Explain the factory double threaded PS pump bolt to me

[thegreatjustino]

Can someone explain how the factory double threaded bolt that attaches the power steering pump to the engine is supposed to work? I have messed with them on two different Broncos, and still cannot figure them out. This weekend I was trying to remove the stock pump to install a saginaw. I took the nut off the grille side of the bolt, but could not get the pump and bracket off the engine. It seemed that the only way it was going to come off was to rotate the whole unit a couple dozen times to unthread it from the block. I ended up cutting the bolt in two and using a $0.79 bolt from the hardware store to replace the factory double threaded one. Just curious how this thing is supposed to work.

 

[jkransbottom]

I don't know how it's supposed to work, but I took the channel locks to mine and unscrewed it from the block in order to get my old pump off. It confounded me for quite a while and I was considering removing the radiator when I realized I could just take it out.

 

[Johnnyb]

Single-thread

I have seen both a double-threaded and regular. Just last week I used two nuts locked together to install one of the double-threaded variety, then removed it when we found one of the regular style in the Pile-'O Parts. I think the regular style may have been used on alternators too.

-J

 

[iwlbcnu]

There is a change over in threads sizes, don't remeber the year, but sometimes the block threads are larger then the front. I always double nut them to remove.

 

[Tuff68]

Bolt size

Wanting to change the doub/thrd bolt to a stock 7" bolt.
??? What is the bolt size for the thread that goes into the block.
Thanks

 

[thegreatjustino]

There is a change over in threads sizes, don't remeber the year, but sometimes the block threads are larger then the front. I always double nut them to remove.

Yes, the front threads are smaller than the engine side threads. However, the bolt is fit so tightly into the pump bracket that it just spins the pump and bracket when you try to unthread it from the block. The bolt does not spin in the bracket. At least neither of them that I have messed with did.

 

[Rustytruck]

The threads in the head on my 74 302 are 7/16-14 the threads on the end of the bracket are 3/8-16 the holes in the waterpump support and the powersteering pump bracket are for a 3/8 bolt/stud and a 7/16ths bolt will not go through them. This is why the stud will not go through them.