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Hello - I'm new to the forum. Recently purchased a numbers matching big block 72. I haven't worked on a car in a looong time but really enjoying getting my hands dirty. I'm replacing the water pump and have run into a problem. I removed the studs from the old water pump and installed them in the new water pump flange. I screwed them all the way down, placed the pulley over them and then attempted to attached the fan clutch but there are no threads left to attach the nuts. The stud is flush with the hole on the fan clutch.
I am perplexed and it seems like I must be missing something simple. I added nuts to the studs, pictured below, to try to get some additional length on the forward side of the flange. This only resulted in 2-3 threads coming through the fan clutch. Plus I don't know if having those nuts on the flange is mechanically sound.
I have a pic of the original water pump below as well. You can see there's a spacer on the forward side of the flange to keep the pulley from rubbing on the water pump. This is needed on the new water pump as well. Is that common? Could this be the wrong pulley?
Appreciate any assistance.
Thanks
John
Install the studs only to the point where the stud thread is fully through the water pump flange and no further, no thread projecting past the back of the flange.
That would definitely solve the problem. Is there a concern about the studs coming loose over time if they aren't fully seated? Is this the way yours are set up? If this is the way it should be done, problem solved. Again, I haven't worked on a car in awhile so I don't want to do something that could cause a larger problem down the road.
Thanks
John
My brother 'dislodged' the fan in my Blazer K-5 4X4, by jumping it and having it hit the fan shroud (engine mounts, I suspect) He put a new fan on (paid someone to do it) and delivered my truck on Sunday nite LATE, (dark...the little shizzle!) with a fan blade sticking through the hood like a sharkfin.
"Maybe he won't notice!" ahh! the memories. He's 60 now!
Good luck.
If you can't get SS316...get the best steel ones you can. with SS bolts and washers....STILL LOCK-TITE them all.
John.....Squint your good eye (lol) along the line of the belts and pulley...should make a perfectly straight line....NO OFF-SET. This will answer your pulley Wrong? question.
I believe you have inserted the studs in backwards. The short threaded part of the stud goes into the water pump flange and it is tightened down against the bulge in the middle of the stud. The fan assy gets installed on the long threaded part and is retained with lockwashers and the nuts (which you have on the backside of the WP flange).
I believe you have inserted the studs in backwards. The short threaded part of the stud goes into the water pump flange and it is tightened down against the bulge in the middle of the stud. The fan assy gets installed on the long threaded part and is retained with lockwashers and the nuts (which you have on the backside of the WP flange).
I was hoping that would be the solution. I tried inserting the studs both ways. The thread pitch is not the same on both sides so the studs can only be inserted one way. UGH!
What was the thread size in the flange on the water pump you removed? The shorter threads DO engage with the flange. Maybe the new pump takes different studs.
The studs are 5/16 x 24 on the long side and 5/16 x 18 on the short side. They fit the same way in the old water pump. The short side doesn't engage the flange. It would sure make sense that the short end goes in the flange.
I ordered a new set of studs that should work. Thank you all for the help!
John
To close out the thread, the new studs I ordered worked like a champ and I'm back on the road. Replaced the radiator, water pump, alternator and wires/plugs. Woohoo! Thanks for the help!
Fan clutch stud problem
