john1989

91 f150 4x4,inline 6,manual trans, hydraulic clutch.

buying it tommorow for a good price, rust free, runs and drives, lifted with new tires!!

only problem is the clutch. the external slave cylinder ? leaks when u press on the clutch, when u take your foot off the clutch , it doesnt come back up very far, u can move it up with your foot,but it falls back.
i havent drove it yet, but the owner said when u hit the clutch it does disengage, but its hard to shift gears, but it does shift, just not that easy, he said something about while sitting at a red light , its easier to shut the truck off to shift gears, then start it back up and go, so basically its harder to shift gear with the motor running, shut it off it shifts fine.

im guessing with the pedal sinking to the floor and with the leak this has something to do with it. so what im thinking is, that the cluctch is not fully disengaged thats why its hard to shift gears, with the leak its not fully disengaging the clutch.
he also said something about a allen or hex srcew the slave cylinder was stripped , and it leaked when u hit the clutch.

would replacing the slave cylinder ( thing on the driver side of the trans that has the line running up to the fluid resivoir on the fire wall ??)

would replacing that fix this, is the leak causing this problem?
also where is the bleeding screw or valve at on these trucks? if i get a new slave cylinder, itd have to be bled.

only f150 i had was a 79 f150 4x4 , and a 98 f150 that had the hydrolock problem, the 79 had mechanical clutch and the 98 i never messed with.

any info or advice would be nice, thanks!!

rdg

A leaking slave cylinder will ruin your clutch. The fluid drips down onto the clutch and ruins it.

I have replaced two clutches and slave cylinders on my 96 F150. My understanding is that the original slave cylinder was a bad design and would leak eventually. The first time I replaced the clutch and slave cylinder with aftermarket parts. After a few months the slave cylinder started leaking again. I added fluid for awhile until I decided to have it replaced again. The second time I had it replaced I talked to a mechanic who said that Ford redesigned the slave cylinder at some point. The best thing to do is get a new slave cylinder from Ford and replace the clutch and slave cylinder at the same time. This is what I had done and haven't had a problem in years.

flareside_thunder

Given the fact that that's a 91 Ford....it should be an INTERNAL slave cylinder not external. That is of course going under the assumption that it still has the factory transmission (M5OD). This is how the slave cylinder is mounted inside the transmission...the UPPER line feeding off of it is the bleeder screw.....the lower is where the hydraulic line plugs in to feed the slave cylinder from the master cylinder.

john1989

okay i drove it today. when youre driving and shifting it, it grinds a bit, sometimes its impossible to shift it in to gear, so you gotta kill it at the stop light in order to shift in to second. ovbiously the clutch doesnt disengauge fully when u hit the pedal.

there is a rectanlge tubular looking thing on the outside of the trans on driver side, it has a hose running to it that comes from the master.
the part that im thinking is the slave cylinder, has a rod that comes out of it and mounts to fork or something that goes in to the bell housing behind the clutch. this fork thing goes through a square hole and you can see the clutch through it. also the master cyliner has a plastic line that runs to the slave, how are you supposed to disconnect it?

any one got a pic of what the trans looks like from behind it where the slave would be if it was external? doesnt realy look like the trans i have, that big hole is up higher , and i dont think the link goes inside the bell housing, the line that runs from the master cylinder runs to what i believe is an external slave, line stays on the out side.

the trans is a manual , 4x4, 1991, what trans could i have in the truck if it aint factory?

Just call me Sean

iTrader: (1)

That picture is the M5OD 5 speed trans, you might have an external slave if it's a 4 speed, or if it's the ZF 5 speed. The M5OD doesn't have a fork that protrodes through the bellhousing, what you see in the picture is what there is. The slave is easy to find, the hydraulic line attaches directly to it. The M5OD (pictured above) has a white plastic ring where the line attaches and you have to push that towards the slave to disconnect it, it's a pain in the *** to get off. If you have an external slave then there's a roll pin that you have to press out to disconnect the line. I pull the slave and lay it against something and tap the pin out with a hammer and nail. It's a bit tricky too because you're limited on where you can put it while the line is still attached.

Just call me Sean

iTrader: (1)

This is the slave from a TOD 4 speed, the one with overdrive:

The dirty black part with the line going to it, and you can barely see the roll pin that you have to get out.

flareside_thunder

What he said^

john1989

thats the trans i have in the pic above!! is that the original trans that woulda came from the factory in my 1991?
if i replace this,bleed it, would this allow me to fully disengage the truck when i hit the pedal? i just cleared some green for this truck , and my wife is kina mad " you better hope that piece of crap works after you put on that new part" i hope so too or im gonna be living in it !!

also on you tube i saw a video about something with the clutch and brake pedal bracket , something wheres out and itll cause the pedal to sag, never watched the whole vid.

i hope replacing the leaking slave fixes it!!! will post up some pics of the truck when i get it home , sitting at a friends house till i fix it.

mitchalvin

There are some problems with the firewall flexing and breaking. If your slave leaks I would start there, usually the firewall starts flexing because the throwout bearing starts to bind on the input shaft. To check the firewall either watch or have someone watch the master cylinder under the hood while the other person pushes down on the clutch pedal. If you have a cracked firewall you will see the master cylinder move when pushing the pedal. There are two fixes for this one is a small plate that bolts on the other is a large piece of metal that will need to be welded on. The larger piece is for the firewall that have broken due to the clutch system.

Just call me Sean

iTrader: (1)

You're in luck then since you don't have to pull the tranny to replace the slave. My book says the TOD wasn't available in '91, but the T-18 still was. The T-18 is a 4 speed and looks similiar to the TOD but I think it has granny low instead of overdrive. There was a recall for firewall flexing on the manual equipped trucks, they added a plate to beef up the firewall. Small or large plate as stated above depending on the amount of damage. There is still a plate there but it isn't good enough, or it separates from the firewall. Mine was screwed back to the firewall with self tappers so I pulled the brake master cylinder and booster, and the clutch master cylinder and welded the plate back to the firewall. Then I removed the screws and welded those holes too for added strength, and also welded all the cracks.