A New Noise - E-e-e-e-e

The only relationship I can guess could possibly be is if the condenser unit was holding pressure against the tube that the clutch cable runs through and by removing it you somehow have shortened the effective length - in other words, removing it tightened the cable? If you have plenty of pedal freeplay, that can't be the case. There is always the possibility that the connection between the clutch housing and the engine is loose and by having the bus partially jacked up to get underneath it twisted just enough so that gap widened a bit. Check those four bolts / studs (one is one of the starter bolts) and check all your motor mounts / transmission mounts for tightness. If you don't find anything external like that, well....

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Now that you mention motor mounts, I need to admit to having done something lame. Here goes (I can only say that I am a beginner at this, so give it to me with both barrels if you must, but this is how I learn).

Jacking to bus up to find the exhaust leaks, we chose to put the jack under what appeared to be a sturdy crossbeam behind the engine. YOu probably can see where this is going. We had the bus up a few inches when suddenly it dropped down. Visual inspection quickly revealed that his sturdy crossbeam was what the rear of the engine was mounted on, and it was itself mounted to the chassis through a big ol' rubber pad assembly thingy. We lowered the jack immediately. I worry now -- um, er, did I do a Bad Thing?

................yes

How bad?

......................Broken rear motor mount?

And the test for that is . . . ?

................I'd listen carefully for a 'new noise'.

:-)

Ah -- I get it -- circular reasoning. I can work with that. Yes, there is a new noise. But the mount looks identical now to how it looked before I did my magic bozo move. If the engine appears to be sitting in the same darn place it was before, as evidenced by the rubber mount thing looking the same, could there have been some hidden damage that tweaked the clutch, causing this whining noise when the clutch pedal is depressed? (A feeling I'm getting right now thinking about how I might have done something bad?)

If the mount is broken won't he get some back and forth motion on the trans.engine when he is in say second gear and taps the throttle?

--Dan E

...............The rear of the engine would only raise up off the rear broken mount(s) when downshifting or hitting the throttle while in reverse........I think. If the rear of the engine is now free to shift to one side or the other or if it now rests a little lower than if the rear mount wasn't broken, I'd guess that the clutch cable & tube and/or shifting linkage might be having alignment problems.

More information, possibly useful, possibly not: the clutch only makes noise when engaged. The release point has not moved at all, higher or lower. It does not make noise when the bus is cold, but once warmed up it does when engaged. It doesn't matter if the bus is rolling or standing. The noise does stop if the tranny is put into neutral and the clutch disengaged, or when put into any gear. There is no perceptible change in performance in any of the gears -- things feel very normal. The noise itself is a grindy noise, like a bad bearing. Loud enough to be very noticeable, but it doesn't scream out or anything.

Does this fit with any of the theories that are being tossed around?

And thanks for the help, guys.

Your latest addition sparked a memory - It's been years, but I had a similar situation with a piece of the engine cooling tin making contact with the pulley or something. I don't remember what triggered it but it seems to me I thought it was clutch related at the time.

If the noise occurs when the clutch is engaged (pedal up and foot off) it prolly is not the throw-out bearing. TO brgs usually squeal just as you start to depress the pedal or, if adjustment is too tight, when clutch is engaged.

See if you can actually isolate where the sound is originating - with help from Inge and either a long hard rod or a rubber hose (to listen with, of course!)

Cooling tin making contact with the crank pulley? I'll look . . . that would be very bizarre that it would sound exactly and only when the clutch pedal is depressed regardless of whether the vehicle is in gear or not and whether or not is it in motion. Bizarre to me, of course, I'm a beginner and know not the wonderous and mysterious ways of the modern automobile.

If the adjustment is too tight, wouldn't that also shift the location of clutch engagement/disengagement up or down on the pedal? The clutch action has not shifted a bit from where it was prior to my magic jack under the motor mount mistake, which shall live in infamy forever.

And, a clarification of language. I was under the impression that a clutch is engaged when the pedal was down. I must have my usage wrong.

My apologies to anyone who has been engaging their brains trying to sort out this issue if I have been giving incorrect information. Just re-read my posts from earlier today with this correction: It's when the pedal is down that the noise occurs.

I will . . . it's raining and dark outside so we'll stay inside. I have some lab notes to go over with Inga, my devoted assistant. When the weather is nicer I'll do some poking around with my hose.

You "engage" the clutch - like, the plates all squish themselves together - to connect the engine to the wheels and make the vehicle move. As is most things in life, when you put your foot in it, everything "disengages". When you do not have "engagement", nothing comes together, and you have no movement - sort of like no sex-before-marriage-plans, I guess.

If a gap had opened . . . would there be an oil leak?

And well.

And in how many other ways can we bring sexual imagery into auto mechanics?

Thanks for the explanation. I did have engaged/disengaged backwards.

Update:

My original post appears below this message, for those who wonder what the heck I am talking about. Short version: new throwout bearing noise when pressing on clutch. Noise appeared after dopily jacking bus up in a Bad Way and after removing old air conditioning from under the bus.

My observations are:

1. The engine mounts are fine. To clarify: aft of the engine in my 71 bus a support beam runs from right to left. The engine rests on this. On the right and left ends of this beam are some big rubber vibration isolation mounts with bolts through them. The rubber mounts rest on support beams that run fore and aft below the engine compartment. Through a magically boneheaded move, I had placed my jack under the side-to-side beam in order to lift the rear of the bus. After I had lifted the bus a couple inches the bus suddenly dropped -- which makes sense since the rubber bits are supposed to be under compression, not be stretched like that. We lowered the bus immediately. Visual inspection today showed that both rubber mounts are fine and no metalwork was damaged.

1. The bolts between the engine and the transaxle are fine. Didn't tweak that area in the drop. I creepered under the bus which was intelligently raised on a couple of those ramps that I bought this morning at Autozone. Smart boy: no more jacking the darn thing up and breaking stuff in the process.

2. I sat in the bus and started the engine and put the thing in neutral. Pressing down clutch causes the noise -- throwout bearing noise. Without the distraction of driving, I listened to where the noise appeared to be coming from. The floor, behind the front seats, pretty much centrally-located.

1. I had Inge, my innocent and devoted lab assistant press and release the clutch pedal while I returned to the bus underside. Under the T/A the noise was not real evident. With one end of a stick pressed against my ear-bone, and the other against the T/A you could kinda hear the TO bearing, but not very prominently.

2. Wondering about the fact that the noise seems to be coming from further forward, I moved under the passenger compartment and there -- from the tube that the clutch cable runs through -- the sound was very evident. It is in contact with the floor of the bus. That's where the sound is coming from.

Conclusion, based on evidence and shaky understanding of how these things work: Removing the A/C unit cause the normal TO bearing noise to become more prominent. I cannot see how a great big metal finned and louvered thing that hung below the cable tubes could reduce the sound, but it did.

I think I got it. My thanks to all for their thoughts and sharing their experience.

Mike Rocket J. Squirrel Elliott

(original post follows)

Here is a bizarre scenario for you. Depressing the clutch could cause the crankshaft to move to the rear very slightly. I believe the crankshaft can move up to .006" and still be within spec. If some piece of tin is that close to the pulley, depressing the clutch could cause contact.

Not likely. But possible.

Max