Did LA water pumps ever get fine thread bolts from the factory?

[Johnny Mac]

One of our friends in the business, caught a shipment of LA water pumps, with fine thread 5/16 - 24 fan / pulley bolts, vs 5/16 course. Was this ever a factory thing? OR just a shipment of mis tapped water pumps?

I hadn't heard of it, but figured you guys would know!!

Luckily they weren't our pumps. Lol

I found this old thread...but nothing difinitive.

La fan blade bolt threads fine???

 

[Inertia]

Yes .

 

[cudamark]

I never ran across a factory pump that had fine threads for the fan bolts.

 

[67Dart273]

I "think" some setups had studs, but they were USS into the pump flange, and fine out on the forward end of the studs

 

[Johnny Mac]

Yes .

any rhyme / reason you can share please?

 

[Johnny Mac]

I never ran across a factory pump that had fine threads for the fan bolts.

me either! So i'm wondering if some parts manufacturer simply tapped the wrong threads, or some odd duck A/C truck with heavy duty cooling had them, or something to that effect. Thanks!

 

[Johnny Mac]

I "think" some setups had studs, but they were USS into the pump flange, and fine out on the forward end of the studs

So double threaded studs (like a rocker arm stud?) with course into the pump flange, and fine there outward.? that sounds vaguely familiar....I'm almost recalling that on a viscous fan setup I had, but i suppose I could be remembering wrong. Probably 20 years ago.

 

[Rat Bastid]

All the OE stuff I remember was coarse thread. All the aftermarket stuff I’ve used lately is fine thread.

I don’t know why the change. It’s irritating for sure.

 

[cudamark]

At least they didn't tap them metric!

 

[Inertia]

any rhyme / reason you can share please?

Early in my career at a dealership, I had taken a box of 5/16 coarse bolts to work cuz I had busted out of my flat rate twice cuz I had to stand in line at the parts counter waiting for 4 coarse thread bolts to replace the fine thread bolts I took out. Used a few outa that box thru the yrs.
Never forgot it, - on reflection, they may have been polys, they used the same pump.
But I do agree, after a few years, they were all coarse .

 

[Inertia]

So double threaded studs (like a rocker arm stud?) with course into the pump flange, and fine there outward.? that sounds vaguely familiar....I'm almost recalling that on a viscous fan setup I had, but i suppose I could be remembering wrong. Probably 20 years ago.

Your memory is correct, as Del mentioned, a fine/coarse stud was often used