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Back Flushing Heater Core

8K views 8 replies 4 participants last post by  sltdak 
#1 ·
I was just wondering if that Prestone Kit, with the tee's that go on between the engine and heater core, is a good way of back flushing the cooling system?

I already have one installed and have used it before, but at the moment, I have no heat. My engine doesn't even get warm, so I'm thinking of swapping the thermostat.

Sometimes, I notice coolant on the passenger floorboard, does that mean there's a problem with my heater core? If so, what all is involved in replacing it?
 
#5 ·
I think it was to both.. But the tee is only good at pushing the old coolant out of the system. In order to backflush the heater core you need to take both hoses off and alternate pressure into both ports. If there's coolant on the floor, then most likely the core is bad (and if you backflush it, you will most likely blow out any crap that is making it an intermittent leak and you will have a constant leak).

As far as replacing the core, it involves discharging the A/C and pulling the entire dash out, then you can pull the airbox. If you are going to do it, replace the evaporator core too, whether it needs it or not. It'll save you having to do the whole thing over when the evaporator blows.

According to Alldata, it's a 5.2 hour job by the dealer. However, that doesn't include the time to empty and then recharge the A/C system.
GROAN...
How long should it take if I do it? Approx. because everybody is different.

Also, how does that affect my engine not getting warm? I refuse to believe a clogged heater core will prevent my engine from getting warm. I mean, the heater core is like an enternal radiator for the cabin, so I would expect a clogged heater core to either make my engine warmer or get warm faster.
 
#7 ·
UPDATE:

When I initially started this thread, I was in the process of swapping out the cheap 195 thermostat for a Duralast 180 thermostat that I replaced because I thought the lower temp thermo was responsible for my lack of heat, before I found it was due to low coolant because water pump was going bad.

While I had both thermos out, I decided to put them in some water and make sure they open when they should and are closed when they should. The 180 thermo didn't open til the water was past 180, I think 190 or 195. The 195 didn't open til well over 200, like 210. So I don't see how my engine wasn't getting warm, it definitely couldn't or shouldn't have been due to the thermo staying open. Under the impression that the heater core was toast, I put everything back together, using the 180 thermo. I mean why not, what's the worst that could happen, right?

So, I put the 180 thermo in, put coolant back in and start it up so the coolant can circulate and I can top the radiator off. After letting it run for a few min, I check the temp guage and the needle moved further then it had for a 10-20 min drive!!! So I turn the heat on and

VOLIA!!! I got heat!!! Well not take your clothes off heat, but I wont chatter and mess my teeth up for 10-15 miles.

I still think I may need to replace my heater core, however. And I may look into a temp sensor as well.

Your engine IS getting warm.. If the thermostat is stuck open, then it will take a LOT longer to get to operating temp.
How about never. The day after Christmas, I drove about 350 miles, from St. Louis, MO to Junction City, KS. Engine did not reach operating temps after driving almost 6.5 hours at 70mph. Same thing on the way back.
 
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