CJM

96 T100 3.4L V6 automatic trans 4x4.

Over the summer I changed the t-belt, waterpump, t-stat, both rad hoses and radiator. Everything was OEM toyota or denso stuff. I got the entire t-belt kit off ebay that everyone uses for the 3.4 engines.I also changed the radiator as the tank was bad.

After the t-belt job everything seemed fine, now its winter and its been VERY cold last few days and I noticed my heat really isnt that hot, warm but not the furnace it used to be.

I checked and the upper hose is warm/hot but not scalding like I recall it used to be (I can physically hold it all day long without even coming close to burning myself) and lower is lukewarm at best. There are no leaks, everything seems full as well. The heat does work but it just isnt super warm. Temp gauge is near middle if not tick mark or so below exact middle. At idle the heat is worse than when driving, while driving it gets better but not much.

When I removed the radiator cap today after driving home and letting sit for 5-10 mins it wasnt hot at all really. It didnt fly out under pressure and I could easily stick my finger in the tank and it warm at best.

Im thinking the t-stat is stuck open or perhaps the heater core is going bad. The truck takes a good 15mins to warm up if not 20mins, shifts seem oddly long and drawn out as well in alot of cases. There is no water on my pass floorboards and I dont recall hearing any gurgling noises either.

Possible the coolant isnt mixed right? I recall at one point I may have added water to premix by accident but cant recall if I dumped it all out or continued on. I had been having leaking from the upper hose, one of the hose clamps was no good. Gonna test it with a hydrometer tomorrow am.

rworegon

Check the fan clutch. It may be locked up. There are threads around here on how to do so.
A stuck open thermostat will keep the engine from properly heating.

CJM

After driving around today I think I might have found the problem. It was to dang cold yesterday. It was around 9F..maybe less, today its about 20F out right now and I have good heat. I also blocked off part of the rad with cardboard. If it continues to give me issues Im going to see wtf is going ok. This sunday Im also going to verify everything is flowing right.

SoCal4Running

I read somewhere that running without a thermostat or one that is stuck open allows the water to flow too fast and never gives it time to absorb heat from the motor and also gives it less time to transfer that heat to the radiator.

The heat from the engine has to go somewhere though, the engine must just keep getting hotter and hotter until Kablamo!

If your system is fully functional then yes get a "winter front" for your radiator.

Toyota~Boy

iTrader: (2)

-10 degrees here in WV the last couple days and my heat has been awesome in the T. I dunno if the T100's have that control switch out on the firewall but if so you may want to check it. If it's stuck you may not be getting proper coolant flow through the heater core. I've noticed that my heat when switch on defrost will flow quiet heavily out the dash vents too. So I may have some linkage issues lol. But my heat is great dude.

snobdds

This is my first thought since the the thermostat is OEM.

CJM

it is possible it is bad. Today was warmer and this morning heat was ok, it was about 15F outside, then when I got off work it was 25F outside and heat was WAY better.

Im going to have to check over all the hoses and see if i have a blockage or perhaps bad switch. I can see the arm move at that switch tho. Im going to have check the hoses all over. I do know the upper rad hose when it was 10F outside was warm/hot but not super hot and the lower was pretty much cold. I recall (might be wrong it was damn cold when I did it and I wasnt paying that much attn) the hose going intot he switcher valve as well as out, but one of the heater core hoses wasnt as hot as it could be. Img onna check it all with a temp gun come sunday and flush the entire system and possibly change the t-stat.

I think either something is clogged or not working right. So far I have pretty much ruled out the t-stat. It would be too hot if stuck closed and nada if stuck closed. I doubt its that at this point. Truck took a good 15mins to warm up and heat was fine tonight on way home. I shouldnt be able to hold onto the upper hose imho, and I can. Its not that hot.

Winkel

Actually, I think that's pretty normal. When it's that cold, I block about half of my radiator with a piece of cardboard and it helps a lot. I grew up in Iowa and that was pretty common in the winter.


Below 10F or so, blocking half of the radiator will help. I wouldn't panic and start ripping stuff apart.

CJM

Well today it was about 35-40F outside and truck really didnt get quite warm until I was down the road a few miles. I let the truck run a good 10 mins before leaving work tonight and again heat wasnt a furnace like it used to be until I got down the road. About 3/4 of the rad is blocked right now.

Looking at the gauge more I swear I can recall the needle covered the little temp logo when up to operating temps, and for sure its now a hair or slightly more below and I can see the temp logo much better.

Was talking to a buddy about this and he mentioned something I forgot about. We had heard a strange gurgling noise every so often over the past few months..which points to a clogged heater core I recall. Also heat gets way better when on the throttle going down the road vs idle. I suppose I might be able to blow the sucker out...

I bought a stant 180F t-stat and the seal but they didnt have the tube gasket at advanced, gonna try a few places tomorrow. Sunday Im going to investigate more.

This whole thing annoys me to no end, but things break. I suppose I cant really complain, I do have 253k. Course what stinks is I wanted to sell the truck this summer perhaps and buy a tundra or a chevy.

CJM

Update:

Last night driving home it was much warmer-like 45F and raining. The temp gauge got about 3/4 of the way to hot and if i sat and idled it climbed quite close to hot. Took the cardboard out today and again it was about 40F outside, temp gauge stayed in the middle.

Went to my friends shop and we looked it all over, decided the 6 month old toyota oem t-stat was bad it seems. We took off the water outlet pipe and it t-stat never closed. Once we replaced it, got better heat but still not great. There was an awful lot of air in the system as well that took us awhile to get out. Checked the hoses and before we started and the heater core hoses werent that warm once they went into and out of the switcher valve, infact the one hose was hotter that came from the block to the switcher but it got cold (about a 20-30F difference) when it came out of the valve, once we fixed the t-stat it was much better. I got alot of air out it seems.

Still heat isnt that great. We decided that:
A). We think because the cat is leaking decently, it is possible the entire truck is running cooler than it should. Said buddy helping me has a dodge with a punched out cat, that sucker will not get up to temp all to well and the truck only has 60k on it. So it is indeed a possibility since my cat is leaking right at the flange and the exhaust is leaking.

B). The heater core is clogged possibly and we will try to blow it out.

C). T-stat i replaced it with was a stant, other one was oem toyota. Looked VERY different and it didnt have a jiggle valve in the stant one. Called several parts supplies, they all list it was the right t-stat and none have a jiggle valve it seems.

CJM

Just wanted to update:
Blew out heater core today, some stuff came out but mostly rust specks/dirt. Heat is 110% better. before middle vents with truck fully heated were getting to maybe 120F, now they top out @ 160-165F.

I also found I need to replace the heater control valve, its cracked on the inlet. So ordered one up, blow out the heater core a few more times. Anything to not to replace the heater core-its not a fun job.