1985 Thunderbird Harmonic Balancer

[melfan]

I have a 1985 Thunderbird with 3.8 v6 that the Harmonic Balancer went out (actually the rubber gasket did). I purchased an after market balancer and there was a vibration.

My mechanic indicated the Harmonic Balancer might not be balanced correctly, so I purchased another one. That seemed to fix it about 95% but the vibration is still there in the 1,000-2,000 RPM range. Not bad, but any vibration is not good. The vibration is at idle and while driving. No change in vibration, no better, no worse as speed increases. Vibration stops after about 2,000 RPM/40-45 MPH. But light pedal it's there.

The question is, is there anything else I should check before bitching to the manufacturer of the Harmonic Balancer?

I checked all the vacuum hoses, fresh tune up, Q/C from top to bottom, no problems.

The engine has about 12,000 miles on a jasper reman.

I was concerned it could be the crankshaft but I figured that would cause a vibration at idle and would get worse.

[stickysilvertbird]

you right if it was your crankshaft it wouldve gotten alot worse by now. i know it sounds stupid but check your main bearings. sometimes bad bearing cause a vibration that doesnt go away no matter what you do. also does it make a sort of whistling (if u had the hood open with the car running)?
btw i love you sig. so very true.. i agree lol

[melfan]

Nope, no whistling sound. My mechanic seems to think there is no way the bearing is bad. BTW, he did the engine swap and does every repair on this car so he should show my car well.

But, could a bearing go bad this soon? The rebuild (swap) was done about 3 years ago, and there is only about 15,000 miles on that. My wife only drives it to work and back and it sits most of the time.

A person from Advanced Auto suggested separating the flex plate from the flywheel, not sure what that would do???

I can't help but blame the balancer because it only vibrated in the certain "harmonic" range around 1,500 RPMs. My mechanic agrees but there is no way to test my theory.

The only other minor item is it runs a bit rough when it cold and acts like the idle is very low and wants to stall but after it warms up it's fine.

The other item is, it still has no power. You punch the gas and it doesn't have the response it should. I am considering getting the injectors replaced, THAT will make everything new except the intake.

Thanks
Mark

[stickysilvertbird]

have you checked that you gasket is seated right? if its not it could be making the HB wobble slightly. also have you tryed puting the original HB on it since you replaced the gasket? after 15k i would say it'd be safe to check your bearings but at that low i should think there wouldnt be much (if any) wearing on it, altho i have been known to be wrong. as for the flex plate & flywheel theory its plausible. if you flexplate is loose it Will ratle and smack againts your flywheel. idk if youve ever had this happen but it sounds sort of like the welds on the heatsheilds on the catalytic converter are broken off on one side and its rattling against the cat and floor board. it sounds almost exactly the same. also that would be a good idea. chck the topside heatsheilds on all 3 cats.. hope this helps you

[rhandwor]

Did you have any balance problems before the new harmonic balancer. Sometimes you find them when trying to set the timing. This could be your poor performance problem.
Did you buy a quality harmonic balancer. You could try one from a junk yard.

[melfan]

could you look at my new thread?

http://www.automotiveforums.com/vbul...d.php?t=895694

Could this be related?

[rhandwor]

Yes the problems can be related. Can you move the harmonic balancer pulley back and forth. A bad thrust bearing will allow the crankshaft to move back and forth long ways on the crankshaft. With the vehicle on 4 jack stands can you observe movement in the harmonic balancer pulley with the engine running. Were all spacers installed when you changed the pulleys. Lay a straight edge across the pulleys is it sitting flat. Was the key for the crankshaft installed when the harmonic balancer was installed. Is it tightened properly and without the sprout disconnected will it time properly.
If the problem started immediately after installing the new harmonic balancer I would start by checking the part number with Ford.

[melfan]

Originally Posted by rhandwor

Yes the problems can be related. Can you move the harmonic balancer pulley back and forth. A bad thrust bearing will allow the crankshaft to move back and forth long ways on the crankshaft. With the vehicle on 4 jack stands can you observe movement in the harmonic balancer pulley with the engine running. Were all spacers installed when you changed the pulleys. Lay a straight edge across the pulleys is it sitting flat. Was the key for the crankshaft installed when the harmonic balancer was installed. Is it tightened properly and without the sprout disconnected will it time properly.
If the problem started immediately after installing the new harmonic balancer I would start by checking the part number with Ford.

I can not move the balance at all. Everything tracks fine. The key is there, I can see it on one of the nuts. The belts trask fine, no vibration or "wobble" at all. I will ask about the spacres when I see my mechanic.

If the main bearing is bad wouldn't it make the noise even with the belts off?

The reason I wonder it is even relate is when the belt is removed the engine runs fine. It only squeaks when the belt is installed.

I have replace these items many. many time before and neve had this problem.

Thanks,
Mark

[rhandwor]

With the belts off spin and listen or feel for any rough alternator,water pump,power steering pump,idler bearing on the air compressor. You have some sort of problem so go slow and check out for any problem. I'm sure you can find it if you take your time. A compressor can cause problems turning off and on this is a common problem on these vehicles.

[melfan]

Originally Posted by rhandwor

With the belts off spin and listen or feel for any rough alternator,water pump,power steering pump,idler bearing on the air compressor. You have some sort of problem so go slow and check out for any problem. I'm sure you can find it if you take your time. A compressor can cause problems turning off and on this is a common problem on these vehicles.

OK, this is getting frustrating. The noise went away. I changed the belt, AGAIN, and the squeak went away as well.

There is still a vibration and I, for the life of me can't figure it out.

I removed the belts, started the car and all seems fine, a funny noise form the motor but I think that is just because the vacuum pump (EAS Pump or Air supply pump) is not hooked up when belt is off. All the pulleys seem fine except for the Air pump, it does make a strange noise when I turn the pulley, sort of a rubbing noise, not there when engine runs. Could this cause a vibration if going bad? These are cheap and easy to replace.

Is there anything else you can think of that may cause a rough idle?

I plan to replace the injectors soon.

Sorry for all the questions this is just very frustrating hunting this down.

Thanks again,
Mark

[rhandwor]

Check the vacuum outlet from the intake for the Tab Tad sensors. It plugged solid on my 1985 T-Bird. My 1985 didn't have an air pump. I have changed them on other vehicles. Without looking at it I can't be sure if it is to noisy.
I think you can buy rebuilt. Listen very close and see if the vibration starts when the Air Cond. compressor clutch engages. Ask the parts store to let you feel a rebuilt or new and check how it sounds according to your cars air pump.
EGR valves will cause a rough idle my 1985 had valve over travel and it would set codes. It would stall the car at a traffic light.