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AH64ID

6.7 Harmonic Damper on a 5.9

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I have been wondering for years if the 6.7 Harmonic Damper would fit the 5.9. The 6.7 version is a viscous fluid damper, like a Fluidamper, but at about 1/2 the cost. Thanks to a TDR member I now know that they fit and what it takes. So my parts are on order, and I will update this thread when I get them installed. Benefits are a smoother motor, and generally just a better part. Initial reports are that the damping is as good as, or better, than an aftermaket damper. Low rpm lug noises are greatly diminished, as is gear roll-over on manuals with HD clutches (like the Con OFE on my truck). The swap requires the damper, fan pulley, and 4 bolts.Damper p/n 4933224 ~$227Fan Pulley p/n 4930580 ~$50Bolts (4) p/n 4937228 ~$3 ea. This is for the standard 6.7 damper, not the newer HO version. The HO version is p/n 5285679 and is ~$466, and still requires the other parts. I am not sure its twice as good as the standard 6.7 damper, especially considering the initial reports on the standard damper.

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Good to know for those who might be wanting one I know on the older ones The dampners are usually different diameters from one generation to the next due to how the accessories are and also some dampners have notches for speed sensors ect. If you go to fluid dampners sight they give a good break down of each dampner so you can see the difference.

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It's on. The install took a little more than 2 hours, and was pretty simple. The hardest part was getting the 36mm fan nut loose. Once that was off the fan/shroud came out easily, then I removed the belt (still in like new shape after 4.5 years and 65K miles), and finally the OEM damper. With my truck being a manual I was able to use the trans as a barring device. In 6th gear you get a little resistance and then the crank stops turning. It's amazing how little force the OEM damper is held on with, but then again these are 3200 rpm motors, not 6500 rpm V8's.

With the stock parts off I took a few comparison pics and then got back to work putting it together. The 6.7 unit is taller, wider, and MUCH heavier. The box for the 6.7 damper states 35 lbs and I believe it, I would put the 5.9 one in the 15-20 range and will weigh it to find out.

I put a little never-seize on the mating surface of the crank, and slipped the new one on. The dowel pin for proper TDC alignment was a little tight so I had to use the 4 bolts to tighten it on, the torqued to 30 ft/lbs, and finally added 60° to each bolt and went on to install the new fan pulley. The 6.7 fan pulley is only different in that it allows for the larger damper, and belt installation without having to pull the damper.

Once the pulley and belt were installed I started the truck up without the fan/shroud to take a peek. Everything seemed to be in working order, so I reinstalled the fan/shroud and went for a drive.

The motor is certainly quieter, and smoother. I would guess that the damper cut out about 80% of the noise I got when I installed the SBC OFE, and all of the low rpm vibrations (thou the test will come when towing). There is noticeably less engine noise accelerating and cruising at a constant rpm. I actually heard a little timing rattle today for the first time since I installed the turbo, which is probably because the rest of the motor is quieter. At idle the vacuum pump sounds 2 or 3 notches louder, but in all actuality the motor is quieter so the pump is more audible. I still have a little bit of gear rollover in the trans but nothing like it was, but again more time will tell. Shutdown is quieter.

It seemed to take a little longer to fire when starting, I wonder if that was because I was paying more attention, or if the nearly 2x heaver damper takes more energy to get spinning and the motor is slower to accelerate to the rpms required for starting?

My OEM damper was actually in good shape, no cracks, or rotation. I am glad it's out thou, as I make a bit more torque than it was designed for.

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Do you subscribe to TDR? Issue 73 had a great article on it. I am not sure they wear out in a specific time, but I do believe it's an "inspect" item at the 100K mile service.

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unfortunatly I dont. I was just wondering because I thought I read something one time that excessive chirping could be from that being bad. Mine chirps loud almost every time I shut it down.

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Got this installed on my dad's 06 yesterday. His truck still has the DMF/OEM clutch. It's amazing what it did for the idle, and the DMF shutdown clatter is GONE! We haven't gotten it hot yet, still has ATF in the trans, but have started and shut it down a few times and it sounds like a different truck. We did it now, so that when he goes to a sold flywheel he won't have to worry about it.

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I finally got around to weighing them both. OE 5.9: 15.0 lbs6.7 : 27.4 lbsSince installing the damper I found that it's also the damper used on the QSB480, which is a 480 bhp marine 5.9 rated to turn 3400 rpms. That's pretty close to my crank power, and I rarely turn over 2500, so I am quite pleased with the damper choice.

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Anybody know the reason they won't work on the early 24 valves? Mine is still the original unit. I've only got a hair over 100k miles on the truck but at 15 years it's starting to make me think about changing it out just to be proactive. I know Fluid damper makes them for my year truck but I don't like the price tag that comes with them. The OEM seems to have done it's job, especially for half the price.... Sent from my DROID4 using Tapatalk

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This might be a funny question, but what exactly wears out on a stock damper? Is it really something that needs replacing? I am almost at 215,000 miles and as far as I know my damper is stock. Does it make a difference if its a 2nd or 3rd gen cummins?

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The stock damper is two pieces of metal connected by a rubber bushing. The glue on the rubber can break down and allow the pieces to rotate, or separate from the damper. I believe it effects 2nd and 3rd gen trucks. If you look closely on the smaller damper in the photos above you can see the rubber ring. http://www.turbodieselregister.com/tdrarticles/tdrarticle73_TechTopics.html

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Oh man!! I had no idea that could happen. I better go check on mine then:ahhh: I could just go look it up, but ill ask since I'm here anyway. How does a fluid damper work then? Does it have oil in it or does it get oil from the motor?

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It is a viscous unit. Constantly adapts to engine load/torque. Also is a one piece unit unlike OEM so no parts to ever wear out. They do appear to be substantially better than OEM but I have a hard time justifying double the cost compared to OEM, especially when mine has lasted 15 years. Sent from my DROID4 using Tapatalk

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Part of my rebuild is a fully balanced rotating assembly, and unfortunately the 6.7 dampers are not perfectly balanced. Of the 2 we tries 1 was 16 grams out of balance and the other 30, mine was the 16. There is also no way to balance them. It it sucks to pull because it has worked so well, but a fluidamper is going on. I can't justify a balanced crank, etc, and then not the damper. So while it sucks I will be able to review them both, thou not apples to apples with a balanced motor and new injectors.

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I presume you are talking about the lack of OE balance? I was shocked, this is the same part number that is used on a 3400 rpm 480hp 5.9.

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Yeah, shocked doesn't quite describe it. I would still recommend it anyday over the stock 5.9 damper, it made a big difference. But if you ever plan on balancing the motor just get the fluidamper.

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