Not on the radiator side, but on the engine side of the fan.


Finally got the new damper on my heap after a few frustrating "Oh Crap!" outburst.

Not to be out done, the engine cooling fan blades are only 1/8" (+/-) from the face of the new damper. At various engine RPM's, you can hear the fan just barely kissing the damper. DOH!

I ended up taking a rather large 1/8" thick washer, punching the ID to close the size of the fan's mounting hub shaft, and then grinding it out to the correct ID. That installed on the main fan-shaft mounting hub/nut thing gives me right at 1/4" clearance between the aft blade edges and the face of the damper.

With that, it runs with no kissing or any other hint of doom.

Speaking of courting disaster, ya reckon I'm in bed with her at this point? I've read threads where folks running the front winter radiator blankets talk of partially blocking the airflow through the radiator can present with the fan having a hard time cutting the odd air patterns. I wonder if the same would hold true on the blow side of things.
I can't see any weird changes when watching the blur of the fan while it spins in different RPM's.


What do you folks think?

 

If it's that close it might be surprising when the fan clutch locks up - you want I should go out and do some measuring?

I don't think disurbed airflow will be a problem.

Notice any improvement in how the truck runs? Those dampers are awful pricey...

 

Hey Dave,

Yeah the fan clutch cycles without the blades kissing the damper.


The Fluidampr? Well, . . . it's kinda weird. While I don't see any dramatic changes, there's definitely some new math going on. The engine does run much smother. I can't seem to locate a particular RPM with the typical harmonics lighting up the change in the cup-holder. Still new with only an hour or so driving time on it.


The only thing I've found quick is that now, when free-reving the engine on up high, there's what I think is the edge of a run-away. It's never done that before! Just a slight but noticeable when looking, pause before the engine RPM drops after one closes the throttle quickly (blipping the throttle ).


FWIW, I've seen quite a few references to the Cummins running a fluid silicon type damper. Its maintenance is covered in the Cummins Operation and Maintenance Manual.

 

Cool. I kinda figured you'd have thought that far ahead.

 

Cummins offers several different types of harmonic dampers, fluid filled included. What type of damper you get depends on the application, genset, industrial, automotive, etc.

I've run fluidampers on gas stuff before and was happy with there performance. I might have to get a couple for my B models, especially since one of them is now in more than one piece and I'll have to buy a new one anyway.

 

A quick trip to fill up with WW fluid presents with the engine decidedly able to rev higher in a WOT run. I'm actually able to hear a more pronounced drop in engine RPMs (albeit subtle) as the auto trans shifts, keeping in mind I'm still running the slippery OEM torque converter. (That won't be as long as it has been ).

The install was a PITA as mentioned in the Oh Crap thread. Further, once I got the crankshaft position sensor relocation kit, it didn't fit. Frankly, it makes me wonder if folks have even tried fitting one to a 1st Gen (at least one like my heap). While the new bracket came as substantial and very well constructed, I had to enlarge the brackets adjustable slots. The original adjustment slots allow up and down movement so one can center the pick-up relative to the damper. I had to wallow them out to allow some side (Left to Right) movment to have the pickup clear the damper with a minimum of the factory spec gap. Then there was this fan thing.

I'm gonna do the folks at Fluidampr a favor and send a love-letter (AKA feedback) so the next 1st Genner that buys one hopefully won't have to deal with this kinda mess.

 

Ya and you will get a replay back like..........I'm sorry sir, the sales men shouldn't have sold you that. they only are available for 94 and up..........at this time!!!!

Glad to see you got it all fig out tho

 

Yup, perhaps after getting my love-letter. As it stands, Fluidampr and Summit both present with this model being applicable to the '92 to '98 12V. I wonder what separates the '92 and '93 from the earlier 1st Gen CTD's regarding the damper.

Funny you should mention the sales people though, the Fluidampr rep told me that Summit should have made me aware of the relocation kit when I first ordered it. Thing is, said kit is not to be found on nether website. When I first discovered it's necessity, the Summit folks couldn't find it in their database. Plain not listed.

 

Yup i think you need to put lots of detailed LOVE.......
In them there love letters!