heater woes :(

i have an 87 that wont blow but luke warm heat...the only time it blows hot is if i turn the heater off, wait a few seconds, turn it back on, and then it only blows for a couple seconds before going to luke warm again. the heater control valve has been taken off so i know thats not the issue, and i have been trying to flush the heater core however i cant get water to flow through the hoses one way or the other. i just got done trying the vinegar flush and that seems to help a little but only to the extent of blowing heat out when the rpm's are raised, otherwise its the same. im really tryin to NOT pull apart my dash for a new heater core...any one have any other ideas?? am i missing something else that could be the culprit or is my core just clogged up beyond belief??
thanks,
jmeti000

if you can't push water through it with a garden hose then it's FUBAR, replace it

lol... well, thats not really the response i wanted to hear... guess i know what i will be doing tomorrow..

Try pressurized air.

Disconnect the hoses directly from the heater core inlet/outlet.

That will give you a better angle of attack on the core itself.

did you make sure your heater was set to the hottest it would go before trying to flush the heater core? and how much pressure are you using on the hose when you try to flush it. i had to use the hose on full blast the first time i tried to flush mine, and even then it took some time to get loosen the obstruction up. i spent 2 hours flushing mine the first time.

another thing to look into if your cooling system is as buggered up as mine was is a new thermostat. mine was stuck in the open possition and would not allow the engine to reach normal operating temps in the winter time. it was a $15 part and was real easy to replace. i would try the flush again and get out all the crud you can- not just the heater core but the entire cooling system then replace the t stat. and if its as bad as you say it is, you might want to try something stronger than vinegar, like the prestone flush additives.

hth
stewie

x2 on the thermostat being stuck open. Is the truck getting up to 210* It should.

We have an identical problem. I did what you did, and I got pretty annoyed after I had gone through the upper hose and lower with little results, so I clamped it on the lower and turned the hose on full blast. Nothing came out... Atleast on the upper hose. I found it on my passenger floor

I'm a little weary of flushing heater cores now. I just replaced mine since that created a leak. Good as new, but yeah it sucks changing it..

I'm gonna say the leak was already present but was being covered up by gunk.

well i fixed it!! i drained out my entire cooling system and filled it with 2 gallons of white vinegar and run it through the system with the heater on full blast to make sure it got around everywhere. then i let it sit overnight and just eat away at whatever the hell it wanted to. this morning i drained it again and flushed out the core...was a little slow moving at first, but i gradually increased the pressure and each time more stuff just came gushing out till after about 5 min it flowed good and was clean as a whistle! now i got air so hot i cant hardly stand it. granted it prolly wasnt the BEST way to go about it...but it definetly got the job done.. thanks to all for your input.

jmeti000 said:

well i fixed it!! i drained out my entire cooling system and filled it with 2 gallons of white vinegar and run it through the system with the heater on full blast to make sure it got around everywhere. then i let it sit overnight and just eat away at whatever the hell it wanted to. this morning i drained it again and flushed out the core...was a little slow moving at first, but i gradually increased the pressure and each time more stuff just came gushing out till after about 5 min it flowed good and was clean as a whistle! now i got air so hot i cant hardly stand it. granted it prolly wasnt the BEST way to go about it...but it definetly got the job done.. thanks to all for your input.

Click to expand...

I think it was the BEST way to go about it. Would you rather pay more for a chemical flush that will kill the water pump bearings. Vinegar is cheap and does the job well.