[69-er]

Seems like I could tap the three holes in the impeller and use a three bolt puller to pull the impeller to the proper location.

Has anybody looked at the pics of my impellers? Any thoughts on which of the two impellers might be more efficient? To summarize, the old impeller is about 4 5/8" x 13/16", the new one, 4 1/2" x 3/4". (The height measurement is near the center) The old one also has a more blended hub as it transitions to the vanes.

I would still like to swap impellers if it would make a difference.

Larry

[69-er]

I just saw Malcolm's post back in '04 concerning pulling the impeller:

"You could pull the good impeller off your old pump if you have the three balance holes. I made up a puller and got the impeller off a '73 pump and a '68 pump quite easily. The bolts in the photo are 5/16" with the heads ground to a T shape so they can be finagled into the balance holes. I clamped the pump in a vice with the impeller up, poured water in around the seal, and heated the impeller hub. The water stops the seal frying.
Malcolm"

Since the holes in the new impeller are smaller, I think tapping them is the only way to go. The old impeller has the larger holes so "T" bolts would work.

Malcolm, what do you mean by balance holes? Balance as in vibration or some sort of flow balance?

Larry

[aronhk_md]

There was at least one person experienced with pump design toward the beginning of the thread. He'd be the one to ask about the impellers...to my eye neither looks to have much of an advantage, except maybe the one with taller vanes.

Not sure if you'd be able to get a tap into those holes deep enough to thread it without hitting the housing behind?

[aronhk_md]

I dont know this for sure, but my thought here is that balance on these impellers is approximate and not like a measured balance....so you could probably take a drill bit to all three of those holes and upen them up a bit if necessary.

[Stuckinda60s]

The holes are there to balance the suction forces on the impeller. If they weren't there, the impeller would have a constant pulling force against it toward the suction.

As far as moving the impeller rather than flattening the plate? That doesn't do anything to reduce the clearance volume of the pump. Within limits, the reduced clearance volume reduces slip and increases efficiency and velocity.

Looking at the two impellers in the pictures, the old pump would be the most efficient because there is much less clearance at the tip of the impeller. Larger clearance allows more fluid to be recirculated, back through the holes on the backside, to the suction. This reduces the amount pumped. The fluid will take the path of least resistance back to the suction. You can see how moving the impeller on the shaft will increase the backside clearance. Flattening the plate will leave that the same while increasing the pump's output.

[aronhk_md]

Originally Posted by Stuckinda60s

You can see how moving the impeller on the shaft will increase the backside clearance. Flattening the plate will leave that the same while increasing the pump's output.

That might be true if you were able to flatten the plate evenly along its entire surface. However, most people are only able to flatten it unevenly around the hole in the plate, which means the rest of the plate is not close to the vanes of the impeller. This leaves the pump inefficient.

[PMDRACER]

The impeller is pressed onto the shaft with a tapered fit, like a ball joint in a spindle. Unless you created some sort of sleeve or other retention device, you will not be able to move the impeller towards the plate.

[aronhk_md]

I was able to move mine as described, though granted it didnt need a lot.

Another thought might be to take a piece of sheetmetal, cut it to size with a central hole and tig/mig/spotweld it in place on the inside of the divider plate?

[Stuckinda60s]

Originally Posted by aronhk_md

That might be true if you were able to flatten the plate evenly along its entire surface. However, most people are only able to flatten it unevenly around the hole in the plate, which means the rest of the plate is not close to the vanes of the impeller. This leaves the pump inefficient.

That's untrue, as well. By decreasing the clearance between the suction and the vanes, you reduce parasitic recirculating losses . You also reduce the volume between the vanes and plate.

I don't care one way or the other how you do it. I'm explaining what's right and what's wrong. Before you make any more statements about it, why don't you do a little research?

I'm posting facts and you're posting what, conjecture?

[aronhk_md]

Originally Posted by Stuckinda60s

That's untrue, as well. By decreasing the clearance between the suction and the vanes, you reduce parasitic recirculating losses . You also reduce the volume between the vanes and plate.

I don't care one way or the other how you do it. I'm explaining what's right and what's wrong. Before you make any more statements about it, why don't you do a little research?

I'm posting facts and you're posting what, conjecture?

Not sure what your issue is, but I'm also not sure how your posts are now facts and mine conjecture.

In bold above you are declaring a decrease in clearance between suction and the vanes as if you are referring to the distance between 2 objects. Vanes are an object, suction is a description of a physical force better described by other terms. You cant have a distance between these two.

In the red portion I highlighted you claim that you reduce parasitic recirculating losses. Parasitic losses are NOT recirculating losses. Parasitic losses are for example...friction. Nevertheless.....it still equals what I said...less EFFICIENCY for the pump.

I understand physics fairly well.

[Stuckinda60s]

Originally Posted by aronhk_md

Not sure what your issue is, but I'm also not sure how your posts are now facts and mine conjecture.

In bold above you are declaring a decrease in clearance between suction and the vanes as if you are referring to the distance between 2 objects. Vanes are an object, suction is a description of a physical force better described by other terms. You cant have a distance between these two.

In the red portion I highlighted you claim that you reduce parasitic recirculating losses. Parasitic losses are NOT recirculating losses. Parasitic losses are for example...friction. Nevertheless.....it still equals what I said...less EFFICIENCY for the pump.

I understand physics fairly well.

What, did you stay out at a Holiday Inn Express, last night, or what? You can either do a little research or you can try to justify your false premises. My issue is that you've given wrong information and are trying to insist it's gospel.

There are two basic sides to a pump, the suction and the discharge, A pump's suction is the area of the pump where a low pressure is formed to allow atmospheric pressure to push the fluid into the pump.

The whole pump is a parasitic loss for the engine, anything which decreases the amount of fluid pumped by it is a further parasitic loss. To be absolutely, perfectly clear, the loss from recirculating discharge back to the suction is called a pumping loss.

Please, if you can offer anything to substantiate your claims, do so. In the meantime, here's a little snippet for you to digest. You can add it to your understanding of physics.

Efficiency loss due to off-BEP operation is primarily the result of recirculation and fluid blockage caused by a mismatch between the pump's design flow and the actual flow. As the flow rate moves away from BEP, there is an increasing differential between the inlet vane angle and the approaching flow angle. Similar losses occur between the impeller vane exit and the volute or diffuser. The result is increased recirculation within the impeller passages and between the impeller and casing.

Here's the link, if you're interested: http://www.lawrencepumps.com/newslet...01_i4_Sep.html

In my profession, I've removed many, many pumps, used for cooling or supply, which were not performing up to snuff. Most of them would have an inserted "wearing ring" on the impeller and a "casing ring" in the casing. The quick fix would be to replace the rings if you had to get the pump back in service, quickly. The proper fix would be to ceramic coat the inside of the casing, replace the impeller and the wearing ring and the pump would be as good as, or better than, new.

[aronhk_md]

Nope, no Holiday Inn...I'm a doctor. And I understand physics well enough to know that in the statements you made above that I highlighted you contradicted another statement you made.

This is what I'm referring to:

"Quote:
Originally Posted by aronhk_md
That might be true if you were able to flatten the plate evenly along its entire surface. However, most people are only able to flatten it unevenly around the hole in the plate, which means the rest of the plate is not close to the vanes of the impeller. This leaves the pump inefficient.


First you state that I'm incorrect stating that the pump vanes not being an even distance from the vanes (due to an inconsistently hammered plate) do not leave the pump inefficient....when in fact they do. Then you immediately contradict that by stating:

"By decreasing the clearance between the suction and the vanes, you reduce parasitic recirculating losses"

Yes, so if you correctly close the gap between the vanes and the plate you increase the pump's efficiency (up to a certain point). Thats exactly what I was saying. Exactly why there is a wear ring in jetski pumps, and when that wear ring wears too much and the gap increases you lose efficiency of the pump.

Sorry if you incorrectly described what a parasitic loss is......nobody here was referring to the parasitic loss a water pump has on an engine. Did you see anyone talking about the differences between an electric water pump and mechanical? No. We were talking about flow around the impeller vanes and the plate.....and YOU the expert spouted the idea of parasitic loss, not me.

End result.....the vanes need to be close to the plate to work efficiently. A hammered/wavy and inconsistent plate is not an efficient way to change this.

I dont need to read the technical articles to know that the statements I made are correct. None of us was talking about volume/rpm/pump design characteristics. If you'll notice I stayed out of the conversation about the vane design/impeller differences as posted earlier. I'm not a pump engineer, and working on pumps your whole life might or might not make you one.

Oh, and all this stuff.....has zero to do with what we are talking about. I was not trying to redesign the vanes angle/height/length, nor was I trying to change inlets or outlet angles/position. We also know that these pumps dont have wear rings, casing rings or ceramic coating, so you can throw all that stuff in here to try and prove what an expert you are to all the others on this board, but I know its just bluster.....you didnt write it, and may or may not even understand it.

"Please, if you can offer anything to substantiate your claims, do so. In the meantime, here's a little snippet for you to digest. You can add it to your understanding of physics.
Quote:
Efficiency loss due to off-BEP operation is primarily the result of recirculation and fluid blockage caused by a mismatch between the pump's design flow and the actual flow. As the flow rate moves away from BEP, there is an increasing differential between the inlet vane angle and the approaching flow angle. Similar losses occur between the impeller vane exit and the volute or diffuser. The result is increased recirculation within the impeller passages and between the impeller and casing.

Here's the link, if you're interested: http://www.lawrencepumps.com/newslet...01_i4_Sep.html

In my profession, I've removed many, many pumps, used for cooling or supply, which were not performing up to snuff. Most of them would have an inserted "wearing ring" on the impeller and a "casing ring" in the casing. The quick fix would be to replace the rings if you had to get the pump back in service, quickly. The proper fix would be to ceramic coat the inside of the casing, replace the impeller and the wearing ring and the pump would be as good as, or better than, new."



Either way I'm done with the discussion. People can make their own decisions on what they think will work. Meanwhile you did give me a good laugh.

[Stuckinda60s]

Oh, my word. A real DOCTOR, color me impressed! I assumed as much from your signature.

First of all, I will rest on my credentials. I'm a Marine Engineer. I don't presume to tell you your profession and would appreciate it if you don't tell me mine.

No contradictions, whatsoever, in what I stated. Very simply, decreasing the visible gap between the vanes and the opening in the plate will decrease the pumping losses period, resulting in more volume per rpm.

Originally Posted by arohnk md

That might be true if you were able to flatten the plate evenly along its entire surface. However, most people are only able to flatten it unevenly around the hole in the plate, which means the rest of the plate is not close to the vanes of the impeller. This leaves the pump inefficient.

Efficiency will be improved. The design is inefficient, closing the gap simply makes the best of a poor design. You obviously have the impression that the problem is the clearance between the vanes and the plate. It isn't. The biggest problem is the recirculation between the suction (area) and the discharge. Reducing that gap, the one right at the opening, will do more than anything else to increase the pump's throughput. Centrifugal pumps don't pump well if they have don't have a positive suction head and if that gap is too large they'll use a lot of their pumping capacity. On your jet ski, do you move the impeller or do you change out the wearing rings?

You also are under the impression that moving the impeller away from the back of the housing has no negative results, that's absolutely not true.

If you read that statement I posted, you would note that the last two sentences read, "Similar losses occur between the impeller vane exit and the volute or diffuser. The result is increased recirculation within the impeller passages and between the impeller and casing." That's exactly what I'm referring to.

You've made some WAG's, you're wrong, live with it.

For the guys still interested, I've detailed the reasons for closing the gap. No ego involved, just good information. George had the right, and simplest idea to help your cooling problems. Make your own choice.

[aronhk_md]

1. I never said closing the gap between the vanes and the opening does not increase efficiency.....I said having an uneven or wavy gap reduces efficiency. If the gap was closer AND even it is better.
2. you are tyring to make it sound as if the relationship between the rest of the impeller/vanes (not just near the tip and the opening in the plate) and the plate is completely irrelevant. This is not irrelevant. It may not be AS CRUCIAL as at the spot you are referring to, but inefficient design or not if the rest of those vanes are just spinning in a bath of fluid with no plate opposed to them at all fluid would not flow in the direction we need it to. The plate serves a function here as well.
3. I never said this was an efficient pump design...I know it isnt.
4. The pump design in the jetski is only similar in some basic ways. To compare them goes beyond the wear ring. I know, and you as well it is a far more effecient pump.
5. I also never said there wasnt an effect at moving the impeller away from the housing behind it. I dont agree though if you insist it would be a major factor when considering whether to close the gap on the vane side of the impeller.

I am not a pump engineer, but have been around and rebuilt pool pumps, large aquarium pumps, jetski pumps and of course automobile pumps (havent rebuilt them, just replaced). Some people in this thread have managed to massage their plates easily. Others have had a hell of a time and had uneven results. Also, whether you are an engineer or not, my understanding of physics tells me the relationship between the REST of the impeller and the plate is important, though I agree the tips of the vanes and the gap at the edge of the opening is most important. But thats just my opinion.

Engineer, doctor or whatever...people make mistakes. You made some in your references to parasitic loss, and you corrected yourself after I mentioned it. I believe you are downplaying the role of the rest of the impeller/plate relationship and concentrating only on the tip of the vanes near the plate opening. Critical - yes. Only factor - no. I also understand what you are saying about increasing the space behind the impeller. Not as ideal as if we could flatten the entire plate and remove volume. I think with most of these plates that isnt an easy task.

But I've said all I intended to say. Ego involved? I don't believe so. To me its just an interesting discussion. But you did make me laugh. Holiday Inn Express was a good one. Still, doctors shouldn't be surprised that at times some patients are more knowledgeable about a medical issue than the doctor is him/herself. At least in certain things. You'd be surprised how many doctors feel threatened by that idea. I try to accept it.

[Stuckinda60s]

Pumps contribute nothing to a system, they are a total loss. I tend to look at things as a system and that will show in my conversation. You're looking at things from a different viewpoint than I. What I said was "parasitic recirculating losses". There should have been an emphasis on recirculating. Not a mistake, outlook. You also tried to say I made a mistake by referring to the clearance between the vanes and suction. You were wrong, pumps have a suction and discharge side, usually referred to, by them in the know, as the suction and discharge. Go figure.

With a knowledge of physics, you should be willing to admit that moving the impeller will increase the clearance at the tip of the vanes and allow more recirculation of water back, through the holes in the impeller, (remember them?) to the pump suction. At no time do you increase a pump's capacity by increasing any of these clearances.

Okay, I've got several simple little questions for you. What is the pressure at the vane tips? At the base of the vanes? Now, what is the area of the opening at the pump suction? At the tips of the vanes? We don't need exact numbers, just a relationship. The important points are the relationship and that the high pressure is at a point where the circumference is greater so that a change in gap will make a greater difference in this area than it will at plate side and result in more slippage. Can you understand that? How much more water will flow through a .050 gap at the tip than at the base of the tips? If you don't think there is much water recirc'ed, take a close at the wear around the holes in the old impeller posted a few replies back.

You've apparently taken my original posting as personal, it was meant to clear up a misleading statement.

Originally Posted by arohnk_md

Whether you're an engineer or not.....

Now that wasn't very nice, I never questioned whether you were an MD or not. Trust me, I'm an engineer

[69-er]

Originally Posted by smamas

Here is a pic of the Cardone 8 bolt pump and my old pump. There is a significant difference in the surface area of the impeller blades. The Cardone is a cast aluminum impeller. I had to do a lot of deburring in and around the impeller blades. Lots of slag left on these impellers that could inhibit water flow. I will adjust the internal housing and post my results after I do the install tonight.

That looks exactly like the pump I bought at O'reilly. Cast aluminum with a steel hub. Mine had been ground to remove the slag/flashing too. My old pump's impeller seemed to have better dimensions and was cast iron. The three balance holes also had better blending instead of a sharp edge at the perimeter of the hole. I swapped impellers.

I am writing up a report on how I did it and a few thoughts on what I found along the way. I hope to be starting the motor for the first time this weekend since its rebuild. Will post results.

[69-er]

Originally Posted by 67_400

I believe this is why the new $250 Edelsnot water pump #8856 comes with a divider plate so they can guarantee no clearance issues?



My temp keeps creeping up on me to the 200s and I have a cast body FlowKrapper pump.

I will pull this pos soon and post the clearance and results.

Welcome page 49! Thanks for the long read George!

It just occured to me, why didn't the designers of this pump incorporate the necessary divider and housing into one assembly? The clearances would then be easily verifiable during manufacture.

[69-er]

Originally Posted by GTOGreg

2nd car I've saved from overheating through this thread. My new build 67 was running up to 235 or so and last week I took the water pump apart to check clearance. It had a brand new divider plate in it and was reading .190-.200. I "Contoured" it to .040 and put it back together, along with a new HD fan clutch, 160* t-stat, and some water wetter/distilled water. I'm honestly concerned about it running too cool now.

Sounds like its time for a 180 degree t-stat. I hope I get that lucky after my pump mods!

It's interesting how I hear suggestions of putting in a lower temp t-stat to try to cure a overheating problem. It just opens earlier. No thermostat installed would give the same overheating result if the flow is inadequate.

[Old Goat 67]

Originally Posted by 69-er

That looks exactly like the pump I bought at O'reilly. Cast aluminum with a steel hub. Mine had been ground to remove the slag/flashing too. My old pump's impeller seemed to have better dimensions and was cast iron. The three balance holes also had better blending instead of a sharp edge at the perimeter of the hole. I swapped impellers.

I am writing up a report on how I did it and a few thoughts on what I found along the way. I hope to be starting the motor for the first time this weekend since its rebuild. Will post results.

Very good 69-er!

Lokking forward to it.

Charles

[69-er]

Originally Posted by R68GTO

I know I'm a glutton for punishment but after finally getting my 400 runing cool last summer (11-bolt) water pump, I decided to put a correct 8-bolt on it this winter. I purchased a correct pump (rebuit from autozone), cast impellar and also the stainless divider plates. Today I went to check the impellar clearance and it is over 1/8". The 8-bolt plates dont have as pronounced of a "crown" to tap down as the 11-bolt. I think I could tap the opening down closer but as I get toward the outer dia. of the impellar I'm afraid that there will still be a large clearance. It looks to me like the impellar is pressed on the shaft too far? The shaft is sticking out about 1/16? Has anyone tried to pull the impellar out? If so, how did you do it? Any other suggestions?

I tapped the holes in the impeller and used a puller. I pressed another impeller on but decided to press it all the way on. There are "spacers" of some sort underneath that look like they might be secured only by the impeller. I was concerened that the spring and seal assembly might come loose if I didn't. The shaft stuck out a little too. But, the backside of the impeller was nice and close to the pump where it has been suggested that it should be for proper efficiency.