Sudden overheat issue. (Resolved.. I think)

I’ll try to make this brief (which I’m not great at) but also get my point across and be detailed.
The other day I was in my truck while running at idle and I noticed my heat wasn’t blowing hot at all. This have never been a problem as after a 30 minutes lunch break, it’s usually like a furnace. So I went for a spin and watching the temp gauge, which over the course of a mile, fluctuated up and down about 3 times, approaching the red zone. Mind you it’s 40 degrees here in NJ. Seemed to do more fluctuating both up and down when I was moving (all less than 40mph). Well I figured I would start with a thermostat. So I replaced the thermostat yesterday, warmed the truck up and hoped it would max out around 190 like it should, it didn’t and ended up reaching between 230-240 according to the scanner. I shut the truck off and when I got out I noticed steam pissing out of the top of the radiator closer to the side of the upper intake hose, and on the front of the upper plastic section that runs across the top. I thought it might’ve been a pressure relief or something (idk what I was thinking) since it was a small area but I couldn’t see the actually plastic due to the steam. Well after waiting for it to cool, it appears a hairline crack has been formed. Obviously the new thermostat didn’t fix my issue. Any suggestions? Seems like I’ll be putting in a new radiator regardless now but I never had an overheat issue before and idk why this could’ve come on so suddenly like this. Please help.

 

Start with new radiator. Then after a week or so check cylinder head leakdown and compression.

If that is the stock radiator in there now you got a great lifetime out of it, the plastic lets go after 15-20yrs.. Hope that's all you need.

 

Radiator bud.

 

Hopefully, hope nothing else let go. Sounded like it got plenty hot. Irratic temps was more than likely low on coolant already, can't measure air temp inside radiator.

 

Do you think low coolant could be the root of my symptoms? I will admit, the coolant reservoir was dry once I started looking into it. However with that being said, I never had an issue with even the slightest inclining of overheating in the past and didn’t notice any wet spots under the truck as if it puked all the coolant at once or something to suddenly cause this. I obviously don’t want to put a new radiator in the truck and explode that one as well trying to see if it “fixed” the problem. Also with the special red Toyota coolant being like 30 bucks a gallon, I’m trying not to dump it on the ground over and over and over again.

This would’ve been great if this happened in the summer when I could run water to flush it good and then drain and refill for the good stuff but of course it’s freezing here almost every night now and that’s not a risk I’m willing to take.

 

Wish i knew if it was the stock one or not. truck has 162k on it and I bought it about 5-6 years ago and have put just shy of 50k on it.

 

You gotta start somewhere, the first step is a radiator so you can pressure test the system,, it won't "explode" your new radiator if it has the right radiator cap and it's good. It'll never be good till it can hold the pressure needed in the system that it's rated for.
I bought the red Zerex asian at NAPA for 18 bucks or close to that. Check you out a cooling system pressure kit at the auto parts to test the system first after you install the radiator, again the cap is just as important as the radiator for holding pressure and rasing the boiling point in the system.

 

Even though there doesn’t appear to be anything wrong with my existing cap I got a new one from the auto parts store that I intend on using. I’m also gonna use that zerex Asian coolant since I went to the local dealership today to get the Toyota “long life coolant” UNMIXED and the guy at the parts counter told me they don’t make it. (They suck so bad) so if I’m gonna use 50/50 it might as well be the zerex stuff.

 

try not to let it overheat to the point of near the red on the dash gauge, the dummy gauge on the dash doesn't start to climb high until temps are critically hot. Gauge will stay in the normal zone well into "too hot but not dangerous" territory. Once it starts spiking things are cooking. Don't want to pop a head gasket or worse.

 

just saw you mentioned 240 on your scanner, that is very toasty

I second the radiator but just to be sure, you put the new t-stat in with the jiggle valve in the 6 o'clock position correct? 12 o clock wouldn't cause overheating but it will cause temps to be a tad higher than they should be

 

If you’re just diagnosing stuff just use water, no point in putting in antifreeze if it’s just going to leak out.


Sounds like your radiator is done though if it’s leaking at seams.

 

The long debated jiggle valve position.. lol never knew there was such a thing until I started reading up. But to answer your question, YES the jiggle valve is at 6 o’clock

 

What’s considered a safe hard number that is high enough to know things aren’t right but low enough to not do harm? Yes I know 240 was too high and that’s my fault. I was in and out if the truck and didn’t realize hot it had gotten til I looked back inside the truck at the OBD2 scanner. Stupid, potentially costly, mistake. Fingers crossed

 

years ago when I first got my truck I hadn't realized that the previous owner had wired in e-fans to a switch that you had to turn on to run the engine fan. Was on a fire road and noticed my temp gauge was nearly at red, coolant was bubbling in the reservoir. I shut it down as soon as I realized but still thought for sure I was screwed but 6 years later she runs like a top.

These trucks are resilient, one of the best engines Toyota has ever made

 

I'm not sure what the hard number is for the overheating danger zone, I'd be curious to know myself. I thought I read here once that around 220 is when the dash gauge will start to climb.

 

based on my own recent experiences, I would say you’re right on the gauge not moving until that 220 mark which to be honest makes the gauge pretty much useless. Doesn’t give you any time before you’re in the danger zone.

tonight I was able to pull the old radiator and get the new one mounted. I could’ve kept pushing but I’m coming down with something (probably the China virus again) so I got to a good stopping point and called it a night. Tomorrow I will reinstall the fan shroud, reconnect the inlet hose and see what kind of progress we made. I saw while I was in there that the truck was leaking at the thermostat. Pretty good too. I’m assuming I just didn’t have a good seat when I installed the new one. There’s no other gasket other than the one that goes around the thermostat itself correct? When I took out the old one all the studs unthreaded from the block instead of the nut spinning off the end, that made things really interesting so if anybody has tips on the for the future, I’m all ears. Truth will be told tomorrow, hopefully.

 

wire brush the threads, double nut the old stud, pull the nuts off, clean well, put the studs back in and put some never "sneeze" on it when re-assembling,,, I pretty much never seeze all my stuff for future.

 

The ends that threads into the block were already never seized and I think that’s why the my came out so easily (usually a good thing, just not in my particular case). The resistance on the exposed thread behind the nut was much more than the resistance of the stud unthreading from the block. I can handle that, it’s whatever. The fun part was when I was putting them back in because the nut had no problem threading forward so the nut would would just move down the stud instead of the stud threading into the block. It would’ve been. I problem if the nut was just stuck where it was

 

You probably already did this but make sure you get the water neck smooth and clean where the hose goes too. Any crusties you leave there can leak too.

 

UPDATE: thought I had it all fixed up last week (Tuesday night) before I was set to leave after work on wednesday to go away for a long weekend. I put the new radiator in, ran the truck, let it drink the coolant and bleed the air, and let it get up to temperature never seeing above 185 while letting it run for at least 45 minutes. Cleaned up my tools and the garage floor while letting it run and everything checked out and looked fine. Shut it off and left it knowing that when I came back from my trip today (Sunday) I would just have to put a couple zip ties on my front grill to secure it and drive it home. Well I started it up and walked to the back of the truck to open the garage door. My wife says “did the water get all the way up into here while we were gone?” (because we had a bad storm while away and heard there was some flooding). Well wouldn’t you know, the wet floor was pink. Enough coolant leaked out of the truck for there to be a puddle at the BACK of the truck. The leak made the coolant reservoir go completely dry. I’m at a loss. There was no dripping when I buttoned everything up and ran the truck Tuesday night. I checked all under it. There’s very obviously a leak now. It appears like the coolant is dripping from somewhere in the vicinity of the thermostat even though the thermostat housing itself seems totally dry from what I can see. I’m going to attach a picture that I took from just above the frame rail inside the driver side wheel well that shows the extremely wet area. The radiator hose going to the thermostat is circled in green and the thermostat housing is circled in orange just to give some reference. Maybe one of you guys can tell me what I’m looking at. I’m thinking it’s either gotta be the thermostat housing or something to do with the water pump (maybe a gasket) any ideas are appreciated. I don’t think there’s much else in there. I don’t wanna take it to a shop and pay them unnecessarily, plus wait until they have availability but I also can’t keep fucking around with this either. I’m borrowing a vehicle currently and can’t keep doing that either. I’m thinking this particular leak has been there since the beginning of this mess and probably the root cause. Any help is greatly appreciated!