It's tough stopping an easy coolant leak

Hi all, long-ish time reader, first time poster. I've had my 2001 Tundra SR5 V8 since January of this year, it's my 3rd Toyota, but the first one that i've ever worked on/serviced myself. This site and YouTube have been such a cool thing to learn from others then learn how to tackle repairs for yourself.

My problem seemed easy and I still think it is, but i'm sure there is one thing that's keeping this fix from sticking.

I first discovered coolant leaking out of the hose connected to the thermostat housing after I had taken my truck to the dealer to have the water pump/timing belt replacement (my truck has 250k on it, i've put maybe 500 on it).

I noticed the leak when I went under the truck to fix something else and traced the leak back to the thermostat housing where it connects to the hose. I couldn't tell if it was the hose or the thermostat & gasket so I ended up replacing what I thought was the more correct choice which was the thermostat and thermostat gasket. I installed the thermostat correctly (tiny pin in thermostat up!), cleared off the calcium deposit around the hose connection, and topped off the coolant in the reservoir a few times, this seemed to work until today.

After I got back home from an errand today I parked my car on the driveway and the truck decided to dump a majority of coolant in the fill bottle down to low all over the driveway. I had driven it a few other times, but with no other issues until today. It's been hotter here in CA so that could contribute.

Could not be burping the system enough? Is it using screw clamps and not tension clamps for the hose? Maybe a new hose to the radiator? Some larger issue? The fluid is definitely coming from the hose now and not the part between the main thermostat housing and the hose connector.

My next step was going to be replace that left radiator hose & the thermostat housing that connects to the hose and use spring clamps, not screw-tight clamps. Or rent a radiator pressure tester from the parts store. Thoughts/suggestions.

This is the truck, i'm a sucker for gold Toyotas. My first Toyota was a gold 04 Tacoma.
https://www.reddit.com/r/ToyotaTundra/comments/g3doiv/new_to_me_also_encouraging_for_a_first_time/

Thanks!

This shot was before I fixed the thermostat for the first time showing the fluid coming from probably the hose.

 

Howdy and welcome!
What about renting a coolant system pressure test kit and see where it’s leaking from?
What about calling the dealer nd seeing if they offer help since they’re the ones who took everything apart??

 

Welcome from CO!

 

That hose looks tired. Might have outlived it's useful life. I replaced mine around 212k with my timing belt change. I had to add some screw clamps because the tension clamps didn't seal the hoses anymore. I would recommend replacing the hoses, upper and lower. Welcome to the forum.

 

Thanks for the answers all. I think I'm going to do the two hoses, both the upper and lower ones, but probably not the outer metal thermostat connector. My guess is that they're not the original hoses, maybe the left one is, but the upper right one has an uneven cut like it's been trimmed down or something.

Thanks @KNABORES i've heard that some screw type hose clamps can create gaps as opposed uniformly applying pressure like the spring type? But damm the spring OEM spring ones are $13 EACH I might just grab new screw type ones. Time to do my first drain and fill now for the radiator. It has brand new coolant from when they did the water pump so i'll try and recover it if i'm careful.

Thanks all.

 

The trimmed one may have split in the past from age and heat. I've heard the same about the screw type, but I had fully assembled mine and attempted to re-use the original spring ones and they leaked. Rather than take the whole thing apart, I added some screw type clamps just in front of the spring ones and the leak stopped. Was not wanting to drain and refill the system to put new spring ones on. And it's my daily and I needed to get back on the road. Haven't had any issues with leaks since.

 

IF you end up needing a replacement radiator, I've came across this when I had issues:
https://csfrace.com/toyota-truck-suv-cooling-systems/

hope you get this sorted!

 

Those worm drive clamps are really good for being over tightened and causing leaks. I would replace both hoses and get new spring clamps from Toyota. When you have the hoses off check the radiator neck for cracks too.

 

Got all the parts except for the hose clamps (I'm gonna try the spring OEM ones which are on a diff order). Was planning on doing this today but will have to wait until the clamps get here.

 

FINALLY was able to do the job today, just took a while between work and other around the house stuff to get to it. It was a pretty simple process.

1. Pinch off the two aux transmission coolant lines to the bottom of the radiator with some towels and vice grips.
2. Open the petcock and drain, then close the drain.
3. Remove the hoses (the bottom of the radiator screw type clamps to the hose were horribly corroded, gross and I could barely get it off). I replaced both the upper and link to the lower hoses at once... just because they both were old and why not.
4. Install the new hoses with the new correct spring type clamp.
5. I followed the guide similar to this video on how to bleed the system.

https://www.youtube.com/watch?v=oQsxmi-CNng

I drove it about 2 miles which is about how long it took for the leak to happen before. Fingers crossed that the leak doesn't re-appear. After I took the old hose off it was so compressed/deformed by the old screw type clamp i'm not surprised that it couldn't hold the coolant back. Thanks for the suggestions all.

The new hose and clamp where the leak was coming out of. All fixed.

 

I learned the hard way to avoid those worm gear clamps on the cooling system, especially if plastic is involved. Glad you got it fixed and happy to see another Toyota guy doing his own work, best feeling when you fix it yourself.

 

I'm heading down this road, hoping I am not losing coolant at a head gasket. 9 bucks for uv dye, and the blacklight is a free rental local. Hoping I find an easy access leak. Some of that stuff is buried.