Squirrely clutch

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  #1  
Old 02-20-09, 08:45 AM
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Squirrely clutch

I drive a 2002 F-150, extended cab, 4.2 V-6, 5 speed manual. Currently it has 108,000 miles.

Approximately 1 1/2 years ago my clutch started acting up. The pedal was spongy. On the way to work one morning the clutch pedal gave out completely. On that particular morning there was ice and snow on the ground, the ambient temperature was zero, and the windchill was -15 degrees. The tow truck driver was in a bad mood and I was pissed off.

I had my truck towed to my mechanic who I've used for many years for various vehicles. He's honest, and I can trust him (shocking I know).

My mechanic checked the master clutch cylinder and it was fine. He told me that the problem was, more than likely, a defective slave cylinder. And, guess where that is located? Anyway, being that my truck had 90k miles on it, at that time, I just told my mechanic to replace the entire clutch assembly.

He did as instructed. When I picked up the truck he told me that the clutch assembly definitely had some wear on it. One of the springs were broken. But, for a clutch that had been engaged/disengaged a gazillion times the assembly was in remarkably good shape (score one for Ford).

The slave cylinder had busted apart. Probably due to the extreme cold temperatures. And, that's what caused my original problem.

Okay, I said all that to say this: The clutch is acting up again. It's not as bad as before. But, I can tell that something isn't right.

On some days the clutch pedal is just as solid and tight as can be. There is absolutely no "play" at the top pedal position. It feels strong.

Then, on other days, there is a 1 to 1 1/2 inch of play in the pedal travel from the top position. I don't feel the clutch actually engaging/disengaging until the pedal has been pressed, or released, about halfway.

I can pump up the clutch and it will feel solid again for a little while. That "little while" could be until later that afternoon or a couple of days later. It doesn't seem to be affected by the temperature this time since this can occur when it's below freezing or when the temps are 80 degrees.

Well, here's the "kicker". The clutch pedal will only pump up nice and solid if I have the brake pedal pushed down. With my right foot pushing on the brake pedal, and my left pumping the clutch pedal a few times, I can actually feel the brake pedal pressure change.

I have always been under the impression that the clutch, and brake, systems are independant of each other.

So, my question is this: On a 2002 F-150, 5 speed manual, is there a point where the clutch, and brake, systems are connected in some way?

And, barring any connection whatsoever, what else would cause this strange phenomenon?
 
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  #2  
Old 02-20-09, 09:23 AM
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There would be no connection in the hydraulic systems. I imagine what you're feeling and interpreting as common ground is the movement of the mounting of the two pedals at the firewall.

As far as the pumping of the pedal to get the movement solid again - it may have some air in it. If you ask your mechanic about he would probably bleed it again and take care of everything.
 
  #3  
Old 02-20-09, 09:31 AM
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I've been racking my brain trying to think of any way those two systems could be connected, and other than the pedal brackets being mounted on the same firewall, I can't see how the hydraulic systems would be connected in any way.

But, it doesn't change the fact that the clutch pedal will "pump up" full and tight only when I'm pressing down on the brake pedal.

If I don't press the brake pedal then the clutch pedal will retain some slack at the upper end of the pedal travel.

So, I got to thinking more about it. Suppose it's not a hydraulic problem at all? Suppose there is an issue with the clutch pedal and where it's mounted to the firewall?

Are these clutches adjustable in the sense of pedal travel?
 
  #4  
Old 02-20-09, 09:42 AM
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Ron..that could be good thinking...had a car back in the early 90's that the firewall actually cracked around the pedal attachment points. Gave very bad pedal feel like a hydraulic problem. Would be hard to fathom on a newer Ford truck though.

Most clutches and brakes have some sort of rod to adjust travel...at least those that I have worked with.

I'm sure Marbob...will have more accurate info.
 
  #5  
Old 02-20-09, 09:52 AM
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When the slave cylinder cracked 1 1/2 years ago, and I had the entire clutch assembly replaced as a precaution (90k miles of use) I had my mechanic do a bumper to bumper, side to side inspection of my truck.

He found everything to be in remarkably good condition.

The clutch pedal is giving that same "spongy" feeling that it did just before the slave cylinder cracked that first time. So, it doesn't stand to reason that the firewall would be cracked or rusted out this time.

But, shouldn't a slave cylinder, if that is the cause of this particular issue, last more than 18k miles?

My mechanic did bleed the clutch system when he installed the new clutch assembly.

I guess there could be air in the line somewhere.

I'm the type of guy who needs for things to make sense. And, in a world where nothing makes sense, you can imagine how frustrated I can get about these things.
 
  #6  
Old 02-20-09, 10:24 AM
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If the clutch was working fine for 18K after the repair and now is acting like there is air in the clutch hydraulics, you should have it bled first and checked for leaks.

If no leaks and that fixes it, watch carefully for any return of the symptoms. Should the problem show up again in a relatively short time, plan on another slave or master cylinder.

My personal opinion on these input shaft slaves is that Ford should have had a "Better idea". But I must have missed their phone call when they were taking a survey.

Don't hold this against your mechanic. We have a tendency to index the condition of what have against when it was new. The reality is we just can't return it to that point, no matter what we put back into it.
 
  #7  
Old 02-20-09, 03:36 PM
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Oh, I hold nothing against my mechanic. He's the most honest mechanic I've ever known. I've been using him for 15 years. He has never once let me down.

When this started happening I went back to his shop and explained it to him. He immediately stopped working on the car he had on his lift and went out to my truck to look at the problem.

Of course my clutch decided, at that most opportune moment, to behave itself. So, he told me that, if the problem got worse, to just bring it back in and he'd see if he could find the problem.

He did say that he highly doubted it was the clutch assembly itself. He said my old clutch assembly was in remarkably good shape for a truck with 90k miles on it. Of course he couldn't tell the condition of the assembly until he took it out. Which, at that point, he installed a new assembly.

He said that, if the condition persisted, he would replace the slave cylinder and the master cylinder. He didn't replace the master before since it was functioning just fine at that time.

Then he would re-bleed the system.

I guess my best bet would just be to take the truck in and have that done. And, hope it fixes the problem.

I appreciate the attempts to help me diagnose the problem.
 
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