Help finding leak

IANOBETZ

MEMBER
1998 CHEVROLET S-10
6 CYL
4WD
AUTOMATIC
190,000 MILES

I'm trying to find a coolant leak in my 1998 Chevy S-10. The leak turned heavy over the last week. The leak is coming from the middle of the engine compartment, dripping off the transmission. I bypassed the heater core by splicing the hoses coming out of the water pump and the leak continued. I can't see under the engine or into the engine compartment toward the back of the engine. How can I determine where the leak is coming from?

9 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Could be an intake manifold leak or a freeze plug blown between the engine and transmission-

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Saturday, October 3rd, 2020 AT 11:15 AM

IANOBETZ

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9 POSTS

I'll ask in a more clear fashion: How can I determine where the leak is coming from?

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Saturday, October 3rd, 2020 AT 11:15 AM

RASMATAZ

MECHANIC
75,992 POSTS

Pressure test the cooling system and closely look towards the back of the engine and front-you're eyes and ears here-could be the cylinder head etc-let me know

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Saturday, October 3rd, 2020 AT 11:15 AM

IANOBETZ

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I can re-create the leak by turning on the engine. The problem is I can't see that far into the engine. I imagine I won't be able to see the freeze plug between the engine and transmission when its leaking. But is there a way I can eliminate other leaks, like the intake manifold? It doesn't sound like much fun if I have to pull the engine for the freeze plug.

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Saturday, October 3rd, 2020 AT 11:15 AM

RASMATAZ

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You have an external leak-you should be able to see it which I'm unable to-If the leak is on a freeze plug behind the engine it will leak between the engine and tranny at the bottom where the tranny meets the engine-confirm it-go underneath and observe-

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Saturday, October 3rd, 2020 AT 11:15 AM

IANOBETZ

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It appears to be leaking from between the engine and the transmission, but I also see quit a bit of moisture where the intake manifold sits on the head, although I don't see the leak itself.

Background: I've been plagued with coolant problems for the last 6 months or more. I've replaced the radiator and have been adding a lot of coolant. The engine wasn't leaking on the ground or driveway but I had to ad coolant. I've also changed the thermostat. 3 weeks ago I finally gave in and added Barrs Stop Leaks.

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Saturday, October 3rd, 2020 AT 11:15 AM

RASMATAZ

MECHANIC
75,992 POSTS

Try tightening down the intake manifold and see what happens-

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Saturday, October 3rd, 2020 AT 11:15 AM

IANOBETZ

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I found a small puddle of coolant underneath the intake hose (that goes to the filter) that I couldn't see until I removed it. I attempted to make the leak happen again, but for some reason (maybe cold tonight) it didn't leak. I'm going to head to Autozone tomorrow to use their pressure tester to see if I can see where the leak is coming from. I'll try tightening the bolts if I still can't find it with pressure.

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Saturday, October 3rd, 2020 AT 11:15 AM

IANOBETZ

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Sure enough, added pressure, found the leaks all around the intake manifold. I replaced all of the upper gaskets. I'm almost done with the project, but having one final problem. I have one left over terminal where I can't find the port. I have attached an image of the terminal. The wire is black/yellow.

Image (Click to make bigger)