Cold Running 62

[ZREM]

Usually I can find what I need to know with a search, so I don't really post much here...but I need some ideas from you guys.

'89 FJ62 I bought in March has always ran cold. When I say cold, I mean the temp gauge makes it all the way up the the bottom hash mark.

I procrastinated in trouble shooting this all summer, and now that we have a high of 7* in Fort Collins today I'm wishing I hadn't.

I figured the previous owner may have removed the thermostat or maybe it was't functioning properly...so I started there.

Replaced the T-stat to find the original O-ring pretty much disintegrated, and a bunch of build-up around the housing where it would seal. So I scraped it all clean, new T-stat, new ring and gasket - go for a test drive to check for leaks etc - and all is well. She gets up to a normal operating temp and the heat blows HOT!

Once back from my test drive, I wait for her to cool, and refill the radiator, as I lost fluid changing the T-stat.

Next morning, back to the same old cold running engine???

Tomorrow I'll replace the radiator cap...any other ideas?

 

[Lost]

check for leaks, drive a bunch to make sure your coolant is properly bled(fill overflow tank)
some like to 'burp' the system while elevating the front end of the truck and idling for 15-20mins, then fill as needed

also check via picture reference if all your coolant hoses are going to the right places.

drive a few days amd keep an eye out for coolant level

you truck will cool down slowly if just just idling properly tuned if its cold out.

 

[wengejor]

burp, burp, burp...keep the overflow bottle filled up. It take some time to get the air out of these things.

Even after a few months of driving around you can still have a bubble in there that will only come out if you're on a long road trip.

 

[NYC FJ62]

Forget burping, sounds like air is getting IN to the system.

 

[Devils Paw 80]

FWIW, mine has always been the same way over 6+ years and two radiators. Only when the temp gauge came up to half way did I notice my old radiator was leaking. Replaced radiator, same story. There's enough heat to defrost, but it never gets toasty warm.

 

[Rigger]

My FJ62 heater works pretty good these days, but it ain't the best heater when the temps are sub-zero. Here is a link to my thread on the topic of a poor-heating FJ62; I hope it helps:

https://forum.ih8mud.com/60-series-wagons/240255-fj62-little-heat-front-heater-help-needed.html

 

[lcolon]

When I was having cooling issues, I borrowed one of those heat scanners. You can then test the actual temp of the radiator, various hoses, the sensor location on the head and look for hot / cold spots... This may help diagnose things. If you have a manual pressure testor, you can also test to see how the pressure builds in the system, whether you can even reach 12-13lbs, and whether this is causing any leaks...

 

[ZREM]

Update...replaced cap today with no change.

Added more fluid, as overflow was low. Checked for leaks at home and at work (snow covered ground makes it easy to see) and found no leaks.

Should start warming up here tomorrow, will try to borrow a heat sensor from work and check around all the hoses etc. Next step will probably be a chemical flush and the burp method this weekend.

Thanks Again,

Court

 

[Cruiser62]

just changed my thermostat today due to the fact that my temp guage wouldn't move above the first line even after running for 30 -45 minutes. Pulled off the housing and the thermostat came out in 4 pieces and all kinds of grime. Once I got it changed it worked like a champ and now almost gets too hot.

 

[ZREM]

Never got around to messing with the Cruiser, but some changes in temp have occurred.

It hit like 38* today, and as I was out running errands I noticed the temp gauge was where I would consider normal (between 1st and 2nd hash marks). This made me a bit curious...so I cranked the heat full blast - it was nice and hot, and the gauge didn't really change.

Next, on my way home I took a 5 minute detour up into the foothills to hit some steep grades. On some hills the gauge would quickly rise (in 3-4 seconds it moved a full mark) and then fall back. On some hills it would remain constant (between 1st and 2nd hash mark). And by the time I got back home, and on flat land, it was back below the 1st hash mark, but not too cold - the heat still worked fine.

Lastly, it has been dripping a tiny bit of coolant while running since last filling the system.

I'm happy it's running a bit warmer, but am concerned at the drastic rise/fall of the temp in a matter of seconds.

 

[Clonestocker]

just changed my thermostat today due to the fact that my temp guage wouldn't move above the first line even after running for 30 -45 minutes. Pulled off the housing and the thermostat came out in 4 pieces and all kinds of grime. Once I got it changed it worked like a champ and now almost gets too hot.

Funny thing our Cruiser hasn't been warming up since we bought it either. Front heater no hot air. Water not circulating to heater. Pulled all the hoses at the heater valve nothing clogged but no water up up here either. Decided to pull the thermostat housing and low and behold another 4 piece thermostat. Bad part is have to order all the parts in. Also where does the round o-ring go. On top of the stat? Never seen this before. Aren't Cruiser's Fun matt

 

[Elbert]

round o ring seals teh thermostat at the top of the housing....if no o ring....coolant will leak past it.

round o ring basically sits on top of the thermostat.

Go to the SOR web site and look up the thermostat...there is a good diagram there.

 

[Elbert]

I recall reading a number of posts about defective temp guages....

Check the heater hoses to see if they are hot with the temp lever turned all the way hot.... if system has run low of coolant you need to "burp" it...no way around that. If the truck has never had new thermostat in the past 5 years....put one in.. plus o ring.

Not many issues for runnign too cold other than thermostat.

Check that heater control valve is funtional (under the hood, on the heater hose up near the firewall.

 

[Cruiser62]

Called all over Eugene and Springfield and the very last place was Autozone and they had the one I needed for a 62. the thermo sits in a lip inside the bottom part of the housing and the ring goes on top of that.

 

[Elbert]

in the last pic above...you see the stuff that looks like mold...on top of the thermostat... Most likely that's what's left of what everyone calls the o-ring... really it's a large rubber type washer.

 

[Devils Paw 80]

just changed my thermostat today due to the fact that my temp guage wouldn't move above the first line even after running for 30 -45 minutes. Pulled off the housing and the thermostat came out in 4 pieces and all kinds of grime. Once I got it changed it worked like a champ and now almost gets too hot.

Where does the temp gauge go now? Is it supposed to get up around 1/2? If so, I may need to look into this.

 

[Cruiser62]

Mine when I replaced it fluctuated between half and higher but now it stays at about the 1/2 mark. I assume that's normal?

 

[the gimpey one]

Anybody got a pic of the heater control valve thingy??