Stop. Hey, What's That Sound? Diagnosis help needed

[Spider951]

Wanted to take my '81 out for a spin, but leaving the neighborhood I heard (barely) a pop sound, followed shortly by a metallic (?) scraping sound and worse, the car won't go well at all (slipping clutch or gearbox issue came to mind); engine revs just fine. Limped back home in 3rd gear sorta (total no go in 1st and 2nd, reverse worked a bit; had to get my son to tow me the last steep hill). I then noticed considerably more play in the clutch pedal (measured about 3 inches instead of the recommended 1 inch) and intermittently (?) difficult to near impossible to get into gear with or without car running. I have drained gearbox oil - it looks and smells OK with no metal shavings (and none on the magnetic drain plug). Refilled gearbox. Adjusted clutch pedal play to about 1", thinking the problem was probably just the clutch cable repositioning itself where it goes through bellhousing (I had replaced clutch, clutch cable, throwout bearing, seals, etc in 2018 [did not resurface flywheel, however] - less than 3000 miles since then with no issues until now). I could then shift through all gears without car running. OK, great, problem fixed? wrong!!. Cranked her up today and get scraping and slipping in any gear. So I tightened the clutch to about 3/4 inch play - still same result. One other possible factor: in 2018 when I removed the engine and transmission I replaced the oil pan seal with a "rubber" (?) one (vendor later sent me a cork one saying the "rubber" ones are poorly made - thanks but too late). The oil pan leaks bad enough to sling oil all the way back to the connection with the driveshaft - so possibly oil on the clutch/flywheel area??, but why now?. I am now out of ideas - probably going to pull engine and tranny again (grrr) to investigate. Any better ideas? Thanks.

[spider2081]

I wonder if the bolts holding the pressure plate to the flywheel loosened and the pop you heard was the pressure plate coming free of the flywheel. You might be able to see if there is any space between the pressure plate and the flywheel by removing the clutch arm rubber dust boot from the bell housing and looking in.

[Nut124]

I wonder if the bolts holding the pressure plate to the flywheel loosened and the pop you heard was the pressure plate coming free of the flywheel. You might be able to see if there is any space between the pressure plate and the flywheel by removing the clutch arm rubber dust boot from the bell housing and looking in.

This is what I'm thinking as well based on the symptoms. The plate is loose and one bolt popped out. Not enough pressure on the clutch anymore.

[Spider951]

That is certainly worth a look. Possible support for that diagnosis is that immediately after the "pop" sound (but several seconds before the scraping and slipping began) I recollect hearing a faint "ping" sound from underneath the passenger side; I now remember that at that instant I thought maybe a spring holding the exhaust pipes had broken, sending the spring flying out. Perhaps the ping was the exit of a pressure plate bolt?? I'll try that. Grazie!!

[Spider951]

Got sort of a look inside bellhousing from clutch lever opening, and I removed flywheel protection cover to get a look from the engine side. Flywheel (what there is to see) from cover side looks and feels greasy/oily, and one of the bolts holding cover is missing. When I reinstalled engine and transmission in 2018 I had to add a couple of washers between each cover bolt and housing to keep flywheel from scraping it, net result of which probably allows a bit of the blowback from the leaky oil pan to get up into flywheel area. At the clutch lever opening I can't see much (no missing bolts evident but can't really tell), but about a square inch of the dust boot is missing. And a very thin rubbery coating on part of the back of the pressure plate can be seen and scraped off with a fingernail. Maybe the area needs cleaning?? I know I will need to remove transmission to do that properly (and fix leaky oil pan gasket & replace boot), but is it possible to clean the clutch/flywheel while in place for a short term test to see if this is the source of the problem? Would spraying brake clean (acetone?) up in there cause any harm (may not accomplish anything)?

[18Fiatsandcounting]

To continue the musical theme, some words by the mighty Led Zeppelin might apply here:
Ooh, trouble-free transmission
Helps your oil's flow
Mama, let me pump your gas
Mama, let me do it all

Well, in thinking about it some more, I don't sense Robert Plant is going to be much help here...

OK, time to get serious. I agree that it sounds like something broke on the clutch. Either the splined shaft of the clutch disc broke loose, or the clutch pressure plate popped loose, or something.

I also don't think cleaning will help. Yes, oil on the clutch can cause it to slip, but this would be a gradual development over time and not the sudden pop and noises that you heard.

What I would do is look into the bellhousing opening (where the clutch lever goes) while someone is pressing and releasing the clutch pedal, and see if you can see movement of the pressure plate, throwout bearing, lever acting weird, etc. A small inspection mirror on a telescoping wand might help. Take caution that the car is firmly supported of course.

-Bryan

[Spider951]

OK, I like it. And maybe from the great Huey Lewis (revised):
I want a new clutch,
One that won't make me sick,
One that won't make me crash my car,
Or make me feel three feet thick.

But seriously, that's a good idea. Thanks.

[Spider951]

I can't see what is happening to the clutch when the pedal is pressed, but I did get a better look inside the bellhousing today by using a flexible snake camera and with my own eyes and flashlight. It appears that part of the throwout bearing may be broken off. In 2018 I replaced the clutch with a new one - the Valeo kit, which included a new throwout bearing. The Valeo bearing is made partially out of some type of resin/plastic/poly material(?) and some metal. The attached grainy photo shows the white plastic (A) and what appears to be light gray metal (B) of the bearing. The plastic must enclose the metal part, but in my case a chunk of the plastic is broken away, exposing the metal (?). There is also a somewhat jagged metal edge just in the upper right of the photo (much better seen with naked eye) that may also be part of the bearing broken off (?). I don't recall exactly what the Valeo throwout bearing looked like when I put it in in 2018, but it appears that something is broken here. If someone has an old one handy to look at (or by memory), does the white plastic encase the metal part all the way around (360 deg)? I do recall thinking in 2018 that the bearing in the Valeo kit looked suspect (weak) compared to the metal one (OE I presumed) it replaced. Can a metal bearing be used as a replacement for the Valeo bearing, i.e. am I looking at a total clutch replacement or just the bearing? I don't really want to go with a plastic/resin one again.
I thought I would be pulling the gearbox, but now I'm thinking of pulling the engine (got to fix that leaking oil pan sometime anyway). I'm assuming I can do what I need to do to the clutch (mainly replace throwout bearing) by leaving the transmission in place (?), and the engine out of the way. [That engine is kind of "smokey" (bluish) anyway; I might entertain some overhaul (rebuild?) to address that while its out].

[18Fiatsandcounting]

I'm having a hard time telling what this picture is of, but perhaps it's because I'm still too pumped after thoughts of Led Zeppelin...*

Anyway, I had never heard of a throwout bearing that was partially plastic, but lo and behold, that is apparently possible: https://autoricambi.us/clutch-kit-1971-85-oem-valeo/

In this AR photo of the clutch kit, is the part in the lower right the one we're looking at in your photo?

So when you look into the bellhousing opening while someone pushes on the clutch pedal, you can't see the lever pushing against the throwout bearing which in turn pushes against the splines of the pressure plate? The clutch disc itself won't be visible, as it's between the flywheel and the pressure plate. I haven't actually tried this myself (with an assistant), so I actually don't know what you can and can't see.

-Bryan

*Back in the 70s, there used to be a show called the King Biscuit Flower Hour on album rock stations. They featured Black Sabbath one time and made the mistake of trying to interview Ozzy after the show, but of course he was so fried on drugs at that point that he just babbled incoherently (kind of like he normally does). So they ended the interview with, "Well, Ozzy is still a little pumped from the show, so we'll get back with him later." I always thought that was hilarious.

[Nut124]

I cannot see how throwout brg failure of any kind could cause the symptoms you have discribed.

If you pull the engine, you can fix any problem with the clutch.

[Spider951]

I crawled back under the car and got a better look with my own eyes (rather difficult to get the eyeballs up to that level while laying on my old back). I retract my previous post about the broken throwout bearing, not because I know it's not broken, but because with that cheap^^%# snake camera it is near impossible to make out details - you can convince yourself you are seeing most anything with that thing (in fact I believe I could make out Ozzy, Elvis, and Yoda in the back corner of the bellhousing...).
I am just going to have to pull something (engine, tranny, both ?). Yes, the bearing is partially made of some composite resin/plastic stuff and metal, not my first choice of materials combination. Still trying to find out if I can replace it with a metal throwout bearing. Probably end up calling AR. Thanks for your attention and comments.

[18Fiatsandcounting]

(in fact I believe I could make out Ozzy, Elvis, and Yoda in the back corner of the bellhousing...)

Cooool.... But I thought Elvis was working at a 7-11 up in Minnesota somewhere?

I agree that the symptoms don't match with a broken throwout bearing, but it sure sounds like something is wrong with the clutch. Doesn't sound like transmission issues, which is good news if true.

I'm kinda thinking, yeah, you need to pull the engine/transmission/both.

-Bryan

[Spider951]

I finally got around to removing the engine. So here's an update, post-mortem, and where to go from here question. (I plan to ask an engine question or two later).
First picture below shows that the clutch disc was basically destroyed - metal fractures in several places (blue chalk arrows); location of opening for splined shaft significantly displaced to one side (eccentric); fine metal shavings everywhere. Pilot bearing was found in place, apparently undamaged, but just loose - it practically fell out when I pulled off the flywheel. Clutch plate appears to be OK. Flywheel OK, but see below. I expected to find problem(s) with the throwout bearing, but nothing appears obviously wrong to me in that department.
Obviously, I'm going to replace the clutch, but I am puzzled as to the cause of the failure and don't want a repeat. Was it just failure of the clutch disc (with less than 3000 miles driven since it was placed in the drive train)? Operator error?: I've been driving standard shift cars since 1968 (learned to drive on a '63 on-the-column standard shift. I'm not ready for the Winston Cup or anything, but I have never experienced anything approaching this level of failure in a clutch).
Another possible culprit (?): I did not have the flywheel resurfaced by a machine shop when I replaced the clutch in 2018 (the clutch was not the problem in 2018 - I merely replaced it in 2018 "while in the neighborhood" when I pulled the engine) - I just smoothed the flywheel with very fine sandpaper and cleaned it with brake-clean (acetone). Pictured below is flywheel as it appeared before my sanding/cleaning in 2018 and then the final photo is flywheel in current state. I didn't know in 2018 (and still don't know) how much scoring, discoloration, etc is too much for the flywheel? I will probably replace the flywheel now.
Any comments or suggestions to help me avoid a repeat will be appreciated.

[18Fiatsandcounting]

Mmmm, hard to tell, always in motion is the clutch disc... Do, or do not, there is no try.

OK, with that Yoda meme out of the way, here are my thoughts:

I doubt it was operator error. Unless you drive like this:
https://www.youtube.com/watch?v=fV7rzFBeUlQ

Looks to me like an issue with the clutch disc, and that could be a failed part, or perhaps it was installed in the opposite direction than it should be? (the protruding part of the central splined collar in the center of the disc should face the transmission, not the engine)

-Bryan
PS: It wouldn't hurt to resurface the flywheel. Any machine shop can do this, and it's $50 or thereabouts. Just make sure that they leave the disc contact surface about 0.020" above the surface where the pressure plate bolts to.

[Nut124]

That is very strange. The Valeo clutches are supposed to be very strong.

Bryan might be on to something with the orientation.