[aronhk_md]

Just put a plate under the impeller with the water pump facing down on an arbor press....then press down on the shaft. Almost the opposite of pressing the impeller onto the shaft. As you saw here some people have a really thick separation plate and they had to smash that plate down hard....leaving them with uneven edges around, which isnt great for controlling that small gap we want.

[george kujanski]

So you say put a plate under the impeller wheel and support the pump in the press by the plate? That would work if there is enuf clearance under the wheel for a plate.

George

[Groucho]

Please, what yrs had the diverter plate?

[aronhk_md]

George....exactly. If necessary it would be easy to bend two strips of steel to go under the impeller....one on one side of the impeller, one on the other. All it has to do is stick under the impeller far enough to give it some support while pressing the shaft a bit at a time. Like hooks on a bearing puller.

Some people indicated their plates were easy to hammer.....others said they had to use a tremendous force and the result wasnt even. Really though the impeller is pressed onto the shaft, so that would be the proper way to adjust. Unfortunately, nobody at the manufacturing facilities has probably ever SEEN a pontiac engine, let alone put one together. Who knows what procedure they have for measuring how far they push the impeller onto the shaft...............they probably know it just has to go on beyond a certain point.

[george kujanski]

Groucho...don't know about the years exactly, but the 8 bolt pump (8 mounting bolts) had the internal divider/diverter plate in addition to the "internal housing" (name taken from the service manual) which surrounds the impeller and closes up the assembly. The later 11 bolt pump does not use an internal divider plate.

The change occurred in '68 or '69 don't remember which.

The first few pages of the "chalk one up for the cast impeller" sticky thread show some service manual pix of both types, I believe.

George

[Groucho]

Originally Posted by george kujanski

Groucho...don't know about the years exactly, but the 8 bolt pump (8 mounting bolts) had the internal divider/diverter plate in addition to the "internal housing" (name taken from the service manual) which surrounds the impeller and closes up the assembly. The later 11 bolt pump does not use an internal divider plate.

The change occurred in '68 or '69 don't remember which.

The first few pages of the "chalk one up for the cast impeller" sticky thread show some service manual pix of both types, I believe.

George

Maybe my question sucked. Does the '65 have a removable plate....requiring the 2nd gskt? If not, is there a way to massage the clearance between impeller and plate as described with the removable plate?

[Skip Wiley]

Unfortunately the clearance fix did not work for me. Gap was at about .20 and I hammered it down to about .08. Still heats up to 225+ degrees and it's only 60 degrees outside. Next I will have to try an electric fan.

[Stuckinda60s]

Skip:

What are your engine specs, what trans, car model, radiator, fan, shroud, etc?

[Groucho]

Ya know, when I was a kid in the 70's, it seemed none of these cars ran hot. Someone mentioned it's the newer oxygenated fuel that runs leaner/hotter than what we had back then. Any thoughts on that?

[69-er]

I'm right in the middle of assembling a 68 400 that has run hot for the customer as long as she could remember. I'm only up to pg 10 of this thread, so I hope I'm not rehashing this by asking this question:

I'm comparing the old pump to the new one. The old impeller is about 4 5/8" x 13/16", the new one, 4 1/2" x 3/4". (The height is near the center) The old one also has a more blended hub as it transitions to the vanes. The old one is also installed further on the shaft. I might be splitting hairs, but could the old impeller be considered more efficient?

Clearance isn't as good with about .200" on the old one, the new one is about .150". I haven't attempted to hammer on the plate to reduce it. I wonder If I could swap impellers? Since it already ran hot, I'm afraid this new pump might be a step backwards.

Also, since the plate is convex which more or less follows the contors of the vanes, I wonder if I were to take the pump casting to my machine shop and have them shave a few thousanths off the gasket surface and use the old impeller if that would be the best of both worlds? It could be installed further on the shaft and have less clearance.

You can a few of the differences in the attached pics.

[Old Goat 67]

69-er,

How about a shot of each pump like the one's I posted on page one of this thread? With the plates clearance viewable.

Maybe then we can advise what we would do better?

Charles

[aronhk_md]

As I've mentioned before, I think pressing the shaft out of the impeller slowly on a press is the better way to get the clearance corrected, as opposed to hammering the plate.

[69-er]

I wish I would have seen your request sooner! Impatience got the best of me; I already hammered the plate!

But here's what I have now with the mods. The old one now has about .090" and the new one, about .050". This is with both plates and the gasket installed.

I also noticed since the plate is more flat, actually a little concave, it doesn't follow the tops of the vanes. Would this reduce efficiency?

[69-er]

Originally Posted by aronhk_md

As I've mentioned before, I think pressing the shaft out of the impeller slowly on a press is the better way to get the clearance corrected, as opposed to hammering the plate.

Was there a procedure outlined earlier in this thread on a good way to press off the impeller? I don't have anything I could get behind the impeller with.

Hopefully, I can get caught up with the rest of the posts to get up-to-date on this topic.

Larry

[aronhk_md]

You dont want to press off the impeller entirely. In the end I took 2 18" long sections of L steel, welded them together quickly to form a U. In the bottom of this U I drilled 3 holes spaced approximately the same as the holes in the water pump impeller. Then I drilled a central hole in it 9/16" in diameter.

This assembly I placed on the arbor press with a brick under each end. I slid the water pump underneath and slid 3 hardened bolts (cant remember what size offhand) up through the 3 holes in the U steel and put a bolt on each one. So now the bolt heads were hanging downward. The bolt heads were inserted into the impeller holes. I had to grind the heads of the bolts a bit to make this work. If I remember I also used small metal shims so each bolt head would stay firmly under the lip of the impeller. So basically the water pump was hanging/dangling from this assembly.

Now I took a 1/2" rod and placed it through my center hole so that it rested on the impeller shaft and pressed it slowly down with the arbor press. My biggest fear was going too far, but it worked because I went very slow and kept checking it.

Basically you want your plate to just touch the impeller with NO gasket in place. So when you assemble it with the gasket it has perfect and tight clearance.

I'm sure someone here can come up with a better system, or maybe just a gear puller that fits and works. I didnt have one handy.

[Old Goat 67]

Originally Posted by aronhk_md

You dont want to press off the impeller entirely. In the end I took 2 18" long sections of L steel, welded them together quickly to form a U. In the bottom of this U I drilled 3 holes spaced approximately the same as the holes in the water pump impeller. Then I drilled a central hole in it 9/16" in diameter.

This assembly I placed on the arbor press with a brick under each end. I slid the water pump underneath and slid 3 hardened bolts (cant remember what size offhand) up through the 3 holes in the U steel and put a bolt on each one. So now the bolt heads were hanging downward. The bolt heads were inserted into the impeller holes. I had to grind the heads of the bolts a bit to make this work. If I remember I also used small metal shims so each bolt head would stay firmly under the lip of the impeller. So basically the water pump was hanging/dangling from this assembly.

Now I took a 1/2" rod and placed it through my center hole so that it rested on the impeller shaft and pressed it slowly down with the arbor press. My biggest fear was going too far, but it worked because I went very slow and kept checking it.

Basically you want your plate to just touch the impeller with NO gasket in place. So when you assemble it with the gasket it has perfect and tight clearance.

I'm sure someone here can come up with a better system, or maybe just a gear puller that fits and works. I didnt have one handy.

Inovative to say the least. I can't quite wrap my head around the "U" configuration, but if it worked, what the hey?

69-er,
You are now seeing the problem clearly. You are going in the right direction. What about a different pump, one with the impeller not pressed in so much? When I was doing this, it seemed they were all assembled a little differently.

[69-er]

Has it been discussed if there was a negetive impact of the impeller being farther away from the front of the pump housing? Or is it just the clearance between the vanes and plate that is critical?

I'd like to try aronhk_md's puller fabrication to swap impellers if it can be determined that my old impeller would be considered more efficient then the new one. I really don't want to look for another pump as the new one has been painted, just about every store in our small town needs to order Pontiac pumps and I really need to proceed with the assembly of the motor if possible.

I wish I didn't flatten the plate now. I saw Malky's (SIC?) post where his vanes follow the contour of the plate. That seems to be a key in this issue. I'm sure I can massage it back to the original shape.

[Old Goat 67]

Originally Posted by 69-er

Has it been discussed if there was a negetive impact of the impeller being farther away from the front of the pump housing? Or is it just the clearance between the vanes and plate that is critical?

I'd like to try aronhk_md's puller fabrication to swap impellers if it can be determined that my old impeller would be considered more efficient then the new one. I really don't want to look for another pump as the new one has been painted, just about every store in our small town needs to order Pontiac pumps and I really need to proceed with the assembly of the motor if possible.

I wish I didn't flatten the plate now. I saw Malky's (SIC?) post where his vanes follow the contour of the plate. That seems to be a key in this issue. I'm sure I can massage it back to the original shape.

I don't believe. Cavitation won't occur between two flat surfaces, right?

[aronhk_md]

The clearance is only important on the impeller side with the vanes. I used the two L shaped pieces together as a U because I did not have a piece of metal that I felt wouldnt bend under the stress. The U shape is very strong. If you had a very thick piece of flat plate it would work too. Its the same reason the frame on a vehicle is made of pretty thin metal but shaped as a box/square.

The plate is available separately from a number of sources including I believe PY. The inability to really get a good fit by hammering is one reason to try it this way.

[Old Goat 67]

Now I got you. Mind slow some times.