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Heater Control Valve 76-78 280z

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Hey guys, is there an alternative/better replacement for the stock heater control valve for a 77 Z? The water leaks and soaked flooring routine is getting old. You can no longer order the 76-78 one through MSA, and it you do manage to find one ANYWHERE else you can expect to pay 250+. Is there any alternative to this expensive part, possibly off a different car? Thanks

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Hey guys, is there an alternative/better replacement for the stock heater control valve for a 77 Z? The water leaks and soaked flooring routine is getting old. You can no longer order the 76-78 one through MSA, and it you do manage to find one ANYWHERE else you can expect to pay 250+. Is there any alternative to this expensive part, possibly off a different car? Thanks

 

 

 

Have you looked at Black Dragon Auto, (formerly Victoria British)? They have a much larger selection of OE replacement parts and at great prices…

 

Heater control valves…

http://www.blackdragonauto.com/icatalog/z/0076.html

 

 

http://www.blackdragonauto.com/index.htm

 

 

I’m sure if you were real creative you could easily adapt a less expensive cable actuated water/heater valve…

 

 

 

 

 

i put a brass hand valve in the cylinderhead.turn on in winter,turn off in summer.then i got 1 of those 5/8 heater hoses with molded 90 and a piece of bulk hose and connected direct to the heater core and shitcanned all old nissan stuff….

 

 

:lmao: … So when you want to turn the temp down a little, you just get out at the next stop light, turn the valve a ¼ turn. If that is not enough, just give it another ¼ turn at the next stop light… :D

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ford diesel pick-ups have a vacuem valve.but the way the 77z hvac system is made you cant get heated air through the vents-its either through the floor or defrost.with me its need heat/defrost now or vent.i had a cable valve on the block about 6" behind the water pump.but when you run the engine hard you are pressurizing the heater core-i blew 1 at the track.i wanted the fewest loose parts.look in a napa catalog-there are many heater valves.

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I fixed my heater valve with an "O" Ring. It was several years ago and has never leaked since. It has been to many years to remember how the valve was put together. The valve was leaking out around the shaft. It has an O ring seal on the shaft. I installed a new one and greased it up. It is a real pain in the back to get to the valve.

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I am 90% sure the ”heater valve” is cable actuated on all 280-Z cars. In the 260 and 280 Z with FACTORY A/C, (the blower fan will be a 4 speed fan instead of the 3 speed fan), only the doors for directing air flow to the various air outlets are vacuum actuated. The heater valve should have a cable connected from the control lever on the dash to the valve itself, no vacuum control.

 

FWIW, I would stay away from vacuum actuated control valves, especially in our old Datsun cars. If you do use a vacuum operated heater control valve, be sure to route the heater water lines as they were in the vehicle that the valve was originally intended for. The vacuum actuated valves don’t really have all that much pull/push power, so water flow through the valve could overcome the strength of the vacuum control, there by holding the valve open or closed or opening/closing valve as the water flow increases/decreases due to the thermostat opening/closing, higher engine RPMs etc. I’ve seen on the Jeep Cherokee/Wranglers, the vacuum actuated heater valve having four ports to divert the flow of coolant in such a way that it never really allowed any back or forward pressure of coolant against the valve, i.e. the valve could easily open and close. Also, being as the cooling systems in our old Datsun aren’t “clean”, i.e. lots of little floating debris, that debris could easily prevent the vacuum controlled valve form opening or closing. .

 

That’s my $.02 on vacuum operated heater control valves.

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Braap, I spoke with MSA and others who seem to think that the later 280z did come with vaccume operated heater control valve could they be giving me the wrong information? I tried buying the valve I needed off ebay but only the cable valve is on there for the 74-76 valve is on there. I think the vac heat valve came on the factory A/C cars during and after 77'. Please correct me if i'm wrong. I would love to be b/c then I could get the part. Thanks

 

OTM- what year of explorer and what would swapping that in entail?

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Hey Datsun,

 

I think the guys at MSA are correct. I'm no expert on the subject, but I did tear mine apart today (trying to figure out why my heater control valve isn't opening) and in my '77 2+2 there is a vacuum line that runs up to the heater control valve (along with a mechanical linkage, and some sort of copper temperature lead looking thing). That particular vacuum hose comes out of the control panel and into a Tee....one side of the tee goes to the heater control valve, and the other side of the tee goes to an actuator that operates a door that directs the air across the heater core or the a/c evaporator.

 

I sucked on the tee, and the door closed to direct the air across the heater core. My guess is you must first select "heat" with the mechanical linkage, then the Heater control valve uses vacuum to open.....but thats just a guess. Tomorrow I will run a vacuum line from the intake directly to the control valve, and hope it opens. If it doesn't open, it will reinforce my theory of how confused I really am :confused: .

 

Chris

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Hey guys, is there an alternative/better replacement for the stock heater control valve for a 77 Z? The water leaks and soaked flooring routine is getting old. You can no longer order the 76-78 one through MSA, and it you do manage to find one ANYWHERE else you can expect to pay 250+. Is there any alternative to this expensive part, possibly off a different car? Thanks

 

 

How about something like this?

 

http://www.partsamerica.com/ProductDetail.aspx?mfrcode=FSE&mfrpartnumber=74819&parttype=394&ptset=A

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I got the operation of mine figured out today ('77 2+2 with factory A/C....although I've removed all the A/C components).

 

The heater valve actually has 2 seperate valves (one beside the other). The water enters the valve through the top firewall inlet (the short piece of pipe from the block). This valve is vacuum operated and opens whenever a "heat function" is selected on the controller (you know, the ones with a red arrow on them....Bi-Level, Heat, Defrost, etc.) This valve does not consider the "temperature" that is selected, only the mode selected (Bi-level, Heat, Defrost, etc.).

 

If the first valve is open, the water then goes to the second valve that is controlled by the "temperature" selector. There is a mechanical cable that moves a plunger in or out of the valve. With "Full Hot" selected, the water flows freely through the heater core.......what I found interesting was that with "Full Cold" selected, the water still flowed through the heater core, but at a much reduced rate. The only way to completely stop the flow of water through the heater core was to select a "Cool" function, thereby closing the first valve.

 

One more item....mine also had a copper temperature lead that went from the bottom of the air box up to the second valve assembly. My guess is that it's some sort of automatic temperature control function (it's now in the garbage if anyone's interested) :D .

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Thank you for clarifying guys. I have a customers ’76 factory A/C car in the shop and it is also a vacuum actuated water valve. I apologize for my misleading post.

 

I am “pretty darn sure" that the ’75 factory A/C cars are sure cable actuated, (both of the ’75 factory A/C cars that I have owned with 4 speed fans are cable actuated heater valves).

 

Again, I apologize for the misinformation.

 

Paul

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Thank you for clarifying guys. I have a customers ’76 factory A/C car in the shop and it is also a vacuum actuated water valve. I apologize for my misleading post.

 

I am “pretty darn sure" that the ’75 factory A/C cars are sure cable actuated, (both of the ’75 factory A/C cars that I have owned with 4 speed fans are cable actuated heater valves).

 

Again, I apologize for the misinformation.

 

Paul

 

I think you are both right. The A/C-equipped cars use a cable actuator to do the temperature regulation (this I know for a fact - I've replaced mine on my '78) just like all the other Z's, but there is an additional vacuum valve that simply shuts off the hot water to the heater core when the A/C gets turned on. This vacuum valve is on-off only, and is in series with the cable operated valve. It does not regulate the temperature.

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My 77' 280Z has aftermarket air, and cable operated heater valve. With that said, does anyone know of a source for a suitable replacement? I have seen the refurbished ones for $250, but I am having a hard time emotionally with coughing up that much dough for this part. A couple members have mentioned Ford replacements. Anybody have part numbers?

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The '85-'87 Buick Grand National has a a pretty cheap vacuum operated heater control valve with 5/8" barbs that could be mounted externally from the heater core box once the stock valve is removed/bypassed. I have always said that if my valves on the '77 and '78 needed replacement again, I would kludge that valve in and make it work.

 

Dunno what could be done about the cable linkage from the thermostat and the capillary tube that does ?, however.

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If any of you need a heater control valve whether it be the manual style with the capillary tube, or the vacuum style in the 76-78 factory AC cars we can rebuild them in house. We usually carry the parts in stock and I rebuild them all personally. Cost for the cap tube style runs about 170.00 exchange and the vacuum style is running about 100.00 exchange. After I recoup my setup costs I'll probably be lowering the price a little bit, especially on the vacuum valves. Both are listed on our online store at www.datsunstore.com

We can also rebuild the cap tube style for the 79-83 zx's or we have a new replacement style valve that is a direct bolt in but it doesn't use the cap tube.

I'm also looking for used rebuildable valves for the 76-78's. Unmolested valves only, and the vacuum valve must have a good vacuum diaphram in them still. The vacuum diaphram can't be replaced or repaired.

Z man of Washington

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Does anyone know if the water flows through the vacuum type valve on the 78 280 when vacuum is applied or when there is no vacuum? I have a GTO valve that is vacuum operated and mounts under the hood, so I would like to use that if it works in the same way with vacuum applied.

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Does anyone know if the water flows through the vacuum type valve on the 78 280 when vacuum is applied or when there is no vacuum? I have a GTO valve that is vacuum operated and mounts under the hood, so I would like to use that if it works in the same way with vacuum applied.

Water flows when vacuum is applied.

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