View Full Version : Water pump drive pulley

02-26-09, 09:14 PM
This may have been answered somewhere in these forums. I have a STS that I'm working on that the water pump drive belt that bolts to the cam is stripped. This is the second one that has been replaced in last 6 months (last time tensioner locked up and melted it. The thing is I noticed that the sleeve that this pulley presses onto came out with the pulley when I removed the 15mm bolt that held it in. At fisrt I didnt think anything of it, I just pressed it out of old one (in a press) and pressed sleeve into new one. But then I realized that this sleeve is supossed to be on the cam (I think). Does this mean it needs a new cam? I removed the cam cover (held in by 3 bolts) and see that it looks like a stud sticking out of the cam. Just havnt been able to find out if that stud is replacable by itself. If it needs a cam I will probly be sending this customer to the dealer, but being that its the front cam I may try and install one myself.

02-26-09, 09:22 PM
Something fishy.....the water pump drive pulley (cam pulley) is pressed onto the camshaft extension. The pulley has a conventional groove in the center sleeve for a puller finger set, as the pulley is plastic composition. The pulley and sleeve are one unit......there is no "15mm bolt".....only (sometimes) a Torx head plastic thread filler trim capscrew used to fill the cam threads which are used to pull the new pulley back onto the cam extension......stacked washers and anti-seized bolt will do the install......flush with the cam snout.

02-26-09, 10:24 PM
It not a 15mm bolt, there are male threads about 3" long sticking out of the cam, yes there seems to be a metal sleeve in the center of the plastic pulley, but this sleeve is larger than the stud sticking out, so I'm assuming the other sleeve was part of the stud sticking out. Because without this other sleeve I can push the pulley all the way to the cam without any force, I can also easily push the pulley on the stud after pressing the pulley on the sleeve (out of the car). I'll take a snapshot of this stud tommarow when i get back to work. The 15mm nut I was talking about keeps the pulley tight against the cam, but as of right now the pulley is too far in and dosnt line up with the tensioner.
I was thinking and probobly will use a couple of washers to space out the pulley so it will line up and inform the customer it may happen again, and if so to take it to the dealer. He is a long time customer and brings all of his other cars to me and this is the first one of these northstars that Ive run into this, it's usually just use a Snap-on puller to remove and an installer to put back together, I didn't need either of these on this vehicle. Thanks for your quick reply Sub!

02-26-09, 10:31 PM
That does not sound like factory. Is it possible that the stud is for a shaft that threads onto the cam and the pulley is pressed onto that shaft? I've never had one off to look at.

02-26-09, 10:54 PM
The water pump pulley unit is a press fit on the end of the cam. The internal threads in the cam end are used with a bolt or special GM tool to press the pulley unit onto the cam. There is no sort of retainer bolt or arrangement.

03-01-09, 11:32 AM
I took good pic's of this threaded stud sticking out of the cam Friday and was trying to post them on here, but it won't let me. I have them posted on my Facebook page, so if you have Facebook look up Neil Jordan and look at the Photo's under Cadillac Gears, otherwise I'm not sure how else to get someone to see this and tell me WTF. It's no big deal, it's probly going to the dealer anyway, I did install 2 washers on shaft so pulley would line up with the grooves of the tensioner. But now I see the pulley wobbles so we probly have a bent cam, and it probly was wobbling before which made the bolt loosen up, causing the pulley not to spin.

03-01-09, 05:03 PM
Once again, there should be no bolt or stud of any sort holding the water pump pulley on the cam snout. The pulley, with integral hub, is a tight press fit. The internal threads in the cam are used for installing a new pulley.

You presently have a jury rig in place that a dealer will have to fix.

The hub or sleeve, whichever you prefer, is an integral part of the pulley, not the cam. If the "sleeve" is separate from the pulley, something is very wrong. You don't press anything apart. You draw the entire pulley/hub onto the cam using the internal threads with either a pulley installer or a bolt/washer set, and then remove the bolt/washer.

03-01-09, 05:40 PM
I'd bet someone installed a new pulley at some point and left the installation bolt in place.

03-01-09, 05:58 PM
Yeah, something's not right. Is it possible that someone machined the end of the cam for some reason ??? The OP states that a new pulley/hub is an easy slip fit on the cam. That's not the way its supposed to be. That pulley presses onto the cam and its tight.

03-01-09, 06:21 PM
I agree. Something is not kosher here.

03-01-09, 06:39 PM
Ok I will just send him to Cadillac, he has had this car since new and has only had the car serviced by us and Cadillac, the only thing I can think is it's something Cadillac did. It's wierd it's not like the hub broke off from the cam, this stud sticks out of the valve cover, from the cam. It looks like the cam is about and inch inside the head. It totally looks factory, at least it is a very clean job if it's not factory, but I totally believe both of you, since I try not to work on alot of Cadillacs.

03-01-09, 10:59 PM
Wait a minute......there IS an extension on the front intake cam specifically for the water pump pulley, but it is machined so the water pump pulley, with its cast-in inner metal hub, is a tight press fit on the extension. The cam extension has its own seal and internal threads...........the front intake cam is the ONLY one of the 4 cams that has this machined extension which sticks out of the cam cover. Take a look just to the right of 2 in the illustration. That's the cam in question.

03-02-09, 09:55 PM
Thanks for the illustration, that makes it clear, and no question that what I'm looking at is a jurry rigged cam snout. And I was wrong about the history of this car, he didn't buy it new and came from some sort of auction -- Bingo there's the culprit, we all know how auctioned cars can be (patched up to sell). So I informed the customer that what he has is a rigged drive pulley and if he wanted it fixed to take it to the closest Cadillac dealer. You were very nice to keep replying and for all your informative info. I know now what it's suppose to look like and I also know I will probably not see one configured like that in the future. I'm still not sure exactly what they did, but the next Northstar I have privilege of working on I will check out that cam snout. Thanks again for your help.