I'm wondering if it's okay to use my 8 gal. pancake compressor to blow out my heater core if I set the pressure at 10 psi or less ? tomorrow I will remove lower rad hose too and attempt to flush rad and get better flow from the petcock ; since it only dribbles now and I think there might be a clog there at the bottom of the rad . am I on the right track doing these things . also does anyone know about using CLR in the system . is it safe to do that ?

thanks

edit: I found a site that says for a 98 , it's unnecessary to remove the dash and all the other 1,000,000 things in order to remove/replace the heater core . Says the access panel on duct on passenger side is sufficient ..
article here - https://itstillruns.com/replace-heat...r-5770333.html
is this at all correct , anyone know? or is it way too simplified etc . . I hope some of you guys in the know can help me with this . there are so many reasons why I'm unable to remove the dash and everything else to get this heater core out myself ..... too old, no place to do the work , rent a room . landlord , HOA will not allow . not enough special tools , pullers etc. , finances .

 

Air compressor won't help with heater core as the blockage is usually not debris but a build up of corrosion in the passages if Coolant wasn't changed or wrong kind was mixed in with the old
There are 3 types of coolant
Green, silicate base, 2 year life
Red/Pink, Organic Acid base, 5 year life

The above 2 can NOT be mixed or a sludge will develop

Gold/Yellow, Hybrid organic acid/silicate, 5-7 year life
This one can be added to any cooling system without causing the sludge

Use your lungs to blow out heater core
Remove the 2 heater core hoses but at the Bypass valve end
Point one down and then blow thru the other one
Refill with water then reverse, put other hose pointed down and blow thru the up hose now, reverse the flow
This will clear out any loose debris
Then mix CLR or Vinegar(not both) with hot/warm water and pour it in to heater core
Wait 20min
Blow it out
Repeat and reverse hoses again
You can usually tell if flow is getting better
So repeat as you see fit

For future reference you should reverse heater hoses at the firewall every 2 years on any vehicle, this will keep heater core cleaner so it lasts longer


The radiator drain plug is usually clogged with debris that has settled to bottom of radiator, and you can use air compressor to push debris out of the way, but it will continue to come back as radiator drains
You can also use a stranded electrical wire, smaller gauge, to push into the drain hole and wiggle it around to move debris off to the sides this will usually get the debris out faster

In some cases the debris has hardened and not much you can do about that, just use lower radiator hose to drain system and wait for a sale on new radiators, lol


Coolant does three things
It raises the boiling point of the water its mixed with from 212degF to 235degF
It has anti-corrosives to prevent metal parts from corroding
It has water pump lubrication additive

As shown above the anti-corrosive chemicals in coolant have a set lifespan, 2 years, or 5 years, that's the part that goes away as coolant ages
And once the corrosion starts in say the heater core and blocks a few passages then changing coolant helps but.............new coolant can't get into the block passages, so they just keep corroding, slower, but damage is done
Using CLR or Vinegar can clear out some of the corrosion and if enough is cleared then a passage can start to flow again and get some protection back
Using CLR or Vinegar on the whole system is NOT good because you can't clear out the debris it creates, and that causes more problems in heater core and radiator

You can use CLR or Vinegar on radiator separately, but best to do this when radiator is removed and lying flat, so you can fill and drain easily

 

RonD -
thanks for all the valuable information , that's such a huge help .