With the cold weather coming I need to get h heater core working.. during the summer my water pump was starting to leak so I swapped it out... Got my fluids out and refilled... Ran the heater on ull while filling to make sure she was going in. But now I have no flow through the core... One hose hot the other warm.im wondering what is the best/ easiest way to get the flow back? I also used the Preston coolent flush additive while I did the work.

Is there a flushing kit I can get or do I need to bring it to a shop.

 

Oh and when I add coolent to tell reservoir, it comes up from the bottom brown. And I need to add coolent every 5-7 days. fluid in the engine and rad is green.

 

To flush the heater core you can just take both hoses off from the intake and the water pump and try back flush it with a garden hose. if you cannot get water to run through it you will have to replace it (requires pulling the dash back and removing the heater box).


But if you are having to add coolant every week you are loosing a lot of coolant somewhere. if you don't have an external leak on the engine, you may have a bad intake gasket or the heater core may be leaking. But a heater core leak will usually result in antifreeze leaking onto the passenger floor in the cab.

 

Question: what was the color of the coolant before the water pump was changed, orange or green?
Reason for asking is that the two different coolants cannot be mixed; they create a sluggy mix that clogs-up everything.

 

Agreed.


The half clogged heater core is the least of your worries. If you can't find any external leaks then you start with internal checks. You (or a shop) can do a block check to see if you are getting combustion gas in your coolant - usually indicating a blown head gasket or cracked head. The other check is to send you oil off for analysis by someone like Black Stone labs. If there is no combustion gas in the coolant but coolant in the oil you probably have a blown intake manifold gasket(?). If you are getting coolant in the oil you need to run VERY SHORT oil change intervals until it is fixed - coolant takes out bearings real fast.




https://www.walmart.com/ip/COMBUSTIO...&wl13=&veh=sem

 

Green.ever since I bought it 2 years ago from the previous original owners family, I have been using green. Im not sure if try have mixed it before but it was green when I bought it.

I will be flushing it out with water hopefully this weekend.

 

So a few weeks ago I took it to a shop and had a system flush. My problem now being that I have flow to the core and still no heat coming out. I have done thermostats, water pump and rad caps. I've checked the spark plugs for build up and checked outside the engine for signs of leaks and nothing... unless I'm missing something in searching the forums at a complete lost

 

how good is the flow through the heater core now?

If it was completely clogged before, you might have cleaned it enough to get a bit of water through it but maybe its not enough for heat in the cab.

Start the truck and get it hot. Then turn the heat on full blast and see if the heater core hoses near the firewall are the same temp. if one is cool and one is hot its still clogged and i would just replace it. Its a pain, but can be done in an afternoon and is not as bad as some people make it out to be. My old 1997 blazer took me 4 hrs to swap heater cores.

on the other hand if you are getting good flow through the heater core now and still dont have heat there is probably something wrong with the blend door such as the blend door actuator. This is what switches it from hot to cold in the airbox.



Also did you ever find where your coolant was disappearing to?

 

I think I lose flow once it hits the core... gonna suck but thinking it's time to rip the dash apart. I don't mind the cold... the wife is gonna kill me tho if I don't get it fixed

 

If you still think it's clogged, why not flush it out with CLR?(JUST THE CORE NOT the engine) Worst thing that will happen is you need to replace the Core