From: Pirtle, John [John.Pirtle@ceridian.com] Sent: Tuesday, July 17, 2001 7:38 AM To: 928 Subject: [928] engine marbles? I've got a marble rattle going on too - can't figure it out. 87 a/t 125k miles. It sounds like marbles or nuts and bolts are rattling around inside the rear bottom of the engine, yet at times it seems to be coming from the torque converter in the rear. Here is a time line - Mid-November - t-belt job, no problems. Jan 1 - installed catbypass. Also did the torque tube/flywheel/pinchbolt procedure for the thrust bearing (and I made sure to move the flywheel rearward before tightening up). March - started to notice the noise on shutdown. At first it was a quick grumble as though an exhaust shield or something was loose. I never could find anything... By May the rattles started showing up at idle. This is whether the engine is hot or cold. Engine temp makes no difference. June 1 - replaced motor mounts. Never found anything loose or touching exhaust/etc to make such a noise. Plus changed oil (mobil 1). Mid-June - replaced a/t fluid, never found anything in the rear to make noise. Last weekend - pulled off the flywheel housing and everything seems tight. Pinchbolt is exactly where I left it 7 months ago. Put the catalytic converter back on, checked all over for anything. All is tight. Rattle really seems to be coming from inside the lower rear engine.... ?? Rattle very *rarely* occurs if I'm in gear. Car drives normally, idles smoothly. Sound does not appear to come from top valvetrain area. It's down low and the back. Any ideas (besides a new engine!) ??? John Pirtle Atlanta 87 Auto http://members.rennlist.com/pirtle http://www.928oc.org From: Jim Bailey [jim@928intl.com] Sent: Wednesday, July 18, 2001 2:00 PM To: 928 Subject: [928] RE: engine marbles? The rivets that get loose are on the torque converter flex plate inside the transmission bell housing used on approximately 86-early 87 only - before and after and the "fix "is to drill out the rivets and use bolts........ the rivets or bolts attach the flat sheet metal flex plate to the splined hub which clamps to the driveshaft at the front of the transmission.. From: Plastow, Colin [Colin.Plastow@fluke.com] Sent: Thursday, July 19, 2001 2:47 PM To: 928 Subject: [928] RE: engine marbles? Somewhere I have a copy of the Porsche service note on the loose rivet problem. If memory serves its applicable for 85 through 87. My 85 has the rivets. I had a similar problem a few years back which turned out to be corrosion on the torque tube spline not allowing the sleeve to clamp down correctly. I would get a rattle at idle but it was more pronounced when the ignition was switched off and the motor came to a stop. This, according to a Porsche tech, is typical of the loose rivet problem so it doesn't really sound like its the problem at hand. One other thing the tech mentioned was that the gearbox input bearing (or bearings?) should be changed when replacing the TT. He said they often get a bit noisy and it was cheap insurance. I wonder if that could be the problem? Colin From: Pirtle, John [John.Pirtle@ceridian.com] Sent: Sunday, September 02, 2001 6:35 PM To: 928 Subject: [928] engine marbles update About a month ago I posted on my developing engine marbles (87 a/t 127k) - this rattle-y noise like loose nuts and bolts occurred mostly at shutdown but progressed so that it was present often at idle. Some of you mentioned this noise preceded your torque tube replacement. Some others brought up a rivet problem where the rear flex/drive plate connects to the torque converter, and I pretty much decided that was my problem. The noise was definitely coming from the torque converter area, and traveling forward in the torque tube. Not looking too fondly to this big job.... Last weekend I got under the car, removed the exhaust and heat shields, and removed the front flywheel/flexplate cover. There is an access hole at the front bottom of the torque converter for the 6 bolts on the drive/flex plate. These should be torqued to 34 ftlb and all seemed fine but I "snugged" them anyway. (I used a screwdriver to turn the flywheel to move the torque converter bolts into position.) At the same time I checked all the bolts up front at the flexplate. The 8 bolts in the center of the triangular flexplate were very tight, but I "moved" them (barely) to make sure they were tight. Same with the 6 outlying bolts on the flexplate. I really couldn't tighten them but managed to budge them tighter. The last thing I checked was the rear torque shaft pinchbolt - there is an access hole in the torque tube. The manual calls for 54-61 ftlb, but I went with Tony's 66 ftlb on my torque wrench (Tony - thumbs up on the website drop boxes!). I started turning, the bolt was pretty tight but it didn't click. I turned again with some muscle... no click. Then came the nerves... is this right? I'm not gonna pop this bolt am I?? Check the wrench torque setting. Turn a little more very slowly. No click. Oh Dear Lord this is a nightmare. Stop, rest, take some calming breaths, pray, give it another small turn. Click. About time!! (This is where you get up and run away before your shark bites you - haha.) Put everything back together - no noise !! I drove the car to work three days last week, and also ran an errand or two. Now when I turn the key off, the engine just shuts down - no rattle-bag of marbles!!! Whew! Glad I didn't drop the rear-end, the transmission, etc!!! SO, I suggest you guys check your rear torque shaft pinchbolt (after you check the forward pinchbolt). BUT I'd really appreciate any thoughts on this - I've got no real clue about the actual cause of the noise. !?? John Pirtle 87 a/t 127k (a quiet car is a happy car, and mine is happier) http://members.rennlist.com/pirtle > -----Original Message----- > From: tom falkenberg [mailto:shaaark89@hotmail.com] > Sent: Monday, September 03, 2001 8:14 AM > To: john.pirtle@ceridian.com; 928@rennlist.org > Subject: Re: [928] engine marbles update > > > john, > when i checked my rear pinchbolt a few months back, it was way loose plus > the threads were worn down/stripped in the area that sits in the notch of > the driveshaft. replaced/torqued/loctited. i had no marble noise though. > could it have been coming from the exhaust/heat sheilds since you removed > and replaced them? > tom > 89 s4 > shaaark > ----- Original Message ----- From: "Pirtle, John" To: "928" <928@rennlist.org> Sent: Monday, September 03, 2001 11:34 AM Subject: [928] RE: engine marbles update > nah - this was a "hard" noise. Think of large marbles made of steel! It > seemed to come out of the torque converter casing. I could feel it (maybe > in my mind) by holding a metal pipe to the casing. Something was definitely > knocking around. > > All I can come up with is the loose pinchbolt allowed the torque shaft to > play so much in the drive flange (the coupling sleeve) that the shaft end > was actually knocking on the sides at very low rpm. > > Check those rear pinchbolts fellas! > > Anyone ever have the rear pinchbolt come so loose that it was no longer > coupled to the trans?? Or does something fail catastrophically before that > point? > > John Pirtle > 87 a/t 127k > http://members.rennlist.com/pirtle > > > From: Kevin Berez [kaberez@mindspring.com] Sent: Monday, September 03, 2001 11:52 AM To: 928 Subject: [928] RE: engine marbles update John, The marbles sound is exactly the sound that came from Valur's car. Turned out the TT splines were flattened and the sleeve on the front flex plate was shattered. A previous mechanic had tack welded the locking collar onto the flex plate sleeve. What a mess. I'd take a very good look at the TT splines because the marbles sound could have been the sound of the TT shaft rattling inside the sleeve. Kevin From: Martin Minnich [martin_minnich@hotmail.com] Sent: Monday, September 03, 2001 12:37 PM To: 928 Subject: [928] RE: engine marbles update I suspect that a loose pinchbolt was partly (?) to blame for my driveshaft rotating in the input shaft to the gearbox, and subsequently failing. Hard to explain how my splines got so worn down if everything was properly snugged. Marty -----Original Message----- From: Paul Jager [mailto:pjager@mnrcan.com] Sent: Monday, February 25, 2002 12:27 PM To: john.pirtle@rennlist.com Subject: Marbles sound Hi John, Your web site is developing into a 928 superstar. Looks great. I was investigating a TT rattle for an S4 that was getting worse daily so I checked the rear pinch and it was loose too! I wonder how many are out there with this problem. Sounds great now. My 87S4 did the same thing and I ended up replacing the entire driveline a year ago, albeit with a POSI trans, low miles parts etc. Might have been just that. Anyway it was your suggestion that got me to go and give it a try - thanks. To explain marbles - a hard connection at the front, and loose at the rear, the shaft is allowed to “wobble” in the support bearings, crashing the balls into the races, giving the marbles sound. Sounds like marbles is like marbles. As soon as you put it in “D” the shaft is loaded and the connection at the rear firms up on one side of the splines and pinch groove. Also temperature plays a part – the bearing clearances decrease and the engine is smoother so the rattling is sometimes less pronounced. If both pinch bolts are at spec, and the sound is still there, there must be excess clearance in the TT Bearings, which occurs due to wear. Regards, Paul Jager.