Thanks guys. That sounds exactly like what it is doing W/R to teh tranny. Sitting as long as it has, I am sure there are more than a few vacuum lines that need replacing. I did notice one line that branced off of a "T" that had been capped as well. It was laying on the fender well on the driver's side. No idea where that one was supposed to go!

Anyway, I got her home about an hour ago. No problems, except for a chilly ride where I bypassed the heater core! Oh well, spring weather should be here for good soon enough!

I won't be working on the old girl until Friday, but maybe I will be able to get my hands on a manual so I can see some of what you guys are talking about.

Thanks for all of the help!

 

A couple of questions for you. The vacuum modulator on the rear of the tranny - can a new one be bought at local auto parts stores or is this something I need to get from a dealer?

Also, W/R to the hubs, a friend has a set of Warn hubs he bought for a Jeep. He said he thought they would fit mine, as most are the same on domestic trucks. Do you know if this is the case? I priced a set of new hubs from Napa for about $70, but he's offering his basically for free.

Thanks in advance!

 

The vacuum modulator can be bought at auto parts store and if the vacuum line has tranny fluid in it, it needs to be replaced. Could be cleaned out, bu t considerinng the age, I would change it.

 

Thanks! Looks like it is pretty inexpensive and relatively easy to replace. Is there anything in particular to look out for when replacing?

Also, Napa lists several different ones with the differences being colored "stripes" on the part. What is that all about & how can I tell which tranny I have? Is there a website that lets me put in the VIN to identify exactly what I have?

 

I don't know. Just tell them what u got and let them figure it out. you know, eng. trans, pu , year etc. Maybe yours has color code on it. Maybe take it off and look before u buy. There is a screw adjustment inside the tube where the vac line connects, but this is preset as far as I know. It changes the shifting somehow.

 

Thanks! I figured I would pull the original one off and take it with me.

With any luck, I will crawl under there tomorrow and see what is going on.

 

That must have been it! I pulled the vacuum line off of the modulator and fluid came pouring out. So, I am about to pull it off and go get another one. I am planning on replacing the rubber lines as well, just to be sure.

Thanks for all the help!

 

OK, so I replaced it after two trips to get the right one. Still not 100% sure I did, but I took the old one with me and it was as close as it gets. Still shifts hard, but not was bad. I replaced the soft vacuum line from the modulator to the hard line (about 8 inches long) and saw no real improvement. Taking the breather off and tracing the line, it ran up the firewall to some sort of connector with two additional vacuum lines on it.


One ran behind and below the EGR (I think that is what it is) and I could not see where it was attached. (beyond # 1 in the photo below)



So, here are the issues thus far. # 1 above is a vacuum line that was not connected anywhere. You can see it is attached to another vacuum line that goes behind the carb to a valve on the other side, under the throttle cable. #2 above is a large line that also goes nowhere. It has some sort of valve in the line. #3 goes to the modulator I just replace. #4 I think is the PCV valve. The top nipple is capped off.

As you can see above, the carb is in rough shape. Of more concern to me is the vacuum lines, as I have several that are on a "T", with one or more lines capped off at various places. I am not a mechanic and cannot make sense of the emissions sticker on this thing.

The third line from the connector on the firewall goes here:


I have no clue what that round thing is or what it does. The vacuum line is connected to some sort of electrical connector that runs back up above the heater blower.

So, here's what is interesting:


#1 above is a line coming from the breather. It was attached to the EGR. I thought the mystery line that goes nowhere looked like IT should go to the EGR, but when I attached it the thing ran like crap & I smelled gas when I parked it. Switched it back and she ran fine. #2 above is the line from the connector on the firewall to the line below the EGR that I cannot see. # 3 is the line to the modulator I replaced.

Also, when driving, it will not go into 3rd gear under 45-50 mph no matter what. Around that speed, I have to let off the gas to get it to go into 3rd. Is this normal or is there an adjustment somewhere I need to tweak?

I am kinda at a loss here. It runs fine, but I am not sure these vacuum lines are connected right. I am very concerned about the carb, but I don't have $500 for a new one. Any suggestions here?

Thanks for all of the help thus far!

 

I'm thinking you have a vacuum leak somewhere which could explain the shift problem. I've never owned the year model of your truck, and can't help with where those lines go. One is connected to the air breather isn't it? That thing that looks like a toilet float ball I think is reserve vacuum. You need a diagram of vac lines and where they go. A vacuum gauge would help diagnose problems.

 

Thanks!

I pulled the line from the "toilet plunger" and tranny fluid poured out of it. I am thinking it was suckin gup fluid and may need to be cleaned out before this thing will shift right.

The vacuum lines are starting to bother me. There are two lines going to the air cleaner to some sort of valve. One is attached to a hard plastic union while the other is attached to a clamp that is part of the union. The one to the union ends at the union, as the other end is broken off. I have no clue where it is supposed to go. Also, either the other line from the air breather or that mystery line has nowhere to go. I have tried hooking both up to the EGR and it now doesn't seem to make a difference either way.

I did happen to luck up on the carb, though. When I took it to get inspected, one of the mechanics at the shop is an old-school Ford guy and told me he has rebuilt hundreds of carbs just like mine. He knew all kinds of stuff about it and told me to bring it to him whenever I wanted him to fix it. I may take him up on it.

If anyone else can identify where these vacuum lines go, I would appreciate any help you could give me!

 

Your carb does not look original. The reason I say this is the large line that goes no where in the above picture(to the right of the number 1) is for the original carb's bowel vent. One end goes to the bowel vent, the other to the charcoal canister.

#1 line coming from the breather does not attach to the egr. #1 should hook to a fitting with manifold vacuum(sucks all the time). The other end of #1 should go to a temperature valve mounted in the aircleaner. The valve should have two nipples. One goes to the #1 line(vacuum source) and the other should go out to the snorkel on the aircleaner that operates a flapper door. Underneath the flapper door should be a round hole where a aluminum flexible pipe hooks and runs down to a shroud around the exhaust manifold. What this does is pull warm air up in the carb when it's cold, to make it run better. This feature is pretty important an worth hooking back up. I found it helps keep the carb from freezing up in the winter, which makes the engine stall and run rough on a cold rainy day.

P.S. About the egr; In the picture above there is a little doodad to the left of the distributor, with two vacuum lines going to it. On vacuum line goes to a tee in the picture. You may have several of these on the engine. These are thermal vacuum switches just like the one in the aircleaner, but these work on water temperature. One of these is were you are going to get the line that runs the egr. They do not want the egr to work when the engine is cold, so they use one of these things to block the vacuum till the engine warms up.

 

#1 in this picture is the main manifold vacuum source for the heater/ac controls. That thing that looks like a tee is a check valve, and the round ball is a vacuum resevoir. During normal engine operation, you have plenty of vacuum to run everything. But when you start pulling a hill or using the engine hard, the vacuum in the system drops. This is ok for everything except the heater/ac controls, which can start redirecting the air to the wrong place if they lose vacuum. So when this happens, the check valve closes, and the heater controls can use the stored vacuum in the ball for awhile till the engine starts producing vacuum again.

 

I went to autozone's site, and this is the only 84 5.8 auto tranny vacuum diagram I could find;

http://www.autozone.com/images/cds/g...3d800ce682.gif

If this looks like your diagram, then we know part of the puzzle. The truck in the diagram was computer controlled, so someone took all that stuff off and and that's why you have the mess. Does the distributor you have now have a vacuum line connection on it(vacuum advance can on the side)?

 

I will try to get a pic of the diagram on the truck tomorrow. It looks somewhat similar to the one from Autozone, but when I printed that one out today and tried to follow it, it got me nowhere. So, I went back to the one over the grill. I hooked up the line that seemingly went nowhere (#1 from the second picture) to the EGR, which is what you said in your post. It goes back to the tree beside the distributor. Best as I can tell, there IS a vacuum line going to the distributor. It is hard to see without taking some stuff off. I will double check tomorrow.

The carb has a blue ID tag on it (again, second picture shows this) with a Ford number on it. I will get that number tomorrow and see if it helps.

As for the breather, it does have a valve on it with two lines. There is one line that stops at a plastic connector with the other end broken off. Obviously, it goes nowhere. The other line was the one going to the EGR. I don't think I know where you are saying it needs to go. I have searched high and low and cannot find any open connection where it COULD go.

As for the temperature valve on the air snorkle, it has been pretty much removed, best as I can tell. There is a vacuum line attached to it, but when you look inside, it looks like the "guts" have been removed. On the bottom of the snorkle, where the flexible line should go, there is a screen that has been bent back to cover the opening. I have no idea where the flex line should have gone, as I can't see anything it could have connected to.

I did find out the motor was rebuilt back in '96 after some water got into the engine and screwed some stuff up. If I had to guess, I would say that is when most of this was removed. It runs fine right now, but I would like to get it back to where it was if possible.

I REALLY appreciate the help with this, as it has turned into a bigger project than I imagined. Since it was free (given to me by my MIL - was my late step-father-in-law's truck), I can't really complain!

 

Hey Littlejon, you're making good progress!!! It's nice to have good people like the members here to help. Franklin2 has helped me in the past both directly and indirectly(just reading his posts), good man. So if he and I say different things, he's probably correct, knows alot more than me.
Anyway, I'm going to try and help since I also have an '84, F-150, 351W. Differences from your's, T-18 4-speed manual trans, 2-wd, no A/C, motorcraft 2150 feedback carb, and still factory original EEC-IV Emmisions w/ TFI ignition. So there will be differences in vacuum hoses and routing.
Since you're really trying to learn, I went ahead and put an album in my gallery called "Littlejon"...https://www.ford-trucks.com/user_gal...&albumid=27801. First picture is of your engine w/ some questions, hope you can read them.
I'm wondering if you really have an EGR back there, can't really tell. I can easily take more pics and post to help in IDing parts. Good Luck!!!