Hi. I know this has been discussed a lot of times but I m still not getting it quite right. The question is how can one identify a flexplate for a V6. I understand that the older ones are for externally balanced engines with weights on it. But do we have the same flexplate style with the batwing like the V8 has when we have a one piece rear oil seal V6 like the 89er. Or is there numbers for identifying those pieces. Thanks for replys.

 

Note sure what you're asking...

Look at the plate. Is it 1/2" thick or so? It's a flexplate. If it's 2" or so, it's a flywheel (stick shift)

If there are weights on it, then it's the early design. No weights generally is a neutrally balanced (late model) design.

 

What I ment by it was if I have a 1989 V6 with the one piece rear oil seal does the flexplate not the flywheel have a batwing weight on it like the V8 one or not. Are those weights for the older V6 easily visible or are they very small. My bird vibrates a lot and so my guess is that someone installed the wrong flexplate some time ago. Thanks .

 

Is the vibration mostly through the steering wheel or mostly through the shifter and floorboards? Just curious. A vibration through the shifter or floorboards usually means transmission, whereas the steering wheel is usually the engine. If you get the vibrating through the shifter/floorboards then I'd check what you said..the flexplate... If it's fine or the right one...or the vibration doesn't go away and it's in all gears....your torque converter turbines might be damaged. But I imagine it's very hard to damage a torque converter on a little old V6.

 

If you have weights on your flexplate, the flexplate itself might've needed to be balanced. 82-86 2.8's were externally balanced on the flywheel/flexplate, yes. But (like was said) 87-92 2.8/3.1's (and probably 93-94 3.4's!) were internally balanced on the crank due to the DIS counterweight. (DIS unused for our Gen I motors.)

So maybe to get the flexplate neutral-balanced, they had to add weights.

 

The vibration is mostly thru the steering wheel and it visibly shakes the corners of the dashboard. Since I changed a lot of things my guess was that it comes down to the flexplate. It visibly wobbles a little but it doesn t seem to be broken in the center. I removed the torque converter but the shaking was still there so it s probably not ATM related. The engine itself seems to run fine. It reves up to 5500 RPM (it was not me doing it but a mechanic, I don t belive in such high RPM) without missing or such but it vibrates a lot. I really sort of hope that it s the flexplate since I don t know what else it should be as I replaced a lot of parts on that engine already. Thanks guys.

 

Am I correct in remembering that you already replaced the harmonic balancer on your engine? Or am I thinking of someone else on the boards?

 

Check all of these for vibrations -

Motor Mounts
Tranny Mount
Harmonic Balancer

Those are all relatively easy to fix/change... If you can see a weight on the flexplate, I'd go ahead and remove it, and have it checked for neutral balance.

 

Yes Nixon1 I m the guy that replaced the harmonic balancer already. The motor mounts are all fine. One strange thing is that it s not the original engine in there anymore as the numbers don t match. My guess is that maybe someone installed an older engine that requires the counterweights but I m not sure. i don t know but could it be a worn camshaft? There is also a very light knocking sound near the number 6 cylinder which can be better heard with a stethoscope and sounds like a valve with too much gap. But then the engine has hydraulic lifters and the sound is very low. Thank you folks.

 

If it's something worn in the camshaft, I'd guess it would probably be a worn exhaust valve. If you think there's something up with the cam, do a compression check on all cylinders. Also, you will probably have a slightly rough idle with an occasional backfire or miss, depending on how bad it is.

My car's got a bad exhaust valve on the #8 cylinder and the whole engine shakes and shimmies nonstop..misses slightly....and registers only 125 psi compression on cylinder 8. All other cylinders are normal at 155-160 psi.

 

The compression is high and about the same on all cylinders due to some carbon buildup. I checked that earlier. Thanks again.

 

Hi I measured the wobble of my flexplate near the teeth and it was 6mm (close to 1/4 inch) front to rear . Is that still acceptable?

 

Everything cleared up now. The crankshaft was bent.