so when i bought my 4runner it was summer, i checked the heater, and noticed warmer air comming out and thought "cool it works! its summer so i ddidnt leave it on more than 5 seconds before i felt hot air was was happy." well fast forward to now... its gettin cold and my heat is hoooorrrible, ive found if i drive for a little while with the temp to hot, and the fan off, if i turn on the fan itll blow hot for about 30 seconds. After that it gets cold again, i made sure the valve was functioning under the hood, and the flap was working... so im thinking i have a clogged heater core, basically i just wanna hear your opinions on that and if you have a good way to clog it? im gonna try blasting it with the hose in the in/out to see what i get.

 

Sounds like a clogged heater core. Those things are b*tch to remove....

Just to be sure, I'd remove the hoses & backflush it in place to see what you get.

Has stop leak or equivalent ever been used on it? That will cause them to become completely ineffective....

 

bah, yea i used some because i had a pinhole leak on the top of my radiator, does backflushing not help with that?

 

Just what engine are you talking here.

I have noticed with the 22r series engines unless the coolant is at the proper level you will not get any heat!!

It is not low enough to cause a overheating issue you just won`t have heat.

 

No. That s*%t completely coats the inside of the heater core & radiator. It GREATLY reduces heat transfer, so don't be surprised if you end up replacing your radiator....

 

I replaced a heater core in my 87 for the same reason. I was curious and cut it apart. It was full of all kinds of slime like stuff. I assume it was stop leak. It was a very simple job to replace for me. Rock Auto had the core for about $30, don't know what they cost now. Radiator is next on the list.

 

so just for future searches on the matter, today i tried to blow some water in through the out side of the heater core, had little flow so i decided whatever, if its bad i might as well go for it....and decided to slowly, use my air compressor to blow some air into it. Well it worked for sure, launched a buncha nasty slime and cooling system diarrhea, and what i assume was some of the stop leak i added in, all over my drive way. flushed again and again going both ways with the hose and now its workin like a champ! Hooked up my thermo probe and got 106F blowin out of it! thanks for the input everyone

 

Stop leak is bad!!!!!!

 

Nice glad you have heat just in time!!!