thrashingcows

Yeah guess that would be the easiest way to narrow that down.

Will do...spinning and checking for slop in the bearing "up/down" and "side to side" should be good enough?

Just replaced the clutch fan a couple weeks ago, new unit. The old one had seized solid and the vibration was present before the new clutch went in.

thrashingcows

Well Spent half the day messin with the front of the motor trying to make sure I found the problem.

I first ran the truck and the vibration was there. The removed the fan and clutch assembly and went for a drive...no vibration. Quickly re-installed the fan and clutch, with in 30 seconds vibration was back.

OK now I wanted to make sure it was the fan and not the clutch assembly. SO off comes the fan and clutch again, the removed the fan and re-installed the clutch...still no vibration. Pulled the clutch and re-installed the fan and clutch assembly...vibration was back.

So after all this I am pretty confident this is my problem. And another thing I noticed is that the fan is tweaked pretty bad. Never noticed that before, but then I wasn't looking either. When I rotate the fan and eye the blades to the harmonic balancer they go from 1/4" to 1" clearance on the balancer. So not only are a couple blades damaged, but the whole thing is twisted.

I measured the fan, approx 20" diameter. Is this the same fan used on the 91-93 IC trucks? And would a 2nd gen unit work as well on my Non-IC rad and shroud? The shroud has an opening about 22" but the motor is sagging on the motor mounts and the fan is close to the bottom of the shroud.

Mark Nixon

Glad you got it fixed and it was pretty simple.
See what diagnosing a problem and using a process of elimination can achieve?
And you DID NOT have to rebuild the trans or clutch, either.

Mark.

Mark Nixon

I didn't see this:
No, the intercooled fan is just enough longer to get into the fan shroud and it is a one-off deal, while an intercooled fan blade will work from 1991-1/2 through 1998 (for sure, POSSIBLY to '02).
The non-intercooled also has slightly wider blades, as well.

I HAVE seen some of the intercooled fans carefully trimmed back to work, which is a viable alternative, provided you get a perfect blade to start with.

Mark.

tech-eh

I love it when im wrong as I always learn something .I didn't know that about the IC fans . How different is the rad support IC vs non IC ??

Mark Nixon

The radiator supports from Non-Intercooled to Intercooled are radically different.

The non-intercooled support has extra supports extending out on the engine side to mount the radiator, a down flow version, to.
Think gasser V-8 style on this one.

The Intercooled support is basically the non-intercooled support with the non-I/C radiator side brace supports removed.
This facilitates both a thicker and wider radiator, a crossflow or horizonal flow, which adds @ 25% capacity over the old down-flow style radiator.
The Intercooled support also employs 2 lower grommet mounts to the bottom core support saddle, while attaching it to the top, via use of 2 grommets, set in 2 flat rectangle brackets (1 per side), which are then retained by 2 bolts.
On the front side of the intercooled core support, down close to the bottom, there are also 2 steel grommet type brackets that the intercooler sets into, by way of studs formed into the Intercooler, which set into rubber grommets.
The top of the intercooler is retained by way of 2 simple grommets, with steel inserts, slid into tabs built into the Intercooler, then screwed into body clips located on the core support face.

Another major difference between the 2 radiator supports is the headlight brackets on an intercooled support (As with ALL 1991-'93 Dodge trucks), are located slightly higher than the non-intercooled 1990 core support, plus the headlight brackets are fully removable, in that they bolt in and the headlight buckets are contained within 1 unit.
Sound familiar?

The 1/2 year diesel 1991 non-intercooled core support is a hybrid between the old style radiator and the new style grille.
I have found that nice specimens of this particular core support are ever increasingly harder to come by.

Mark.