Engine Vibrations

[AussieBronco]

I haven't done any more work on troubleshooting it. I have been away for the last 3 weeks. I plan on replacing the harmonic balancer, then motor mounts and hopefully will yield some results. I'll definitely update with hopefully auccessful results. I also currently don't have have any accessories connected including the water pump.

 

[broncnaz]

If the motor mounts were that bad you would see the engine torque over when you tap the gas. It really would have showed up when you had the engine unhooked from the tranny.
Any other issues with the engine? noises ect? Stilll could be the wrong flywheel just that early on the balancer was keeping the vibration in check somewhat and 200 miles later the balancer can no longer keep the virbations in check. I'd probably replace both the flywheel and balancer then if vibration continues you know its internal which isnt good.

 

[AussieBronco]

I think I just had a break through tonight. I put a new distributor in and threw the timing light on it to make sure the timing was right. I went from it wanting to stall when retarted to wanting to stall when advanced and never saw any of the degree marks, so my new theory is that the outside ring on the harmonic balancer has moved from where it's supposed to be. I'll be getting a new one in the morning and will report back.

 

[DirtDonk]

What condition is the damper? Does the rubber look deteriorated? Is it original, or has it been replaced?
You should make sure the outer ring has moved first, then buy a new one. There are (or should be) "tick" marks that line up so they will show when an outer ring has slipped. So look for those telltales before spending money on something that might be fine.
Another reason to check first is that, if it's still ok, it might still be off. If the damper has ever been replaced, it could have been the wrong one for the engine. Ford has used several different timing pointer locations over the years, so make absolutely sure that yours is for a Bronco, and that your engine is from a Bronco.

Where is your timing pointer? Someone might be able to compare locations with a known-good Bronco engine.

Worth a shot anyway.
And when in doubt, pull the number one spark plug and make sure that the piston is coming up to TDC on the compression stroke (pressure past your finger over the plug hole) and then watch the piston top with a flashlight through the plug hole. When it gets near the top, watch for the marks on the damper to line up with the pointer.

Good luck.

Paul

 

[DirtDonk]

Nevermind. I re-read and see that it's out of a T-bird.
So make sure that the damper matches the T-bird application instead of the Bronco.

Sorry bout that. Forgot what we were working on.

Looking back at the picture of the damper, it sure looks good to me. Said that before, but didn't remember talking about it last month. I don't see any marks though, so bummer about that. Would have made it nice and easy to determine.
Is that the pointer just to the left and behind the damper? Looks the same type with the magnetic crank-trigger pickup like the Explorer uses. Is that the one that the engine came with? If that's the same pointer, and the same damper, then my theory about mis-matched components doesn't hold water. Bummer again. I was hoping it would be that simple.

Good luck.

Paul

 

[broncnaz]

Had a buddy with a 85 bronco that had the rubber come completely out of the balancer once. he comes to me and say my truck is making noise after I shut it off the engine. I go out and sure enough its making noise after its shut off then i see the ring just spinning arouund the balancer. but his engine didnt vibrate at least not at idle.
the outer ring and rubber is normally for higher RPM harmonics the main balance of the engine is built into the balancer hub on most balancers but some may have minor balance on the outer ring as well.

 

[DirtDonk]

Same thing with my friend's '75. But his had an automatic tranny, so perhaps the torque converter was able to dampen some of the harmonics too? At least that's what I suggested when we were trying to determine whether it was worth driving all the way home without the outer ring on. We did, and it had no vibrations or ill-effects.
Presumably your buddy's '85 was an auto as well?
Wonder if that can make the difference, as AussieBronco's is a manual trans.

Just thinkin' out loud. As usual.

Paul

 

[AussieBronco]

Yes that is the pointer just to the left of the of the top. I agree, it does look like the balancer is in reasonable condition. I have never pulled a balancer off, but I'm guessing there is a keyway on the crank and maybe something has happened there and it has rotated slightly. Anyway I need to borrow the balancer puller from checker anyway so I'll just pick a new balancer anyway, then compare the timing marks on the new one vs the old one before install the new one. At least this has given me some hope even if for only 18 hours!

 

[AussieBronco]

I got a new harmonic balancer yesterday and it fixed the vibration. I am so happy I got to the bottom of it. After removing the old balancer it appears that the outside ring was about to fall off. Thanks everyone for your help. I really appreciate all the ideas that the good people on this site provide.

 

[DirtDonk]

Well, just goes to show that looks can be deceiving! Your old damper's elastomer lining sure looked to be in better shape then most. And it sounds like it was not that old or high mileage a unit.
Usually these things last half of forever. Hmm, wonder if it got contaminated with something, like power steering or auto trans fluid?

Anyway, glad you got it licked. Now onward!

Paul