Michigan

Tiny
Ford Man
Jan 14, 2011.
What about water pump weep hole?

Tiny
Fixitmr
Jan 14, 2011.
I've check all the hoses an cannot find any visible leaks. As far as the puddle goes it's basically right under front, middle of engine, 6 inches behind the fan, Right under the waterpump but don't see a leak. It's cold out now (0 to -10) so yes something screams when I start the truck but I kinda think that's from the alternator (Have had to replace them on other GM products). Maybe it is the water pump making the noise.

Tiny
Cologuy
Jan 14, 2011.
My guess is the pump is where your leak is coming from ! It will only leak with a hot motor, or while running. With the temps in your area.
To test the pump. Grab the fan shaft & wiggle it (while motor is warm). If there is any movement, your pump is shot. Another trick to proving the leak is coming from the weep hole on the pump. After you park it for the night (day?). Place a dry rag under pump to catch coolant ( REMEMBER to remove rag before restarting motor! ), Leave sit for several hours so that motor cools to the point of being cold. If the rag is wet, the pump is leaking. Before making this last test, make sure the motor got to running temp, & it has a full load of coolant !

Ford Man in Michigan

Tiny
Ford Man
Jan 14, 2011.
Just stopped at a local mechanic and he thinks it is the intake manifold gasket just wondering if that makes sense. He look at it very quickly with a flashlight and mirror and didn't think it was the water pump.

Tiny
Cologuy
Jan 14, 2011.
Could be. But if that is the case. You should have cream colored foam on the inside of your oil cap, or inside the valve cover. With the puddle you mention. That points to the pump ! Do the rag test I spoke of.A sure fire way to prove, or disprove if it's the pump.

Ford Man in Michigan

Tiny
Ford Man
Jan 14, 2011.