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Heater Core Flush With Pressure Washer???

JeepMaz

NAXJA Forum User
I have a '98 Cherokee with weak heat. I had 2 coolant flushes last year before a family friend pulled the input and output hoses on the heater core and flushed it out. That worked last year. This year, weak heat again. After a coolant flush last weekend at the local dealership left me with an overheating and stalling truck due to "difficult air pockets in the system" and still weak heat (and $160 lighter wallet), I want to flush the core. However, I live in an apartment and don't have access to a garden hose.

Question: Can I use a pressure washer nozzle at a self serve car wash to flush the sucker out? Does anybody know if this will cause any damage or do more harm than good? Anybody ever tried it before?

Thanks for your help!
 
A pressure washer may be a bit much for a heater core - design pressure is around 15-20psig, and even water mains are pushing that (your garden hose is typically 30-50psig.)

I probably wouldn't use any more than a garden hose - but if you want to target the heater core, remove the hoses and do like you were planning on doing with the pressure washer.

Probably have better results with volume than pressure anyhow.
 
put a garden hose in the end that coolant usually flows out of. turn it on full blast and let it go for a few minutes. that usually clears them out.
a pressure washer may very well blow out the welds in the heater core. then you'd be tearing the dash apart instead of unplugging your heater core.
 
codyj86 said:
put a garden hose in the end that coolant usually flows out of. turn it on full blast and let it go for a few minutes. that usually clears them out.
a pressure washer may very well blow out the welds in the heater core. then you'd be tearing the dash apart instead of unplugging your heater core.

Probably work better if you run the heater core "backwards," tho. Scale deposits are like fish scales - they have "direction." Backflushing works because you're getting water "under" the scales to break them loose...
 
When I did mine I let it run backwards until it ran clean, then switch directions until it ran clean, repeat/lather/rinse etc. I think I went back and forth about 10 times until it ran clean both ways. Got lots of crap out and great heat afterwards. I tend to shy away from caustic flushes since some of the acidic chemicals can attack copper things like heater cores which are a bitch to replace.
 
You can see the heater core or the radiator start to swell, after about 30 PSI. If there are any week spots they will likely pop at around 40 (or even lower).
Getting the heater hoses off of the heater core can be a pain. Brute force can cause damage.
 
On behalf of your rig, DON"T DO IT! It is like using a sledge hammer to crack an egg and makes as much sense. Check out Prestone's flush kit ($4) at W Mart and install it as directed. Attach your garden hose and back flush following the directions. Use their flush cleaners or vinegar and water and allow it to work and then flush it again. The crap you get out of your system is like using a Rug Doctor for the first time on your dirty carpet. Crappy crap crap. You must run your heater during the whole process to get the full effect. The flush kit allows you to clean it up without removing radiator hoses and making as much of a mess in the driveway. And don't forget to use distilled water mixed with your antifreeze for the final fill.
 
A) Since you are pumping water into your system, where does the antifreeze go to compensate and make room for the water?

B) How do you get all of the water out of the system and then fill with mixed antifreeze?

I never really looked at these flush kits but you mention "not making a mess"....but where does all of the old antifreeze end up?

X2 on not using a pressure washer though. Unless it was on a really low low setting. Not sure what type or how powerful of a washer he has anyway. So best recommendation would be to say don't use it.
 
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