TDC marker in bellhousing mysteriously damaged

[zuhandenheit]

This is so damn weird.

I'm running an AAZ in an 82 diesel.

Recently I had some injector pump problems -- new to me, recently rebuild IP began leaking from the input shaft after a few hundred miles. It looks like the rebuilder failed to check the bushing and merely replaced the seal, which blew due to excessive shaft play. I installed a replacement IP a few days ago and discovered that the tip of the TDC indicator has snapped off. I turned the crank and looked for debris, missing bolts, or other damage, and didn't see anything except for a few small scratches on the edge of the pressure plate. It's possible they were already there. I didn't have any trouble timing the motor -- only the tip of the marker is missing.

The motor runs fine.

I figure there are two possibilities: one, something fell into the hole or a bolt came loose inside the bell housing. As I said, I checked the pressure plate bolts by turning the crank and looking through the hole, and they were all in place.

As for the possibility of something falling into the hole -- I replaced the IP a few months ago and so the hole was open. I also had another problem recently: my alternator mount bolts loosened and the vibration caused the nut on the long bolt on the left side to come loose. When I discovered this, the nut was gone. I assumed of course that it had fallen onto the road -- maybe it somehow bounced into the hole in the bellhousing? This seems extremely unlikely to say the least, and I'm not sure that it would be big enough to do the damage I saw.

My concern now of course is that my clutch assembly is missing a bolt and/or there's something inside the bellhousing. (There almost certainly is, right?) I'm trying to think of what could have come loose: if it were one of the crank bolts, I don't think it could have fallen out of the clutch assembly and caught against the edge of the pressure plate. My first thought was that it would be one of the pressure plate bolts, but no. Are there even any other fasteners in there? (I don't remember.) Maybe it could be a part of the starter, but it's working fine.

I don't know what could have fallen in. Maybe I didn't return the cap to the hole after timing the motor recently. Also, it's not an especially secure fit and I think has previously come loose on its own. It wouldn't be easy for something to fall into the hole -- there isn't much around it that could come loose, it's a small hole, and the motor is tilted the opposite direction, so if something were bouncing around on the top of the motor, it would tend to go to the front.

One more thing: some time ago, I noticed some aluminum shavings on top of the bellhousing. I couldn't find the source and they didn't reappear.



All told, my best guess is that something fell in while the motor was running, hit the top of the pressure plate, scraped against the inside of the bellhousing (spitting some aluminum shavings out of the hole) and struck the TDC indicator. It probably fell to the bottom and won't likely do any further damage (but yeah, I know -- it would be stupid to gamble on this and leave it alone).

Of course I don't want to pull the transmission or motor. I'm thinking I may be able to bend the shield at the bottom of the bellhousing to take a look and hopefully remove whatever I might find.

Just had a thought: I saw recently that there are cheap boroscopes available on Amazon -- I thought it would be nice to get one anyway, and so just placed an order:

https://www.amazon.com/Depstech-Semi-rigid-Inspect...+Borescope

Anyway, I'm looking for help brainstorming this. Has anyone heard of anything like this before?

[MarkWard]

There is a recent thread where some of the pressure plate rivets were rubbing the bellhousing. I recall it was a diesel as well. What clutch and flywheel are you running? Flywheel bolt is not going to find it's way out of the clutch. I would not go about bending anything. You should pull the transmission out and see what happened. I can appreciate not wanting to go through the fire drill.
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[zuhandenheit]

I'm running the stock diesel flywheel and clutch. I installed the clutch maybe 3000 miles ago and have had no problems until recently. I did replace the transmission maybe 1000 miles ago, at which time I saw no problems in the bellhousing or with the clutch!

[zuhandenheit]

I've got a boroscope on the way, which if necessary I can insert through the starter mount. I'll take a look with that before I pull the trans. I'm working alone and don't have a lift, and although most of the procedure for trans removal is painless, the process of actually removing and installing the trans is a real pain.

The boroscope should be long enough to give me a view of every part of the bellhousing . . .

This is so weird.

[zuhandenheit]

I poked around with an endoscope and couldn't find any problems. It was driving fine . . .

But last night, I started having trouble shifting -- suddenly very hard to get in and out of gear. I checked the linkage and didn't find any problems, and then, again, what looks like specks of aluminum on the bellhousing around the hole.

So the transmission is coming out.

Again, I have an almost new diesel clutch. Flywheel is in good shape and was resurfaced.

I'm thinking maybe with the increased power of my AAZ, I should upgrade anyway -- suggestions? I'll post pictures of the postmortem.

[zuhandenheit]

Okay guys, you were of course right:

I pulled my transmission and found that the pressure plate had come apart.

It has probably about 5000 miles on it. The friction disk has plenty of material and looks fine. The flywheel was resurfaced when I replaced the clutch and looks good. The bellhousing has a groove cut into it and the TDC marker is, again, partly damaged.

My financial situation is less than ideal. I would really prefer to just replace the pressure plate. Here it is:

I have an AAZ with a Giles performance injector pump and a new turbo running about 18 psi -- this setup makes for more power than I need. But based on when I first saw the damage to the TDC marker, this happened when my motor was actually making a lot less power. Do I really need an upgraded clutch? This is the stock diesel clutch.

Do I need a different clutch? Will I have to mix and match parts?

I'm at your mercy and really need some help! This is currently my only vehicle and I'd really like to get it sorted ASAP!

[zuhandenheit]

Also, I meant to ask: What the hell could have caused this?? Is there something else that could be wrong? All bolts were in place and well torqued.

[zuhandenheit]

So, I'm thinking that for now, my best bet is to stick with the stock diesel clutch.

I can get a LUK kit for about $150, a Sachs kit for $200, or just a pressure plate for $100. Again, I'm not seeing any problems with the friction disk, but if the LUK kit is good, I'd rather spend the extra $50 for a full kit!

I'm easy on clutches, generally. In fact, I've never worn out a clutch in any of my cars! I can't think of anything I've done that could have caused this.

I guess I have my old pressure plate somewhere. My old clutch was working fine when I replaced it, but I had the transmission out and decided it would be a good idea to replace the clutch.

I'm having a really hard time understanding what could have caused this!

[MarkWard]

Looks like what failed are the 3 metal straps that hold it together. It's a weak design, but common. Performance pressure plates will stack the bands to strengthen them. If you don't mind the labor, just install a stock pressure plate and stop driving it like you stole it. I got 45,000 miles out of a stock diesel clutch. When you can afford it upgrade the entire setup including the larger input shaft. Well worth it.
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[zuhandenheit]

Thanks a lot Mark.

As is obvious, I don't know much about clutches.

I have two used clutches. One was replaced due to oil contamination -- it didn't show much wear. The replacement was a used clutch in good shape. When I was doing my engine swap, I replaced everything with a new Sachs kit.

So, I have two used pressure plates -- one Luk and the other Sachs, which as far as I can tell are in fine shape.

As I said, my friction disk was unmolested. So, given that funds are tight, I'm thinking about using one of these two pressure plates (probably Luk, given the failure of this Sachs plate). What do you think?


By the way, here's the damage to my bellhousing:

It's a shame about the TDC marker. I couldn't remember if it was a part of the casting, or something attached. I have timed the motor with the marker like this before I knew what was wrong and I didn't have any trouble, but it still kind of sucks.

What if I cut a little triangle out of some sheet metal and attached it over the damaged marker? I don't know really how to attach it. JB weld would probably be okay. 3M panel bond would maybe be better (man this stuff is awesome). I don't like the idea of gluing, of course. I have a mig welder but don't have the means to weld aluminum.

Or, I could cut a bit of sheet metal into a strip, bend it 90 degrees and cut one side to a point, and then screw the other side into the bellhousing above the damaged marker.

It's workable as is and maybe I should leave well enough alone and be glad there is no serious damage, but it would be nice to have a more visible marker.

I've tried to clean up all the aluminum dust. I'm a little concerned about contamination to the throw out bearing, but I figure aluminum dust won't likely damage a steel bearing.

Anyway, my theory now is that the straps let loose one at a time, first damaging the bellhousing but not affecting the shifting. The last time I tried to drive the van, it was having trouble going in and out of gear. I drove for just a few minutes and then took the van home and started taking out the trans. Clearly at that point the last strap had broken loose.

I've heard that it's possible to get the straps replaced, and this pressure plate has maybe 5000 miles, so it's something I'd consider if it's not too expensive.

Anyway, even given the vastly increased power of my motor, given the very short life of the clutch I wonder if there was some kind of defect.

I truly believe that I'm quite gentle on clutches. I've been driving stick almost exclusively for 20 years (more than half of my life) and I've never killed a clutch. I'm the only driver of the van, and in the time since I installed this clutch, there haven't been any incidents like hard clutch dumps, burning clutch, whatever.

But yeah, I guess I've been heavy on the accelerator, especially as I've been trying to keep timing and boost set right.

I can't believe how much power I'm getting with this Giles pump, new turbo (just a k03 but brand new and again set to 18 psi), and intercooler. And the power band is just fantastic -- I get 18 psi and great acceleration all the way through the power band.

The first strap must have broken before when I was running a modified but far less powerful pump, but I clearly broke a least one or two straps once I got this pump.

[MarkWard]

Compare the strap direction on both used pressure plates. They may be opposite. Using bolts instead of the rivets you can double up on the straps. You can also notch the stamped part so longer bolts act as stops.
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[zuhandenheit]

Thanks Mark. Sorry for the delayed update.

I'd like to upgrade the straps on the original pressure plate.

For now, I stuck in the LUK plate. It's running okay, but I'm getting a little shudder. The plate looked fine -- no signs of having been overheated or anything -- but I didn't have a good way to check for straightness.

I'll mess around with the Sachs plate and try to make something better. I've got that second Sachs plate and another from some maybe a Mitsubishi eclipse, which may have usable straps.

If anyone wants to drill the straps out of some old plates and send them to me, I'd be really super appreciative!!

It sucks to keep pulling the trans, but so it goes.