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Frost plug locations for 1991 gmc 3500hd

My thermastat froze shut and I am replacing it. I need the locations of the frost plugs on the passenger side. My truck started off with a small steady drip. Tried to follow the leak back up the motor and all I could see was a bolt on the starter. Inspected the hoses at the firewall which were ok. Also top of the motor hose was ok. I was told the frost plug could be rusted so it could be leaking. Upon further inspection of the hoses the leak became a steady leak. Not a full out pouring of fluid. The radiator still has fluid. The leak stopped after turning off the truck and let it cool down. I started my truck again hoping to follow the leak no luck. Shut it off and then about 30 min later tried to start and locate leak origin now truck won't start. Have no idea how to get truck started or fix leak.

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  • kevin carpenter May 11, 2010

    well there is a freeze plug right behind the starter you have to remove the starter to get to it. you also have stated that the vech will not start cranks but will not run our will not crank?



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I think you mean freeze plugs, any way there will be three on each side of engine block below exhaust manafolds. to get to the one on the right side clear to the rear of engine, the starter will have to be removed. if its the one in the middle, motor will have to be jacked up and motor mount will have to be removed to get to it. also there are freeze plugs on back of engine block, behind flywheel if one or both of them are leaking trans. will have to come out to replace them. also chk. the rear of intake were intake, and head, and block come together, same in the front could be leaking there also. as far as your truck not wanting to start i will need a little more info to help with that, like is it gas or diesel? if its gas does it have spark? can you hear fuel pump run and relay click? i will try to help the best i can but i need the info.

Posted on Jan 27, 2009


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