Help! Longtime lurker, and created an account just for this purpose. First off, I'm not terribly knowledgable, but I learn quickly (particularly with images). I've read a bunch of threads on here that seemed to help folks, but a lot of the stuff was over my head, so I'm creating a new thread in hopes that someone can dumb it down a bit for me (thanks in advance).

Edit - Sorry, it's a 92 Pickup 3.0 V6

The truck is my daily driver, but my wife drove the truck to work last weekend since I had both kids (tough to fit both of em in the cab lol), and called me saying the truck was smoking. She said she thought the coolant was empty, but the truck wasn't overheating. Drove over in our Nissan and filled it up for her (A bit too much since it was dark and I didn't think to bring a flashlight with me). She drove it home and didn't have any issues. I took it to work the following Monday, and it started smoking pretty heavily after about 15 min of driving - still no overheating according to my temp gauge. Pull over, open up the hood, and see white smoke pouring out of the back middle of the engine. It started shooting out of one of the hose connections (I'll try to add some images below), so I add some coolant since it's bone dry, and make it to work (only like 4 more blocks). Get out there on my lunch break to take a peek, and the ground is covered in antifreeze.

Open up the hood and I see some antifreeze (I know, it should have been the red Toyota stuff, but this is literally all we had at the time) dripping from a couple places. Most of the smoke seems to come from the left half of the engine, though, and I cannot freaking find where the hell it's leaking. I haven't had much time throughout the week to take anything apart, but am hoping to this weekend. Hence my post. I need some help. Wtf do I test to find out where it's leaking? What do I take off to see better? What parts? Any direction is helpful.

FWIW the truck only seems to leak after running it. If I fill the reservoir tank and just let it sit overnight there's no leak. It only starts once I have the engine running for a bit - which leads me to believe it's something to do with the pressure built up during running. I read a few threads as I alluded to earlier, and initially I suspected it was only happening when running the heater, but I debunked that theory yesterday driving to work in 20 degree weather and no heater lol.


#1 Antifreeze shooting out of hose connected to left side of this thing.

#2 This is the bottom of the thing I'm pointing to in image #1. Has antifreeze dripping from the bottom of the metal thing.

#3 Also dripping from this hose. My finger pointing to it.

 

In your first & second pic, that is the heater control valve and they can fail over the years. Relatively inexpensive, approx 40 bucks if I remember correctly. It controls the flow of coolant thru the heater core, the cold/hot slider on the HVAC controls.

The second pic is where one of the heater core nipples exit from inside the vehicles cab into the engine compartment. Could be just the hose or heater core. Big job to replace heater core.

If you can pressure test the system it can possibly help you pinpoint the issue.

Might try replacing the control valve first and hope it is spraying on the heater core outlet.

 

Thanks for your reply! So the heater control valve could leak without the heater actually running, correct? And yeah, I have been told that they basically built the whole cab around the heater core in these vehicles.

I was under the assumption that pressure testing can tell you that there is a leak somewhere, not where. Am I incorrect in that assumption?

 

$18 or $38 at RockAuto https://www.rockauto.com/en/catalog/...ter+valve,6860
I generally discourage replacing parts without a clear diagnosis, but for the price I'd probably just go ahead and do it.

The reason that it only leaks when it's been running a bit is the thermostat. Coolant doesn't flow through the heater connections (or even the radiator) until it's warm enough to open the thermostat (though that's only a matter of minutes). As a result, a regular simple pressure test could miss it. But the most common pressure testers hook to the top of the radiator (the "cold" side of the thermostat), so should show up your leak. Autozone has a loaner pressure tester; I'd start there.

Edit: if you pressurize the coolant, where's it going to go? Right out the leak. It doesn't work every time, but I'll bet you'll find your leak immediately.

 

Thanks guys, I appreciate all the assistance. I'll snag a pressure tester from my father-in-law or something and see where that gets me.

 

That's the truth. Replaced my core last year, a job you only want to do once!

 

Holy crap.... Alright, I know who I'm coming to if that's the case! Lol

 

Hey all, I found that damn leak. Coming from that little upside down u shaped hose (water by pass hose?).

Just wanted to thank everyone for the advice. Now the pain in the ass task of getting in there! Lol tight quarters

 

If it is the hose I'm thinking about it must have been spraying pretty good to get coolant over on the control valve. Happy that you were able to find it and thanks for posting update.