Need help ASAP... harmomic balancer wobbling?

[Kerpal]

While checking my timing yesterday I noticed that my harmonic balancer appears to be wobbling slightly at idle.... it looks like it's moving forward & backward a couple mm as it spins. If I run the engine at about 1500 rpm or higher the "wobble" goes away (approx... I need to have someone else look at the tach while I look at the balancer). Is this normal at all, or a sign of a bad balancer?

My engine does shake a little bit at idle, but I don't think it vibrates any worse than most 5.0's I've seen, and it's a little out of tune anyway. It seems to run okay, other than that it's been getting pretty terrible gas milage for the past couple weeks. I haven't had much time to figure out the cause, but it's obvious that it's running rich just from the increased raw gas smell.

Oddly enough I randomly found a guy's website whose balancer went bad right after I noticed this about my own... his crank snapped and destroyed his entire longblock so of course now I'm REALLY parnaoid. I'm going to make sure all the balancer bolts are at least snug when I get a ride home later...

I don't want to move the car until I find out if this is normal, but I really need to use it later today if at all possible, so any quick responses would be greatly appreciated.

Hopefully this is totally normal and you guys will have a good laugh at my lack of knowledge... I'm crossing my fingers anyway.

 

[Daggar]

Well there's really no way any of us are going to be able to diagnose the problem over the internet beter than you can standing right infront of it. If you think it is actually moving foward/backward at idle then I'd swap it. Relatively easy thing to do compared with building a whole new motor.

 

[SamSnyder]

If it's moving forards and backwards it sounds like it is loose. Have you checked the bolt that holds it on? 15/16" and I believe it's supposed to be tightened to 90 ft lbs of torque. I just replaced a balancer yesterday. NAPA had a new (Chinese-made) one in stock for $64.

 

[Kerpal]

Well, I could probably take a video clip of it, but I don't know where to host it...

I just talked to the local Mustang shop & they said that probably means it's getting worn out. Apparently they see a lot of orginal balancers wobble like that. I guess I better replace it, like you said it's a lot easier (and cheaper...) than building a new engine.

Is the Professional Products street balancer a decent one? That's what I can get locally, I'd really rather not have to be without a car for a week while I wait to have one shipped... unless the professional products is total junk.

The shop is a 40 mile round trip, I assume I'm okay to drive over there since it only wobbles at idle anyway (?). It's probably been doing this for a while and I just never noticed it...

Thanks Daggar...

 

[Foxfan88]

i have the same symptoms as you, i have terrible gas milage and when i try and adjust timing, the balancer wobbles at idle, i havent noticed the WHOLE balancer moving but it wobbles noticably, like when i first start he motor and shine the gun at it. The marks i've made on the balancer will move right to left about an inch, then after a minute or so it goes away.

Plus i put it at what the balancer shows as 10 degrees.
SO i am running 10deg with 87 octane and every so often i get detenation. I dont if hot weather can affect it or not.

 

[Kerpal]

You shouldn't get any detonation with 10 degrees on 87 octane... unless I'm mistaken 10 degrees is the factory setting.

Sounds like either your balancer is marked wrong or something else is causing the detonation... has the car had a complete tune up recently?

 

[DouglasOhio]

Kerpal and foxfan, id get a new balancer if i was either of you. Foxfan, if your getting detonation with 10* on 87 it sounds like your balancer might have jumped the keyway. Only way to tell is to remove the balancer and check for the keyway being sheared or bent, and now that you have it off anyways, you should put a new one on anyways. Its worth the peace of mind knowing your 5lb balancer isnt going to kill somebody flying out of your hood at 5500rpm at the track.

 

[HISSIN50]

Most likely is that the outer ring slid on the inner rhub (the elastomer is all that bonds the two together). The outer ring often shifts fore and aft (as if someone hit the front of it with a hammer). So one part will hit the timing cover (extreme cases), etc.

As for watching the balancer to notice run-out, I dont like doing it. The rear of the balancer can create an illusion (hypnotic, isnt it?) .

But with the motor off, I like to look at the elastomer and see if there are parts bulging or cracks. Then look at either side of the elastomer, and note if the outer ring or hub hangs out (or in) further than its complementary hub/ring. they should be tabletop even.

PP is a nice balancer. Street units go for ~80 bucks online - probably more in town.

If not, a Pioneer (3021 is the part # IIRC) works pretty well for folks and is avl at some parts stores.

Good luck.

 

[SamSnyder]

Hey - DouglasOhio, what do you know about the key being bent/sheared? I just suffered a partially sheared key 4 days ago, with the balancer having its key slot being carved sideways about 10 degrees, and the key being shaved lower, with about 4/100's still protruding above the crank snout at the front end, up to almost full height at the rear end against the timing sprocket. This suddenly happened during normal street driving (although it was the day after I got it back from the AC shop, so who knows what they were doing with it?). But anyway, my buddy and I attributed it to a freak balancer failure, and both had the opinion that there was still enough key protruding above the crank to do the job, particularly since the balancer is a press-fit. Do these things regularly happen? And am I at risk for normal street driving, going with the original key somewhat shaved as described? If not, can I get the key out without pulling the front cover? I initially started trying to tap it out with a punch, but it wouldn't budge, maybe because the timing sprocket was still on the back end of it, plus I was afraid of losing it in the pan. What would you do about it?

 

[Kerpal]

Thanks Hissin... I was wondering if maybe I'm just seeing an optical illusion from the back of the balancer... I still think it may be wobbling a little, although probably not nearly as much as it appears to be. It definately is hypnotic. Kind of like staring at your washing machine run.

The balancer doesn't look that terrible to me, but I'm no expert... I'm gonna take it by the local stang shop in a little while and have them look at it... they have a good rep in my area and I trust they'll give me honest advice. If they say it's looking worn I'll just pick up that PP balancer.

 

[HISSIN50]

Thanks Hissin... I was wondering if maybe I'm just seeing an optical illusion from the back of the balancer... I still think it may be wobbling a little, although probably not nearly as much as it appears to be. It definately is hypnotic. Kind of like staring at your washing machine run.

The balancer doesn't look that terrible to me, but I'm no expert... I'm gonna take it by the local stang shop in a little while and have them look at it... they have a good rep in my area and I trust they'll give me honest advice. If they say it's looking worn I'll just pick up that PP balancer.

Sounds good. I have had alright luck using a V-clamp to pin a straight edge to the motor (some place where the accessories are not able to suck it in, etc. ). I use the straight edge to block off the rear of the balancer from my vantage point, but allow me to see the front of the balancer. Then I compare the run-out (oscillation) of the front edge of the balancer vs the fixed straight edge. Peripherally I cant see the rear of the balancer since the straight edge blocks it.

For some reason I can see run out easier from under the car also (not as much of the washing machine phenomenon going on. I like that analogy BTW).

Your plan sounds good though. Good luck.