1999 no heat valve? flush? ...


stinkhorn88

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I've owned it for a year. Heat no work-y recent development.

One of the first things I did when I bought it a year ago was flush the whole coolant system (drain, ran to hot with just water/drain X3, fill).
This fall I replaced the water pump.

symptoms now - engine/coolant warms up to normal temps, after running ONE of the two hoses going to the heater core is hot, the other is cold.

my understanding is it's probably: clogged heater core OR non-functioning heater valve (or both)

this video on how to back flush happens to be pretty much the same vehicle
https://www.youtube.com/watch?v=M9SIafVsqyc
BUT in his truck, the passenger side hose (with the valve) is the hot hose and the drivers side hose is the cold one. in my truck it's the opposite - the hot side is the drivers side with out the valve.
some posts have suggested just swapping the two hoses to reverse the flow in the core, but that leaves the crap somewhere in the system. ARE the hoses swappable in trucks with the heater control valve? Does it NOT matter which one is where?? What is the valve's purpose?
 
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adsm08

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A heater core doesn't care which way coolant flows. It will work correctly as long as it is actually flowing. So you can swap hoses even if you do have a money valve.

The stated engineering purpose of the heater core shut off flow to the heater core when the AC is on so that it can cool more efficiently, gaining about 2 degrees of cooling. It's real wold purpose is to break so you have to spend money to fix it.
 

RonD

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+1 ^^^

Heater core is non-directional, just tubes with fins that heat up as warm coolant flows thru.

You can remove the hoses, cold engine, and you won't lose too much coolant, then use garden hose to flush in both directions.
You can get some heater hose of correct size at auto parts store, by the foot, so you can put a length on both heater core fittings and point it down to the ground while flushing, or into a bucket.

You can also blow out the heater core, just by mouth, and refill with Hot Water and CLR or vinegar mixed in, let it sit for 15-20min then flush it out, repeat as you see fit

Yes in 1999 the valve on the heater hose stops flow thru the core ONLY when cab is set at AC MAX
Fresh air vent is closed and heater valve is closed in AC MAX, that's the difference between AC and AC MAX


And just as a heads up, coolant has corrosion prevention additives for the system, if/when heater core gets plugged up passages that means there is no coolant flowing in those passages, so no corrosion prevention....................

And this is how/why a heater core springs a leak, so plugged up core is not just a heat issue, it will leak if left alone

So always good to flush core separately, and well, when changing coolant, and yes reverse hoses on heater core whenever you feel the need, just good practice
 
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stinkhorn88

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the ONLY function of that valve is to stop the flow thru the heater core on Max A/C? and at that point it doesn't matter if it's on the in or the out side, same result? huh.

so, swapping the goofy thing out with a new one and doing a decent heater core only flush is my mission.
 

adsm08

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No, deleting the stupid thing and doing a good heater core flush is your mission.

Unless you live in the 7th circle of Hell. Then replace the valve.
 

stinkhorn88

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No, deleting the stupid thing and doing a good heater core flush is your mission.

Unless you live in the 7th circle of Hell. Then replace the valve.
not worth the hassle at all, eh?
A/C works. but i rarely use it, I can't stand the way it dogs the engine when it engages.
does the vac line need capped if deleting?
 

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No, it isn't worth the hassle. New heater hose and be done with it.
As for the line, just fill it with super glue.
 

stinkhorn88

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No, it isn't worth the hassle. New heater hose and be done with it.
As for the line, just fill it with super glue.
i like your style.
 

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Just as a heads up.

After you have the valve off look thru it and see how large the opening is, you want similar size opening to slow down coolant flow thru the core.
It isn't "rocket science" exact but the flow thru the core is set so there is a balance of coolant flow thru the engine and core, so not too much to one and less to the other.

You can use smaller hose inserted in one of the hoses or ???
Doesn't matter which hose, in or out, flow will be slowed either way

Heater core and radiator do not cool equally which is why flow is balanced, core only cools when Heat is selected and fan is on and then it varies by fan speed.
So you want enough flow for good heat in cab but not too much or radiator has less flow so engine runs warmer than it should on a hot day when heater wouldn't be used
 
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stinkhorn88

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success, thanks guys. have heat.
slowest part was thawing my 50' garden hose (threw it on the roof to thaw it - 35 today but 8 2 nights ago).

need to finish topping off the coolant once cooled down and cap the vac - and choke the delete(?)

Just as a heads up.

After you have the valve off look thru it and see how large the opening is, you want similar size opening to slow down coolant flow thru the core.
It isn't "rocket science" exact but the flow thru the core is set so there is a balance of coolant flow thru the engine and core, so not too much to one and less to the other.

You can use smaller hose inserted in one of the hoses or ???
Doesn't matter which hose, in or out, flow will be slowed either way

Heater core and radiator do not cool equally which is why flow is balanced, core only cools when Heat is selected and fan is on and then it varies by fan speed.
So you want enough flow for good heat in cab but not too much or radiator has less flow so engine runs warmer than it should on a hot day when heater wouldn't be used
that is a useful tip, but aren't the core lines roughly that tight? wouldn't it do it's own restriction far far more than a little spacer on the in or out flow line?


7$ hose (thought I grabbed female/female to make it even easier to switch back and forth but Lowes had wrong product in wrong box and I didn't check) worked great


deleted. $6 heater hose $4 barb
 


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