'98 TJ 4.0L Manual

Have developed a rattle somewhere in the engine. Has gotten
progressively more noticeable at idle and very low RPM. Just can't seem
to pinpoint it over the engine noise. Any typical problems I should
look for? Its not in the tranny since the noise can be heard at idle.
Water pump is new. Maybe the AC compressor bearings, but AC works
fine.

 

GTK wrote:
> '98 TJ 4.0L Manual
>
> Have developed a rattle somewhere in the engine. Has gotten
> progressively more noticeable at idle and very low RPM. Just can't
> seem to pinpoint it over the engine noise. Any typical problems I
> should look for? Its not in the tranny since the noise can be heard
> at idle. Water pump is new. Maybe the AC compressor bearings, but
> AC works fine.

AC compressor is tested by listening to it with the compressor off
and the compressor on. If the noise goes away with the compressor
on then it's the electric clutch. If the reverse, then it's the
compressor bearings.

Initial thought is a cracked exhaust manifold. Usually around the
lower collector or back on cyl 5/6.

How's the cat? is the rattle coming from it?

Also check the motor mounts to make sure they haven't gone byebye
and let the engine or exhaust rattle up against something.

--
DougW

 

GTK wrote:
> '98 TJ 4.0L Manual
>
> Have developed a rattle somewhere in the engine. Has gotten
> progressively more noticeable at idle and very low RPM. Just can't
> seem to pinpoint it over the engine noise. Any typical problems I
> should look for? Its not in the tranny since the noise can be heard
> at idle. Water pump is new. Maybe the AC compressor bearings, but
> AC works fine.

AC compressor is tested by listening to it with the compressor off
and the compressor on. If the noise goes away with the compressor
on then it's the electric clutch. If the reverse, then it's the
compressor bearings.

Initial thought is a cracked exhaust manifold. Usually around the
lower collector or back on cyl 5/6.

How's the cat? is the rattle coming from it?

Also check the motor mounts to make sure they haven't gone byebye
and let the engine or exhaust rattle up against something.

--
DougW

 

GTK wrote:
> '98 TJ 4.0L Manual
>
> Have developed a rattle somewhere in the engine. Has gotten
> progressively more noticeable at idle and very low RPM. Just can't
> seem to pinpoint it over the engine noise. Any typical problems I
> should look for? Its not in the tranny since the noise can be heard
> at idle. Water pump is new. Maybe the AC compressor bearings, but
> AC works fine.

AC compressor is tested by listening to it with the compressor off
and the compressor on. If the noise goes away with the compressor
on then it's the electric clutch. If the reverse, then it's the
compressor bearings.

Initial thought is a cracked exhaust manifold. Usually around the
lower collector or back on cyl 5/6.

How's the cat? is the rattle coming from it?

Also check the motor mounts to make sure they haven't gone byebye
and let the engine or exhaust rattle up against something.

--
DougW

 

That was my first thought... exhaust manifold.
-jenn


On Tue, 19 Sep 2006 20:36:49 -0500, "DougW" <post.replies@invalid.address> wrote:

>>Initial thought is a cracked exhaust manifold. Usually around the
>>lower collector or back on cyl 5/6.

 

That was my first thought... exhaust manifold.
-jenn


On Tue, 19 Sep 2006 20:36:49 -0500, "DougW" <post.replies@invalid.address> wrote:

>>Initial thought is a cracked exhaust manifold. Usually around the
>>lower collector or back on cyl 5/6.

 

That was my first thought... exhaust manifold.
-jenn


On Tue, 19 Sep 2006 20:36:49 -0500, "DougW" <post.replies@invalid.address> wrote:

>>Initial thought is a cracked exhaust manifold. Usually around the
>>lower collector or back on cyl 5/6.

 

The rad fan clutch will/can make a rattle when it fails.

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/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

GTK wrote:
>
> '98 TJ 4.0L Manual
>
> Have developed a rattle somewhere in the engine. Has gotten
> progressively more noticeable at idle and very low RPM. Just can't seem
> to pinpoint it over the engine noise. Any typical problems I should
> look for? Its not in the tranny since the noise can be heard at idle.
> Water pump is new. Maybe the AC compressor bearings, but AC works
> fine.

 

The rad fan clutch will/can make a rattle when it fails.

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/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

GTK wrote:
>
> '98 TJ 4.0L Manual
>
> Have developed a rattle somewhere in the engine. Has gotten
> progressively more noticeable at idle and very low RPM. Just can't seem
> to pinpoint it over the engine noise. Any typical problems I should
> look for? Its not in the tranny since the noise can be heard at idle.
> Water pump is new. Maybe the AC compressor bearings, but AC works
> fine.

 

The rad fan clutch will/can make a rattle when it fails.

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/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

GTK wrote:
>
> '98 TJ 4.0L Manual
>
> Have developed a rattle somewhere in the engine. Has gotten
> progressively more noticeable at idle and very low RPM. Just can't seem
> to pinpoint it over the engine noise. Any typical problems I should
> look for? Its not in the tranny since the noise can be heard at idle.
> Water pump is new. Maybe the AC compressor bearings, but AC works
> fine.