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I've been struggling with a leaky heater control valve in my '84 for a while, and finally found a good answer! I have seen a few suggestions on how to repair this valve, but I think I've found a better way. The heater valve for an '85 Buick Century 3.0 L V6 fits even better than the stock '84 Corvette valve! Here's a shot of the '84 "octopus" valve:
And here's a shot of my new Buick valve:
It fits directly to the tubes to my heater core, and the tubes are even the correct spacing and the correct diameter! The water flow is correct (bottom to top) to purge bubbles from the core, and bypass of water from the rear of the intake manifold to the water pump is correct when the valve is off! 4 Seasons p/n 74800. And RA has them on sale for less than $5! Such a deal!
Last edited by Hot Rod Roy; 02-02-2017 at 04:46 PM.
It fits directly to the tubes to my heater core, and the tubes are even the correct spacing and the correct diameter! The water flow is correct (bottom to top) to purge bubbles from the core, and bypass of water from the rear of the intake manifold to the water pump is correct when the valve is off! 4 Seasons p/n 74800. And RA has them on sale for less than $5! Such a deal!
The 74800 valve has been an accepted/recommended valve for many years. The number looked familiar -
A push towards the top so others might take notice - I don't need and don't buy from RA
The 74800 valve has been an accepted/recommended valve for many years. The number looked familiar -
That's news to me! I've tried all the SEARCH functions I could think of, and couldn't find this info, but then again, that SEARCH system just gets me frustrated! You're right again, as usual!
I have to wonder though...why not just eliminate this fussy part? The blendair door does the job of managing heat just fine.
That might be true in Utah, but in SoCal it gets pretty warm, so I'd rather not have any more heat in my max A/C air, or in my cool vent air than necessary. My original only lasted 33 years, so I don't think it's too fussy! Now I'm good for another 33!
Originally Posted by WVZR-1
The 74800 valve has been an accepted/recommended valve for many years.
I've seen it recommended to cannibalize and replace the core of the stock heater valves, but not as a complete replacement valve. After figuring out how the valve worked, I was surprised that it could be used complete, as is, and it fits so good, and does everything right!
I thought for sure someone would let me know this would cost me points in my NCRS judging!
I picked up a brand new heater valve off of amazon for roughly $120, it was an exact match to the original in my 84 except it was painted black, vs the original being silver.
Here she is:
ACDelco 15-5344 GM Original Equipment Heater Water Flow Control Valve https://www.amazon.com/dp/B000C9DDMG/ref=cm_sw_r_other_apa_0-OjAb6SC040N
My '84 isn't stock (ls swapped) but uses a simple one way valve on the inlet side of the heater core. It doesn't have a bypass but my surge tank with pressure cap is on the firewall and is in the highest spot of the coolant system. Haven't any issues with it. I think these type of valves run about $15-$20.
02-02-2017, 04:29 PM
'84 Heater Valve
