Jim, yes thanks, saw that in the instructions. Eric, holy cow. Amazing how much energy is contained in a spinning 8 inch disc of metal.

 

mine recently came apart, luckily at low power backing into the garage. started to change it out, realized my water pump is weeping and radiator is leaking, so good time to get deep into it!

 

Replaced a weeping water pump and now hear a clunk in what seems to be the bottom engine (not in the valve area and pistons, etc. seem fine). My friend put a stethoscope with a metal rod at the end on it (we thought it was a failed rebuilt water pump) but he thinks it is the harmonic balancer (1966 327/300 PS A/C).

Is there a way to tell for certain before I dig into it and waste money on a part I don't need? He suggested taking off all the belts and cranking the engine to see if it still made the noise. I don't know about that, but am looking for some expertise before I dive into this.

Thanks...

 

Go underneath the car and visually inspect the balancer. The one that failed on my car had a strip of rubber between two different parts and yours could be deteriorating. See if you can move the balancer with your hand in any direction, this will determine if it’s faulty. Replacing the balancer now is way easier and cheaper than when it comes apart at highway speeds, I recommend changing it now if you’re not sure.

I had to replace my power steering pump, all brackets, water pump, and belts. Good luck!

 

Notice the rubber band between the two metal parts.

 

YIKES! So sorry to hear about your situation. I will definitely try that and see what I see.

Ron,

Thank-you very much for your help! This is my first time with a possible harmonic balancer issue in 40+ years of messing with cars, so your help is greatly appreciated.

Do people suggest using a rebuild kit or just getting another one?

There seem to be 2 part numbers--3896903 and 3896904. Did you happen to see if the part number was stamped on the part?

Thank-you again--

Cheers,

Richard

 

Hi, my car has a 454 engine which is externally balanced. I would suggest getting a new balancer from Summit, etc which will have a warranty and you can also get one that is rated for higher RPMs. If your engine is internally balanced you have a lot more options when selecting the balancer for your car.

 

Also my car didn’t have the original balancer, it was a replacement. Here’s what I ordered.

 

If you have an original balancer and desire to maintain the originality then they can be rebuilt. DamperDoctor is one source I've heard of but have no experience with. If you decide to go with a replacement, check the numbers on your current balancer to see if it's GM, how rare it may be, and offer it up on the classifieds for those restoring their cars.

They don't as far as I am aware, but all balancer manufacturers should place reference orientation marks on the two components so that any shift can be seen.

 

First, THANK-YOU for your great note. This is my first time in 45+ years of working with older cars I have ever had to replace a harmonic balancer, so I am learning a lot.

I will DEFINITELY do as you suggested and make this part available to everyone if it is, in fact, original. I don't believe that the engine has ever been out of the car, so my expectation is that it is the original part. As for refreshing it, that is an option, but since I do not have a judged car, I will probably just go with the repro part (it seems that Volunteer Vette has the correct part at the best price) so I will get that one. There is an NOS one and a re-built one on other sites. They run 4-5 times more than the repro, so for me, that is not really doable at this time. I will also check with DamperDoctor later today when they open (West Coast) and discuss all this with them as they are probably very knowledgeable as this is their business. Thanks so much for giving me their information.

Another question: Should I invest in purchasing a new bolt and washers for this? They are relatively inexpensive--this is one of those situations where the shipping is more than the part--but I prefer to keep the originals if possible. A word on my philosophy for THIS car: IF I can afford the NOS part, I buy it. If I cannot, I do not, as in this case. However, if keeping the factory bolt and washers is possible, I will do that even though the repros are not that expensive.

Cheers!

Richard

 

By bolts, I'm assuming you are not only speaking of the single center balancer bolt but the 3 pulley bolts as well. If the bolt heads are not rounded and the threads are clean, I'd just use what's there. The large center bolt doesn't really hold the balancer on as it's a keyed, press-fit on the crankshaft. The three pulley bolts share the load and as long as they are not severely rusted to the point of shear failure (which I've never seen), should be just fine.

Just my take on repro fasteners and parts, I always strive to reuse original parts while having no desire to have my cars judged. I believe originals are always of higher quality and should be reused as long as the strength is not compromised. Plus, "reproduction" hardly ever means it is exactly like the original part.

 

Excellent advice. I have spoken to Damper Doctor, and he and I agree that refurbishing the original part is the best (and actually cheapest!) way to go.

SO, I will be removing the part, sending to him, and he turns them around in a few days, so really a good deal all around AND I get to keep my original part. He felt the same way on the fasteners--if they are good, reuse them.

Thanks again for all your help. This Forum is amazing, and by that I mean the PEOPLE on the Forum (like you) with all their experience and knowledge are the best.

Cheers!

 

I'm glad to share my view – opinion! – and relate experiences I've had. You're welcome.
Please do post a follow up on Damper Doc's customer service and apparent quality of repair. It can only add to the conversation and assist others coming down this path after us.

 

Definitely will do!

Cheers!

 

Quick update--

Removed the harmonic balancer today. Found that the pulley bolts were finger tight!!!! Never touched that part of the engine before, so a huge surprise. Key was sheared off and had rotated in the balancer. I was basically one start from losing the engine. Very strange. No bolt in this one--0124529 FO425H matching number engine, so made late. I thought they started putting bolts in earlier than that, but whatever. One less part.

Anyway, sending the mangled balancer to Damper Doctor to see what he can do. Probably have to sell me another one since this one is pretty beat-up and the rubber is coming out all over. We shall see. Seal is gone, so looking for a suggestion as to which one to buy.

VERY lucky that I did not have a catastrophic failure...I think I will buy a lotto ticket tomorrow...!

Cheers!

 

How is the keyway slot in the crank snout? Hopefully it's tight for a replacement key and not wallered out. (I believe the only fix for wallered out is to have the slot welded and recut -- which requires removing from the engine.)

 

I caught my failure before it did any real damage. It would have been a different story if the ring could fit between the core and the timing cover.

https://youtube.com/watch?v=-wJowNN2FzI

 

YIKES! Glad you were able to catch it in time!

Cheers!

 

We are going to take a good look at that, of course. I think it is fine since the key sheared off and we had to use a lot of trial and error to get it out of the slot as it was in there very tight. Have my fingers crossed that it is still OK.

Thanks very much for the help, however. We thought of this but will make sure it is good before we replace the balancer.

Cheers!