JunkFanatic

Sorry, this is kind of long:
The original radiator had a small leak at the top, and was also being held together with a coat hanger so I went ahead and got a replacement and it turns out that I needed it because when I went to drain the original radiator, the drain plug just broke out of the radiator (now way to put it back in). So we got everything hooked back up with the new rad, new lower hoses, and a new alternator since I wasn't getting a charge. Got my rebuilt carburetor put back on, filled the radiator with water and Prestone coolant flush, and then fired it up. Took a few tries, but it idled great and didn't die! So YAY! I let it warm up and then turned on the heat per the instructions on the bottle, let it run for ten minutes, cool, and then drained it. I repeated this two more times, the last one being with distilled water, and each time the temp gauge stayed just under half way. What came out was really clear, still a lot of green coolant, but no rust or any other junk. So today I mixed some coolant with distilled water and filled up the radiator and reservoir, fired up the engine and let it run. When the needle was just under half way, I turned on the heat and let it run. I kept checking the level (cap still off) and although there were some air bubbles the coolant actually started to run over the top, so I pulled some out with a syringe and when it got lower I added some. I repeated this for the next few minutes. I took a look at the temp gauge and it had climbed to right between the red and middle, so I turned off the engine, and for some reason turned off the heat. That was a mistake, because the coolant started to pour out of the radiator. I quickly turned the knob back to heat.

So at this point I'm not really sure what happened. It's possible that I had turned the heat on before it had warmed up all the way, but I'm not sure. I also noticed that the top radiator hose was not as hot as it was yesterday, while flushing the radiator, and I could also squeeze it very easily. After checking the article about the dual valve thermostat, I'm kind of thinking that that may be my problem, but I'm just not sure. Sorry for the long post, but any help would be appreciated, Thanks!
http://www.flickr.com/photos/109250620@N03/11712118735/

JunkFanatic

Okay, so I tried running the truck again. It warmed up, and just under 1/2 way to the red, coolant started bubbling out of the radiator (open cap). I turned on the heater, and the level went down and I saw a few bubbles, but there was soon a lot of steam coming out of the cap and around the thermostat housing. I put the cap back on, but it continued to steam so I turned it off. During all of this, the temp. never got above half way, and there was no steam from the exhaust. There is an exhaust leak coming from underneath the exhaust manifold, but it doesn't smell like exhaust. Any help would be great, thanks!

Derick195

is your fan clutch staying engaged when it starts running hot on you? let it get to where it trys running warm and see if the fan is still engaged if it is just free spinning i would say that could be a problem. When you replaced the radiator did you replace the thermostat too?

crazytexan

iTrader: (1)

Gauge could have been reading air and not water. I just let it run with cap off till I cant fill it no more, Cap it, run it, then when it cools repeat it again, But normally just 1 heat cycle works for me. The overflow should do alot of the bleeding/filling for you.

rworegon

Did you fill the block with coolant through the upper radiator hose? This ensures the block has coolant before the t-stat opens.

JunkFanatic

The fan clutch seems to be spinning all the time, or at least I didn't notice it stop. I just replaced the thermostat yesterday, but it did the same thing, but I did have the cap on. It was still registering under half way on the temp. gauge, though. I did notice that the nut for the temp gauge sender is corroded, but the contacts on the plastic piece itself look brand new. I currently have the truck raised from the front on some jack stands, so the radiator fill neck is the highest point.

Derick195

the fan clutch will always spin but that don't mean its engaged when mine was trying to run hot when i went riding and started getting on it hard it would register 3/4 the way up and i could grab the fan clutch and stop it, having said that it obviously wasn't cooling the motor down, this is just the only problem ive had with mine running hot and ive swapped motors and radiators more times then i can count. Never yet have i had a problem bleeding the radiators afterwards, all my 22r's get a v6 radiator put in them just so i dont have to worry about over heating

JunkFanatic

Okay, well is there a good way to test the fan clutch, I don't really want to stick my hand into that thing . I was also wondering about the water pump. Like could that cause it to overheat? And that's also what I'm confused about because although it spews steam after about ten minutes of idling, it isn't overheating according to the temp gauge. But crazytexan, what do you mean by it could be reading the air temp not the water temp?

Derick195

Mine steams to after it gets warm that's normal any motor running 200 degrees will produce steam if it's not over heating anymore you should be fine, but as far as the fan clutch goes I just let my fingers drag across the blades if it don't slow down then it's engaged but if you rev up the motor and the fan pulls more air then that's another good indication it's engaged if it don't blow more air then it's diss engaged

FGZ

I'm not crazytexan, but I am originally from TX and everyone up here looks at me like I'm crazy when they see the 4R but I think he was talking about your coolant temp sensor and how it will give different readings if there is an air pocket vs when it is submerged in coolant.

JunkFanatic

Okay, I think I'll try and run it one more time with the cap off and check the fan too. I read this: http://forum.ih8mud.com/79-95-toyota...h-service.html
so if there is any doubt I'll probably try that out. And the steam is like a lot, like there is some from the cap, but also a lot more, which I'm wondering if it could just be coolant that is on the radiator itself, and just steaming off I'll have to check and maybe try and clean things up a bit.
Haha, I'll have to see a picture of that 4R, FGZ! Does anyone recommend an aftermarket temp gauge?

Derick195

You can always put a aftermarket gauge on it they are cheap, extremely simple to install and will give you more f an exact temp that you are running we sell them at Oriellys for $20

JunkFanatic

So, went out to try it today, cap on, and it didn't steam at all. Ran maybe 15-20min, and it was all okay. The gauge is definitely not working, as it stayed at about 1/8 of the way up for the entire time. I'm gonna start with replacing the stock sender and if it still doesn't work, then I'll check out the aftermarket gauge. When I turned the heat on, it definitely wasn't HOT, like my mom's van, but it was warm, and when I put my face to it, it felt pretty warm. I guess it's alright though, so I'll keep an eye on it. Thanks everyone for their ideas and suggestions. I really appreciate it!

Derick195

a factory thermostat runs 195, if you even get a 180 degree it will hardly show on the stock gauge mine has a 180 in it and it only warms up to 1/8th the way

JunkFanatic

I just checked the box, and I used the 195 degree one. I have to gauges, an SR5 and the stock one, and when I tried the SR5 it shoots straight up to red. I'm pretty sure the engine is heating up, because the radiator and hoses all felt really warm. The temp sender is really corroded, that's why I thought it may be the problem.

rokblok

iTrader: (1)

I'm not certain that a stock idiot light sender and SR5 gauge are compatible. Or vice versa.
I know the SR5 oil gauge will roast if used with an idiot light sender, I presume the same for coolant temp...

JunkFanatic

I read through this thread a few times: https://www.yotatech.com/forums/f116...w-pics-179106/ , and I didn't see anything about the temp gauge in it, but I wonder if there could be. I did unplug the oil pressure sender to be safe but I'm not sure if the guy I bought the gauge from knew about that, though, because he said he had used it in his non-sr5 truck, so I'll have to see once I get the new sender. It's just weird that I am having problems with both temp gauges. One stays too cool, and one shoots straight to the red. I'll have to try disconnecting the sender with it running tomorrow to see if that does anything, because I guess that will tell you if it is the sender, or the gauge. I'm having another issue with the engine, though, that is a bit more worrisome: https://www.yotatech.com/forums/f123...-noise-277076/ I'm hoping it is just my bad exhaust, but I'm not sure.