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.


Re: Loud grinding on start-up
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=2115147590
(More Off Road album links at bottom of the view page)

Micah wrote:
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Re: Loud grinding on start-up
How about a sticky bendix drive?


Mike Romain wrote:
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Re: Loud grinding on start-up
     Ditto. Although it's a combination of solenoid and ratchet, now.
Whatever they call it.
        God Bless America, Bill O|||||||O
mailto:LWHughes3rd@aol.com http://www.billhughes.com /

Jon wrote:
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Re: Loud grinding on start-up
Micah wrote:

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It sounds like you ass-umed wrong.

Re: Loud grinding on start-up
On Wed, 20 Dec 2006 16:41:15 -0800, Micah wrote:

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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.

--

Re: Loud grinding on start-up
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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Re: Loud grinding on start-up
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.

--
Simon
"I may be wrong, but I'm not uncertain." -- Robert A. Heinlein

Re: Loud grinding on start-up
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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Re: Loud grinding on start-up
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:

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--

Re: Loud grinding on start-up
Micah wrote:

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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.

Re: Loud grinding on start-up
Outatime wrote:
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You're both ASSUMING it's the transmission for no good reason.

--
Simon
"I may be wrong, but I'm not uncertain." -- Robert A. Heinlein

Re: Loud grinding on start-up
Simon Juncal wrote:

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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.

Re: Loud grinding on start-up
Outatime wrote:
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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=2115147590
(More Off Road album links at bottom of the view page)

Re: Loud grinding on start-up
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The pilot bearing and the clutch throwout bearing are two different
things; I was referring to the throwout bearing.

Re: Loud grinding on start-up
Outatime wrote:
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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=2115147590
(More Off Road album links at bottom of the view page)

Re: Loud grinding on start-up
Mike Romain wrote:

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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.

Re: Loud grinding on start-up
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=2115147590
(More Off Road album links at bottom of the view page)

Outatime wrote:
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Re: Loud grinding on start-up
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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Re: Loud grinding on start-up
Micah wrote:

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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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