928 Block Damaged by Water Pump Repair
10-13-2009, 07:01 PM
#61
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My post #31 was to bring this back to the top in order to find out what the procedure was to use this tool. Now that Greg Brown is here, I am sure he can clear things up for me. I am not sure how many people are in front of me wanting to use this tool, but I wanted to get on the list.
10-13-2009, 07:35 PM
#62
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The block is made of Reynolds 390 high-silicone aluminum- it eats HSS and carbide tools. The cobalt drills we supply are dead after a few holes- they are "consumables". It really needs diamond-coated cutters to get any kind of tool life, but thats out of the question, so we went with easy to replace cutters- you can't get custom stepdrills from Home Depo.
And cavitation in this kind of centrifugal pump is NOT an issue- there are bigger deviations than the screwheads in the pump, block and impeller surfaces as-cast. This is not a high-pressure hydraulic system.
This repair thing is not done for money on my part or Greg's part. He and I spent a good deal of our own money and time designing and building this tool as service to the general 928 communty. It is available for loan to anyone, and the money covers insert, cutter, and shipping costs. Its NOT for making a profit...and its a good deal cheaper than a new block!
So, Rod, I am done defending the design here. Everything was done for a reason, and it works fine so far. We'll just have to disagree about, well, just about everything. You are obviously free to do it any way you want. After 40 years in this business, I've learned there is more than one way to do anything, and what ever way works best for you is what you go with.
Steve
And cavitation in this kind of centrifugal pump is NOT an issue- there are bigger deviations than the screwheads in the pump, block and impeller surfaces as-cast. This is not a high-pressure hydraulic system.
This repair thing is not done for money on my part or Greg's part. He and I spent a good deal of our own money and time designing and building this tool as service to the general 928 communty. It is available for loan to anyone, and the money covers insert, cutter, and shipping costs. Its NOT for making a profit...and its a good deal cheaper than a new block!
So, Rod, I am done defending the design here. Everything was done for a reason, and it works fine so far. We'll just have to disagree about, well, just about everything. You are obviously free to do it any way you want. After 40 years in this business, I've learned there is more than one way to do anything, and what ever way works best for you is what you go with.
Steve
Rod, you seem to have missed the other N threads on block machining. Your input several months ago when Greg B was discussing the design would have been good to have. In any case, Greg B did have a new Laso pump eat into a block with only a few minutes of running. IIRC, he didn't complete the first dyno sweep. The issue of fluid dynamic forces causing or not causing the the impeller migration seem almost irrelevant - the impellers eat the blocks and almost always with rebuilt pumps. Why? Don't care. We need a way to fix the blocks. Sure, eight screws is overkill. Two or four might do the trick. Hell, some of us have used metal epoxy to fix the block with success.
If you'd like to contribute and make yourself useful.... there seems to be a large variance across engine blocks and water pumps in the clearance between the block surface and the impeller. It would be both timely and useful if someone with easy access to the right books or tools could calculate the minimum and maximum useful distance between the impeller and block surface. Too far and the pump won't pump. Too close and various bad things happen.
If you'd like to contribute and make yourself useful.... there seems to be a large variance across engine blocks and water pumps in the clearance between the block surface and the impeller. It would be both timely and useful if someone with easy access to the right books or tools could calculate the minimum and maximum useful distance between the impeller and block surface. Too far and the pump won't pump. Too close and various bad things happen.
Rod:
Thanks for your critique. As Steve says, there are always different ways to approach a problem. I decided, early on, that I was going to retain the insert with 8 screws....no science....it just looked like it would never move or distort with 8 staggered screws. Maybe 2 or 4 screws would have been plenty.....maybe just epoxy would hold it....I didn't want to kind out...it has eight screws and I suggest using epoxy.
Here's some information on the costs of building this tool and repair kit....just for your education.
I personally have right at $800.00 of my own money in this project. No time included. Steve Hattori has a similar amount invested...and much more time. Greg Nettles donated a Snap-0n 1/2 drive air drill, so that people would have something to turn the cutter with. The "token" $200.00 charge covers shipping, inserts, drills, taps, etc. Those costs are about $100.00 per use. That leaves $100.00, per use, to pay back the "investment". Let's see....that will happen....never.
If I was going to charge for use of this tool and repair, with the intention of making money, It would be more like $600.00 per use. Even at that, it would take 6 or more uses to "recover" just the cost of building this....no mention here of our time!
If you'd like to donate some pieces to improve the use of this tool, I'd encourage you to do so. We've donated about as much as we can afford.
Thanks for your critique. As Steve says, there are always different ways to approach a problem. I decided, early on, that I was going to retain the insert with 8 screws....no science....it just looked like it would never move or distort with 8 staggered screws. Maybe 2 or 4 screws would have been plenty.....maybe just epoxy would hold it....I didn't want to kind out...it has eight screws and I suggest using epoxy.
Here's some information on the costs of building this tool and repair kit....just for your education.
I personally have right at $800.00 of my own money in this project. No time included. Steve Hattori has a similar amount invested...and much more time. Greg Nettles donated a Snap-0n 1/2 drive air drill, so that people would have something to turn the cutter with. The "token" $200.00 charge covers shipping, inserts, drills, taps, etc. Those costs are about $100.00 per use. That leaves $100.00, per use, to pay back the "investment". Let's see....that will happen....never.
If I was going to charge for use of this tool and repair, with the intention of making money, It would be more like $600.00 per use. Even at that, it would take 6 or more uses to "recover" just the cost of building this....no mention here of our time!
If you'd like to donate some pieces to improve the use of this tool, I'd encourage you to do so. We've donated about as much as we can afford.
I am VERY aware of costs to manufacture these kinds of things.
I was stating my opinion and backing it up with my history. Somewhere along the line it was stated that I should do it myself and sell it if I can, indicating this was a for profit venture. If not, fine, I am glad there are people helping us with our vehicles.
I agree whole heartedly
10-13-2009, 07:59 PM
#63
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Rod, the impeller has many blades with sharp edges and is made of cast iron- it has no problem chopping 3-4mm out of the block before it falls off completey and is destroyed, itself, in the process...as are the drills and taps used in the repair. The carbide form cutter Greg had made will need resharpening after only a few blocks are done...
No offense taken here... its all good
No offense taken here... its all good
10-13-2009, 09:38 PM
#64
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I actually have no idea of when the impeller first came loose. We had broken the engine in and had dynoed it to tune. I then drove it about 75 miles to get some miles on the engine. No sign of any problems. It was back on the dyno running normal with normal temperatures....no sign of any problems. We had shut the engine off for a few minutes to do some adjusting. When I started it back up there was a funny noise from the pump area. It ran for about 30 seconds, while I got out and listened to the noise. The water temp was climbing instead of going down, and I shut it off. The damage was about .090" deep.
I assumed that the impeller came loose (due to heat soaking) and did all that damage in those few seconds.
I assumed that the impeller came loose (due to heat soaking) and did all that damage in those few seconds.
__________________
greg brown
714 879 9072
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Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
10-13-2009, 09:39 PM
#65
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My post #31 was to bring this back to the top in order to find out what the procedure was to use this tool. Now that Greg Brown is here, I am sure he can clear things up for me. I am not sure how many people are in front of me wanting to use this tool, but I wanted to get on the list.
12-14-2009, 10:43 AM
#66
Rennlist Member
BUMP for the waiting list.
Greg, can you tell me where I am now on the waiting list? I am off work for two weeks over Christmas and was hoping to do this fix if at all possible.
Thanks
Greg, can you tell me where I am now on the waiting list? I am off work for two weeks over Christmas and was hoping to do this fix if at all possible.
Thanks
12-14-2009, 02:44 PM
#67
Nordschleife Master
$200 for this tool is a STEAL.
You 2 have gone above the call of duty making this availible at that price!!!
I was expecting closer to the $600 range.
You 2 have gone above the call of duty making this availible at that price!!!
I was expecting closer to the $600 range.
12-14-2009, 03:07 PM
#68
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Steve and I laugh with each other about this....that we are loosing money, every time the tool gets used....but that we are making it up in volume.....
Dumbasses.
12-14-2009, 03:12 PM
#69
Rennlist Member
Don't feel bad. My family's lumberyard has a manager that says the same thing. He eventually does seem to make a profit though. Been the manager since 1971 and is third highest paid person in the company even more than his district managers.
12-14-2009, 03:12 PM
#70
Rennlist Member
You'll make a profit on this thing, just might not be from where you expect it. Isn't life funny that way?
12-14-2009, 04:38 PM
#71
Nordschleife Master
Somehow, we ended up doing this for all of the "928 Kingdom" as a favor...not sure why, but it is going to take about a 100 years to make back the costs of just building the stuff. Not to mention the time...
Steve and I laugh with each other about this....that we are loosing money, every time the tool gets used....but that we are making it up in volume.....
Dumbasses.
Steve and I laugh with each other about this....that we are loosing money, every time the tool gets used....but that we are making it up in volume.....
Dumbasses.
12-14-2009, 04:42 PM
#72
Somehow, we ended up doing this for all of the "928 Kingdom" as a favor...not sure why, but it is going to take about a 100 years to make back the costs of just building the stuff. Not to mention the time...
Steve and I laugh with each other about this....that we are loosing money, every time the tool gets used....but that we are making it up in volume.....
Dumbasses.
Steve and I laugh with each other about this....that we are loosing money, every time the tool gets used....but that we are making it up in volume.....
Dumbasses.
"But I make a profit of three and a quarter cents an egg by selling them for four and a quarter cents an egg to the people in Malta I buy them from for seven cents an egg. Of course, I don't make the profit. The syndicate makes the profit. And everybody has a share." Chapter 22, pg. 241
12-14-2009, 05:18 PM
#73
Rennlist Member
That makes my head spin
12-14-2009, 05:20 PM
#74
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Jeff, thanks for the good vibes- its kind of "pay it forward" thing....Colin illustrates that it will be a long amortization schedule...Brendan- thats not funny...
12-14-2009, 05:54 PM
#75
Rennlist Member
GB,
I bumped this thread on #66 because I was wondering where we were on the list of users. Back on October I was 4th in line. I was wondering where we were since I have 2 weeks off coming up over Christmas and was hoping to get this done if possible. Should I PM or email you instead of bumping this thread? Just let me know the easiest way to get a hold of you.
Please let me know.
thanks
Mike
I bumped this thread on #66 because I was wondering where we were on the list of users. Back on October I was 4th in line. I was wondering where we were since I have 2 weeks off coming up over Christmas and was hoping to get this done if possible. Should I PM or email you instead of bumping this thread? Just let me know the easiest way to get a hold of you.
Please let me know.
thanks
Mike