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Harmonic Balancer Vs. Water Pump Conflict

Dibbons

Dibbons

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After installing the timing cover, water pump, and harmonic balancer on this rebuild 340 project, the engine now rotates with extreme difficulty over 90 degrees of rotation. At first, i squirted VD-40 in the spark plug holes believing maybe one cylinder was a little dry, put that attempt provided no benefit/improvement.

Then I noticed that during a portion of rotation, the bottom of the water pump has no clearance with the harmonic balancer (photo #1). I don't know yet if the problem is with the pump, the balancer, or both. This problem really took me by surprise.

The smallest feeler gauge I have is .004" which I can fit it during partial rotation. Then at a different point it won't go in the space between the water pump and balancer. Then I placed some blue masking tape all around the balancer and found during rotation the tape starting to fold up on itself (photo #3). I have no idea what the normal clearance in this area should be. I do have another spare (old) harmonic balancer on hand (photo #2). The water pump and timing cover are new.

If I install an new balancer and still have the problem, I will really be perplexed. Standing by for input from my Mopar brothers. (also posted on FABO) Thank you.

IMG_0182.JPG


IMG_0183.JPG


IMG_0184.JPG
 
You have 3 choices:
1) Remove WP and clearance the rib between the bolt holes
2) Remove balancer and take about 0.010" off of the OD on a lathe
3) Run it "As is" and it will self-clearance quickly....

:thumbsup:
 
ckessel said:
I vote for doing some whittling on the pump.
Click to expand...
I thought of doing that. However, being the fact the balancer only rubs during a portion of the rotation leads me to believe the balancer is, at least in part, at fault. If it rubbed all the way around 360 degrees, then it could be solely the pump's problem. I'll keep checking.
 
I no longer have the box for the water pump, but I don't see anything but one choice for small block water pump with outlet on the passenger side. I almost feel like taking the water pump and balancer from the 318 that the 340 will be replacing and see how that works out.

The bolt holes and gaskets for the new water pump and timing cover matched with the engine block perfectly.

I thought I was doing the right thing when I installed the balancer before final tightening the cover and pump so that the oil seal would be centered on the balancer. I don't see how that could cause a problem.
 
Your really over thinking this. Remove the water pump and remove material from the rib between the bolt holes!
 
You did it correctly by centering the timing cover with the installation of the balancer. You can pull the balancer and relieve the pump a little, but, I am suspicious of the balancer. If you decide to relieve the pump bottom and reuse that balancer, at least draw a line across the front of the balancer, from the outer ring across the rubber and onto the balancer center. Watch it down the road, if the line gets displaced, replace the balancer. I would probably replace it anyway. I replaced the balancer on my '72 318, the rubber was deteriorating. That outer ring starts slipping and you can not time your engine.
 
Bird 426 said:
You did it correctly by centering the timing cover with the installation of the balancer. You can pull the balancer and relieve the pump a little, but, I am suspicious of the balancer. If you decide to relieve the pump bottom and reuse that balancer, at least draw a line across the front of the balancer, from the outer ring across the rubber and onto the balancer center. Watch it down the road, if the line gets displaced, replace the balancer. I would probably replace it anyway. I replaced the balancer on my '72 318, the rubber was deteriorating. That outer ring starts slipping and you can not time your engine.
Click to expand...
Good idea! That has happened to me
 
Seems suspicious it only happens over 90 degrees. How far out of round is that balancer?
 
Wonder if the balancer is bent. Or the crank snout from some caveman moving the engine around.
 
Yep something seems mixed matched or the waterpump isn't the same design as the factory one. More research needed.

Sure just hack up the parts so they fit. How about milling the balancer in a lathe? :rolleyes:
 
It that balancer is 7.25 inches in diameter then it is the water pump. If the balancer ran dead true there would be a couple of thou. clearance, and there is no way the factory used tolerances like that for that application.
 
Personally....i dont really trust a 50 year old damper not to fail and cause a much bigger problem. I would start with something new and make sure it clears of coarse.
 
Update: I removed, cleaned, and painted the water pump from the 318. I cleaned up and painted the circumference of the other spare harmonic balancer. Now need to substitute these other parts and see what happens.

IMG_0200.JPG


IMG_0201.JPG
 
Has anybody actually checked the runout on a factory dampner? I'll bet they aren't all that acurate.
Doug
 
Update: Test fit the used 318 water pump to find all kind of clearance with the currently installed harmonic balancer, which will be swapped for another one regardless (photo #1). Found the installed new water pump had clearance issues! (photo #2) Very frustrating trying to restore a vehicle in this day in age.

IMG_0203.JPG


IMG_0205.JPG
 
On the WP in the top pic, the rib is located at the bottom of the bolt hole boss and causing the interference. The WP from the 318 has the rib about 1/3 up from the bottom of the bolt boss giving ample clearance. Yes, chineze parts suck for sure...
 
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