Mystery Coolant Leak Only -20 or Colder

Hey guys,

Had this problem last winter too and just kept an eye on it, filling up the coolant as needed. I don't use my truck that often because I have a company truck for personal use, but this is a reoccurring problem I would like to get fixed before I have to put the ol' taco back into service full time.

When it gets cold, it springs a leak. I'm beginning to think its a warped mating surface between some component (maybe water pump) and the engine block, possibly bad gasket to go along with it and when it gets cold the metal shrinks causing enough of a gap to leak. It doesn't happen when its warmer than -10°C (14°F). All summer its been good, no leaking anywhere even when I run the truck it doesn't drip anything. I used the truck about 2 weeks ago and when I parked it back in my driveway there was a puddle under it a couple days later when the temps took a dive.

Truck is a 2007 2.7L auto with approx 230,000 kms which is about 143 000 miles.

Shout out some ideas, I can pick away at it since its just parked for the majority of the time. Your suggestions and input is appreciated.







my apologies, but when you swap from iphone to youtube quality goes down.

https://youtu.be/KwKR5NHRhFk


Cheers

 

Had a buddy with a Volvo that did that, ended up being the water pump gasket on his car. Could always try a pressure test, that'll pinpoint things way easier, or throw some dye in the system.

 

Is there a freeze (expansion) plug up there?
Install either a block heater, or recirculating heater.

 

canadian vehicles are all sold with block heaters from factory since early 2000s if im not mistaken.

 

last year when i looked for the leak there was dried up coolant all down the side where its all wet now. is there a how to on pressure testing cooling systems? ive never played with that before.

 

Could always give this a shot if you've got a compressor. And I can't recall off the top of my head if tacos have that same setup, so it may not be possible.
https://www.youtube.com/watch?v=0CfIo9niyXQ
If not I'm sure a local mechanic could probably pressure test it for pretty cheap, only takes a couple minutes.

 

Yeah that seems pretty slick. That's something I can do in my garage for sure. Just have to keep a close eye on the pressure not to over pressure the system and blow out a gasket or something, that would be bad!

 

A mechanic at my work suggested i check all the hoses for loose hose clamps and replace with constant torque style if they were working loose. this is not the case because they are all the pinch style where there is always torque. i checked them anyways and there is no leaks at any of the hose fittings i could see. he also suggested to check the torque on the water pump bolts, he said he has had them and many other things work loose from vibration and heating and cooling cycles on engines so i did, and they were not loose, but i did get a little torque out of them. seemed as though they should have been tighter. so i then moved onto a pressure test. i got a new cap and cut the insides out of it so it was just the rubber around the top to seal it off, removed the overflow hose and put a tire valve on it and zip tied it tight, pressured the system with a small bicycle pump and a digital pressure gauge. worked pretty good!

cap is rated at 15.6 psi so i put 14psi in it at the highest point. it held this pressure and was at 13.5 about 20 mins later after checking it a few times thats where i suspect i lost the .5psi. keep in mind the truck had been in my garage for a few hours at this point and also had been started once or twice.

everything seemed pretty groovy, felt like i found the culprit.... NOT!! parked it outside overnight and sure enough in the morning when i looked, that dam red coolant dripping off the bottom of the rad support and on the ground. ill have to dig deeper into it when it gets colder. starting to warm up now.

 

Plastic radiator tanks where they meet the aluminum core is common for leak at cold temps. Seen it many times sounds like radiator to me.

 

im going to keep an eye on in and double check the block heater port. havent had any time lately to play with it. its been warm so its not leaking and my girlfriends head gasket went in her civic so i had that thing torn right down to the block. all back together and driving again now so i can maybe spend some time on the taco.