l15punk

hey i'm new to the forum. i have an 88 toyota with the 3.0 in it and i am having a weird heat problem. at idle i have no heat but if i give is some gas or i am driving it works fine. i have replaced my thermostat to see if it was that and that didn't fix it. i flushed and back flushed the heater core and that was ok. i am just at wits end. any help would be great. and i did search but i didn't see much so. well thanks

billmaness

My only new vehicle was a '88 xtracab with a 3.slow. I had the same problem (when the truck was new). Never did figure out why. There are some Threads that discuss this topic but I don't have the answer - just can't sleep.

idanity

i am replacing my heater core.
it was full of goop and muck.

at the very least, i would remove both heater core hoses, and hose out the heater core w/a garden hose, then distilled water, till it comes clean.
then do the engine and radiator.


if at any time in its past, anyone poured in the "stop-leak" into the radiator, it will build up in the heater core too.

once that path-way is clear, your heat should work better.

l15punk

thanks for the replies. i did flush the heater core out and back flushed it and it was clear not murky at all. someone may have poured stop leak in it in its past but i have owned it for about 5 years and the heat worked up until about a month ago. i am starting to think i might just have a big air pocket in it.

82yota

I've got a similar problem in my truck only I don't know how it ever performed before because as soon as I got it I changed the motor out. But a diesel should put out lots of heat. I think there may be a bit of air in my system. I might put one of those little air bleed deals in by the heater core lines to get the air out of it. I really need the heat as my windows aren't defrosting fast enough right now.

funjumper

Check the heater valve and cable attachment point for the cable that opens and closes the valve. If the cable slipped the valve may not be opening all the way.
When you took off the parts to get to the heater core to flush it, did you check out the heater valve and make sure that the cable was set to fully open and close the valve?
I spent 20 minutes or so the other day setting up the the heater valve on a 3.4 conversion I am working on. I had to move the cable in the clip a few times to get the valve to fully open and close as required. I didn't install the hoses until I got the valve set up correctly. This allowed me to see inside the valve to set up the cable correctly. I would have been done in 5 minutes if I hadn't been working alone.

notanymore

what he said, my truck used to have problems where it wouldnt blow hot air when i wanted it to and it turned out to be the cable had broken.

l15punk

thanks for the help guys. i will take a look at the cable when it stops raining and i will let you know what i find out

ozziesironmanoffroad

question guys, sorry to hijack, but its the same thing. my truck has heat, in fact its quite hot, but as soon as i turn on the blower, it cools down, and in about a minute its as cold as the air outside. ive already flushed the heater core and cooling system, should i flush the core again? my heater valve is fine, im at my wits end!

idanity

yup, the valve is very important.
good replies all

i would fallow the above replies.
and see if your thermostat is not failing or stuck open. leaving your engine unable to stay at normal operating temps.

i just replace my heater core/ and radiator.
all hoses, thermostat and flushed it 7 times and now have really good heat (not as good as my bmw, but its ten times better than it was)

jht3

recently my 4runner started doing the same thing. now if i let the engine idle, it only blows cold air. if i rev the motor up and hold it, it will shortly start blowing nice hot air.

what gives? i don't see a solution in this thread, just a bunch of parts thrown at the problem.

DCYota

Well, the solutions are all there...step by step. Flush and backflush the heater core. Check the valve cable on it and make sure it's operating as it should. Check/test your t-stat to make sure it opens at the proper temperature, and closes as it should by using a stove and pot of water. Make sure there are no air pockets in your coolant system. That's not "throwing parts at a problem", that's taking it step by step and going through the paces to find the possible solution to the problem. The only "part" to throw at it thus far is a t-stat if it's not working. Depending on which one you go for (single or dual stage), it's either $18 or $30 from the dealer.

TORTIS

iTrader: (1)

you guys hang on, spring is almost here a funny story. i had a 70 model bronco,. the first winter i had it i froze my butt off, could figure out why the heat didn't work. couple of weeks before things warmed up a friend off mine was sitting the truck, and he leaned over and pulled on the heater knob which made the heater work. on the chrome piece it said "pull for heat" or something close to it. i still feel like a fool.

jht3

i need to check my receipts, but the thermostat should only be 1.5 years old. i had the timing belt done and water pump replaced, but i don't recall if the dealer replaced the t-stat. if it wasn't, great....that's an easy and cheap replacement. but the temp gauge reads just like it should. a stuck thermostat should result in either the engine overheating or running cold, right?

doubt it's the valve cable, as that wouldn't just fall out of adjustment

DCYota

Well, "go bad" no...but it can break or stick...causing some problems, as any cable can. Even if the t-stat was replaced, you may as well check it. Not all t-stats (even Toyota ones) are reliable. Some come from the manufacturer bad. I've gone through a couple of new t-stats in old rigs that were new off the shelf...but didn't work.

jht3

i'm having a hard time believing it's the t-stat. they usually fail open, resulting in a low reading on the temp gauge and poor fuel economy (well i already have poor fuel economy)

any idea how the rear heater plumbs in? the rear heater is effected the same way.

ARSmay

This man speaks the truth.

pig

This is exactly what mine is doing too?

last night I flushed and backflushed, and tested the heater core/cable/valve, then made sure it was left in the open position.

after a looooong test drive, the heater blows just like outside vent air... then when I check the in and out hoses from the heater core, both are plenty hot...so much so that you can touch them but you could hold on to them for more than 1 or 2 seconds... so I would think that would indicate that the heater core would be circulated with plenty of hot water?

am I missing something here? is it possible that my blower could be doing anything other than blowing across a hot heater core? btw, it blows plenty strong...just cool.


how would I bleed off an air pocket?

4Crawler

iTrader: (3)

Might check the air flappers under the dash are hooked up to the control levers and that they are moving properly. For air pockets, elevate the front end, open rad cap and heater valve and run engine until hot and the t-stat open. Air bubbles should come out of the open rad cap.

pig

will try the air pocket bleed....

as for the flaps, I'm able to switch from floor to mid to defrost ...just no hot air...