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1989 GMC Sierra 1500 Leaking Coolant Behind Engine

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New User

Jun 27, 2020, 6:18 PM

Post #1 of 3 (297 views)
1989 GMC Sierra 1500 Leaking Coolant Behind Engine Sign In

I have a 1989 GMC Sierra 1500.
I have coolant dripping out of a small hole, between the oil pan and transmission cover.
I think this is the torque converter cover.
would you please help me figure out where this leak may be coming from.
Thank you
oil pan to the left. transmission cover to the right off screen blocked by the exhaust pipe.the drip is a small hole. It may be a vent hole on the torque converter, but I am not sure

(This post was edited by Hammer Time on Jun 28, 2020, 3:50 AM)

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 27, 2020, 9:05 PM

Post #2 of 3 (283 views)
Re: 1989 GMC Sierra 1500 Leaking Coolant Behind Engine Sign In

Please try to reduce size of that pic it overwhelms the view
of the page and all subsequent posts.
For now on leaks like that sure doesn't seem like oil or other does look
like coolant so look up higher than that with mirror at any engine type this
would have (state which may help too sport) could be intake, a freeze or AKA (core plug) in rear of
a head or gasket higher than all of it.
Also if nothing put system under pressure with a pressure tester then if need be remove the
cover look again if any view up.

Don't forget all hoses that are higher or go over or near top of engine including heater hoses, at clamps.

One real sneaky type of leak is a pinhole in a coolant hose that can spray a fine line like a thin fishing line maybe only
found by hand or paper blocking it and getting wet while under pressure. Don't exceed the 15lb rating of the pressure
cap plus do not start engine with typical pressure tester on it ones I know do NOT stop pressure from rising
due to engine warming up can blow out weakest link usually the water pump
you don't need to add a problem,

Happy hunting you can find that,


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 28, 2020, 3:53 AM

Post #3 of 3 (267 views)
Re: 1989 GMC Sierra 1500 Leaking Coolant Behind Engine Sign In

I deleted that picture for the time being as it is way too large.

This leak is more likely coming from above and running down the back of the engine. As Tom suggested, you need to pressure test the system and examine the top very carefully. There are a couple of freeze plugs in the bell housing area but it is far more likely to be coming from above that.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

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