MTL_4runner

I am going to change it for sure....I worried about exactly what you mention.

Gerdo

Of course the waterpump is buried inside with the timing belts. Probaly time to change them also, belt tention pulleys, flush the cooling system, thermostat, belts, hoses. Did I forget anything? Sorry, I didn't have a heat issue but while I was changing the timing belts I did all of the above work also. Most shops dont even suggest the extra work but the parts are cheap compaired to the labor. Don't go cheap on parts (timing belts, water pump, tension pulleys). I used Toyota parts because the first set lasted the first 90k without a problem. I will do the same thing at the next belt change (180k)

glader60

I have the same problem. The heat works good when the temps are above freezing, but is only luke warm whe it gets really cold. It gets much worse on the highway than around town. I checked the heater core flow with a hose which was okay. I checked the valve on the hose to the heater core which was also okay. Car never runs hot in the summer. If I put a piece of cardboard in front of the radiator, the heat gets better, but not great.

It's my wifes truck, and she's always cold, so I have to fix it. I just installed a heated seat kit in drivers seat, and it will fry your a$$ on high. Kit was $75 and I installed it under the leather in under 3 hours. Well worth the cost.

Back to the heater. I'm getting ready to do the timing belt and water pump. It doubt it's the water pump, I've never seen pump that the fins were so rusted it caused low flow. Maybe on some really old car what didn't use cooand. Besides, if that was the problem, it would run hot in the summer, which it doesn't. So, here's what I think it is: The heater core. I'm sure you know the heater core is just like a radiator. I think several of the core tubes are clogged, but some are clear, that's why the hose test has flow. My truck was from the south and with heater off most the time, the coolant doesn't flow through the core, which could cause it get blocked over time.

I'm going to get some high quality, flush, and drive the truck with it in and the heater on for a couple of days and see it that helps. I might even try to get some flush into the heate core and let it sit there for a couple of days.

MTL_4runner

Let me know how that goes because that is definately the exact same problem.....no overheating or overcooling just crappy heat from the heater core. If you do redo the waterpump or the heater core please do post pics of the old ones. The heater core would be worth cutting the ends off to check what it looks like inside too. I was going to try a flush but you'll need to add at least double the amount of radiator flush to make any dent in rust/scale deposists. I'd take out the thermostat too (very easy, 3 bolts) to let the stuff circulate much better and then replace the thermostat when you are done because it will make a difference I found anyway. Keep posting and we'll get this mystery figured out in no time.

By the way, where did you buy your heated seat kit? Any pics of the install?

glader60

I saw the heated seat kit on ebay. They have a web site http://www.heatedseatkits.com I called them and they gave me the ebay price with free shipping. It came with everthing needed to install it and has a high or low setting. Sorry, no pictures during the install. You just need to remove about 20 hog rings, pull the leather off, stick the heating pads on the foam, and then put the leather back on with the hog rings. It came with very detailed instructions and they have an 800 number for help. Took about 2 hours, I was really taking my time. I brought the seat in the basement where it's warm. These are so worth it. The seat is really warm (bottom and back) within 5 minutes and cooking in 10 minutes.

I don't plan to replace the heater core. I think it's buried in the dash. I might bring the truck to a radiator shop, disconnect the hoses to the heater core and see if they can just connect the heater core alone to a flushing machine. Just hope it doesn't spring a leak. They should also be able to measure the flow in gpm to see how much it flows, which should determine the condition.

MTL_4runner

Definately replace your thermostat too.....it is cheap and easy to do.
Also post a pic of the old waterpump if you do go ahead and change that too.

MTL_4runner

Just wanted to update this thread since it seems like I no longer have an issue with heat in the 4runner anymore. I can't say that there was any one thing I did that made it all better, but I will say at least what I did so hopefully this will help people in the future having similar issues.

Since the issue started I have flushed the system throughly at least 3 times (filling with Dex-cool twice and finally with Toyota pink, although Toyota red would work fine as well). Each time I flushed, I made sure to unhook both the radiator and heater hoses (and on the last time I removed and replaced the thermostat while flushing.....so I backflushed where the themostat was too). Flushing was simple, just took a garden hose with a nozzle and sprayed into each coolant opening, hose etc and flushed until I saw nothing but clear (and did it several times). I also inspected the inside of the radiator using a flexible light (like this) and a dental mirror and there didn't appear to be any deposits at all (so I am glad I didn't pay for a radiator recore). I also inspected the heater core in a similar manner as best I could although it was very difficult to see much of anything because the tube openings are so small. So I put all the hoses back on, I replaced the thermostat with a new OEM one, refilled with coolant and started the truck and took it for a spin. The heat was definately better but is seemed that it got even better over time. It now heats quite well again (enough so we need to turn it down anyway) so I feel pretty confident the issue is now over.

At my next timing belt change I will change my water pump too so I will post pics if there are any anomallys found there too.

DoubleZero4x4

I had an 87 Camry that had the thermostat stuck open. I the summer time even in the hottest of days with the AC going full blast sitting stopped in traffic, the temp never got past 1/2 way, but when I moved to MN and the warmest it got was -5 in January, I had ice forming on the inside of my windows. Solution before fixing thermostat was a simple piece of cardboard across 1/2 of radiator.

You couldnt even see it from looking at the car because I stuck it in between radiator and other piece. Worked great.

I would check the thermostat before I worried about the heater core.

MTL_4runner

Well, I hate to resurrect this old thread but the heat in this truck is still totally unacceptable when the temps are really cold outside. Now I am positive this is not a thermostat issue because I've replaced it twice already and the truck gets up to temp right where it should. I also have very good rear heat but the heat up front is still very poor. So I am going to figure out the issue come hell or high water because up here a vehicle that doesn't heat well is just about worthless for 1/2 the year.

The radiator doesn't seem plugged and appears to flow properly (checked visually and with a garden hose). I haven't checked the water pump but I am beginning to suspect the heater core itself. Now today I spent a few more hours just taking apart the dash to see if a linkage slipped off, climate control doors were working and everything seemed to be working fine. So I then looked at why I had the strange situation of heat in the rear, but no heat in the front. So now I need some help again from someone in a cold climate to check the inlet and outlet on both the rear heater and main heater core. When I was outside today with the engine warmed up and the front/rear heaters on full blast in the truck (ie the heater coolant valve was full open), I just felt the inlets vs outlets with my hand. Now curiously the inlet and outlet on the rear heater were pretty close and both were quite hot to the touch (the return was just a bit cooler than the inlet). The inlet for the main heater core was very hot too (almost enough to burn me if I held my hand on it), but the outlet was fairly cool to the touch (ie warm, but definately not nearly as hot as the rear heater outlet). So could someone with a 3rd gen (perferably a 96-97, but any year would be helpful) in a reasonably cold part of the country check the temps on theirs for me?

Pic of what I need help with:

MTL_4runner

I did a bit more reading in the manual last night and it said that both the inlet and outlet should be hot to the touch (which makes sense.....unlike the main lower radiator hose up front which is usually cool when the weather's cold outside) so there's definately an issue. The problem is that I'm not sure if the blockage is in the actual heater core itself or in the return line going to the motor. I suspect the heater core still because like I mentioned, the return line for the rear heater was hot and if there was no flow on the return line to the engine, then I should have little or no heat both front and back. I don't know why I didn't catch this sooner but I asked the parts guy at the dealer how often these get plugged and he said not very often so I may be that rare case indeed. I am going to buy a new heater core, install it inline with the coolant hoses and run the engine up to temp and see how hot it gets (including how hot the inlet and outlet are). This way I won't waste a full day installing a part if the old one is actually good (and hopefully I can return the heater core at the dealer if I don't need it). If the old one is clearly bad, I'll install the new one and take lots of pics of the process so others have something to go by if they run into the same issue (I'll also cut open the old one to see what the issue actually was). It's definately not something I'm looking forward to that's for sure!

Can someone still verify how hot the return line on their main heater core (per above pics) gets vs the inlet, I'd be most appreciative for the info!?

farmerj

One thing that I do a lot on heaters is to pull the hoses and back flush with a garden hose and clear water. Often times this will be loaded with crud.

on my 88 4runner, I had a prestone flush t in the valve side of the core. I fought this for 2 years trying to get heat. New T-stat, control valve, control cable core. And a few others. I finally had that hose left to replace with the flush tee in it. When I pulled it out, someone had put it in before us and crushed a 3/4" fitting into a toyota 5/8" hose. It was basically half plugged.

Much better heat, but I have noticed that I need to get in and adjust my controls. I keep having to push the heat setting to the right. It is very sensitive to any movement and will get cool with only about 1/4" of movement.

MTL_4runner

I have tried garden hose forward/back flushing the core before and really didn't get much of anything out so either the return hose is plugged or the heater core is terminally blocked. I am hoping I can get a cheapo heater core to try and see if it does get hot. If so, the heater core is definately the cause. I wish I had a lighted borescope with a camera so I could see what the inside looks like before I even bother (same with the engine block, heater hoses, radiator, etc), but that's pretty $$$$ equipment no doubt.

Still looking to verify how hot the return line on their main heater core, anyone?

jrallan26

My truck had a heating issue. Plus I was also getting a check engine light. I replaces the thermostat at 60K miles. No issues ever since.

Have you replaced your thermostat?

MTL_4runner

Here's what I had written in post #69 above.

MTL_4runner

I did a little research on heater cores and possible issues why there would be little or no heat and I can across this which pretty much points directly at a blocked heater core as being the most likely cause. Man, I wish I had a borescope so I could just take a peek in there and see right away if that was really the issue or not.

Article
When no or low heater output is not due to a blower problem (plenty of air coming out of the ducts but the air isn't hot), the list of possible causes include:

MTL_4runner

I have also seen a few people using Prestone Super Flush (aka oxalic acid) in some clear PVC tubing (that way you can see what the stuff looks like and if the acid is actually doing it's job). If I end up having to replace the heater core anyway, then it won't hurt to run some of that through there in a last ditch effort to remove any buildup possibly blocking heat transfer. Who knows, maybe I might be able to add something to the board on this (maybe the next Seafoam for your cooling system?!). I'll let you all know how I fare after I give the organic acid a try.

Elmerbuch

I would say it is not the water heater
i have the same exact problem front is luke warm air but the back could burn your hand off. I don't know why this is but i replaced my water pump last year so i doubt that thats the problem

MTL_4runner

I tore the entire top end of the motor down (for another reason) and from what I saw there was alot of calcium/mineral deposits in the cooling system so my bet is that the inside of the heater core looks quite similar and therein lies the issue. I might see if I can find a radiator shop to do a chemical flush on the system for me after I get it all back together but for now I am 99% sure that's what the problem is.

You can see the pics of inside the motor over here:
http://www.ultimateyota.com/index.ph...22768#msg22768

stormin94

As for the Original 2 year old topic, My heater works damn good!!! It'll about burn ya out, even on the coldest of days......well, as cold as it gets in Northern California...about 20*, but I've had it in 15* and it still worked just as good.

ARB1977

Alittle off topic but the internals of your engine look pretty damn good for 140K, what oil do you use? Just courious how often did you have your cooling system flushed before you experienced problems?