Temp needle not going UP (1 Viewer)

[brokeassyota]

Cruiser started running hot, changed thermostat. Was about a gallon low on coolant, filled it up. Drove for a few days, 18 miles round trip to work. The needle hardly moved into the white. Heater blew hot air, not as hot as I recall it being. On the 4th day pulling into the driveway it started blowing steam. The little hose that goes from the block to the firewall right behind the header had sprung a leak. Pulled thermostat and tested it, opened at 160*, it is a 180* thermostat. Of note is when I pulled the thermostat for testing the housing was full of coolant like it hadn't been circulating. Replaced little PITA hose, let truck run in driveway for 15 minutes, needle moved about 2-3mm into the white. Drove to the liquor store for rum and the needle stayed down. Left the store restarted the truck and the needle had moved up about 4-6mm into the white. As soon as I started moving it dropped down again.
This has me stumped.

 

[WJB4000]

Did you bleed the air out of the system good after replacing the thermostat?

 

[brokeassyota]

I let it run with the radiator cap off while squeezing the upper radiator hose until it stopped burping air.

 

[Elbert]

did you replace the large rubber washer or what some people call the o-ring that sits in the upper thermostat housing? If not, then this is most likely your problem.

 

[brokeassyota]

Yup. Replaced the soggy ring of rubber goop.

 

[John McVicker]

Easy to install the T-stat upside down, might verify that you didn't.

John

 

[brokeassyota]

Nope, it is installed correctly, both times.

 

[John McVicker]

How about getting a laser temp gun to verify temp readings.

John

 

[brokeassyota]

Was thinking about replacing the temp sender.

 

[Output Shaft]

Mud is rife with postings of guys trying to hunt down perceived over/under temp cooling problems... going to the end of the earth replacing everything...only to find out in the end that the gauge was not reading correctly and there was not actually a temp problem at all.

Not to say that this is the problem here... but a quirky gauge (that are known to be quirky) has to be considered... along with all the other obvious things. Definitely the first call of action is to get a 2nd reference thermometer.

A thermostat opening at 160º will show low temps on the gauge.
A brand new 180º thermostat starts to open at 180º not 160º. I Just tested one.
When the top thermostat housing is removed, there better be coolant in the lower housing.
Overheating can sometimes make a thermostat no longer work properly. I'd replace it.

 

[brokeassyota]

Was considering that as well. Will take the thermostat back to oreally in the AM and get it swapped out. Also going tk pick up a new sending unit as they are cheap.
Adam G

 

[Output Shaft]

I would recommend getting a new Toyota sender. I purchased a AFT MKT temp sender years ago, from a big LC store, and although it worked, the needle on the gauge was no longer in the same position it used to be (either high or low, I don't remember). I got rid of it and installed a new Toyota sender and the meter then read where it used to... in the middle of the gauge.

 

[Slow Left]

Did you know if tap water or distilled water was used to fill the cooling system? If there is a clay like sediment in the bottom of the radiator overflow container, then you can assume that tap water was used and that sediment build up could also be in other places within the cooling system, preventing effective flow of coolant.
Doing a professional flush where they add in some chemicals to try to redissolve and push all that stuff out might help.

You might also assume that there is still air stuck somewhere in the system. I find that 'burping' with one of these funnels helps (and also running both front and rear heaters on full hot, so that coolant circulates through their cores) and it usually takes ~45mins to burp all the air out.

Funnel:
http://www.amazon.com/dp/B001A4EAV0/?tag=ihco-20

Additional directions - http://www.instructables.com/id/How-to-Burp-your-cars-cooling-system/

 

[brokeassyota]

Lol! Dude this is an '85, I am sure it has had everything short of beer in the cooling system.
Problem is solved. thermostat was opening too soon. Temp is at 50% of white and holding after 20 minutes of idling. Both heaters are blowing hot air and all is well. Apparently the Isrealis make one hell of a crackerjack thermostat.
Thanks guys!
Adam G

 

[Slow Left]

Lol! Dude this is an '85, I am sure it has had everything short of beer in the cooling system.

Ha, Ha! Nice...in that case I'd probably lean towards a Canadian beer (playing the odds that they have cleaner water)...say...a Labatt's?

Glad you got it sorted out...for another 30 years...