I have a knocking sound that comes and goes and is fairly quiet and usually presents itself when fully warm after a drive. It's about once every second. It is coming from the engine at the passenger end and sounds internal maybe, at least in top end. Valves? Bearings? Could my 1.8 roller rockers need adjustment? I remember the rocker noise being a lot lighter of a sound and faster. If it's not that what else could it be?

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2001 Bonneville SSEi. 1598xx mi.
great car. Wrecked


Burnt Bonny.

Note if you pull the injectors to obserbe fuel delivery...make sure you leave the plugs in and disconnect the ign. Believe me

Not sure if it could be the harmonic balancer, but it is an easy check. Just pull your belt loose (engine not running) and see if you can move or twist that thing at all. There should be no movement in it. Then start the car up and run it for just a short time (remember your water pump isn't working right now). See if there are any different noises or lack there of. This will at least let you eliminate some possibilities.

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1999 Bonneville SE with the heart of a 07 Grand Prix

viewtopic.php?f=19&t=25803

You didn't answer all these questions, particularly whether it's vehicle speed related or engine RPM related. Your oil pressure would be a help also. You're not really giving us anything to go on at all.


If it's only at idle, and goes away as you nudge the throttle, it's the harmonic balancer. If not, it's probably the motor if it's rpm related. The rockers don't need (nor is there any) adjustment. I assumed you would know this since you are the one that installed them.

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Comprehensive guide to troubleshooting, rebuilding, and modifying Eaton Superchargers

I haven't checked on whether it varies with engine speed or not. I will do that next time I hear it. I've only heard it while parked. I do NOT have the Supercharger and so I don't think I have a harmonic balancer. My oil pressure is fine. It varies between 40 and about 90.

I will listen more carefully for the RPM related concern the next time I hear it.

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2001 Bonneville SSEi. 1598xx mi.
great car. Wrecked


Burnt Bonny.

Note if you pull the injectors to obserbe fuel delivery...make sure you leave the plugs in and disconnect the ign. Believe me

Every engine has a harmonic balancer, on these cars it also serves as the crank pulley. I do not know of a single engine that can survive without some sort of balancer...

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Bye Bye:

RIP sandrock

Chris, I'm very well aware of the fact that you have an L27 with no supercharger.

Your harmonic balancer is right below your water pump. The rubber erodes, allowing the inner and outer halves to clank. It's more of a clatter than a knock though, and if it doesn't go away as you tip into the throttle in idle, it's the motor, not the balancer.

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93 SSEi, 95 SLE (supercharged) 97 Buick LeSabre Limited
PontiacDad at WCBF '04: Cruise control? That's like surrendering!
Comprehensive guide to troubleshooting, rebuilding, and modifying Eaton Superchargers

Well I feel ignorant. I helped rebuild a couple motors as a kid but I don't remember hearing anything about it. Is there a thread that discusses the complete operation of these motors? I will have to search and read the FSM too.

Wasn't doing it today. The sound I remember sounded more of a knock. I will look at the HB tomorrow in the light.

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2001 Bonneville SSEi. 1598xx mi.
great car. Wrecked


Burnt Bonny.

Note if you pull the injectors to obserbe fuel delivery...make sure you leave the plugs in and disconnect the ign. Believe me

Pull on the belt. The harmonic balancer shouldn't move more than 1 or 2 degrees. If it doesn't move and doesn't make any noise, it's the motor or something else mechanical. Most likely the motor itself due to the noise being at idle and not moving. That rules out steering and suspension, as well as transmission.

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Click here for mod list for both cars
93 SSEi, 95 SLE (supercharged) 97 Buick LeSabre Limited
PontiacDad at WCBF '04: Cruise control? That's like surrendering!
Comprehensive guide to troubleshooting, rebuilding, and modifying Eaton Superchargers

I had the noise again after my road trip. It was 140 mi on Wa State fwy. So it was like 75-95 throughout the drive. When I pulled into the store the sound was present. I didn't check for exactly where the noise was coming from, but just tapped the accelerator and it disappeared. I'm gonna finally pull the belt and check the HB as soon as the snow stops or as soon as I can get out there anyway.

I was pricing a new HB at about $70 rockauto.com. They also have available an HB repair sleeve. Will either or both of these fix my HB if that's the problem? And how involved are both of these repair procedures?

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2001 Bonneville SSEi. 1598xx mi.
great car. Wrecked


Burnt Bonny.

Note if you pull the injectors to obserbe fuel delivery...make sure you leave the plugs in and disconnect the ign. Believe me

The repair sleeve is to fix a worn shaft where the front seal rides to stop an oil leak. Nothing to do with the worn rubber.

I thought this would be simple check. With the belt on I get movement of the HB pulley. About a inch+ belt travel until the crank is too hard to turn. With the belt off the HB still turns until the crank is too hard to turn. As far as top to bottom and side to side movement there is no discernable movement.

The sound is only after coming to a stop to idle shortly after sustained RPMs/Speeds and a touch of throttle clears it. It sounds from or behind water pump / HB area

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2001 Bonneville SSEi. 1598xx mi.
great car. Wrecked


Burnt Bonny.

Note if you pull the injectors to obserbe fuel delivery...make sure you leave the plugs in and disconnect the ign. Believe me

With the belt off, the HB should not turn BY HAND. Don't expect rocket science. It should be rigid. Visually inspect the face of it for cracks in the rubber around the outer perimeter just under the edge of the belt grooves. This is a 5-minute diagnosis that should have been done a month ago.

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93 SSEi, 95 SLE (supercharged) 97 Buick LeSabre Limited
PontiacDad at WCBF '04: Cruise control? That's like surrendering!
Comprehensive guide to troubleshooting, rebuilding, and modifying Eaton Superchargers

You don't want to turn the HB far enough to turn the crank, just try to rock it back and forth and see if there's anymovement to the HB before engaging the crank.

While you had the belt off did you check for play in any of the accessories?

Also, when you say a touch of the throttle clears it, do you mean that if you touch the throttle and let off the noise is gone, or does it come back when you let off?

Thanks for making this clearer. Before I was thinking the rubber was in between the front and rear HB faces and I couldn't find it. The Rubber is in tact on the front face with no deterioration or cracks. No doubt about it though: with belt off I can turn the HB 1/4 turn or so by hand. Again I get no wobbly motion, just rotation around the crank shaft axis

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2001 Bonneville SSEi. 1598xx mi.
great car. Wrecked


Burnt Bonny.

Note if you pull the injectors to obserbe fuel delivery...make sure you leave the plugs in and disconnect the ign. Believe me

that's what I wanted to know movement w/o engaging the crank- I don't thinks so. I think the movement I feel is with the crank engaged- I'll check again

I will check the other accessories at that time.


The throttle kills it, it does not come back. This indicates HB and not internals?

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2001 Bonneville SSEi. 1598xx mi.
great car. Wrecked


Burnt Bonny.

Note if you pull the injectors to obserbe fuel delivery...make sure you leave the plugs in and disconnect the ign. Believe me

[/quote]

that's what I wanted to know movement w/o engaging the crank- I don't thinks so. I think the movement I feel is with the crank engaged- I'll check again

I will check the other accessories at that time.


The throttle kills it, it does not come back. This indicates HB and not internals?

Also after rereading Will's post I think I need to further check under the lip of the HB rim to see if the rubber there has deteriorated.

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2001 Bonneville SSEi. 1598xx mi.
great car. Wrecked


Burnt Bonny.

Note if you pull the injectors to obserbe fuel delivery...make sure you leave the plugs in and disconnect the ign. Believe me

There was no HB freeplay at least with the belt on.

None of the accessory pulleys seemed to be loose.

I could not get a good enough look at the rubber under the rim of the HB Pulley to see if it has deteriorated

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2001 Bonneville SSEi. 1598xx mi.
great car. Wrecked


Burnt Bonny.

Note if you pull the injectors to obserbe fuel delivery...make sure you leave the plugs in and disconnect the ign. Believe me

Noisey at idle and goes away when accelerating - y/n
noise goes away at idle with belt removed - y/n
you can turn the outer pulley by hand and the crank does not turn (with the belt off) - y/n

If you answer yes to all 3 of those, I will put my money on the HB being bad. Is it bad to runit like that, no, but it will only get worse. You can also get them from the Pick and Pull pretty cheap if you are low on cash, but do not expect it to last 100k.

You're not getting it. If the HB is moving that far, it's bad. Forget your other accessories if the HB is doing that with the belt off. Think about it for a minute.

And your rubber is NOT intact if the HB is moving that far. You're missing the rubber separation around the outer edge. It's a crack you're seeing, not a dark line.

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Click here for mod list for both cars
93 SSEi, 95 SLE (supercharged) 97 Buick LeSabre Limited
PontiacDad at WCBF '04: Cruise control? That's like surrendering!
Comprehensive guide to troubleshooting, rebuilding, and modifying Eaton Superchargers

Y, unknown, N

It seems very clear to me about the movement of the HB. There is NO freeplay. It moves with much force and it is obvious it is turning the crank right off.

The only time I get the knocking noise is at idle after hard long distance driving. As such it makes it difficult to check things. Like I can't kill the motor, remove the belt and retest. Just touching the accelerator kills it and it doesn't come back.

I think it's a bearing or something, but I will (today or tomorrow) recheck for free play again. With my motor sick I cringe at running hard down the freeway 50 miles

_________________
2001 Bonneville SSEi. 1598xx mi.
great car. Wrecked


Burnt Bonny.

Note if you pull the injectors to obserbe fuel delivery...make sure you leave the plugs in and disconnect the ign. Believe me