Removing transmission

If the phenomenon you describe did occur, there was something wrong in the system other than the entrapped air.

Use your head, if you push the clutch pedal down part way and hold it there, any expansion of the fluid (or entrapped air) could cause pressure to build and alter the position of the TO bearing because the system is sealed as soon as the MC piston moves far enough to close off the reservoir port.

Once the pedal is returned to the UP position the fluid must be free to return to the reservoir and since the return port is open when the pedal is up, any expansion of the fluid/air will merely push the fluid into the reservoir.

Anecdotal experiences that describe abnormal operation can only be the result of abnormal conditions such as reservoir port obstruction.

Thats terrific in a perfect world. What happens if the pedal doesn't fully release? What if the system has a pinhole leak in it somewhere? What if the slave cylinder is leaking air into the system? Your assumption is a perfectly operating system under perfect operating conditions. Thats great, if it happens.

No one said all things were normal. No one assumed (except you and Tbone) that all things were in perfect operating order.

Yet, you've just given an example of how a "normally functioning system" might not be as normally functioning as it should be.

Perhaps thats why, when finding such a situation, you check it for further problems. Instead of Budd saying, "air could be trapped and apply pressure to the TO bearing, " and you saying, "nonsense, never happen, not a possibility, you suck as a mechanic," you might sit back and ask why such an event would happen, and what other possible problems are present. Thats why good trouble shooting is essential, and why instead of backpedalling and putting conditions on your claims (now you admit other problems might help cause exactly what Budd is saying) that it couldn't possibly happen.

But you admit its possible under certain conditions. You also seem to think its a perfect world, and only one problem happens at a time.

Uh, John? The OP was concerned about bearing wear in a system that wasn't "normal" . . . . For such systems, "normal" is a range of specs and clearances to allow for SOME variations in operations. If the system is already out of spec, then . . . . . .

In my case, it was learned at the school of hard knocks. . . OJT. So I had to analyze and correct usually without the aid of an instructor or even a manual.

But it also meant I had to do trial and error testing and then determine the benefit or hindrance of each step.

ah, "IN A NORMALLY FUNCTIONING SYSTEM" . . . that's the key isn't it? FYI, that is not as normal an occurrence as many might think.

Now you're getting the hang of it.

Yes, it can, because the system is already not in spec. The clue? The worn bearing.

John, do you believe the history books are dead accurate? Just for kicks, read "Bury My Heart at Wounded Knee" and see the history of the west from Lakota eyes.

My point: neither you nor Tom B. realize that not everything follows the "rules".

Budd

The principles of operation are the same, Tom, and in basic design they are the same.. Did you know that some HD clutch systems use a 2 pound residual valve ( like a disk brake) to reduce the possibility of air / water contamination? It uses a slightly heavier return spring to compensate for the pressure.

Btw, you never had a master cylinder piston that couldn't retract properly, have you? Like I reminded John, the system is already screwed up. It is not a perfect text book scenario, Tom.

As for foolish appearances, Tom, that would be anyone that doubts the experiences of a older, more experienced, person and discards them out-of-hand for the simple reason that person is (older, grayer, more experienced, the answer isn't found in some text book, disagrees with some popular answer[correct or not], or . . . . pick as many as you want).

Tom, I'd like to know who made you official spokesman for this group. At this time, anyone that disagrees with Tom's claim of being group spokesman and that no one supports me as a person, they may post a rebuttal.

Don't turn this into one of your diatribes.

-- Budd Cochran

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Really? What was your first clue? Maybe it was the bearing wear?

In function, they are the same. Heck, the earliest hydraulic brakes were plagued with contamination probs because of the lack of residual pressure valves.

A hydraulic clutch or braking system is nothing more than a pedal / master cylinder / line(s) / slave (wheel cylinder / piston) setup. The only difference is that lack of a common residual valve in the clutch system in most applications.

Yep, as in a pedal being ridden, a master piston not retracting completely, a clogged port, a clogged cap vent, a pinched or plugged line, a flap of rubber inside a flexible line, . . .shall I go on? The system is defective, so air can be the problem if not the whole problem.

What if the port's plugged due to neglect, contamination or some other thing not found in your manual?

AHA!!!!!! But that's only one scenario. How about the system that worked fine until a hole wore in the metal line between the master and slave cylinders, but a few days after the A.C.E. certified mechanic repaired it, the clutch wouldn't engage?

I'll save you the effort . . .he had replaced the steel line with copper tubing ( hey, it's not a brake system, right?) and chassis flex pinched it shut while the pedal was down. All I did was replace it with steel line and tighten a couple of frame to axle bolts and set it back out. In this case, the steel would have eventually worn thru again, but it wouldn't have crushed.

Outside your little book, ain't it? Btw, It took me a week to convince him that the flexing had even existed . . . .I loosened the bolts, stuck a twenty between the line and frame, jacked up the same side of the vehicle. If he could pull the bill out without tearing, he would prove I was wrong and could keep it.

I didn't lose my twenty.

-- Budd Cochran

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And if the pressure exceeds this extra 2 pounds, this system will STILL vent it off to the reservoir just like the ones without it so what is your point?

First of all Budd, you DON'T KNOW what in the system is screwed up. It could be and probably is just a bad bearing and nothing more, it happens. It could also be operator error or just excessive usage as we discussed. Maybe there is something else wrong with the system and if so, then the air would again, not be the cause of the problem, it would be the defective component and the problem would exist whether there was air in it or not.

Just because you are older does not mean that you know more and to think so is foolish. I don't dismiss you or your input out of hand but that does not mean that you are always right. It does seem Budd, that once you have an opinion, you are correct and if someone does not agree with you, they are wrong, simple as that damages your credibility, take it from someone that knows. You made a claim that air in the system would ALWAYS cause this problem and that is incorrect, regardless of what the popular answer is.

Where in the hell did I claim to be the spokesman for anything???? I simply made a comment that was true, and nobody in the list denied it, including Max.

I can see where this is starting to go and like I said, I have no intent of going there.

Then you have a defective clutch master cylinder or pedal linkage and you would have the same expansion problems regardless of any air in the system, unless ofcourse, you also believe that fluids don't expand when heated.

Then you would run out of fluid and would have shifting problems LONG before the TO bearing failed, unless of course, the TO was defective to begin with.

It would be a highly unusual situation for this to happen but even if it did, the air introduced into the system would cause clutch disengagement problems long before any possibility of trashing the TO but unless we also have a defective master cylinder or pedal linkage, there would still be no added pressure from vapor expansion.

Perfect no, normal yes, and if a component in the system is defective, then IT is the cause of the problem, not the air.

The claim was that the design of the system itself was the cause of the premature bearing failure and was then added that air in the system alone would also cause this and both of these statements are incorrect.

Then if the system has a defective component, then that is the cause of the failure (including the TO itself), no air in the system. The funny thing here is that nobody knows if there actually is any air in the system anyway, LOL.

If it did happen, then the problem is elsewhere, not the air that may be trapped in the system and if one of these conditions existed, it would happen and probably be worse if there was NO air in the system as a expanding fluid puts MUCH, MUCH more pressure than a much more compressible expanding gas.

Actually, he did not. Learn how to read.

Back pedaling again? Your claim was and has been that entrapped air alone will cause the TO bearing to apply even in an otherwise normal system. A failure of the pedal to release is an abnormal condition. Budd is claiming that entrapped air alone caused the TO to apply and that a simple bleeding cured the problem. If the pedal wasn't in the full up position and bleeding was used to cure the problem, the problem would recur; Budd claims it didn't.

And one of the problems wasn't self-applying.

Correct, and that lack of a RPV means ANY pressure buildup in the system will be equalized in the reservoir.

From your first reply on 10/27 (QUOTE) "However, an improperly bled hydraulic clutch can, when the system gets warm from under the hood heat, hold pressure on a throwout bearing . . .just like it would be if you rode the pedal. (END QUOTE)

Your original claim made no mention of abnormalities other than entrapped air and now you want it to sound like you meant entrapped air in an already malfunctioning system. You and your buddy Max fail to realize your back pedaling is obvious in a forum that archives previous posts.

Your anecdotal claim was that the problem with the forklift was solely caused by air entrapment and that simple bleeding cured the problem. If you were as savvy as you claim to be you would know that simply bleeding air from a system with other malfunctions would have been only a temporary bandaid; the problem would have recurred.

The comment was directed at Max but if you want to catch it go right ahead. If you'd step away from the mirror for a while you'd realize that you're not the only one here with lots of "in the trenches" experience.

That's the gist of it, I don't think that anyone here denies that air entrappment in an already plugged up system might cause the problems you claim but your original post and subsequent posts make no mention of other problems. Go back and read the thread.

Really? because I'd like to see where I claimed anything of the sort. I suggested that air could do that under certain circumstances, but not all by itself.

Yet, not being able to see the device that Budd was working on, you're willing to claim otherwise.

Hell, I remember doing a clutch on a late 80's F250, 5spd built by Mazda, had the concentric slave cylinder. Bleed procedure required vigorous pumping "10-20 times". This step was to be repeated at least five times. After the second round of pumping, the clutch was operable, but air was still in the system. In this case, I suppose I could have waited a week for the air to work its way to the top, if it would. Its an open system and yet, I doubt after having bled it, that the air would have come out on its own.

I know thats an "open system", but I seriously doubt that the air in the slave cylinder would have just worked its way out. Why? Well, interesting that you migh ask that..... see, the BLEED valve is at the top of the cylinder, so air comes out the bleeder first (wonderful how they think of such things). The line from the master cylinder went into the lower side of the slave cylinder, thus making it impossible for any air in the slave cylinder to get out unless the system were bled.

Oddly enough (haha), I recall a bunch of hydraulic systems with the bleeder at the top of the slave, and the feed line at the bottom of the slave cylinder. Probably the same reason they put the bleeder on the top of a caliper, or the top of a wheel cylinder, and feed it from the bottom. And yeah, I know you'll say that the expansion should push the fluid back to out the top. But the likelyhood of that happening while someone keeps operating the master cylinder is minimal.

Yeah, its so unusual to have air trapped in a slave cylinder. Next time I see it happen, I'll be sure to document it with all the pics I can get, and have a notary certify my statements for you two.

I'd tell ya both to go back to school, but the proof is under the truck in your respective driveways.

John,

Learn to read.

I said in one instance, the rented forklift, trapped air caused a bearing problem,which indicates it can happen elsewhere.

I also stated that the perfect system only exists in text books.

-- Budd Cochran

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I don't claim I am, but Marsh monster treats experience as a bad thing to have.

Don't have to. I remember what I said. My mistake was in forgetting that not everyone remembers this is life, reality, not some textbook.

-- Budd Cochran

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The same as before, that the system is not a perfect system, it's reality. It's made by man not God.

And neither do you. The OP didn't say.

Yep. Had a freshly rebuilt alternator freeze up in the parking lot at the parts store right after I had exchanged it for my defective one.

BTDT.

Wrong, Tom. If the system is defective, air could be the problem since AIR IN THE SYSTEM IS A PROBLEM IF IT GETS INTO THE SYSTEM.

Well, Tom, being younger sure hasn't stopped you from thinking I'm less intelligent, trained, experienced, skillful, ad nauseum than you in the past.

The fact you have admitted, in the past, to not having much experience should be enough to suggest that you listen and learn from others with more experience.

I don't claim to be right all the time, and yes, you have dismissed my input out of hand, but be that as it may, I do have experiences you have not had, will probably never have, since you no longer work commercially in automotive repair. This instance is one of those times.

Oh, dear . . .Tom, you have a tendency to attack another's credibility as soon as yours in in jeopardy.

No, Tom, read my original statement, the one not spun by you, and you will see I said having air in the system is always a problem.

A blanket statement, implicating you take the position of speaking for everyone.

Too late, you already did.

Budd Cochran

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Yeah, they did, but since it's info from a man that worked as a mechanic on them back then, you would question it.

Go on believing that, John, if you wish. I have experienced otherwise, but since you do not accept my word. . . .

I am not backpedaling. From the original poster's statement, I assumed the system was known to be defective. My stupid mistake. I forget that reality doesn't always exist here.

It did.

Well, gee, John . . . .we rented the truck for six weeks and the problem never came back. Now, since the bled out fluid had no foreign matter in it, just bubbles, the reservoir had no crap in it, I think it would safe to say the problem was the darned air in the system.

-- Budd Cochran

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LOL, you are kidding, right???? We are not talking cutting edge stuff here and it doesn't have to be "perfect" to work properly.

I never claimed to know but I do know that the TO bearing did not fail due to the design of the system as he suggested.

If the system was defective in a way that forced it into a fully closed mode, the problem would still happen even if there were no air in the system so the air itself is not the problem, only a contributing factor.

I am not all that much younger than you are Budd and in some things I do know more than you but I never claimed to more about everything because that simply isn't true. If you think that you really know more than I do about everything, then you are just being both ignorant and arrogant.

When did I say this and about what. Sure, there are things that I don't have a whole lot of experience with and the same goes for you.

Just because I know longer do this for a career doesn't mean that I still don't work on vehicles. Now I do it for myself and to help out a few friends so the experiences still keep comming, just not as often.

Where exactly is my credability in jeopardy here? I am not attacking yours as you may think, I am actually trying to help you maintain it.

Air in the system is a problem but it will not in itself, cause the slave cylinder to put excess pressure on the TO bearing. There would have to be another problem in the system for that to happen and that other problem would be the real problem.

Ok, poor choice of words there. I should have said nobody else in the thread but even in the group, I don't see anyone jumping in to say you are correct here and lets face it, I am far from the group favorite.

Just because you want to believe this, doesn't make it true.

Now who's backpedaling? Not long ago, you weren't allowing for variances, every system was exactly the same.

Agreed. There was a flaw somewhere between the pedal pad and the flywheel.

Which expands more when heated equal amounts: air or brake fluid?

And what is your attitude saying about you? This comment of yours is very arrogant in itself in that you presume to dress another person down.

Yep, for one, I've never given birth to a child. The problem is, Tom, that you're unwilling to accept that another person could have more experience / knowledge than you. It didn't happen to you, it's not in the manual, therefore it can't be true is the way you see things.

As for your question about when you said how little experience you had, just go back a year or so to the time you screwed up how a differential works. IIRC, it was stated by you that you had less than a year experience working as a tech.

Keep it up, Tom. Good joke!!!

You claiming your trying to help my credibility is like you tossing a drowning man an anchor

Oh, yes, the mighty Tom has spouted. He knows all and sees all and nothing can happen unless he wills it.

Ri-i-i-i-ight . . . . . .

And I don't claim to even try to be the group favorite, but on the other hand, John Kunkel is the only other one arguing I can't have had the experience with air in a system that I said I did.

Really? Then learn to express yourself without offending.

-- Budd Cochran

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It is not what I say can or can't happen, it is the laws of physics, and high school physics at that.

Now who is the one not holding up to there word? So much for having an intelligent converstation.

It's really funny, Tom, that you apply the "It's physics" claim yet have denied it existed at other times.

And my statements do not violate the laws of physics.

Gee, a double standard. You can disrespect me but get ticked off if someone disrespects you.

-- Budd Cochran

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