Definitive '83 Fed 300CD vacuum thread
 

Having worked through my Coupe's vacuum systems without the benefit of any document that was completely accurate or comprehensive I decided to build some.

They probably apply to most 617 systems with AC and auto tranny with the EGR intact. All the systems on my car appear to work correctly, so I'm assuming they are correct. I customized various documents to make them reflect what is in my car: a 1983 Fed 300CD with auto tranny and A/C.

For non-coupe owners I can't say whether the blue lines in the coupes are reflected in any sedan or wagon app. For the non-diesel owners I can't say whether the additional reservoirs shown in the diagrams that I deleted should be there, since they're not in my car.

I added the shutdown lines (brown and brown+purple) to the diagrams since they did not appear to be integrated to other diagrams I could find.

pic to go with the drawings
 

Lines for the engine. Off of the first branch from the pump

lines for accessories
 

lines for other consumers, off the second branch from the pump

Cool info, thanks, yes, that blue vac line is for the seat back locks.

Thank you. That's just what I need for the vacuum problems I've been having.

I have been wondering about the seat back arresters in the coupes. I think it is a safety hazard by not having them working in case of a front end collision. I was trying to think of a way to make them manual with some kind of lever that is in the same place as the push button on the side of the seat back. That would get rid of all the vacuum stuff all together. Any ideas?

Unless you're going to replace the seats, I can't really think or a way to re-connect the actuators to a mechanical lever. I didn't think fixing the vacuum was that big a deal. I agree on the safety aspect, though. A folding seat in a collision seems bad.

For troubleshooting mine, I started at the seat itself with a Mity-Vac: do the actuators move with vacuum applied? If no, fix them; if yes, move upstream. Then under the hood, with the window open and the doors closed: using the Mity-Vac on the check valve on the blue line only (and a lot of pumping) do the locks engage? (You need the window open in order to check without opening the doors since that dumps vacuum; I forget if the ignition needs to be on, but I don't think so.) If so, then the leak/problem is probably in one of the other systems - A/C or central locks - and those systems are preventing forming enough vacuum; if not, then the problem is in the blue line. It might be a sticky door switch, since that electrically dumps the vacuum relay, or the relay itself (you could remove the relay completely and the seats would lock, but not conveniently auto-unlock when you open the door).

My seat backs didn't work except in defrost, until I fixed that A/C pod. I had a little routine of starting the car, selecting defrost and waiting for a screech of the seat back springs rotating after the system built vacuum, then selecting normal. Once they're locked they stay locked via the check valve unless vacuum is dumped by opening the door, pushing the seatback button, or it leaks out. The leaky A/C pod wasn't a factor except for the first latching after closing the door - and my A/C system didn't route air correctly, of course.

I have worked with the vacuum systems a lot on these cars, but never actually tried to fix the seat back arrestors. I just capped off the T going to the blue line so everything else would work. I did not know about the dump valve when opening the door, so that may be where the leak is in my coupe's system. Thanks for the info, I can sure use it......Rich

Behind the glove box, looks like the attached. Blue line comes in, normally connects directly. It's not in the FSM diagram, which is why I pasted it into the first pdf in the thread. Upper, center.

The pic is with the dash pulled, but you only need to pull the glovebox liner to access.

That dump valve
 

My dump valve was sticking open so I just bypassed it and dump the vacuum manually using the release button. The problem Im having now is that one of the arresters on my drivers seat doesn't want to disengage when the vacuum is dumped. All the others do though, the second one on my drivers seat and the two passenger sides included. Anybody else ever had this problem? I've never taken the seats apart before and would like to be able to check the arrester without actually having to take the seat out of the car. Is this possible?

Removing the seat is not a big deal, just remember about the seat belt slide rod-thing. Maybe lube or cleaning the locking jaw/clamp mechanism might let it release.

If you don't want to remove it due to weight, you can undo the four (or five if you count the slide rod) bolts and lean it back. That'll give you access without removing it.

Unless you and the POs were very very clean people, I'd consider removing the seat and cleaning and lubing the slides. It was one of those small but subtle improvements: hey, this thing IS adjustable.

Watch lifting with your back, don't ding up your console. Then clean the goo from the spilled coffee and soda off your floor and recover that loose change.

300CD vacuum
 

Thanks guys, this is the info I needed.


tombinps