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Just noticed my 94 GMC suburban 5.7 leaking antifreeze at the rear of the engine. It drips from the heater hose area, down onto brake lines, or trans cooler lines, onto the exhaust manifold on the passenger side and pools around the starter transmission area and drips on the ground. Seems to leak more once the engine gets hotter. I have checked the heater core lines and they look ok. Even the heater hose looks ok. Doesnt look the best but doesnt appear to be leaking. Right in front of the heater hose where it mounts into the intake manifold, it appears to be wet there. Looks like its anti freeze. Do you guys think I have a leaking intake manifold gasket? I have attached a picture of the possible leak.
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It does have one of those plastic quick disconnect fittings where the heater hose mounts to the intake manifold. Once I took it apart a little better to see how the intake manifold mounts in here, it leaves me scratching my head. As you can see in the pictures on my original post, the antifreeze is on top of the intake manifold. It was pooling around where the quick disconnect fitting is. Sorry for the lack of mechanical terms here but there was a rectangular box ( i want to call it map sensor maybe) It mounts on a bracket which mounts onto a stud which goes through the intake manifold. You can see where the bracket bolts onto a stud and you can even see some of the sensor itself in my picture in my first post. This rectangular box has a vacuum line that goes from the throttle body to this box. Anyways, I removed this bracket with the box still attached so I could better see down in there. I removed the stud that goes through the intake manifold in the same spot.
I cleaned everything up the best I could, and started the engine. I could see anti freeze starting to seep out where the intake manifold bolts on. This was seeping out were I removed the bolt. I let it run for awhile and the only spot that was leaking was the intake manifold where the stud was removed. I shut the engine off, cleaned up around where the leak had started and put the stud back in and tightened it up. restarted the engine and went under to look for leaks. I also wiped the antifreeze from the bottom while I was down there. Let it run for awhile about 20 minutes and I didn’t see the intake manifold leaking at all where it was when the stud was removed. After letting it run for awhile, still no more leaks. I put everything back together and I am going to drive it some, and clean the garage floor up and see if its leaking when I get back.
What confuses me is that it almost couldn’t be the intake manifold gasket. Because in order for the antifreeze to leak out the gasket, it would have to defy gravity and work its way up on top of the intake manifold where it was pooling originally.
I poked around all the heater core lines with the truck running and didn’t see any leakage. It doesn’t appear the t stat is leaking and running back the intake manifold either It just seems concentrated in that one corner.
It could be the intake manifold gasket.Don’t
forget the cooling system is hot and under
pressure. keep us posted on your progress.it started leaking again and was wet around the same spot, this time it wasn’t wet on top of the intake manifold though. I already got it disassembled. Can someone tell me the correct tightening procedure and torque specs for a 94 5.7
see if this helps.
Thanks College Man again for your help. Sorry for the delay, however I wanted to give it some time to leak if it was gonna. I replaced the intake manifold and valve cover gaskets last weekend. I would be lying if I said it went smoothly, but I eventually got everything back together correctly. So far I am not seeing any leaks or smelling antifreeze at all, so I believe that did fix the problem. Since I recently had the heater core lines off to flush the core, I opted to just remove the heater hose from the core instead of messing around with that crappy plastic heater hose connection. I figured if I looked at it wrong it would break so I just avoided it all together. Thanks again.
when i come to messing with the plastic heater hose connection at the heater core i just bust them off and attach the hoses back up with hose clamps cause the plastic connection will eventually brake …just some advice ive seen it that too many times easier to fix now instead of fixing after it breaks on the side of the road…
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