Loud grinding on start-up

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258 YJ, Peugeot trans. When I start it cold, I get a loud metallic grinding sound. Rev the engine to 2,000 RPMs for a couple seconds and it goes away. Sounds like it could 'possibly' be coming from the pilot bearing. I replaced my clutch this spring but left the pilot bearing alone because i didn't have a puller and the clutch I had in there only had 20k or so miles on it. Assumed it would still be OK. Anyway, if I start the engine warm, no sound. Looked at the Haynes troubleshooting section, no mention of such a sound. Tried starting it cold in neutral with the clutch engaged with the same results. Thoughts? Thanks.

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If it makes noise when the clutch is engauged, it isn't the bearing because it isn't moving then.

I would suspect a loose pressure plate bolt maybe.

Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id !15147590 (More Off Road album links at bottom of the view page)

Micah wrote:

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How about a sticky bendix drive?

Mike Romain wrote:

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Ditto. Although it's a combination of solenoid and ratchet, now. Whatever they call it. God Bless America, Bill O|||||||O mailto: snipped-for-privacy@aol.com http://www.billhughes.com /

Jon wrote:

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Micah wrote:

It sounds like you ass-umed wrong.

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On Wed, 20 Dec 2006 16:41:15 -0800, Micah wrote:

My BA10 had the same noises. They got progressively louder until I pulled it to swap in an AX15. The thrust bearings on the input shaft had given up and the noise was the input gear grinding on the slinger washer. Needed the input shaft for a clutch alignment tool, didn't bother re-assembling the rest before trashing it. I'm no fan of the puny French 5-spd.

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That sounds like it. Guess I'll start looking for an AX-15. I've wanted one ever since day 2 of owning my YJ when I found out my transmission was made by the French.

And since the general consensus is it's not my pilot bearing, I guess I ASS-UMED right.

Thanks guys. Will Honea wrote:

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Why are you looking for trans problems? I've re-read your post and nothing in it suggest the transmission is making a noise... what happens when you start it out of gear without the clutch depressed? If it has clutch start then disable it.

I would be looking at the starter, and the fan clutch and work my way in from there.

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Simon
"I may be wrong, but I'm not uncertain." -- Robert A. Heinlein
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I'm siding with Simon, here -- you've absolutely ruled out the pilot bearing by starting in neutral with clutch engaged. You'll absolutely rule out the transmission if the noise occurs when starting in gear, clutch disengaged.

Simon Juncal wrote:

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With that BA10, you really should do one more step: tc in neutral, transmission in various gears. There are some strange interference possibilities in the BA10 if the thrust spacing is buggered. That should pretty well eliminate the transmission.

BTW, the BA10 - AX15 swap is NOT a drop-in swap! Do a little research before you start it. All sorts of bits and pieces get involved, some being real PITA stuff - like the transfer case input shaft and the pilot bearing.

On Thu, 21 Dec 2006 07:52:53 -0800, Jon wrote:

--
Will Honea < snipped-for-privacy@yahoo.com>

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Micah wrote:

I see no evidence to indicate that your TO bearing could not be ultimately at fault.

ASS-UMING anything is never a good thing. I say a teardown is in order.

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Outatime wrote:

You're both ASSUMING it's the transmission for no good reason.

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Simon
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Simon Juncal wrote:

You have a point, Simon. It's as good a place as any to start I suppose. Back in the good old days, we used a screwdriver or piece of rubber hose up against a suspect part to find out exactly where a noise was comming from. The ear doesn't work neary as well as it should for this sort of work.

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Outatime wrote:

The pilot bearing 'cannot' be the problem because the noise exists with the clutch pedal up which means the pilot bearing is 'not' in use at that time.

The pilot bearing only spins when the clutch is depressed, otherwise it is fixed solid to the clutch.

A bolt coming loose from the pressure plate after a clutch re+re is not unusual at all though....

Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id !15147590 (More Off Road album links at bottom of the view page)

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The pilot bearing and the clutch throwout bearing are two different things; I was referring to the throwout bearing.

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Outatime wrote:

The throw out also isn't supposed to be turning when the clutch pedal is out.

Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id !15147590 (More Off Road album links at bottom of the view page)

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Mike Romain wrote:

Unless there is a lot of freeplay, it normally does; most self-adjusting clutch release assemblies keep lateral loads to a minimum while minimizing freeplay, which usually spins the bearing without a load when the clutch is fully engaged. Most TO bearing problems I run into in commercial vehicles make noise regardless of pedal positioning.

The sound that a dry/pitted TO roller bearing makes is very distinct. We normally lube TO bearings from underneath the bellhousing when clutch freeplay is adjusted (usu. every 10K miles or so), but most mechanics are too lazy to bother these days. Their redemption comes in the form of a complete clutch assembly replacement on a weekend they would normally have off.

All of the armchair quarterbacking here can't replace disassembly and inspection, which is what I recommend.

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If you spin the throwout bearing on a Jeep, it will fast burn a hole in the front bearing cap or seal cover or 'nose' of the cover. It will then hang and burn all the fingers off the pressure plate.

This was a common problem with the mechanical linkages if they were not adjusted correctly. If they were too tight or if someone used the clutch pedal as a foot rest, good bye pressure plate and tranny nose. (bearing cap) Common enough failure, that the local Jeep shops even stock new bearing caps...

There is no adjustment on the new hydraulic systems so if he has throw out bearing noise, his new clutch was incorrectly put together or they used the wrong parts.

When I hear his symptoms on a new clutch, I think loose pressure plate bolt or even a loose starter.

I have also seen bad noises happen on start up just before the transmission falls out of the Jeep because the installer forgot to torque the bellhousing bolts.

Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id !15147590 (More Off Road album links at bottom of the view page)

Outatime wrote:

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my starter and all bellhousing bolts are torqued to whatever spec is listed in the haynes manual. you guys i believe are right, now that i think about it it makes sense that the clutch engaged proves it's not the pilot bearing... and clutch disengaged with transmission in gear proves transmission is fine... which seems to be the case.

if it was the throwout bearing, i'd kill someone, my last one went bad after 18 months, that's why i had to replace the clutch in the first place. My clutch, by the way, is hydraulic, not mechanical.

I still haven't found the cause. one of these days I'll get a friend over to start the engine while i try to locate the source of the noise... it usually doesn't last long enough for me to clamber out and start prodding around.

Thanks for the suggestions. Mike Romain wrote:

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Micah wrote:

I've replaced TO bearings with high-quality Timkens in the past and had them croak again within 6 months. The bearings I bought were aftermarket units however, and I truly believe that most anything 'aftermarket' these days isn't worth installing, even if it has a lifetime-warranty; what's the point of a warranty if you have to tear it down again every year to replace those 'free replacement' junk parts?

If you have to do it all over again, stick with OEM-sourced parts only. I've heard arguments pro and con on this one over the years. Even if aftermarket parts are cheaper and supposedly very high quality, the aggrivation factor alone demands that I use only OEM parts from now on. And that includes (especially!) remans, however, I never install a reman-anything unless absolutely necessasary; go with new parts whenever possible, even if it costs 10X more.

I'm curious what it ends up being however; my money is still on the TO.

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