S4amoht4

I flushed the heater core yesterday. There was enough cotton fiber looking gunk with stop leak all in it come out to knit a sweater with. When I removed the lines to the heater control valve I saw that it was crammed full.

After a few hours of forcing water back and forth through the lines, it finally flushed. Heat works perfectly now. Hopefully I won't wake up tomorrow morning with coolant all in the floor board.

Thanks to every for helping me out with this problem. Yotatech saves the day again!

shaeff

If you do end up having to change out the heatercore, it's really not THAT bad of a job. Just take your time. There's a link in my signature for heater core replacement. I did it on my '94 Pickup.

#1 thing to check is always the heater valve on the firewall. I've seen the cable slip off on numerous occasions (not on mine, though), so when you try to adjust it to let coolant through the 'core, it doesn't open.

#2 is always try to flush the core out, and ALWAYS try back flushing it. Back flushing does wonders, and will loosen up any gunk built up inside.

If you replace the heatercore, make sure to pick up new O-rings for the extension pipes, and make sure yours aren't bet. If they are, new ones aren't very expensive from the dealership. A bit of FIPG on the o-rings isn't necessarily a bad idea, either, but not too much.

When you're done, park on a steep hill, block a wheel, and burp the system with the heat on full blast (full hot and fan on high). Then re-check the coolant level.

S4amoht4

Thanks, Shaeff. That writeup will be very useful if it does come down to replacing the heater core. For the moment, I don't have any coolant leaking from the heater core. I'm not sure why the po had all that crap clogging the system. Time will tell I suppose.

I figure I would note a couple tips for anybody that might be having the same problems.

1. It's relatively difficult to get a water tight seal from the water hose nozzle and the heater hoses. I used a 'blue' paper towel, folded into and wrapped around the water hose nozzle to create a conforming medium. I then poked a hole in the towel to allow water to flow through and then shoved in into the heater hose. This allowed for a temporary water tight connection to keep the water from spewing back at you when the pressure started building up.
2. Don't use too much water pressure. From what I read it would be relatively easy to cause more damage to the core with too much pressure.
3. You can also use a compressed air nozzle, in a similar manner as the water hose. Just make sure to use a air tank that has a pressure regulator so that you can turn the air pressure down to minimize damage to the heater core. It really didn't take much pressure at all to release the clog.
4. I read on a seperate thread that you should reuse the spring type clamps that are already installed on the heater core, if possible. They do not cut into the hose and they will also allow the hose to shrink and swell while maintaining an appropriate amount of pressure to keep the line from leaking.

Thanks to everyone for helping!

DupermanDave

This was my problem when my heater quit working. I also flushed my heater core and found it has a leak. Flooded the entire inside of the truck.

shaeff

No problem.

To make things easier, Prestone makes a universal coolant flush kit. I never used the whole kit, but on numerous cars of mine, I installed the T adapter that goes in the heater core inlet hose. It's good for burping air in the system, as that's one of the highest hoses in the engine bay. If you wanted to make flushing easier, you can just disconnect the feed side of it and plug it with a spare piece of hose+large bolt or something, then leave the other side attached to the heater core.

The hose will screw right on to the fitting.