thermostat temp (1 Viewer)

[leonard_nemoy]

After researching the topic of horrible heat in my new to me 91 fj80, I have checked my coolant level and quality which seems fine. I parked on a hill and attempted to burp the cooling system and checked the valve on the firewall which works and has hot hoses on either side. Still poor heat. In an attempt to check my thermostat without removing it I used an infrared thermometer and measured the temp of the thermostat housing and hoses once my temp gauge in the truck got to the middle. The housing was approximately 170 f and the hoses were anywhere from 150 to 160 depending on the hose. I measured the temp of the
heater vent with the recirculation off. Driving down the street giving it gas the temp was approximately 110 at the vent but would quickly drop to 90 whenever I let the truck idle. My question is if 170 deg f is the correct temp for the thermostat / housing. I would think it should be closer too 200. If this seems to cold then I will proceed to installing a new thermostat and making sure I got the o ring correct. I am just trying to avoid any unnecessary repairs and rule out everything but the heater core. Thanks for any replys and I really appreciate the wealth of knowledge this forum provides. Ps the rear heater works great and according the po the thermostat was replaced when he recently installed a 3 row aluminum radiator

 

[izzyandsue]

Very similar problem as I have, front takes a long time to produce heat, rear heater puts out 125+, front 80-100, hoping someone has a solution.

 

[leonard_nemoy]

Yeah I would like to get this figured out as ice fishing season is quickly approaching. I don't think it is the blendoor either seeing as how I get some heat and I can defiantly hear the door moving when I switch from hot to cold.

 

[Alleycats]

Actually the thermostat for the 3fe comes in 180 or 190F so you should be seeing 180 or 190 depending on which is in yours.

 

[CJF]

I'm starting to think 91-92 front heater cores are prone to clogging.

 

[leonard_nemoy]

I am starting to lean towards a clogged heater core. I talked to the po and was told the new thermostat was a 180 degree thermostat, so seeing 170 on the housing sounds about right as I would assume it would measure lower than the actual thermostat. Also the fact that it gets hotter as the rpm's climb makes me think that the pressure is forcing more fluid through the core. Tomorrow I am going to change a motor mount and try running some water throught the heater core to see if I have good flow or not. I will post my results.

 

[izzyandsue]

Spock,
did you figure out the root cause yet? I used my pyrometer today to get data. Engine warmed up pretty quickly, within 5 minutes of driving. The rear floor heater was pumping 88-89F air, the front only 67-72F on 50% fan, full heat. On the highway, the rear got to 103F, the front 87F at the highest. At parking, full engine hot, rear was down to 95F, front 72F. I am trying to figure out what to chase next to increase cabin heat. Will try "burping" next, the truck has a new thermostat and radiator by PO, and verified all working correctly by Yota Master Tech.

 

[westafari]

I picked up one of these recently to use for burping my truck, it works like a champ! http://www.amazon.com/Lisle-24610-S...=1419258868&sr=1-2&keywords=spill+free+funnel

My local Napa store had them in stock. There was a ton of air in my cooling system and I'm still not sure I got it all out. My heat was working well yesterday but today it seems to have cooled a bit again. I think the next thing I'm going to do is back flush the heater, there must be some crud in there somewhere thats partially clogging it.

 

[izzyandsue]

That looks interesting. Is this how you used it?

 

[westafari]

Yep! Exactly like that. It comes with several radiator caps and one of them fit my 80 perfectly.

 

[izzyandsue]

Awesome, got a one day delivery from Amazon, will do this tomorrow.

 

[leonard_nemoy]

I got a shop flushing the heater core as we speak then they are going to use their snap on radkit to put a vacuum on the cooling system and make sure it is 100 percent burped. I will update later when I pick her up

 

[leonard_nemoy]

Shop said all kinds of nasty stuff came out of my heater core. They put 30psi of air through it then flushed with a garden hose . Heater blows nice and hot, now I am hoping the heater core doesn't start leaking.

 

[OLD DAWG]

Had to have a radiator shop flush the cores on the wifes 97. She has great heat now as well. I had tried it at home backflushing and all and couldn't get much heat. Warm wife=happier life

 

[westafari]

I'm glad to hear these success stories about making the heat work. If I can't get mine flushed out I may have to resort to taking it to a shop. A cold wife and 2 cold kids does not make for enjoyable winter Land Cruising.

 

[izzyandsue]

Okay, done did it. Brown Santa delivery the funnel. Adapter fit perfectly as you said it would. Starting from cold truck, hasn't run all day, fitted funnel with half distilled water half AUDI VW coolant until it was above the heater valve. Started truck with fan off, full hot air, waited until it got to running temp. Then timed 15 minutes of hot running. Squeezed hoses to see of anything moved, but I didn't have my eyes on funnel all the time. Level in funnel raised a couple of inches.

Turned off engine, poured most of excess into expansion tank to proper level and closed it up. Mother, moment of truth started truck and turn heater to 50%, fresh air, got to 99F. This is with truck still just idling in garage, colder outside than yesterday when it would hover mid 70'sF. Will test during drive tomorrow morning with recirc air, but can only assume it will be a lot warmer. So first impression, 20 degree raised by doing this. Say $1 per degree, but priceless.

 

[westafari]

Awesome!! I think I need to do mine again with my truck parked at an incline. When I first did it that funnel was bubbling like a witches cauldron. Glad that helped you!!

 

[izzyandsue]

Thank you again. And by the way, I think it ran for 25 mins after warm, not 15. Temp increase was easily measured

 

[izzyandsue]

Tested it last night, 30F outside. Thermostat up to temp in 4:30 mins or so while driving, cabin really warm in just under 8 mins.

 

[Tenzig Norgay]

Muratic acid cleans the heater cores out real nice, did mine like ten years ago. You can also back flush the heater cores all by themselves by disconnecting the inlet and outlet hoses.