Metal Vs. Plastic Heater Control Valve

hawkfan

Active Member
Pulled over to check a log and saw smoke coming from under the hood. Saw coolant spurting out from the plastic heater control valve diaphragm. I'm aware that the original was metal. Is the metal heater control valve better? The plastic ones are really cheap and available at my local parts stores, but if the metal one is better and more reliable, I will pay extra for it.
 

1952ray

Scrambled Dog
Buy the metal one, they WILL last longer. He'll mine is 27 years old and still works fine. Heat and plastic do NOT do well over time
 

earlbrown

runs with scissors
My metal one rusted out about 10 or 12 years ago. I went with plastic since it was at the parts store and GM discontinued the metal ones.
 

whitehot1

Well-Known Member
My plastic heater control valve is around 17 years old and still works good and has never caused a problem.

I do think i will replace it next spring though since a new one is only $9.59 at the local auto parts store.
 

bison

Moderator
Staff member
Ive seen both chit out. Most recently the metal one. I just pushed the linkage upward and it freed itself but was definitely stuck.
 

hawkfan

Active Member
I ordered an AC Delco metal valve, but it won't arrive for another 6 days. In the meantime, I'll get a $9 plastic valve from the auto parts store. My issue with the plastic valve is that once the diaphragm goes, it's a pretty serious coolant leak. On the metal valves, the diaphragm is 'isolated' from the valve itself by the linkage arm.
 

CzyKats44

Dis-Member
Not to thread heist, but what does it do? (I understand it opens and closes the loop with HVAC vacuum control to the heater core) ... I though in other cars the coolant always flows through the heater core 24/7 and temperature was adjusted only by the blend door?

I currently have a plastic one that has some melt marks on it from being in close proximity to my HA turbo. I have it adjusted out of the way now but it wasn't always. Planning on going metal due to the proximity of the hot area.
 

hawkfan

Active Member
Not to thread heist, but what does it do? (I understand it opens and closes the loop with HVAC vacuum control to the heater core) ... I though in other cars the coolant always flows through the heater core 24/7 and temperature was adjusted only by the blend door?

I currently have a plastic one that has some melt marks on it from being in close proximity to my HA turbo. I have it adjusted out of the way now but it wasn't always. Planning on going metal due to the proximity of the hot area.
It just lets the hot coolant circulate through the heater core when a vacuum is pulled on the diaphragm. You might be better off with a metal valve in a hot air. They do cost 3 to 4 times as much though. The plastic valves are really cheap and readily available.
 

whitehot1

Well-Known Member
I was looking around on ebay and found a new metal heater control valve for a very good price and should be here by Tuesday 9 Dec.

I was going to wait until spring of next year to replace it and just get another plastic one at the local auto parts store. But after reading some reviews that said they lasted them for 10 months or so,i decided against it.

I would have to kick myself in the behind if i left my current 17 year old plastic heater control valve installed (pushed my luck with this one i think) or bought one of the questionable new plastic ones and it failed shortly after installation.
 

whitehot1

Well-Known Member
I received my new AC Delco #15-5320, GM# 25523118 metal heater control valve today. It wasn't due for delivery until Tuesday 9 Dec. but early is good with me. The car is put away for the winter so i may not install it until next spring.

It didn't look bad right out of the box. But since i didn't have anything to do i spent a few minutes and polished it up a little.

If anyone is interested the ebay item number is 261662273045
 
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