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Discussion Starter · #1 ·
I have a new to me 1980 280 ZX

Looks like switches & vaccuum doors to switch up, mid, down do not work. Seems to always blow towards floor.
Looked at shop manual and it looks like a very complicated job

Read factory manual and My guess is that the vaccuum controlled actuator system if fubar, possibly a hose or god knows what
Looks like there is a big vaccuum tank somewhere with 6 or so hoses coming off of it
They meet at this hoky vaccuum distribution valve on the heater controller (pull radio and heater controller)
Any time I have to fiddle with the brittle interior parts my arse tightens....

Anyone have any posts or links to problems like this? My search turned up nothing
 

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1983 280ZX Turbo
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Start with the ones you can reach. And the dash is easy to pull anyway. It takes about 90 minutes to get it out, probably about the same to re-install it. The process is outlined here if you search. I've probably had mine out half a dozen times.
 

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Start off first by checking the hose connection at the vacuum tank in the engine compartment. Its common for the hose ends to split and leak there.
 

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Discussion Starter · #6 ·
Thanks guys, thats EXACTLY the problem !
Right under the hood....easy to get to!
Only problem is that the old Vac line split and left me with a 3" stub before it goes into the firewall !

I am thinking of sliding some shrink wrap tubing over that little stub I have left
Last thing I want is a dash pull over something so simple
 

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Um, "replace all vacuum hoses" might reasonably start under the hood...(y)(y)
 

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Discussion Starter · #8 ·
Yes! Just found the problem!
I have a great idea.
Granted, replacing the entire section of hose is the best move
Seems like the failure mode of this old tubing is that it longitudinally splits when you shove a barb into it
I have a 3" stub of old tubing going into the firewall that I'd really like to not do a dash pull over
What about using a pc of heat shrink tubing as kind of a hose clamp to the prevent it from splitting more?
 

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1983 280ZX Turbo
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As a temp fix for a day or two until you can hit a parts store, OK. As a fix for longer than that, not good.
 

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Next time, it will be the spaghetti of hoses inside the dash! For me the next project. I used a slightly larger hose on the outside of the vacuum hose to temporarily keep the old hose from splitting further. Patch work until there is not enough meat to work with.
 

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Discussion Starter · #11 ·
There is another idea! Take some larger hose and slide it over the Outside Diameter of the old brittle hose!
 

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Discussion Starter · #12 ·
I know this is all cheezery, but the alternative is a dash pull and potentially broken and snapped brittle plastic dash parts....no thanks
 

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Use a piece of copper tubing inside the old hose that just fits tight enough to prevent an air leak. I guess I'm thinking of a brass vacuum line.
 

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Discussion Starter · #14 ·
Wow, thats some small tubing! Almost capillary tubing! The ID of that tubing is ).125" or, about 3.0mm
 

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Yes it is. If I remember correctly, I cut the piece from the vacuum advance line on an old distributor.
 

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The small vacuum hose you're referring to is called HVAC hose. You mentioned how the hose splits when you try to put a barbed connector into it. NEVER use a barbed connector or one with a bulbous area near the end or it will split the hose. For a butt connector you need to use a factory Nissan unit. They are smooth connectors and work great. There is a lever on the lower dash panel right above the drivers right knee. That is a useless function lever but it usually has a pair of the necessary butt connectors on it. Drop the panel, locate both butt connectors, disconnect the hoses from one of them and use the other one to connect the two hoses coming from the heating system. Doing this you'll be bypassing the lever and yet the circuit will be complete. Take the remaining butt connector and use it on the hose coming out of the firewall to connect the new hoses in the engine compartment. Using a piece of heat shrink over the entire connection will work fine, just don't get it too hot to shrink it. You can use a heat gun on low instead of a lighter to shrink it. The heat shrink will act as a great splint. Another method is you can also NOT use a splint on the inside and just use a piece of hose that fits over the OD of the HVAC hose like para32 mentions. Use some silicone spray to get the hose to slip on easier. Your choice on which fix to use. I've had both methods last for many years. It's a good idea to replace all the hose under the hood because that goes bad before the rest of it. Just make sure that you use the same size of hose on the OD as well as the ID. I do carry the hose in stock and sell it by the foot. Z man of Washington
 
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I have a new to me 1980 280 ZX

Looks like switches & vaccuum doors to switch up, mid, down do not work. Seems to always blow towards floor.
Looked at shop manual and it looks like a very complicated job

Read factory manual and My guess is that the vaccuum controlled actuator system if fubar, possibly a hose or god knows what
Looks like there is a big vaccuum tank somewhere with 6 or so hoses coming off of it
They meet at this hoky vaccuum distribution valve on the heater controller (pull radio and heater controller)
Any time I have to fiddle with the brittle interior parts my arse tightens....

Anyone have any posts or links to problems like this? My search turned up nothing
Yup it's a pain in the neck. Do yourself a favor and replace all of them. They are the same size. About 25' or 30' will do it as I recall. The FSM shows where they go. I did it on my 75 and it's still working years later. The system is also dependant on various vales and doors operating correctly. All go together to make it work. It's a pretty simple system when you finally understand it.
 
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