Coolant leak causing , trans fluid hot.

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99 4.3 c1500 leaking coolant and smells like burning coolant. Sears didn't think it ws a big deal. Local mechanic wanted 100 parts and $450 in labor. They didn't know where leak was exactly. I looked for leak and initially couldn't find any. But coolant was everywhere underneath. Drove to work no problem driving back my "coolant low" displayed then the "Trans Fluid Hot" was displayed. I pulled over asap and let cool 2 hours, checked the transmission fluid and it was light brown. Then drove home. Looking at this weekend saw same coolant on bottom of engine, oil pan, and transmission pan (gravity right?) On top hidden on the in a groove was a small collection of coolant. Do i remove all hoses and valves to check intake manifold gasket or use stop-leak products like Prestones flush/cleaner, engine block stopleak, or other stop leaks (i found some at autozone and some Wal-Marts)??

[newdude]

Have the cooling system pressure tested. Make sure they look up top and underneath for a leak. Skip the stop leaks and have it checked. Its clearly leaking somewhere if there is coolant in places there shouldn't be any.

[Swimmer8366]

Check water pump had same problem with my truck ended up being problem

 

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[ifixedit]

It's probably showing the trans fluid is hot because your radiator is low on coolant, the transmission cooling lines connect to the side tank of the radiator, low coolant and hence tranny fluid gets hot. First thoughts are it sounds like it could be an intake gasket leak, they will sometimes seep and coolant will come up around the area where the intake bolts to the heads. Also, check your oil to see if it's now a milkshake, dead giveaway to a leaking intake gasket, coolant going internally into the crankcase. If that isn't the issue I do know the flimsy pot metal heater hose connections on the intake manifold can corrode over time and leak or be at a point of completely falling apart. Had one on my 98 Yukon that was really bad and had to replace it. Whatever you do, DON'T use any kind of stop leak products, find the problem and fix it correctly. Stop leaks are a band aid at best and can totally plug up your entire cooling system (i.e., read that as overheating) along with plugging up the heater core, the radiator passages and so on, then you've really got yourself a mess on your hands. Yes, it could possibly be the water pump as well but you will typically have a leak right at the front of the engine and the coolant will likely puddle up on the ground right under the front of the engine when you are parked.

[Imagein]

I had a radiator leak that I was not able to find. It turned out to be a crack at the very top of the radiator, under the protective "shroud".

It took a radiator shop to find it, as it did not appear until after warm up. I was only loosing a pint of coolant a week or so.

 

Make sure if it is the radiator to have them put in a grounding strap as the replacement radiators are not metal throughout. He explained this to me but I have since forgotten the reason why. Maybe someone on this forum can explain it.

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1995 GMC C1500 5.7L TBI LT Stock