Hi all -

I've started troubleshooting an oil leak on the old 300/4.9L (looks like timing cover seal) and become aware the harmonic balancer should be replaced as well due to rubber deterioration.

The van is a 1977 E150 but the engine is an early 80's (I believe) from a donor van and has been in there for many years.

Part ID on the balancer is C8TE 6316-A, which according to my research translates to part number C5TZ 6312-J. I've found one available on Rearcounter.com and have made a price inquiry to the seller, but am curious as to just what the differences might be between that and a more commonly available replacement like maybe C5TZ 6312-L or aftermarket equivalent. In fact the C5TZ 6312-L (ID # D8TE 6316-B) per Ford part books is listed as correct for 1973-81 non-california engines, and the C5TZ 6312-J doesn't show up anywhere except the pulley ID charts. Any thoughts? Experiences with aftermarket replacements?

In general the balancer is a triple-sheave with two 3/8" for alternator and a 1/2" for power steering (no A/C), all same O.D.

Thanks, Mark

Well, at least there's SOME rubber left ;-)

 

If a little downtime isn't a problem there are damper rebuilding services, "Damper Dudes" is pretty competitive with buying new.

 

That'd be a great alternative to some parts store piece.

Parts are very similar, too:

https://damperdudes.net/harmonic-bal...-back-of-ring/

https://damperdudes.net/harmonic-bal...ly-is-smaller/

One has the front pulley slightly smaller than the others.

I've just used the Dorman harmonic balancer and have had no issues with it for many miles.
https://www.summitracing.com/parts/r...BoCCXMQAvD_BwE

 

Cool - thanks for that tip on Damper Dudes - they seem very reasonable and quoted a 1-day turnaround!

 

Thanks for the links and your mention of the Dorman part. I was a little put-off by the Dorman based on a 'less-than-stellar' review on the Summit Racing site, but the local O'Reilly's actually shows they have one in stock so I may go that way, even if it's just to tide me over pending a rebuild.

This old fella is my daily commuter driver so minimizing downtime is pretty important to me.

 

BTW the lead on the C5TZ 6312-J on Rearcounter.com turned out to be a dead end as they didn't actually still have one.

Ditto for an attempt at the C5TZ 6312-L from a different Rearcounter supplier.

A rebuild sounds nice. Wonder how they ensure the timing marks end up properly aligned - guess that's another question for them before sending it in.

 

They must have some fixture that aligns the inertia ring TDC with the keyway, and indexed the correct number of degrees. It's worth taking the time to verify on installation that this was done correctly with a piston stop tool I suppose.

Crankshaftcoalition.com is kind of like Wikipedia for engines, it has an article that talks about how and why balancers work. A crankshaft can actually twist back and forth up to couple of degrees, that's why a balancer is needed. At a certain speciific RPM, the crankshaft will achieve resonance, This is a Bad Thing, as it can cause crankshaft cracks or even break it. Like a guitar string, there are also resonances at certain harmonics or multiples of that frequency. The goal in design is to engineer those resonance points away from the usable RPM range but it still must be a problem or they wouldn't use them. I'd expect that a defective balancer contributes to excessive main bearing wear and oil leaks, too. The heavy steel outer inertia weight sandwiched by rubber leads and lags the crank under power and deceleration, and absorbs the torsional vibrations and smooths out the resonance. Pretty cool, huh?

 

PartsVoice.com = You have to register to use it, but searching for parts is free. Type the part numbers without any spaces or hyphens, like this: C5TZ6312K

PartsVoice has faaar more sources than rearcounter has.

See 6312 in 1964/72 truck parts catalog pic:

 

Thanks NumberDummy - I'd been eyeballing that 6312-K part on ebay as well and was really thinking about pulling the trigger on it until I saw the info in the part number page you posted: 'Uses 1/2" belts' (plural, as in apparently for all 3 sheaves). So it probably wouldn't work so well for me.

Aaand, on top of that the parts listing finally shows me a usage for the 6312-J part: 65-71 300 L/D........oh, wait......... AND 240! YIKES!! I've always thought this engine didn't seem to have the pull I remembered from the original 1977 300cid engine, and the guy I bought it from was kind of a mad tinkerer gear-head (and probable meth-head) so no guarantee the engine was original to that early 80's van it came out of.

Now I gotta check out the block casting numbers and maybe measure the stroke. The rabbit hole deepens...

 

The problem with NOS parts made with elastomeric (rubber) is it may soon fail. Maybe not, but it's tough to gauge a part sight unseen. That's why the suggestion for the "Damper Dudes".

 

That was also on my mind. On the other hand I've had some pretty bad experiences with new aftermarket components (notably motor mounts) which supposedly had bonded rubber construction.

So, yeah - a rebuild by some people who do a lot of them sounds pretty good.

 

Thanks for the links, and for mentioning the Dorman part, though one out of the three reviews on the Summit site is none-too-kind. Good to hear you've had a better experience.

 

Just an update and info...

I ended up installing the Dorman part (594-077) balancer which was happily available at a local parts store so got my daily driver back on the road.

Couple observations on the Dorman part:
>>There were paint runs down the machined sealing surface of the hub - thankfully some Brakleen and paper towels got it off without resorting to any abrasives, though it was a bit tedious.
>>The timing mark was about 14 degrees retarded compared to the original and I had to file some new marks. Glad I checked. Also no secondary mark for the pointers cast into the timing cover.
>>Even with the above noted issues I'm just really glad they make the part available at this point.

Thanks to the kind folks who replied to this thread as well as the many in other threads which ended up helping with balancer & timing cover removal/installation and so forth.

 

Odd on the timing marks being off. My last one was too. However, I've bought 2 from them and the previous one was spot on.
I thought maybe it had to do with all the performance mods/changes I made, cam degreeing, etc. so thought nothing of it and just cut my own marks too.

Glad you got it set up and going though.

 

One more thing...

Regarding installation of the balancer I read many threads on technique, with most advising to just use the mounting bolt to pull it on but a few adamantly opposed to that and insisting on use of an installation tool.

The instruction sheet that came with the Dorman part (yep - I actually read that stuff, though sometimes only afterwards, hah) was of the 'must use installation tool' school of thought. Anyway I decided an installation tool might be a good idea but of course I didn't have one and rain was threatening my project. Then it dawned on me: the mounting bolt thread is 5/8-18, which happens to be one of the most popular sizes for any number of puller tools, some of which come with nuts (for whatever reason). So I picked on one I had (happened to be a hub-puller) and used the screw & nut along with the heavy mounting washer to install the balancer. Even without a thrust bearing on the 'installer' it went on pretty easily - I just kept the nut/washer interface lubed.

So I just thought I would pass that along for the next guy who reads all the threads on harmonic balancer removal/installation like I did. :-)