Clutch not working correctly

[RSchanz]

So, brought the truck to my mechanic to look into my head gasket issue and coincidentally on the way in turning the corner the truck kinda ground when downshifting to 3rd, didnt think much of it. When getting ready to pick the truck up mechanic called me and asked if I ever had issues with the clutch, I said no.

He ended up saying that his guy topped off the slave cylinder and I should monitor situation. (I dont think he bled it properly, heard him say he just pumped the clutch like 20 times - side note). He said its probably not the master cylinder because it would leak onto my foot. Drove the truck home and by the time I got back I could barely shift it into gear especially without grinding. There is also very little pressure on the clutch so I'm assuming a fluid leak somewhere. At the moment the head gasket is leaking when hot and onto the slave cylinder and dripping down so it's hard to pinpoint if its leaking DOT fluid or coolant. Any ideas on trouble shooting? Could the coolant be leaking on the slave and creating this issue somehow?

This type of issue is new to me so bear with me, thank you!

 

[Philthy Phil]

Are you losing dot fluid? I'd wash it down and re-bleed it and have some one hold the clutch down and see if it's losing pressure or fluid anywhere. Do this while the engine is off and cool so your not adding coolant seepage into the mix. You can remove the clutch inspection plate to see the actual engagement/disengagement. I'm not ase certified but that's where I'd start.

 

[RSchanz]

Are you losing dot fluid? I'd wash it down and re-bleed it and have some one hold the clutch down and see if it's losing pressure or fluid anywhere. Do this while the engine is off and cool so your not adding coolant seepage into the mix. You can remove the clutch inspection plate to see the actual engagement/disengagement. I'm not ase certified but that's where I'd start.

Makes sense. I'll check master cylinder fluid level. Might be a stupid question but the truck being hot or cold shouldn't make any difference at all right?

 

[Big Bart]

RSchanz,


I do feel that hot coolant leaking on your clutch slave cylinder could cause it to fail. Although the slave can handle the heat. (Coolant and engine are about the same temp and exhaust at times even hotter. Brake fluid is able to handle high temps.) The slave likely cannot handle water and coolant if it can get inside the rubber boot (Very likely), then into the cylinder, and thus causing seal failure or corrosion that will then cause seal failure. (Why you perhaps are low on fluid.)


However these trucks are getting old. So everything you have not replaced in the last 10 years (Or longer.) is wearing out. So its not a stretch to have multiple things failing in the same month or even week. Also to no fault of the mechanic, he tried to bleed the clutch system, so maybe it only had 20 some pumps left in it.


So I would look to see if you believe the clutch slave is pushing all the way properly and if the clutch arm/throw out bearing arm is swinging its full arc. If not just upgrade the whole enchilada if funds are available. Do the clutch master, clutch slave, and flexible brake line to the slave. (I have an auto so sorry if no brake line between frame and tranny.) Then you know with certainty that all is replaced, all is working, all should be good for another 10 years+. If you do not address your head gasket then you may have to replace the slave again sooner but at least it should last for some time till you address the head gasket.


If the clutch master, slave, and arm all are working. Then it’s time to pull the tranny and look at the throw out bearing, clutch, pressure plate, pilot bearing, and flywheel.


If all that is good then next step is look inside the tranny for issues. (Not likely in this case based on what you mentioned.)


Good luck and let us know what you ended up doing!

 

[RSchanz]

The master cylinder was bone dry like had to put my finger all the way in and touch the bottom before touching fluid. I’m assuming this should be full to the rim? Guess this means good news is that it’s likely slave cylinder or the line.

 

[Big Bart]

Well you have definately found another symptom of the problem!

If you fill with brake fluid, bleed the system, you should be able to find your leak.

As mentioned if in the budget, say $110 VS $50, do the master, line, and slave. Then you should not have to deal with the clutch hydraulics for some time. Do one part and perhaps next month you are down again doing the other half.

You should also lubricate the clutch pedal bushings and if suggested by this group (I have an auto.) the clutch fork where it hits the slave cylinder.

Still cheaper and much easier than a clutch replacement or tranny rebuild.

All the best!

 

[IDIBRONCO]

As mentioned if in the budget, say $110 VS $50, do the master, line, and slave.

I've seen where you can buy these as a pre bled kit. It's more money, but worth it to me. I HATE trying to bleed out a hydraulic clutch.

 

[RSchanz]

Thanks for the tips. Any pointers on brands to buy? I saw one video of a guy who used a slightly more expensive but much more burly metal one. No link to purchase though

 

[Big Bart]

Nothing brand specific, I try to find parts houses that sell higher quality stuff. For instance locally I do better with Orielly's, Napa, and a local outfit Hub Auto than with Autozone. I sometimes use Rock Auto but only when sure of what I need and when I have time. (Incase I have to do a swap or return.)


When at Orielly's I always ask what other brands besides their OEM stuff they can get for me. (Their low end stuff I have had issues with from time to time.) They tend to have the cheap stuff in stock but can order the better products. They can see on their parts screen what the other offerings are. Often they stock better brands/parts at their distribution sites. They can order and get those brands that afternoon or next day. "Special Order" stuff is something they do not carry but can source, takes days and you get hit with shipping.


So if they have Motorcraft (Ford), A/C Delco, LUK, BorgWarner, Bosch, or Standard brands they often are $5-15 more but are generally better built and will last longer in most cases.


I usually see if they can get Motorcraft quickly and then go to other brands from their.


Hope that helps you find the right stuff. Again sometimes we just need to get back on the road and we have to roll the dice on what is in stock.


Also some food for thought when you go to bleed the system -


If you have a compressor go to Harbor Freight and pick up a vacuum brake bleeder kit. (Like $20-30) It sucks the bake fluid through the system if its a open system. One benefit is it will generally suck the air out of the lines and slave if the air pocket is caught in a high spot.


Keep in mind if its not a open system try to push in the master cylinder a little to see if you then can vacuum bleed. Either way it helps bleed your system or becomes your brake fluid catch bottle as you manually bleed.


All the best and let us know what you end up with for parts and how it all works out!

 

[RSchanz]

If you have a compressor go to Harbor Freight and pick up a vacuum brake bleeder kit. (Like $20-30) It sucks the bake fluid through the system if its a open system. One benefit is it will generally suck the air out of the lines and slave if the air pocket is caught in a high spot.

What would I need the compressor for? I did find the tech article that explains bleeding MC/SC https://www.oilburners.net/threads/tech-101-clutch-mc-slave-bleeding-procedure.62121/. I think its for 7.3 but I'm assuming the procedure is the same.

I also found this video which is very helpful and makes it seem pretty simple

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[Big Bart]

The vacuum bleeder at HF (Also many others make them.) uses compressed air to actually create the vacuum in order to suck out the brake fluid. Think of a straw in a soda. So if you bought the HF vacuum system and did not have compressed air all it would be able to do is collect the brake fluid when you manually bleed. It would not be able to suck the brake fluid out.

There are also some systems that lock onto the master cyl, pressurize the master, and push the brake fluid out. But these are pricey and if they or your reservoir pop off brake fluid goes flying and makes a big mess.

But for decades mechanics bleed brakes like the video above and did the slave manually. So no harm in doing it old school either. Just sometimes you get air trapped and you spend hours trying to get it to bleed out.

 

[RSchanz]

But for decades mechanics bleed brakes like the video above and did the slave manually. So no harm in doing it old school either. Just sometimes you get air trapped and you spend hours trying to get it to bleed out.

I have experienced this while bleeding brakes on my mountain bike

 

[Big Bart]

Let us know how it all turns out. Hopping this is a easy one for you.

All the best.

 

[RSchanz]

Slave Cylinder is now replaced with a metal one from O'reilly's which came out to $40 so I would say not too bad since it's not plastic. Very easy install clutch runs smooth now. Thanks for all of the guidance.

For anyone reading this and attempting to change and/or bleed the system. I would say that it's not very hard to bleed the air out with a friend despite what you read elsewhere. Simply have your friend pump the clutch 20 times and hold it down, when they hold it down open the bleed screw and prepare for fluid to **** out of the bleed hole. Stop the stream mid-**** by tightening the bleed screw. Repeat this step probably 10 times and make sure to continue topping off the master cylinder.

Also, I kept the plastic tie from the old slave cylinder so if anyone needs one message me and I can mail it to you.

 

[Big Bart]

Glad it worked out and your back on the road!