Fan belt won't tighten

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krick3tt
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Re: Fan belt won't tighten

Post by krick3tt »

Don't be shopping at Lowes or HD for pinz parts http://www.mcmaster.com/#metric-hex-nuts/=pwbzcg
Any man who thinks he can be happy and prosperous by letting the government take care of him:
better take a closer look at the American Indian.---Henry Ford
Dogslovetrucks
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Re: Fan belt won't tighten

Post by Dogslovetrucks »

Took the "New" fan nut from SAV to a machine shop here in Jacksonville. They confirmed the thread was originally not cut correctly. They re-tapped the threads to the correct M14x1.5 size (for free, thank you very much Liddy's Machine!) Installed the nut with all washers on the outside, tightened up all is as it should be!
76 710K
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ScottD
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Re: Fan belt won't tighten

Post by ScottD »

Reviving an old thread because I think I might have a similar problem. Newbie here. The fan nut came off while driving in a similar manner to the op. Was able to retrieve the nut which showed the threads were stripped off leaving little thread shavings on the male threads of the alternator. The threads on the nut were stripped but also corroded, so I just assumed the corrosion caused them to fail, and ordered a new nut from SAV. The threads on the alternator shaft look good.

Since it didn't happen unless there are pictures, here is one of the fan nut with the threads basically stripped off and corroded,

The new nut arrives today, and it doesn't thread on very far. Cleaned off the threads on the alternator thinking that may be the problem, but it still only threads part way in. After reading this thread I am wondering if the new nut is not threaded correctly like the OP experienced.

I can get a 14mm 1.5 tap and run it throught the nut, but I wanted to see if any others have bought a replacement fan nut like the OP only to find the threads were cut wrong.
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rmel
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Re: Fan belt won't tighten

Post by rmel »

This may be more due to someone over torquing the fan nut than corrosion.
A not so common mistake but a mistake is to confuse the torque spec for the
Main pulley for the fan nut -- yikes that's a lot of torque! The fan nut is a standard
right hand thread but the fan rotates CW direction -- to loosen, some people get
worried about that and over torque. Depending upon the hardnes the nut may
fail first but damage the shaft. I doubt your new nut is incorrectly threaded. I'd
bet your shaft threads are damaged.
Last edited by rmel on Thu Jul 06, 2017 10:32 pm, edited 1 time in total.
Puller: 71' 710K 2.7L EFI aka Mozo
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Rescue Pinz: 73' 712MK

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ScottD
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Re: Fan belt won't tighten

Post by ScottD »

Thanks for the quick reply! I think I can take the fan off and run a die over the shaft threads to clean them up. They look ok, and the nut was the one the shed it's threads, but they could be boogered up a bit. I had to order the tap and die, as 14mm 1.5 isn't a size I could find locally, so one way or another I can sort it out. Was just wondering if anyone else had found the threads on a new nut were cut wrong. It was surprising to me that the OP found that as the cause of his problem.
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rmel
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Re: Fan belt won't tighten

Post by rmel »

It's a Steyr unique part, if you got it from EI or SAV it's going to be cut correctly.
Get a caliper on the threads to make sure you didn't loose diameter on that shaft.

Ya! Metric, still a novelty here in the USofA :wink:
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712MK

Driver: Ron // KO0Q
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ScottD
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Re: Fan belt won't tighten

Post by ScottD »

Got a tap and die, and the threads on the new nut checked out just fine. Cleaned the shaft threads of corrosion and bits of the destroyed nut and it now all bolts up just fine. Glad to have it back running.
The true Pinzgauer´s
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Re: Fan belt won't tighten

Post by The true Pinzgauer´s »

It is a known problem since the haflinger times. if the outside belt drive disc becomes play, the clammping nut is turning open. it starts at each reducting running speed, the crankshaft slows shockly down, the belt slips ( at every thiegthness) and the fan inhibit by the belt. because the fan drive is splitted ito two pieces, the beldt slips over the surface of the cooling fan, but the outside beltdrive disc becomes a torc knock. dust , mud, water and loosened clammping nut makes a faster worn out. it is a slow damaging with making some rattling noise, especially at changing engine speeds and idling running . rattling is coming from setting shims and loosing clamping nut. the clamping nut is worn out in a con shaped form, because of tensile load n the thread and the belt tension. on the thread never comes a looking fluid to fix it. some worn out nuts are holding because from the air entry water runns through the hole of the clammping nut at began to rust. at this cars you can see that the nut hold only on the top of the thread and not in center. four setting shims ( in meaning of 1mm thickness) have to be put in at alltimes, one ever between outside beltdrive disc and nut, because a shim can eliminate the opening twist from Pulley Disc to clammping nut, the surfaces of all pulley parts in the connecting areas have to be flat and clear.

So check fist the connecting part of the fan drive, because here your probies starts.
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The true Pinzgauer´s
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Re: Fan belt won't tighten

Post by The true Pinzgauer´s »

further pics
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The true Pinzgauer´s
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Re: Fan belt won't tighten

Post by The true Pinzgauer´s »

further pics
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ScottD
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Re: Fan belt won't tighten

Post by ScottD »

Thank you for this information. The fan nut was worn out more at the opening than deeper inside, so it did display the cone shape you refer to. The half pulley was lost when the nut came off while I was driving so it was replaced with a new one. It is possible that it was worn, but there is no way for me to know now that it is lost. I will go back and check the play with the new half pulley and nut.
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ScottD
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Re: Fan belt won't tighten

Post by ScottD »

I just took the fan nut off to examine the play and fit of the half pulley. It is good news and bad news. The half pulley is new, and fits very tightly. There is less than .2mm gap between the flat on the pulley and the flat on the fan. There is also very little play when I rotate the half pulley. That is the good news.

The bad news is that part of the flat on the pulley is very worn. Here is a picture showing how it is worn. When I got the truck, the fan belt was very loose. Maybe 5 cm of play in the belt. So with the belt tightened correctly, there are less shims between the two halves of the pulley and so a little bit of the flat on the fan is now engaged and it does not move around. However, it is not well supported and I am thinking that although it is working now it is asking for trouble to not replace the fan.
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The true Pinzgauer´s
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Re: Fan belt won't tighten

Post by The true Pinzgauer´s »

Hello ScottD,

you can overhaul the connecting part of the cooling fan. The Fan have to be removed from Alternator. mostly the fan can be removed by pulling by hand, first spray some rust dissolver on, and pull carfully without twisting the fan on the alternator axle, maybe one person catch with both hands( hand gloves advisable) the fan, another person knocks with a light metall stick and hammer on the alternator center, better on the loosened clammping nut ( without any shims and half pulley disc AND the space from fan to downside nut have to by more than 5mm distance (at 4mm distance the both parts are connected)).if the fan loosen one subsection , spray on rust-dissolver and flush out rust by moving in and out the fan. for reinstall the surfaces have to be metall clean, for resetting take a mixure of oil and anti-seize ( silver type, non ceramic).

the special tool to pull-off is only needed by rusted on parts.

the shown damaged connecter can by short welded ( spot welded) after remove. first remove the zinc plated at damage and welding zone and cover the thread for the pull off section. weld on short points and cool it seconds after by compressed air -flow gun or water bath ( it also can by welded in a water filled trough). after welding it can easy hand machine worked, for rust protection spray on thin layer of anti-rust spray.

the plastic part of the cooling fan can not removed from metall connector without damaging, new rivets and new balancing. Plastic part also didn´t resist a chemical bath for new electrogalvanizing ! so please don´t dismantel the cooling fan wheel !
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audiocontr
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Re: Fan belt won't tighten

Post by audiocontr »

1973 712m
1968 Haflinger
1965 Pathfinder
1978 GMC Palm Beach (Hey, its got 6 wheels!!)
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ScottD
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Re: Fan belt won't tighten

Post by ScottD »

I can try repairing it. There is nothing to lose.
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