This problem pops up on the forums now and then, usually attributed to worn accessory bushings. The car I am dealing with, second case in fact, the water pump round piece to which the pulley attaches with the four bolts, has somehow "traveled" about quarter of an inch back thus causing the water pump pulley to rub against the timing belt cover and unwanted obvious misalignment. This piece should be pressed on and it's hard to imagine how it would move back like that, but there it is... marks and all. The pump in question is OEM Volvo, the second case a Hepu.

I just measured a pump on my shelf, a Hepu and one on a PNP engine on an engine stand that is a GMBH

They each have the same measurements.

The shafts on both pumps stick out in front of the flange for the pulley to align on and its 10 mm.

The over length in question here from the back of the pump housing to the flange front is 131 mm. or 5.157 inches.
If you throw behind the pump a gasket you will be all over the 5 & 3/16" or 132 mm.

If you have those like dimensions then there is a cover problem with the lower grooves.

If not you will have to pull the flange forward with heavy duty puller, fun getting that in there on the car or removed the pump and press the shaft down or flange outwards.

Phil

This is what's driving me crazy: both pumps' flanges are 10mm from the end of the shaft. There is no reason for the misalignment problem which is what concerns me much more than the pulley rubbing the cover. After I install everything, the water pump pulley is too far in, about 1/4 inch! Why? There is absolutely no reason that I can see! the harmonic balancer and the P/S pulley are fine as far as alignment but the third pulley, the water pump, is off by 1/4 inch. The only reason I could see was that the water pump flange had somehow moved back that distance but that's not the case as apparently all pumps are like that. I can remedy the situation by shimming the 1/4 inch out, but what the hell is causing it?!

Machine man has provided measurements so you can compare them to your pump.

Chris Mullet found the casting on a Hepu pump where the TB cover may be pushed out a little causing the cover to rub against the water pump pulley.

I have suggested the TB cover may sticking out from the inner part of the cover. You might also look at the inside/against the engine piece, there may be a tab that is keeping the upper cover from seating properly this would push out the upper cover an 1/8 ". I can see this in a couple of spare TB covers I have.

This information should help solve the mystery.

"The only reason I could see was that the water pump flange had somehow moved back that distance but that's not the case as apparently all pumps are like that. I can remedy the situation by shimming the 1/4 inch out, but what the hell is causing it?!"

It is not that the pulley has moved back, but more likely the TB cover is moved forward.

I think the pump is fine and there is some interference with proper seating against the groove in the pump where the cover meets the pump or between the fit of the inner and outer plastic pieces of the TB cover.

Dan

Mystery solved: the Volvo pump that had misaligned things had somehow, in the way of failing, slid back, impeller shaft and all, about 1/4 inch. When I compared it side by side with two other pumps it became obvious-the whole pump was actually shorter. The flange is always 10mm back from the tip of the shaft. How that shortening had happened and why, well, we'll never know! The timing belt cover was positioned properly, the rubbing damage occurred due to the whole impeller shaft being out of position and too far back by 1/4 inch. Thanks to all!

I don't understand how you fixed this?
Dan

I changed the pump. All the problems were due to the old pump's impeller assembly sliding back (toward the engine) 1/4 inch, enough to cause pulley misalignment and the water pump pulley to rub onto the timing belt cover. The impeller's assembly movement was likely caused by the internal bearing failure of the pump. Basically the pump, even though a Volvo OEM, was shot, it was pretty old...

They do wear out, did the shaft move in and out.
Dan

I agree!

The stuff I put out there would be an extreme example of one thing going wrong with the assembling or machining and cascading!

I do not know why they put those grooves into the left side of that investment casting to hold the covers left edge?
Where do they think it can go, its bolted on and fitted to the lower half and back enclosure plate all the way around.

I wish they had all of that "thought effort" into making the lower halfway shields removable, to clear the underside completely. No pulling of the crankshafts pulley unless you need to change the seal of course!

Phil

Here I go guessing again!

The only way I can see how it can happen is the entire shaft bearing assembly, as a whole, is not located into the housing correctly.

If the housing was bored short in its depth or the shaft is not seated all the way into it, the excess would be left towards the engine.

They would have to push the impeller onto its shaft farther down to get it below finished surface of the impeller cavity!

On a Volvo OEM pump I believe the impeller has a thru bore. So its possible to adjust it just like a flange.

The Hepu has the impellers shaft end is struck to form a mushroom head. Its bigger than the bore of the impeller. I have not torn one of those down to see how the bearing location is established.

I have torn an Volvo OEM down and it has a smooth shaft from end to end. Now It is smaller in diameter on the impeller end and bigger on the flange end. But its still a straight two diameter ground piece shafting.

The center area under the bearing is as large as the flange end.
I am sure they located the roller bearing from a shaft end or at shoulder transition but which end I cannot tell you or which methods.

My money is on the impeller and its pressed on deeper than normal to compensate since you have the 10 mm depth in front. That is, if the shaft assembly "is"normal.

If none of this happen then the shafts overall length is short.
To be that, the rear of the flange would be right up against the front of the housing! No space at all.

What gets me is this a new pump? Or has been on the car for awhile being used then how come its showing up now ?

Bottom line is, something is a bummer!

Phil

I've had this problem before - but not because the flange travelled. In my case the pump casting was so cruddy that the belt cover wouldn't sit down in the little "grooved" area on the pump. Of course I didn't realize how messy the casting was until I put it together and saw the pulley rubbing. Mine wasn't a whole 1/4 inch off so I was able to Mickey Mouse it by inserting a couple small flat washers at each stud between the flange and pulley. I think it was a Hepu pump.

The belt cover should fit far enough back that there is no space between it and the engine block.

I also have never seen this in all the Volvo water pumps I've changed in a 240 and 940. Can you compare the new pump length to the old, though I doubt it is this as you stated you noted this with 2 pumps. Are you sure the pulley is seating correctly and not wobbling? Can't think of anything else.

I have never heard of this but it could be the timing belt covers are not correctly seated on the engine?
Dan

This is what I thought but I had put a new cover (Volvo OEM) on it recently and was upset with myself thinking I had fitted it badly, but then I looked a the alignment of the pulleys and sure enough the pump pulley was sitting too far inboard so it rubbed. Then I looked at the pump and saw that the shaft was sticking out too far so that when the pulley fit on top it slid too far back and thus hitting the against the cover. The pump is Volvo which makes it even more bizarre. I'll try to post a picture...

You might also look at the inside/against the engine bottom piece, there may be a tab that is keeping the upper cover from seating properly this would push out the upper cover an 1/8 ".
Dan