Heater Issue

[TXRick]

I've looked and read all the forums stuff...
I've flushed the heater core, replaced thermostat, control valve, a few other things.

I think that there is a blockage and I need to find where to flush out next.

When I am running around town and the heater is off, i can feel heat coming from the vents. When I turn on the heat, it's hot for a min and then gets cold.

I think the fluid is filling the heater core and heating the liquid but its slightly blocked so it cant flow out and be replaced with newly heated fluid. Does this sound feasible? I've flushed the core so could it be blocked later down the line or before...by the time I get this figured out it'll be spring...

 

[piecesparts]

My heater core got to the point where it was not giving out any amount of warm air to support my driving on a cold day. We took the lines from the engine off of the heater lines and added a chemical flush to the heater core and then flushed it out after allowing it to soak. Now the heater works just fine.

 

[gamefreakgc]

My heater core got to the point where it was not giving out any amount of warm air to support my driving on a cold day. We took the lines from the engine off of the heater lines and added a chemical flush to the heater core and then flushed it out after allowing it to soak. Now the heater works just fine.

This.

Your return line is most likely blocked so the coolant isn't flowing through. It gets hot from the sending line due to proximity but once you send cold air over the heater core it cools off since the fluid isn't moving.

You're not leaking coolant are you?

 

[piecesparts]

The design of the Toyota heater core and the placement of the supply lines is a major problem in this process. The engine is lower in the engine bay than the control valve and the path to the heater core, thus leaving the venting and flow at risk for not getting enough water through the heater. The type of antifreeze that is used with the Toyotas is the red and that type is noted to leave a lot of sludge. So with the cheesy design and the antifreeze that leaves a sludge, the problem amplifies itself.

 

[Paperjam]

The Toyota red coolant is notorious for making water pumps and radiators leak early. I've seen toyotas roll though my bay with less than 60k kms on them and their pumps are all crusty. I would reccomend the global yellow color, seems to work the best. Also before you try chemical flushes try pushing water backward and forward though the heater core, it only flows one way normally, so pushing backwards helps sometimes, I've had luck with that before, also considering our winters are much much colder.

 

[TXRick]

No not leaking anywhere and am using 50/50 green antifreeze. I'll flush it again...caught a cold this weekend so I'll get on it this week and report back. Thanks!

 

[Ol'Blue]

How are you flushing it?

 

[smoltz]

I had heat issues with my 97 w/ 140k miles. Although it was like that when I bought it at 120k or so. I flushed the coolant and verified heater control valve were OK at 120k, but heading into fall this year I decided to resolve the issue.

Symptoms were that heat worked OK down to 40F ambient, but below that, not very effective. Sometimes after stopping and restarting the car it would work better than usual. Looking at intake and outtake lines showed that not much was flowing through. Ended up replacing the heater core. Fixed.

Cut the old core open after, a lot of corrosion.

 

[pluton]

The type of antifreeze that is used with the Toyotas is the red and that type is noted to leave a lot of sludge. So with the cheesy design and the antifreeze that leaves a sludge, the problem amplifies itself.

Factory fill, or tap water refill?

 

[BlackCat914]

Factory fill, or tap water refill?

The Toyota red coolant I bought when I put a radiator in my GX470 was already pre mixed.

 

[piecesparts]

How are you flushing it?

We took the hoses off at the firewall and pushed water with a chemical mix into the heater core area. It then was allowed to soak for a period and then we flushed with fresh water from the outlet side. We did this twice and now the heater works quite well.

 

[Ol'Blue]

We took the hoses off at the firewall and pushed water with a chemical mix into the heater core area. It then was allowed to soak for a period and then we flushed with fresh water from the outlet side. We did this twice and now the heater works quite well.

Ok, if it is not too bad the chemical flush will work but when it is real bad, it takes that VERY HOT WATER and pressure to break that junk loose.

Blue

 

[TXRick]

We took the hoses off at the firewall and pushed water with a chemical mix into the heater core area. It then was allowed to soak for a period and then we flushed with fresh water from the outlet side. We did this twice and now the heater works quite well.

Yeah, I didn't do any chemicals. What do you suggest? It's freaking cold and raining now....

 

[piecesparts]

My heater had reached a point where there was no heat coming from it, so we went at the process of doing it only once and not just trying to flush it with water and hope that we got the sludge out. While in the shop, we pulled the heater hoses off and pushed the chemical mix in and let it have time to work, then we flushed. Before hooking things up again, we injected chemical flush once more and then flushed a second time. I work long hours and I did not have time to be doing this every day or every other day, so we did it to the max the first time. It was worth it.

The T4R is transportation to and from work in all kinds of weather, so that is the approach we used. Once and done.