Rattle Rattle Rattle

[BumbleBeat]

More info on rattle #2. Complete description:

After fully, fully warmed up (15 minutes or so; probably 5 minutes after up to full operating temperature) I start getting a nasty rattle. It's in time with the engine rpm. Higher pitch than a rod knock, more of a clack. It comes on slowly, getting louder and louder the longer you drive it. It first begins in the 4500rpm range, but the range gets wider and wider the longer you drive it. It's at it worst when driving a constant speed. A slight amount of throttle makes it stop, as does just letting off the throttle. 20 minutes or so after it starts it's almost constant, doesn't get quiet with throttle trickery. Thinking it might be pre-ignition, I checked the timing (which was on the money), then retarded it a good 10 degrees to be sure it couldn't pre-ignite. No change in rattle so ruled that out (and set timing back to normal). After quite a bit of test driving I found that it only happens with the clutch engaged. Once fully warm and full-time rattle, at any speed and any gear I can push in the clutch and rev the rpms up and down and no rattle that I can detect. I'm now thinking pilot bearing or clutch release bearing for several reasons:

-When clutch is disengaged (no noise) there's no load on the pilot to make it shake, and the throwout bearing is being squeezed, preventing it from rattling.
-It's at it's loudest when maintaining constant speed or very slight deceleration, when the drivetrain is at is lightest load. Enough to start a rattle, but not enough to hold things in place.
-Clutch engaged, lift off of throttle increases the load on the drivetrain, and the noise goes away. Now enough load on the pilot to keep it from rattling.
-Clutch engaged, add throttle also increases the load on the drivetrain, noise goes away. Again, enough load on the pilot to keep it from rattling.
-The noise is in time with engine rpm

I'm not sure which is the more likely culprit--the clutch release bearing or the pilot bearing. Are either (or both) common noise problems with Beats?

[Seventynine]

what's your valve clearances like?

I'd give the head a once over, check for stuck/sticky valves. clearances. get the intake off and check to see if they're all closing fully.

also, when you say "more of a clack" would make me think a blowing exhaust close to the head, check manifold/gaskets etc.

what colour were the plugs when you took them out? if it's running slightly lean you could have burnt an exhaust manifold gasket out

[BumbleBeat]

Thanks 79. Haven't had the valve cover off yet. Plugs are dark, rich if anything. Don't know how old they are, just got the car. The thing about valvetrain, I can't see how valve noise would occur when driving in gear, but not occur by just revving the engine to the same rpm while not it gear.

[Andrew Fisher]

Both Beats I've had have had an annoying rattle at about 2800 - 3000 rpm, especially on increasing revs. The only cure is driving it harder so the period affected lasts less.

Very annoying in slow traffic. Sorry can't help more sounds like a clutch issue (problem 2) to me.

Good luck! The other option is to get a VERY LOUD STEREO.

[BumbleBeat]

Thanks Andrew. I'm thinking all 3. Clutch, loud stereo, drive hard. That should do it.

[old'uns]

mines had a 'rattle' or 'whine' of some sorts for 3-4 yrs now.
i've always thought it's backlash or worn bearings in the 'box?
when replacing the aux belts i spun the alternator and AC by hand, nothing too loud to suggest bearings on those

loud stereo is a good call .....new HU, new component door speakers along with tweeters in pods alongside 2 other smaller ones and a big black box behind the passenger seat sorted it........

[Andrew Fisher]

(You must understand, I know nothing)

At least it's on the transmission side. Are you sure it's not something like a cv joint boot clip or something getting physically free and spinning round and clattering on something?

Has the car been used much? I found that the latest one I've got had hardly done anything or been properly lubricated for ages, and it loosened up quite well with a bit of honest use.

Please post some more pictures! I think you could fit two in the back of your truck.

[BumbleBeat]

Ha ha old'uns, it probably doesn't take a lot of stereo to be head banging loud with such a small interior!

Andrew, I don't think it could be cv joint related because it tracks with engine rpm, not kph. I have a clutch on order, we'll see what she looks like when I open her up.

[Seventynine]

Thanks 79. Haven't had the valve cover off yet. Plugs are dark, rich if anything. Don't know how old they are, just got the car. The thing about valvetrain, I can't see how valve noise would occur when driving in gear, but not occur by just revving the engine to the same rpm while not it gear.

Engine load

[BumbleBeat]

The load doesn't change appreciably on the valve train. Note, too, that the rattle occurs under light load. Heavy throttle (load) takes it away, but it also goes away by coasting in gear. It seems to me it has to be clutch or transmission. Both of those see an increased load whether by increasing the throttle or lifting the throttle. When lifting, the load is backwards--the tires are forcing the transmission to spin against an engine that doesn't want to. I'll find out soon I expect, I'm almost done with the clutch replacement....

[BumbleBeat]

The clutch is in. The first rattle is gone, the second one (the scary one) is not, sigh. Once I saw the clutch I didn't expect it to fix the second one. The four compression spring in the disk were loose (the normal cause of the annoying rattle), but everything else was solid. The input shaft to the transmission was also solid, I couldn't detect any play in it. Not sure where I'll look next.

[old'uns]

not many things left then?
AC compressor / alternator bearings
layshaft/end bearings etc in the box of magic tricks