Fan blades hitting shroud

slcullen

New User
Late model 8N. I bit the bullet last week and replaced the front axle pin. A job getting it out, but got 're done finally. Took it for a brief drive and no problems. Attached the mower and after hitting a fairly shallow dip, I heard the fan blade hit the shroud lightly. Continued mowing with no more tings. Well yesterday, the tings were back in full force. The blades are hitting the shroud without the tractor being in motion. I rev the motor and the noise starts. Can't tell where the blade is hitting the shroud, but can see a fan blade or two with dings on the tips. Think I've got to take the hood assembly off to fix this problem, but once it's off, what do it do once I find where it's hitting the shroud? Do I try to grind the shroud, bend the edges of the shroud, or even grind the tips of the fan blades? Thanks, Spencer in Tallahassee
 
(quoted from post at 05:49:04 06/14/18) Late model 8N. I bit the bullet last week and replaced the front axle pin. A job getting it out, but got 're done finally. Took it for a brief drive and no problems. Attached the mower and after hitting a fairly shallow dip, I heard the fan blade hit the shroud lightly. Continued mowing with no more tings. Well yesterday, the tings were back in full force. The blades are hitting the shroud without the tractor being in motion. I rev the motor and the noise starts. Can't tell where the blade is hitting the shroud, but can see a fan blade or two with dings on the tips. Think I've got to take the hood assembly off to fix this problem, but once it's off, what do it do once I find where it's hitting the shroud? Do I try to grind the shroud, bend the edges of the shroud, or even grind the tips of the fan blades? Thanks, Spencer in Tallahassee

Did you remove the radiator to replace the axle pin? It's hard to see how could do it without though.

I recently changed my axle pin and had the same problem because my rubber pads were worn out and this caused the radiator to mount down lower, which caused the fan to, slightly, hit the top of the shroud.

I ordered and installed new pads but then the fan hit the shroud in center right of the shroud. I then noticed that by loosening the two radiator mounting bolts, the ones that pass throught those rubber pads. I could pivot the radiator in and out. By sliding the right side of the radiator away from the engine/fan I stopped the rubbing and the fan seems pretty well centered in the shroud all the way around.

Hope this helps.

Jerry
 
Had this problem on a Z Moline, but a fans a fan. Turns out the fan itself was out of balance bad. Replaced it problem solved. That said if your
fan is balanced good, obviously you don't want to take material off the tips unless you do it uniformly on all 4 tips. Check your bearings for the
fan to make sure they ain't no wiggle there, cause at high rpm it will deflect the fan enough to get into the shroud. Lastly while it's apart, find the
shiny spot where it was hitting and tap it back about a quarter in. making sure that that don't knock the rest of it out of round. That's all I got,
good luck. DP
 
Fan blades hitting shroud

Grab the fan and see if it shakes side to side - Water pump bearings could be worn.

If water pump checks out, use a flash light to see where the fan is touching then use a long rod to reach up and adjust the shroud before going through all the trouble of R&Ring the hood.

You do not want to remove any material from the fan blades as it will affect balance.
 
(quoted from post at 08:49:04 06/14/18) Late model 8N. I bit the bullet last week and replaced the front axle pin. A job getting it out, but got 're done finally. Took it for a brief drive and no problems. Attached the mower and after hitting a fairly shallow dip, I heard the fan blade hit the shroud lightly. Continued mowing with no more tings. Well yesterday, the tings were back in full force. The blades are hitting the shroud without the tractor being in motion. I rev the motor and the noise starts. Can't tell where the blade is hitting the shroud, but can see a fan blade or two with dings on the tips. Think I've got to take the hood assembly off to fix this problem, but once it's off, what do it do once I find where it's hitting the shroud? Do I try to grind the shroud, bend the edges of the shroud, or even grind the tips of the fan blades? Thanks, Spencer in Tallahassee

There is not a lot of clearance there and the radiator has to be positioned "just right" or you get your problem. Loosen the radiator bolts and try to adjust the position to eliminate the contact. I would caution against grinding on the blades.

TOH
 
Not uncommon.

Good advise below.

You need to first determine where the fan is hitting the shroud.

You probably need new radiator mounting pads. Be advised that replacement pads vary in thickness according to supplier.

The radiator mounting bolts should not be tightened more than is necessary to collapse the lock washer. Overtightening will break the solder joint between the bottom tank and the core support.

Do not grind the fan blades.

Dean
 
Take a look at about 80 of these old
tractors and you'll find that 70 of them
have warped or bent, ie; unbalanced fans.
So I'm not terribly concerned about an
unbalanced fan.
A guy could fart around for a day on this -
pulling the shroud a few times, tweaking the
radiator, tapping here and bending there and
maybe the guys who advised against grinding
the blades have a precision way to balance
their fans. I don't think all that matters
much, so I just carefully mark the ends of
the blades and grind about 1/32" off of
them.
 
PS,
He reason I know these fans are often bent is because I almost always check the fan on a new to me tractor if I have to pull the radiator for one reason or another.
With the radiator off it's pretty easy to put a ruler between the engine and fan tips and see how they all 4 measure.
You can easily bend the blades and make all of them equal from the head. I figure within a 32nd is good.
What setting do you use when all four are different?
Dunno. I just wing it.
Oh, and there's guys who just take their fan shrouds off too.
I guess they're too lazy to even grind a little...
 
Thanks gentlemen. All I've been able to do since posting is to check the fan blade for wobble. It's nice and tight. So as soon as I can get some help, I'll take off the hood and see where it's hitting. Can't tell with a flash light. Will post an update when I've done that. And since I don't have a sheltered place to work on it right now, I have to work around the afternoon rain we've been having all week.
 
Finally got back to the fan problem after spending a week with a muscle spasm in my back. Wound up removing the fan and grinding the tips of the blades. Installing the fan and without the hood attached, it ran with absolutely no fan hits at any RPM speed. However.......with the hood attached, the blades not only hit the shroud, but hit the radiator fins as well. This was turning the fan by hand. Bent two blades and that got it out of the radiator fins. Had to loosen the radiator bolts and move it slightly right and left, and up and back. Very small adjustments and after half a dozen of them, we hit the right position. No noise right now, but it comes back with the grill installed! Will get the 16 or so acres mowed and then see if I can get the grill in without bringing back the problem. Thanks for all the help and keep your fingers crossed for me! Spencer
 
The placement or "tilt" of the N radiator is adjusted by the top
radiator hose. Side to side adjustment as you have noted.
Obviously grinding your fan blades made the problem worse.
I would start with a replacement fan, new or used.
That one is ground and bent, so will never be close to balanced.
Fans and adjustments are cheap compared to radiators.

Then adjust the radiator for proper clearance. Since you said
putting the hood back on made a difference, I would think your
top hose may be out of adjustment.

The only way I can see the grill affecting it is if that grill
straightens your hood up and makes the fan hit the shroud.

Given the choice, I would use a new fan and scrap the shroud.
 
(quoted from post at 21:29:18 06/24/18) The placement or "tilt" of the N radiator is adjusted by the top
radiator hose. Side to side adjustment as you have noted.
Obviously grinding your fan blades made the problem worse.
I would start with a replacement fan, new or used.
That one is ground and bent, so will never be close to balanced.
Fans and adjustments are cheap compared to radiators.

Then adjust the radiator for proper clearance. Since you said
putting the hood back on made a difference, I would think your
top hose may be out of adjustment.

The only way I can see the grill affecting it is if that grill
straightens your hood up and makes the fan hit the shroud.

Given the choice, I would use a new fan and scrap the shroud.
agree. I have Ns with & without shrouds in 100+ weather & I sure don't see their value. Yes, I have heard/seen the admonition a thousand times that you 'must' have the shroud, but still don't buy it. BTDT If you have overheating problems, look elsewhere.
 

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