Stuck clutch pedal, again...

[kturner]

I have a 97 2.3l that doesn't get used very often. A few years ago, the clutch started acting up. Occasionally, it felt like on longer trips, it would lock in the up position. Letting it sit for a while would 'resolve' the issue. I ended up changing the master cylinder but it still did it so I changed the slave cylinder as well. Now it's doing the same thing again. A few days ago, I was a few miles from home picking up some fast food. I went to leave and the pedal wouldn't depress. I tried (gently) a few more times and it started moving. I made it 3/4s of the way home and got stuck at a stop sign. I fiddled with it for 10 mins then had someone come pick me up. After about an hour, I went back, figuring the clutch pedal would work at this point but it was still stuck. I verified the quick release coupler was firmly connected. Still no movement. I opened the bleed nipple a little bit and some fluid came out. Still no movement. I disconnected the coupler and reconnected it. This caused fluid to come out of the slave cylinder, introducing some air into the system. The pedal moved some now but still got stuck before disengaging the clutch. A few tries after this, the pedal started working (as well as it could with that much air in the system) and I was able to drive it home. I don't know if it started working due to reseating the coupler, some fluid coming out or if it finally sat long enough for the issue to 'resolve itself'.

I just got one of those cheap connect to your phone borescopes and I'm going to use it to look around inside the bellhousing to see if anything looks out of whack. Most replies for symptoms like this say check your coupler, reseat your coupler, etc, but that's all been replaced relatively recently. Any other culprits that people have had to deal with?

I may still replace the master cylinder again, even though it only has, at max, a few thousand miles on it. Anyone have a recommendation for where to get a good quality master cylinder?

Thanks

 

[Bird76Mojo]

Inspect your fluid line very closely. Look for any smashed, flattened, or melted spots on it. It could theoretically be acting as a check valve.

I also wonder about your pressure plate. It's possible that a finger broke off and has lodged itself in the assembly somewhere.

You might also inspect your clutch pedal pivot where it mounts to the cab. Look for anything that might have lodged itself in there.

Other than those three things, I'm at a loss on this one. Not much to go wrong on these systems.

 

[adsm08]

I have seen a broken pressure plate cause the pedal to lock in the up position. But I doubt your 2.3 was doing what I did to cause that. I also fractured the clutch disc and broke a damper spring or two.

I would start by unhooking the pedal from the rod next time it does it and see if the pedal is stuck. If it isn't there is something in the hydraulics or clutch causing it.

 

[pjtoledo]

when it hangs up again, grab an assistant and have them push on the coupler while you're pushing on the pedal. use safety goggles in case the fluid squirts out.
have the assistant use them too!

while pushing on the pedal carefully open the bleeder, that will verify the coupler is working, or not.

check the alignment of the pushrod in the master.

 

[kturner]

Thanks for the suggestions.

I checked the hydraulic line, no signs of squashing, abrasion, melting, etc. The top of the pedal seems fine, nothing dangling around that might get stuck in the pedal assembly. I didn't see any obvious damage to the pressure plate, though it did have some surface rust. There was some fluffy looking stuff stuck in some places. I figure its either clutch plate dust or a mouse decided to build a nest in the bellhousing while the truck was sitting.

Does anyone have a diagram, disassembly pics, or anything else that may shed some light on how the check valves in this quick disconnect coupler are supposed to work? This seems suspect to me for two reasons. One, when the clutch pedal gets stuck, it feels exactly like it does when I intentionally disconnect the coupler. Just a slight bit of give, but solid after that. Second, when I disconnect the coupler, fluid pours out of the slave cylinder side of the coupler. It looks like the slave cylinder side of the coupler also has some sort of mechanism inside. I'm assuming it's supposed to engage the other side to open the check valve, but I don't know if its supposed to keep fluid in the slave cylinder when its disconnected or not.

 

[Bird76Mojo]

Pictures would be worth a thousand words here. Specifically showing both ends of the coupler when it's disconnected. It does sound like you're narrowing it down though. The coupler is definitely a good place to start investigating. Not sure why I didn't think of that. I guess I just always took it for granted that they work well, because all of mine have always been flawless.

 

[kturner]

I took a closer look at the coupler. On the master cylinder side, there is what appears to be a spring loaded plunger of some sort. I can depress this and fluid comes out. On the slave cylinder side, there appears to be a rigid part that depresses that plunger. So it would appear that as soon as the coupler is connected, the rigid part opens the plunger and it stays this way unless you disconnect the coupler. There appears to be a seal on the slave cylinder side which surrounds that rigid part. I didn't measure it, but it looks like the other side of the coupler must push this seal out of the way. On mine, that seal does appear to be torn. I can see how that would allow fluid to spill out of the slave cylinder when the coupler is disconnected, but I don't see how that could contribute to the solid clutch pedal. In any case, it's not like I can replace it without swapping the slave cylinder which is what I was hoping to avoid.

I did find a service bulletin which sounds similar to the solid clutch pedal issue. It describes an internal leak in the slave cylinder due to the lip seal failing as the culprit.
https://www.thedieselstop.com/faq/9497faq/tsb/tsb/files/972217.pdf

Looks like I'm dropping the transmission again. I think the last one I put in was whatever advance or rockauto had in stock, and it appears to have failed after a few thousand miles. Is there any brand slave cylinder that is trusted to be longer lasting than others?

 

[Bird76Mojo]

If you can locate a Motorcraft slave then that's what I'd use. Looks like there are several listed on Ebay if you check the box to search in the description, and include "97 Ranger motorcraft slave"

Just be sure to read the fine print and make sure it's not a "direct replacement for motorcraft" - be sure it's the actual Motorcraft brand.