Hellish trans sound with audio link

[northoak]

Hey folks sorry to be blowing up the boards, my 84 720 quickly developed this terrible sound when I rev the engine in neutral. It also happens when I release the clutch in gear. Maybe im in trouble? Im pretty sure it's coming from the trans. It shifts ok, I just replaced the master and slave because I caught some leaks but the noise remains. Please let me know if you have heard this noise before, there is a link to it below

 

https://clyp.it/25peotu4

[Lockleaf]

Can you control the sound with the clutch pedal? Push the pedal in, sound goes away? Let it out in any scenario with engine running, and it makes the noise?

[northoak]

Thanks for getting back, I tried pushing the clutch pedal in and reving it and I get the same sound.  Maybe this means it has more to with rpms?  It seems to hit in all gear but most audible in neutral and right when I release the clutch.  So yeah no controlling the sound, I can't tell if it goes away or gets drowned out as the rpms get higher.

[northoak]

also its loud here in oakland, The high pitched pterodactyl sound in the one i'm talking about.

[datzenmike]

If the clutch pedal is 'in' the transmission should be disconnected and nothing inside spinning.

 

If it does this with the pedal up or down.... look for something else other than the transmission. Could be anything else from the release bearing forward.

 

Fan belt?

Alternator bearing?

Power steering reservoir empty?

Clutch fan?

[wayno]

If you push the clutch in while it's running, put it in gear and rev the engine and it is still making the noise, it's not likely the transmission itself.

If you let off the clutch in neutral while it is idling and it starts making noise, and then push the clutch back in and put it in gear and it stops making noise, then it likely is the transmission. 

[northoak]

Wayno: Good to know! I did thst test and the pterydacdyl remains when in 1st with the clutch in.

 

Mike I topped off the power steering and did a lil flush procedure and the problem remains. Unfortunetly I have to work at 530 am so I probably wont get to check those other things to night

[datzenmike]

Well the clutch disconnects the spinning engine from the transmission.

 

Clutch pedal down, no part of the transmission should be moving, but the release bearing and pilot bushing are in use.

 

Clutch pedal up, the input shaft and counter shaft and bearings in the transmission are turning and the pilot bushing is not.

 

 

So, if you feel it's coming from the transmission about the only thing you can check is the transmission oil level. If it's run dry, you can probably still save the transmission.

[kelowg]

Sounds like throw bearing,but could b trans bearings. on my 521 t/o bearing pulls back enough to not touch pp. So if urs is riding up against pp full time,might b wearing out. Try pullin out slave and wire arm all the way backed off. See if noise lessens or stops.

[Stoffregen Motorsports]

Other possibilities for dinosaur type noises:

• Dust shield broken, or loose. The one between the engine and trans. It could also be bent and hitting the flywheel.
• Something in the bellhoising, like a loose rock or some kind of debris.
• Loose bellhousing to engine block bolts.
• Could be a whistling from a broken exhaust or catalytic converter.
• EGR leak.

(I've seen all these before)

 

Easier to start finding out what it's not. Take the fan accessory belts off and start it up. Is the noise still there? Bang around under the truck for anything loose. Tighten it. Is the noise still there? Etc...

[wayno]

You should get under the truck while it is not running, grab the clutch pushrod between the clutch arm and the clutch slave and make sure there is play/slop, if there is no play/slop you may have lost the throw out bearing, if no play/slop you need to quit running it as it will destroy the clutch cover if ran that way for long.

[northoak]

wayno: do you mean that the clutch fork should have some play?

[datzenmike]

The later slaves (after '72/'73) operate without play, there is no adjustment. You may be able to push the arm to the rear slightly, never tried this..

 

There is adjustment on the clutch pedal. There should be about 2mm or 1/16" of looseness before there is firmness when pushing down on the pedal with your thumb.

[Stoffregen Motorsports]

You should get under the truck while it is not running, grab the clutch pushrod between the clutch arm and the clutch slave and make sure there is play/slop, if there is no play/slop you may have lost the throw out bearing, if no play/slop you need to quit running it as it will destroy the clutch cover if ran that way for long.

It will also destroy the crank.

[wayno]

wayno: do you mean that the clutch fork should have some play?

 

Yes, the clutch arm/fork should have just a little bit of play/slop, that rod between the clutch slave and clutch arm should not be tight, if it doesn't have just a little play it will eventually smoke the throw out bearing.

When one looses a throw out bearing it will squeal, and one can even feel the pedal vibrate when one pushes the pedal down sometimes.

[datzenmike]

Destroy the crank? Very unlikely. That's what the thrust bearing is for on the middle main bearing. It supports the crank against the pedal pressure during gear changes or waiting at the lights with the clutch down. The release bearing and/or the diaphragm fingers will wear out long before the thrust bearing does. 

[Stoffregen Motorsports]

You better believe it. Constant pressure on the thrust bearing wipes the oil off, overheats and destroys the bearing and can even wear deeply into the crank.

 

I've even seen it so bad that the rods started to show signs of side wear.

[datsunaholic]

You better believe it. Constant pressure on the thrust bearing wipes the oil off, overheats and destroys the bearing and can even wear deeply into the crank.

 

I've even seen it so bad that the rods started to show signs of side wear.

 

Yup.  I've seen it too.  Though most of the engines I've seen with ruined cranks from wiped thrust washers were engines used in boat racing when the pillow block being used as a thrust bearing (for the prop shaft) failed, making the thrust block the center main instead.  Not supposed to work that way.  But I've seen it with a clutched engine in a car with no axial thrust too.  It's one of the reasons it's not recommended to sit at traffic lights with the clutch disengaged, although most (including me) do.  I'll pop it out of gear and release the pedal if I know it's gonna be a long light.

 

Of course, insane was the engine I pulled from my 4X4 that had the thrust washer center main forced on to the #5 main bearing saddle.  Someone had put the bearings in, in the order they came in the package- thrust washer on #5, wide ones on #4 and #3, and narrow ones on #2 and #1.   It just ground the thrust washers to pieces. but I didn't notice until the timing got erratic from the crank sliding back and forth.  Crank survived that one, though.

[datzenmike]

Funny.. I always neutral the transmission at lights or any time I stop for prolonged traffic wait. I guess the point I was making is it doesn't happen from normal use or even a lot of use. 

[Stoffregen Motorsports]

The point I was making was that you really need to make sure the clutch is adjusted properly (master and slave) or bad things can happen.

 

BTW- good story, as always, Wayno.

[wayno]

Destroy the crank? Very unlikely. That's what the thrust bearing is for on the middle main bearing. It supports the crank against the pedal pressure during gear changes or waiting at the lights with the clutch down. The release bearing and/or the diaphragm fingers will wear out long before the thrust bearing does. 

 

These thrust washers are out of a MG1600 engine, I found them in the oil pan, they got thrown because whoever was driving that MG kept their foot on the clutch pedal while sitting in intersections waiting for the light to turn green, this engine is known for doing this, it does ruin the crank, but it can happen to any engine if there is pressure on the crank long enough, this set of thrust washers got real hot, you can see it was HOT!!!.

[datzenmike]

Again, not likely to happen. There isn't one post here about an L series with failed thrust bearing, of all the millions of accumulated miles and abuse. Could happen.... but doesn't happen. Someone should idle one with the clutch down and hold it till the release bearing starts to growl. Time it with a calendar. These things are built tough, they're 'over engineered'. They will last hundreds of thousands of miles without problems. Could happen.... but doesn't happen.

[Stoffregen Motorsports]

Are you saying pics or it didn't happen? Maybe it never happens here because we always warn people to have their clutch adjusted properly. Maybe it doesn't happen because these Datsun owners are enthusiasts and try to take care of their vehicles.

 

Either way, forewarned is forearmed.

 

But you're right, in all the years building Datsun engines, I saw this happen only about 7 or 8 times.

[datzenmike]

Exactly. The chances are the same as a plugged oil filter or flatcat posting in Cuz.

[northoak]

shifting continues to be a little rougher than I would like but the hellish sound has pretty much vanished.  I believe it was the power steering  fluid being low that was actually causing the noise.  I am worried their may be a leak in that system but only time will tell. Thanks again y'all!