Harmonic Balancer looks bad

[1TDUBB1]

I've got an 85 GT convertible that has a few oil leaks (looks like its just from the valve covers)and a small coolant leak. So I bought all new valve covers, gaskets, and the coolant leak looks like it's coming from the timing cover, so i ordered the cover and figured I should do the timing chain too and why not go with the under drive pullies.


After removing the Harmonic balancer, It looks like it needs to be replaced to......

So whats the difference between the 28oz and the 50oz. Is it just weight savings or do I need to order one or the other. I also noticed on LMR that there's only 1 that specify's that it's for the GT, all the rest just say 5.0.

https://lmr.com/products/79-93-Musta...onic-Balancers

I was going to order the 50oz performance one because it's in stock and don't want to wait on the 28oz one. is it worht the weight, or do you have nay other suggestions?

Also thinking about the high flow water pump but will that hurt the heater core. I do have the reducer in line.

[wraithracing]

The difference between the balancers and the flywheel has to do with the imbalance the engine is setup for. Being an 85 model yours is the 50 oz setup, so you Have to order a 50 oz balancer. The same is true if you needed to replace your flywheel. Using the incorrect weight will cause an engine vibration and possible damage to the rotating assembly. Good Luck!

[mudgepondexpress]

You could speedy sleeve the balancer...

[KevinK]

You could speedy sleeve the balancer...

Check to see if you can find a sleeve kit for the balancer.

[ashley roachclip]

Looks like the rubber is failing , not the crank sealing surface .

[stangPlus2Birds]

That Harmonic Balancer is 100% trash. The rubber has failed.

When you get a new Harmonic Balancer, mark a line between the outside ring and the inside hub. Otherwise, when the outside ring starts to move, you'd have no way of knowing. Once the outside ring begins to move at all, the Harmonic Balancer is garbage.

Good Luck!

[1TDUBB1]

Thank you Stangplus2 birds. I think I learned more from that than I have the 24 hrs. of YouTube "professionals" i've been watching

[1TDUBB1]

WHat about these performance ones is it necessary?

[stangPlus2Birds]

WHat about these performance ones is it necessary?

For any multi-piece harmonic balencer, then alignment/truth line should be marked between the inside hub and the outside ring. I've seen some recent OEM harmonic balencers come with alignment lines.

The problem of the harmonic balencer outside ring moving, or the rubber/what-ever intermediate material degrading effects all gas engines by all manufactures.
Like with everything else, some engines might run smoother, and the balencer might be designed to be very robust and last a very long time.
However, imho, after ~15+ years, any harmonic balencer would be at risk. Even if the car was never started and kept in a temperature and humidity controlled area.
Parts fail due to age and use. Yea, an $2000+ harmonic balencer could be designed that would last a long time. But, that's not realistic for 99.9% of the vehicles.

Fwiw, iirc, there is a solid harmonic balencer for a 5.0. If that does exist, then *I* would never run that on anything other than a 100% track car.


The outer ring, and the rubber/whatever intermediary help to absorb/reduce the vibrations and harmonics of the engine.

A solid harmonic balencer is using it's weight and the very slight "twisting/torquing" of the crank to absorb/reduce the vibrations and harmonics of the engine.
Imho, the solid harmonic balencers also often don't work as well at reducing the vibrations of a stock/near-stock engine as a cheap POS China clone oem style harmonic balencer.
But, a solid harmonic balencer is really meant to hold up to extreme abuse - like what is seen on qtr mile cars.

Btw, I'm sure that some people that are solid harmonic balencer leg-humpers would disagree with me. That's fine. I guess that I, and every vehicle manufacture, will have to disagree with them.

Fwiw, I would not be surprised if some lower HP engines did start coming with solid harmonic balencers. A solid harmonic balencer would be cheaper to make. With some of the hybrids, they have gas engines that run in a very small rpm range.

So, be careful to not over-generalize any of my comments above.

Good Luck!

[ashley roachclip]

The solid harmonic dampener were used by a number of manufacturers in stock applications.
General motors is one , and today it is a standard thing .
Honda , Toyota.
Yes I still use a stock dampener on my 347 with nitrous .
It is just cost effective in my case .
I replaced mine last year , because it was separate it seemed , like yours .
The biggest problem is when they get like this , they will come apart , and the only thing keeping them from flying is the pulley mounted to the main hub .
And then it is impossible to time the engine with a timing light, as the Mark's will not be accurate

[darkd0r]

Anyone have experience with the Fluidampr?

[854vragtop]

That Harmonic Balancer is 100% trash. The rubber has failed.

When you get a new Harmonic Balancer, mark a line between the outside ring and the inside hub. Otherwise, when the outside ring starts to move, you'd have no way of knowing. Once the outside ring begins to move at all, the Harmonic Balancer is garbage.

Buy a new balancer! Mine failed on my '85 GT convertible at about 190K miles while I was driving. Heard a loud CLANG and then the engine started vibrating horribly. Popped the hood and found that the rubber had failed and the outer ring was just flopping around. Save your $$ on towing costs and just replace it now. I bought mine from NAPA.

[ashley roachclip]

Fluidamper Is a great product .
If you are building a high powered race engine , I would go for it , but if this is a street driven fun car , just buy a stock replacement.