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You can quickly test the thermostat in a pot of hot water. Just make sure to use something to suspend it in the pot while the water is getting hot, do t let it just rest on the bottom.
but assuming the thermostat is opening I’d agree with trying to assess the radiator.
If the radiator were clogged, would it take any water? When I poured water in it, it started flowing out of the intake, so I know it went down the radiator and all the way to the intake.
I can’t ever recall seeing any Toyota radiator clogged to the point where there was no outflow. What was more common was sections of a radiator get restricted or blocked that impaired the flow of water enough to cause overheating.
you could take your hand and place it over different sections of the radiator core and feel colds spots vs hotter areas. In the old days we’d pull the radiator and sublet it to a radiator shop who could remove the tank and run rods down each row to remove the blockage, then braze the tank back on. The radiators these days that have the crimp strips securing the plastic tank usually don’t get this type of work. The cost of the rod out, vs getting another inexpensive radiator has phased a lot of these old methods out.
when you bought the vehicle and before you replaced the timing chain set and water pump was there any issues with the temp, or has the running hot only started after the work was done?
I can’t ever recall seeing any Toyota radiator clogged to the point where there was no outflow. What was more common was sections of a radiator get restricted or blocked that impaired the flow of water enough to cause overheating.
you could take your hand and place it over different sections of the radiator core and feel colds spots vs hotter areas. In the old days we’d pull the radiator and sublet it to a radiator shop who could remove the tank and run rods down each row to remove the blockage, then braze the tank back on. The radiators these days that have the crimp strips securing the plastic tank usually don’t get this type of work. The cost of the rod out, vs getting another inexpensive radiator has phased a lot of these old methods out.
when you bought the vehicle and before you replaced the timing chain set and water pump was there any issues with the temp, or has the running hot only started after the work was done?
There was no issue with the temperature. If anything, it seemed like the truck would run a bit cool as the temp gauge would be about 1/4 from the bottom.
The part about the radiator being only partially clogged makes sense, but I'm not sure if it's worth spending another $250 on a CSF radiator to find out that wasn't the issue.
Have you looked at your Rad at all? I couldn't find you mentioning it anywhere in the thread. It could have a blockage of some sort in it. When I was having over heating issues, the Rad was the last thing I looked at, because the PO said it was brand new, and I did run water through it and it appeared that it flowed decently out of the other end. When I finally pulled my Rad, there was a dark spot in one of the bottom corners that I couldn't see while it was mounted. Replaced the Rad and my temp has never gone past about 40% on the gauge since.
Just a thought from my experiences.
Another quick question regarding a clogged radiator - if it was clogged enough to cause it to overheat, but otherwise had no problems, wouldn't the themostat still open, so the top hose still would get warm and the thermostat housing would be closer to 190F instead of 135F?
With the thermostat removed, and the vehicle running, can you physically see fast movement of water with the radiator cap off?
I will try that. I just removed the thermostat and boiled it. It had a bunch of gunk on the bottom that I cleaned off, but it was fine when I put it in boiling water.
The other concerning thing is there's a little puddle of water under the exhaust pipe:
Not sure if the head gasket is bad (aka I screwed up), but there's no foam or bubbles in the radiator, and when I hit the gas it does suck down the coolant.
That little drip out of the exhaust pipe is perfectly normal when the truck is cold. Especially in cold, humid, weather. I see it from both of mine all the time during warmup.
and when I hit the gas it does suck down the coolant.
Perfectly normal to see the level in the radiator drop slightly when you rev the engine. When you let it go back to idle, the level will return to about what it was before you reved it.
Bear in mind, as well, that as the engine warms up, the level in the radiator will rise, often overflowing the cap, if you have the cap off. As the metal(s) in the engine heat up, they expand, displacing the water in the water jacket. When it cools down after shut down, it will suck the water formerly expelled during warmup back in. That's the reason, well, the main reason, for the over flow tank. The water can flow out into it, after the water jacket pressurizes, controlled by the pressure setting of thee radiator cap, and when the engine temperature decreases after shut-down, it can suck the expelled water back in. That's why the cap has 2 ways for the water to flow. One way is out through the heavily sprung portion, that's the pressurizing part of the cap, and other way allows the water to flow back in with no restriction. That's the center part of the cap, with the very light spring on it.
I doubt the headgasket is a issue, but this is where the chemical block test is handy to quickly eliminate it as a issue.
Here was our general plan of attack when dealing with a high temp gauge.
1) inspect coolant level and pressurize to look for external leaks. Hoses, water pump, radiator tank seams, etc were the main focus on the 22R#
2)block test. If it fails, the head’scoming off. If it passes, then ...
3)pull thermostat and check. (Regardless of the outcome, we always put a new one in)
if the vehicle passed all the above checks and we still had a issue we pulled the radiator and sent it out for inspection. It was typically rodded out or condemned; requiring replacement. The vast majority of the time the issue was resolved at this point.
Techs would sometimes think the gauge was faulty, and run the FSM electrical test. Often the gauge would test out of range and the tech would have us order a new gauge. It NEVER fixed the problem. The new gauge would show the same as the old. At any given moment we’d have a dozen different gauges sitting on the parts shelf from misdiagnosis. As much as I love my FSM and swear by them, they were not all that complete when it came to electrical. Especially their ohms numbers.
So, I gave up and had a friend come over and look at the truck. I put the gutted thermostat in and showed him that the upper radiator hose was getting hot and that the truck wasn't overheating. We also boiled the thermostat and saw that it was working, but when I put it back in the truck, the gauge showed it was overheating again.
He ended up saying the engine bay and engine didn't seem hot at all and that it didn't seem like it was overheating and started suspecting the temperature sender. I told him it was a new Toyota OEM sender. Then I remembered I bought it on eBay and went to go to the eBay listing, only to find that the seller's store had been closed by eBay, and a few negative reviews saying that the seller was selling counterfeit items marked as OEM parts. We immediately went to Autozone and bought another (non OEM branded) sender, put that in and started the truck back up. Sure enough, the thermostat popped open when the temp gauge showed about halfway, and everything seems to be running great. Upper radiator hose gets hot, gauge reads a little less than halfway.
I suppose I deserve it because I tried to save $20 on a sender by buying it on ebay and ended up spending $350 replacing a head gasket.
TL;DR: I got scammed on eBay and ended up replacing a headgasket because of it.
Bummer about the fake temp sender
I'm still troubleshooting mine that occasionally runs hot but not past white range. All check out OK,except radiator that might have been neglected.
did you happen to compare temps between top and bottom hose of your radiator? I'm getting around 50-degrees F difference.
Re: sucking coolant down, I observed that on mine when revving, too.That was before I thoroughly burped the system. My hypothesis is When T-stat is still closed and there is air below theT-stat, the waterpump sucks coolant from bottom hose of rad,sends it up toward t-stat, compresses air a little.T-stat is closed so no coolant flows back into top hose,
Bummer about the fake temp sender
I'm still troubleshooting mine that occasionally runs hot but not past white range. All check out OK,except radiator that might have been neglected.
did you happen to compare temps between top and bottom hose of your radiator? I'm getting around 50-degrees F difference.
Re: sucking coolant down, I observed that on mine when revving, too.That was before I thoroughly burped the system. My hypothesis is When T-stat is still closed and there is air below theT-stat, the waterpump sucks coolant from bottom hose of rad,sends it up toward t-stat, compresses air a little.T-stat is closed so no coolant flows back into top hose,
I'm going to try driving the truck today, so I'll let you know the temp difference.
Originally Posted by wallytoo
ouch. look back at the second post in this thread.
I know, I guess the thermometer was showing low readings on the thermostat housing, so I was thinking that the thermostat wasn't opening. I was more worried about warping things if it was overheating but shouldn't have put so much trust into the dash gauge.
Originally Posted by Jimkola
I’ve seen some of the listings on eBay and thought they were misleading, but counterfeit!? Damn.
Yeah, unfortunately the coolant temp sensor for the ECU came from the same person. I'm ordering an OEM part from the dealership now.
Thanks for the help! I will test drive and update this thread again.
The mental turmoil trying to work through what should be fairly straight forward certainly sucks. It’s one of the reasons I avoid buying parts from most of the chain parts stores. I’d be curious to know the name of the ebay seller.
I still believe that on a whole, most dash gauges are fairly accurate. If you see a temp gauge creeping up, or a oil pressure gauge dropping down, it should be taken seriously. It may be just a bad input from a sending unit, or something mechanical, but I’d never ignore.
you may have done some redundant work, but I wouldn’t consider the headgasket a waste. Replacing 22R head gaskets is a very common repair. I feel if it’s time to do a timing chain then you really should do the headgasket at the same time as preventive work.
The mental turmoil trying to work through what should be fairly straight forward certainly sucks. It’s one of the reasons I avoid buying parts from most of the chain parts stores. I’d be curious to know the name of the ebay seller.
I still believe that on a whole, most dash gauges are fairly accurate. If you see a temp gauge creeping up, or a oil pressure gauge dropping down, it should be taken seriously. It may be just a bad input from a sending unit, or something mechanical, but I’d never ignore.
you may have done some redundant work, but I wouldn’t consider the headgasket a waste. Replacing 22R head gaskets is a very common repair. I feel if it’s time to do a timing chain then you really should do the headgasket at the same time as preventive work.
I'm more worried about a head gasket failure from something I did wrong, though the truck seems to be running fine.
I took it out for its first drive, kept it below 20 mph because the entire front and end steering is all new and completely out of whack (I eyeballed the toe). The temp gauge did creep up a bit past halfway, which had me worried, but suddenly went back down. I guess the thermostat finally popped and it cooled down to normal temps.
This was the ebay seller (and in hindsight I don't know what I was expecting from an $8 sensor... I paid about $9 for the sender as well which turned out to be bad, so this will be replaced ASAP as well).
That is awesome! I'd love to buy that but it looks like it's unavailable right now. Also I plan on getting a CSF radiator in the future (if the truck doesn't blow up for a few months and I can trust it) and I think that needs a different kind of cap.
This was the ebay seller (and in hindsight I don't know what I was expecting from an $8 sensor... I paid about $9 for the sender as well which turned out to be bad, so this will be replaced ASAP as well).
Yep, that part is probably fake, especially for the price.
05-19-2020, 02:29 PM
