Lower radiator hose isn't heating up

[giro]

On my 92 V6 manual, I've had some various radiator issues over the years. Nothing too major….there's a small leak at the very top that I had fixed for a few years with QuikSteel, and I think I had a couple small leaks in the main body of the radiator that I used one of those "radiator fix" additives on maybe 5 years ago.

Recently it felt like the lower hose of the radiator wasn't hot, and since I had a new toyota thermostat in my box of parts I installed it. The old one had part of a rubber gasket caught in the spring, so it seemed like it probably hadn't worked in a while.

But now after replacing it, the lower radiator hose still doesn't warm up. It could be that my trips I'm checking it on are too short. Or that the new in the packaging thermostat from Toyota but that was likely 10 years old is stuck closed. Other than that, I'm wondering if there is something more serious, like something gummed up in the engine that is preventing flow. The antifreeze I took out looked pretty good, and I put in fresh stuff.

The QuikSteel seal at the top of the radiator was leaking so I took it off. Now I need to patch that again, and the first attempt didn't hold. The radiator is pressurizing, and the engine temp is staying a little below halfway. This is my only leak, so I'd like to fix it up but would rather not deal with replacing the radiator right now. Any suggestions on fixing it. I'd rather glue/epoxy it, so what's worked for you?

Thanks!

 

[KidVermicious]

I've seen JBWeld hold forever, but the right way is to have a radiator shop solder it. They can probably do it right on the truck.

You can bench test that thermostat, and I would before throwing any more parts after a trouble you haven't isolated yet. I wonder if your radiator fix stuff you poured in there finally got around to clogging the radiator up completely.

 

[nevada]

how long are you driving it before checking?

and why are you checking the lower hose?
is the heater blowing warm air?
the temp gauge in the correct spot?

its cold outside, of all the hoses, the lower will be the coolest.

if you want it to get hot, you may have to just let the truck sit and idle for 30 minutes. even then it may never get hot.


there is also the chance that the radiator is clogged, as suggested above, but likely you would be having an overheating problem if that were the case.

 

[giro]

We're having a cold week now, meaning it isn't getting above freezing for a week. But driving up to our rental is normally plenty to heat it up, and the heater is blowing hot air. It's only 8 minutes away, but with some elevation. Today after finishing there I drove up a couple more hills, and still the lower hose was cold/very cool(looking at the FSM's it looks like the upper hose is the return from the engine, and the lower one brings the antifreeze back to the engine from the radiator, hitting the thermostat, and then the water pump).

I didn't think the radiator was clogged as it drained fine a week ago, but that's at the other lower corner. If the thermostat was nonfunctional for a while, the "fix it" additive could have clogged the other corner. I had tried to unhook the lower hose when replacing the power steering return line but couldn't get it disconnected easily.

After I get the snowblowers ready for the storm I'll play with the truck a bit. I don't think my soldering irons are powerful enough to fix the small crack, and I don't want to test my luck with welding it. Ohhhh, but I have a torch somewhere, which is what was needed for soldering copper pipe and our gutters. Fun!

But I'll also drain the antifreeze again, bench check the thermostat (along with the old one and any others I have around….82°C should be somewhat standard), and try again at getting that lower hose off. Once it's off, I can drop some water through to see if that end is plugged or not. (also need to replace the rear window motor, and look at the leaking wiper fluid reservoir that the exploding fan might have taken out)

On rockauto a new radiator is about $100, so if it is plugged I'll just order a new one and kill a few birds at once.

 

[nevada]

I don't think my point was clear.

im not sure you even have a problem.


what made you think to check if the lower hose was getting hot?

 

[77'911]

Just install a new rad, coolant/distilled water mix, t-stat, and your good for a long time. Your lower hose should be getting hot if the cooling system is working effectively.
regards

 

[giro]

Ok, played around with it yesterday for a couple hours, and Nevada is probably right that it's likely working fine. I had been told in the past to check that feed line once warmed up to make sure the t-stat is working. The short story is it looks like that depends on when your t-stat opens, and in this case (and one back with the 3000gt) I was probably fine.

For the longer story, I drained the fluid and started checking things. Bench tested the new and old thermostats, and both open around 82°C and are full open at 94°C (our boiling point), though the new one opens further and generally works better. I added an additional trickle hole to both. I wanted to check the water pump blade but couldn't reach it with my fingers, but pulled out another 3+" gasket ring part (likely from old thermostat, which also had one piece stuck in it's spring). I then checked the radiator, running water through from both the inlet and the cap. Water flowed fine from those to the lower tube, so there's no plugging to be worried about.

I tried soldering the mini cracks at the top of the radiator that it's had for the whole 8 years I've owned it. The solder didn't seem to bind to the metal the way I would expect, even with a little flux. I might not have heated it up enough, and maybe needed to switch to MAP from propane. I have a feeling this is still going to leak some, and soldering it while full would probably be tough. If it's still a problem I'll try a new thing of QuikSteel or some JB Weld. I could put in a new radiator, but if this is the only problem, my last patch lasted for 4+ years, and I'm only now putting on 3k/year, it really doesn't seem worth the time.

This time I flushed the system, both to do it and so that if my thermostat install wasn't right I would leak mostly water instead of antifreeze (it was fine….that first time I just hadn't realized the gasket went over the edge of the t-stat). On refill it had the same "no heat in the heater" issue, even when going up and down steep hills. But once it sucked in some more antifreeze it got better, and it should be back to normal after a few hot/cold cycles.

I ran out of time to check the window wiper reservoir while I had the fan out of the way, but I got it back together before the snow hit so now I can take it out in our 15" of fresh powder.

 

[94_4runner757]

Any luck?