1995 no heat front or rear after tstat replacement (1 Viewer)

Bambusiero

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Chandler, AZ
FYI. The last time I did a coolant flush, upon the last step in the process, topping of with distilled water with a radiator fill funnel, I could not get any heat coming out of the heater, no matter how long I waited for warm-up. WTF? Didn't make any sense. Eventually, I pulled the hose off the firewall heater valve, burped some coolant out of the hose, replaced it, and viola - got heat. Maybe there was a bubble preventing any heater coil flow? This was a very puzzling 1st, having done all this many times before.

In other words, there was nothing wrong, but it acted wrong anyway. Could happen to you.
 

LINUS

Waiting for the Great Pumpkin
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T-stats “fail open” - and this sounds like that.

Have you watched your heater valve move based on where you have the heater control/slider position in-cab ?

Before tearing into the dash or re-breaking the coolant system, I’d verify the valve is moving & if it isn’t - manually open it & see where your heat in-cab ends up.

Do you get something like a 1/4 guage on the engine temp - or does it run right to that middle-zone?
 
Joined
Apr 15, 2019
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Leavenworth wa
T-stats “fail open” - and this sounds like that.

Have you watched your heater valve move based on where you have the heater control/slider position in-cab ?

Before tearing into the dash or re-breaking the coolant system, I’d verify the valve is moving & if it isn’t - manually open it & see where your heat in-cab ends up.

Do you get something like a 1/4 guage on the engine temp - or does it run right to that middle-zone?

I have removed the cable from the mixer and have it open all the way. And yes I have tried it both opened and closed. There is a very small difference in temp with it open. And it does go to the middle and stay there. Very little fluctuation if any. Regardless of position of hot/cold slider.
 
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Leavenworth wa
Before I put this tstat in, it would not even get up to temp while idling. I would have to drive it or sit there at about 2500 rpm. It does have an aftermarket mishimoto radiator. But the flow is fine through it.
 

LINUS

Waiting for the Great Pumpkin
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If you’re getting to that ‘numb zone’ in the cluster, sounds like the t-stat is working.

IDK - is the blue devil stuff still in the coolant, or is it something you run awhile & dump?

I didn’t catch how old the 80 is or miles on it, but either way sounds like you’re breaking it all open - might as well try to flush the main heater core while you R&R that t-stat.

Upside is you’ll laugh at how dinky the NAPA one is compared to the heft of the OE one.

For peace of mind, test your new t-stat prior to install and for giggles check your old one in boiling water on the stove - both should open if the NAPA one isn’t already failed open.

GL
 
Joined
Apr 15, 2019
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Leavenworth wa
It is a 1995 with 290, 000 miles. Just broke in. :) going to get a 6bt or a ls within the next 2 years.
The blue devil you leave in there. But it has been in there all summer and the heater worked perfectly fine. It seems like the heater slider is only opening part way not all the way like it use to. The reason I say that is because of the terrible racket clicking that happens when I adjust the heat slider all the way to heat. I did find a rats nest in the fan and had to replace that. But the blend door has always clicked since I bought it. I would like to fix that while I'm in there. This isn't my only rig so it's not a big deal if it's down for a little while.
 
Joined
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Leavenworth wa
The blue devil is still in there, it has been in there since June, I just ran it without the tstat for the summer. They suggest running it without a tstat for a couple of heat cycles at least. The rig is a 1995 with 290,000 miles on it. Just broken in. I did a flush before I did the blue devil. The blue devil worked BTW, I no longer have any oil in my coolant.
The heater always worked until I put the tstat in.. The problem is I took the head unit out and put some rcas on the back to an amp at the same time. I just think it is weird that I no longer get any heat to the rear as the slider never adjusted that anyways.
When I first got the rig the fan blew a bunch of leaves out the vent so I replaced the fan as it had a rat nest in it and ended up getting stripped. But the problem with the blend door making the clicking sound never went away. The only thing is now it sounds like it did when I had the slider about mid range. And that's about how much heat comes out the front. Mid range. The cadence of the clicking directly corresponded to where the slider is. So I think it may have something to do with the blend door as well as the slider.
Thanks
 
Joined
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Leavenworth wa



!!!!!!!!
Thank you! This is what I have been looking for!
 

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