Replace big block water pump idler pulley - how?

I want to replace the water pump idler pulley on my big block because the bearings feel worn out. I bought a replacement from O'Reilly Auto Parts. When I looked up the part originally it was a Murray 45900 as shown on this link:

http://www.oreillyauto.com/site/c/detail...7&ppt=C0331

But when I called to find out if they had it in stock, they told me it cross-referenced to a Gates 38038. So I bought it, and it looks like it might fit. But the old pulley has a threaded stud in it that I don't know how to remove, or even if it's removable. I tried tapping it out with a hammer but it didn't budge. Has anyone tried to replace one of these? Is it even removable? If it is, how do you get it out? See the attached pictures.

Here are some pictures

Front of old and new pulleys

Back of old and new pulleys

If you look closely at the old pulley you will see the tack welds holding the 2 cover plates on that protect the bearing ... notice I said WELDED , you are not going to get the threaded stud out by trying to tap it out without destroying something.

JohnRR is right. The cover is welded in multiple places around the front of the pulley (that cover is visible when installed on the engine). I cut mine off thinking I could just replace the bearing. However after getting the cover off and the stud out (which you will also have to do), I discovered that the cover also serves to hold the bearing in the pulley. It is not a press fit and you would have to weld a cover back on to be able to use the original pulley.

jess

Thanks for the info, I did not notice the weld.

It seems like the real irreplaceable part is the stud with the flat side to line up with the "D" shaped hole in the bracket. If you cut off the original pulley front cover and remove the stud, will it fit into the replacement pulley? Is it a shoulder bolt that press fits into the pulley and if so is it the right diameter?

Mega Parts carries a very nice reproduction of these pulleys!!

Quote:

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If you cut off the original pulley front cover and remove the stud, will it fit into the replacement pulley

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Yes, fits perfect, that is what I did. I also found a small suitable washer to serve as a guard for the bearing seal.


Jess