Matt_4runnin

I have had issues with my 4runner since I bought it. The people before me must have abused the heck out of it. I have done general upkeep/restoration/maintenance such as tuneup, brakes, flush of all fluids. I do know that the vehicle has had issues with overheating in the past, but it has a new radiator, fan clutch and all hoses from previous owner. Also, HG and water pump done at 140k. I had trouble with the heater last winter, but it was never bad enough to deal with in the winter months. When I finally checked it had green antifreeze in it. I flushed it out myself with a backflush kit, but had to throw green back in it because i was on a time crunch and couldnt wait for red to be ordered. Went through a bit of a fiasco with the stealership but finally got it flushed out and changed to red. The heater completely quit working at that point. I hooked up a hose (as many have done writeups on) and flushed out the heater core back and forward for a couple hours. Now, I have heat when the engine is over 1300 or so RPM. I have checked the baffle system in the dash and all works there, road speed seems to have no effect. I checked the plugs for a sign of HG leakage, the vehicle does not use oil or water far as I can tell (I've been messing with it so much hard to keep tabs on water level). Ive never had issues with it overheating in the 90 degree summers or -10 winters and temp stays where it always has so I think that rules out the water pump? I don't really want to pay the shop to start replacing things unless theres a fairly obvious solution. I'm at the end of my wits here and am about ready to sell it and find another, older, easier-to-work-on-myself-vehicle. Any ideas?

DewDog

Have you replaced the thermostat? And are you getting any heat from the back floor heater?

Matt_4runnin

I have not yet, didn't think it was an issue considering it hits temperature right away and stays there. Think its worth it for a cheap try and see if it works fix?

I get heat for a short while from the rear heater, then it goes cold too. Both front and rear blow plenty of air its just cold air

DewDog

Its a pretty quick fix, but it may not cure the problem. My parents corolla would get temp. no problem but no hot air would come out so I just put in a new thermostat and it worked. Its kinda hard when you don't have truck in front of you.

rworegon

Is the heater valve under the hood working? Cable hooked up to it and moving freely?

https://www.yotatech.com/forums/f115...-valve-225742/
https://www.yotatech.com/forums/f116...estion-226597/

Matt_4runnin

If 20 bucks fixes my problem right now I'll scream (anger and joy). Its worth a try. Ill have some time in my uncles shop early next week and Ill definitely get one before then.

Yes, the valve is working properly. I've been through (nearly) every post on this site and a couple other sites about the issue and think I have all the basic parts checked and functioning. I do appreciate you checking as I may have missed something stupid-simple.

TheDurk

Do you have the digital or manual control system? I would guess a Limited has the digital. Those things have a self-diagnostic system that reads out trouble codes on the temp readout. Take a look at the on-line FSM for instructions. No reader needed. It's worth a try--it'll check your actuators and sensors. You may have a case where a sensor is telling the system no heat is needed while you are freezing your a$$ off. My WAG from what I've read.(The heat ON, then going OFF leads me to this thought.)

wii_tarded

have you check the lines from the block to the heater core....just throwing ideas out.

Matt_4runnin

The control system is manual. I believe the issue lies in the coolant temperature in the engine or the availability of warm coolant to the heater core. I'm going to follow DewDog's advice and replace the thermostat tomorrow or the next day. Does anyone know if it is possible that a water pump could function part of the time without the timing belt slipping? does it have a clutch mechanism of any kind?

rworegon

There is no clutch mechanism on the water pump.

kev

thermostat is partially open, all the time. Must replace!
Voice of experience!!

DewDog

Make sure you get all the air out of the system when you replace the thermostat. If you have air in the system you will never get proper heat. I like to use a Lisle coolant funnel, they work really well.

Matt_4runnin

Oh man I've never seen one of those before! That looks like it will make burping the system much easier. Before I've just parked on a hill and tried to keep the neck full without overflowing coolant into the fan.
Looks like my first order of business tomorrow will be a run to town. I have seen the brand Kuzeh thrown out there for OE thermostats... is there any reason a Napa or O'Reilly brand wont suffice?

DewDog

I allways get OEM stuff, I don't think it makes a difference on a thermostat.

tunnelmotor99

I definitely agree with changing the thermostat out, but when someone mentions overheating and head gasket problems followed by heater trouble I can't help but think about that stop leak powder that people dump into the cooling system as a band aid fix. That stuff causes more problems than it claims to cure like clogging up heater cores and thermostats. I worked on a honda CRV last year that had dual zone HVAC and it had heat only on the passenger side. Turns out they had overheated it (mall security vehicle) and dumped a crapload of that stop leak powder in the coolant. The powder plugged up half of the heater core and no amount of flushing and backflushing could get that stuff out!

Matt_4runnin

Okay, Ill see what happens after I get the thermostat replaced Wednesday but that may be the only fix. If so, its gonna be a long, cold winter!

wyoming9

iTrader: (1)

Don`t forget another cheap fix would be the radiator cap I was having heat issues in my 87 4Runner replaced Thermostat and cap big difference.

Now unless global warming has caught up to your part of the country it gets almost cold in the winter up there.

I know with my 4Runner it takes almost 8 or 10 miles to start getting hot air driving 45 to 55 mph and this is in 25 degree F temps.

Drop the temp to below zero it could take a little longer at 60 degrees I have all the heat I need

It seems funny to see down Parkas and beanies at those temps I would hate to see if it got cold

blake.nemitz

i would say its probably the warm water valve that is impeeding coolant flow through the heater core, bypass it and see if it works, if it does there is your culprit

Matt_4runnin

I was in danger of rounding the nuts that hold the thermostat on so I took it to the shop. Cost half an hour labor. When I drove it home on the highway (2200 rpm sustained) the heater blew HOT (almost scary warm... burning temp) but as soon as i started to idle again it went cool again, so im going to bypass the valve tomorrow, will update then

Matt_4runnin

She Lives! Heat blows nice and warm now and vehicle heats up properly... I never did bypass the valve, but I may try doing that to see if it makes it even better.

Thanks to all for your suggestions and perspectives!