1987 f150 slipping clutch.. Straight 6 300

Discussion in 'Trucks and Trailers' started by JLSLLC, Mar 3, 2012.


    JLSLLC LawnSite Gold Member
    Posts: 3,442

    Its my work truck, its a four speed manual 2wd... A few times recently the truck has been acting up... The clutch slips but as it warms up, or you drive it more, it goes away.., or gets better. I can understand this because of the clutch heating up and getting stickier.. One more thing i know could be an issue is the valve cover gasket is leaking at the very back of the engine, requiring the upper intake manifold to come off., i cant seem to get at the bolts in the back to snug them up, I Havent torn it down yet, I plan on fixing that too,asap. But does anyone think that this helping my clutch slip? Its not gushing out but i see oil spots everywhere i stop, I feel that it could be part of the problem, but also am concerned if this is the clutch showing signs of being worn, or the pressure plate or etc isnt functioning all the way.. The Pedal and hydraulics seem to be in working order.. Anyone ever have this kind of problem?? Thanks for reading, This is my favorite site:weightlifter:

  2. jsslawncare

    jsslawncare LawnSite Bronze Member
    Posts: 1,674

    I would replace-
    1. valvecover gasket
    2. rearmain seal
    3. clutch
    4. slave cylinder.<-Replace this because you are already there.
    The oil could be coming from the rear main or valve cover. I think the rearmain is a one peice seal, so to replace it you have to remove the clutch (so I would replace it too).
    Do it now before the grass season starts. Good-luck.
  3. 32vld

    32vld LawnSite Gold Member
    Posts: 3,984

    The clutch gets better because the oil gets worked off.

    The oil is most likley from your valve cover gasket.

    I have yet to see an engine that had to first have an intake manifold removed to replace a valve cover gasket.

    A temperature will not effect the pressure plate.
  4. jsslawncare

    jsslawncare LawnSite Bronze Member
    Posts: 1,674


    Take a look at a fuel injected Ford then (you will have to remove the upper intake plenum) and if it slip's enough temperture will affect it because the pressure plate works off of spring pressure.
    Also look at the oil sending unit. Go by my list and you'll be fine.
  5. Birdhunter1

    Birdhunter1 LawnSite Senior Member
    Posts: 312

    On that engine yes the intake must come off, 32VLD the engine in this truck is an inline 6 not a V6, the intake plenum sits over the top of the valve cover.

    On that valve cover it isn't just the gasket you have to worry about, often times the cover itself will warp ever so slightly at the bolt holes if it is over tightened.... easy fix with two pieces a piece of hardwood underneath and a piece on top using soft blows with a hammer.

    Also take a look at the side cover, they were notorious for leaking as well.

    The 5-speed manual transmission you have in that truck is not a very heavy duty transmission and the clutch is rather weak. Likely it is a clutch issue as well but the valve cover gasket is not a hard fix if you are 1/2 way mechanically inclined.
  6. hosejockey2002

    hosejockey2002 LawnSite Bronze Member
    Posts: 1,195

    The OP said he had a 4-speed. He's probably got the old 4 speed manual with overdrive. I don't think they put the 5 speeds in the F150 in '87.
  7. Birdhunter1

    Birdhunter1 LawnSite Senior Member
    Posts: 312

    Misread it, they made two 4 speeds too. one was a heavy duty sucker with a granny low gear, the other was lighter with an overdrive gear. I know very little about the overdrive manual, but the 4 speed with granny low is the one I had, Borg-Warner T-18 if I remember right.

    JLSLLC LawnSite Gold Member
    Posts: 3,442

    Thanks for all your replies!! I plan on tearing it down this week if i get a chance. Its a four speed, no granny gear... I wish it did have one:dizzy: I'll try to get an engine shot today while im checking it over, getting ready for the season to come:cool2: good luck everyone!
  9. unkownfl

    unkownfl LawnSite Gold Member
    Posts: 3,838

    Put the truck in high gear going around 20 and try to accelerate. If the rpms climb faster than the truck picks up speed you know it's your clutch. The valve cover issue shouldn't effect the clutch unless some how magically it is getting on it and if it were the case your clutch would be shot and wouldn't get better. The bellhousing makes a good seal and the flywheel is in the way for the rear main seal to leak onto the clutch. It would have to leak like a faucet in order to get your clutch wet. 32v a lot of cars require the intake to be removed in order to change the valve covers.
  10. JLSLLC

    JLSLLC LawnSite Gold Member
    Posts: 3,442

    ok so i didnt get a pic of the engine, got too dark. The clutch has been normal ever since the first day i posted. Ive tried all gears, at all rpm's, and different driving habits and weight in the back... Its been "normal"..i'll keep my fingers crossed.. I changed the oil last week, and its a half quart low!, i see spots on the ground still,. Really gotta get some more pics for you guys.. Im hoping its just the valve cover gasket, but i am preparing myself just in case its coming apart..:cry:

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