Question about 1999 GMC Jimmy

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1999 Gmc Jimmy water leak under the transmission

I found a leak of antifreeze under my truck (99 Jimmy). I thought it was my heater core but a friend of mine told me that if the heater core goes bad, it leaks in the inside of the truck. He told me it may be a hose, and he explained to me that as the car get hotter the leak get bigger (Which its true). My problem is that I can't find the leaking hose. The leak is located right above the transmission and leaks right under the driverside. Now I have followed the two main hoses that go to the transmission from the radiator, but they are connected under the passenger side, left side of the transmission. I have tried to use a mirror and a flashlight to look for the leak above the transmission, but I am not getting it. Am I going have to start taking parts out from under the vehicle to get a better view or am I going have to take the dash out? I am trying to do as much as I can to learn how to fix my truck. Do you think you can help me? I just don't know where to start. Thanks.

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I believe the heater hoses are on the pass side on your truck, but have you checked where the heater hoses go into the truck? Otherwise on the driver side I would check 2 things after I checked the hoses 1. Intake manifold check it up and down they are bad for leaking at one of the corners. and it could be running down the back onto the ground. 2. check the freeze plugs. if you can go to autozone see if they will loan you a coolant press test kit other wise they are about 30$ for one .With the car off top the coolant off and press the system to what the rad cap is rated 15 or 16 ect. get your flash light and chase the drip. I would say the intake is your first shot at finding it. if you have a uv light you can also add dye to the system let it run and find it. First get some thing to stand on get on over the intake and find the coolant just remember it can leak from here and run and drop there. hoses , intake , freeze plugs

Posted on May 25, 2009

Testimonial: "Thanks! This information really help. I know its a little late but thank you so much. I did follow the leak and it was the head gasket. "

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