Another waterpump conversion thread 'old seal / modern seal'

Hello together,

I just had to decide between either revive my thread from 2011, when I developed and designed a procedure to change the seal design from the oldest 308 waterpumps to the latest - and finally reliable - 308/328 seal design. Or making a new thread.
Meanwhile I have rebuilt a few of those old waterpumps with this method, because almost all the even worst original pumps are worth doing this, compared to the scrap repros, we get nowadays. Which are much too bad for coming from China ( I saw great Chinese machinery recently ). They are such crap, that I assume, they probably come from India.

This was my thread from 2011:

http://www.ferrarichat.com/forum/technical-q-sponsored-algar-ferrari/328021-308-w-pump-altering-design-old-new.html

But I decided to make a new thread, because the pump, I now got commissioned is the first one with the small bearings. The earliest design.
After some research and brainstorming I came to the conclusion, that increasing the dimension of the bearings was not the right solution to make the pumps more reliable.
Most pumps I had so far all had the inner bearing failed and so has the one with the small bearings.
If the bearing size would be the culprit I think, that the outer bearing should fail first.
I simply state, that it was the unreliable seal, which destroyed the inner bearing while leaking and finally flushing out the bearing grease.

But now for my conversion of that small bearings pump.

What I got, showed the typical failure mode of badly corroded seal seats both on the shaft and inside the housing.
Since my procedure requires to make the seal seat on the shaft smaller anyway as well as the seal seat inside the housing, corrosion must be VERY bad to make these pumps beyond repair.

Here are a few pictures of what I got:

The pump complete:

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The housing seal seat:

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Inner Bearing:

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Seal seat on the shaft:

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The procedure on the seal seats is basically the same like on the large bearing pumps.
I had to take the housing onto my lathe and after exact alignment of radial and axial runout I could clean the seal seat.
this time, because badly corroded I had to cut a bit more material and made the outer diameter of the reducing ring, that it was a press fit for the cleaned inner housing diameter. Pressed in with a light smear of Loctite 648 to be on the safe side regarding leak tightness. The inner diameter is once more the required press fit for the new one piece seal.

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Next step to do is to adapt the shaft for the new seal. The diameter of the old seal is 18mm and the new seal requires 16mm. This is a good thing, because it makes it possible to remove the worst corrosion and create an new surface. Though this shaft was scarce. But with the last half mm I achieved the required perfect surface for the new seal. Of course also the shaft had to be aligned to achieve max. radial runout of 0.01mm. BTW. New repro shafts have radial runout up to 0,1mm.

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Finally - for the moment - the housing got a good glass bead blasting.

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Like said. Basically it's the same, like I showed in my thread, mentioned above. But because the seal seats were very bad on this pump, but perfectly to recover and since it's the first pump with small bearings I rebuild and convert, I wanted to revive the topic.

Now the parts wait for reassembly. More to follow.

Best Regards from Germany
Martin

 

Hello together,

o.k.
Waterpump topics seem to be discussed quite extensively, but I like to bring things to a proper end. Therefore here's a brief completion of the procedure.

Yesterday I assembled the cleaned and machined parts again with two new bearings, the one piece seal and made it ready for shipping back to the owner.

After insertion of the inner bearing, the leaf spring and the circlip it's important , that the circlip sits properly in its notch. So I double checked.

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Then I pressed in the new seal with the usual method.

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The impeller got a quick polish. Technically irrelevant, but I like it, when all parts match in appearance.

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Ready for shipping:

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Best Regards from Germany
Martin

 

Not surprising, since these converted waterpumps are still 'original, just improved.
But I have no doubt, that some prefer the inferior original internals, since these were once invented at the sacred site.

But without kidding. That two-piece-seal technology was state of the art for decades and actually noone cared about it, since the waterpumps mostly did last for the average lifetime of cars back then.
And if not, they were cheap.
Different thing here.
There are four different versions of waterpumps for the 308 and 328. Small bearing and two piece seal, Large bearing and two piece seal, Large bearing and reversed two piece seal. Large bearing and one piece seal. And the latter was finally reliable.
All actions, Ferrari took between the first and the last version were simply some kind of 'act of desperation' for me.

Best
Martin

 

Brian,
because I no more think, that the bad design was the bearing size, but the seal, which is now updated to the latest design. We saw it, when increasing the bearings didn't lead to the final, satisfying solution.
The pumps remained unreliable even with big bearings, because the seal was still the same, leaked and finally flushed the grease out of the bearing.
I know, that theory and experience sometimes differ, but calculations led me to the result, that the small bearings could easily stand the loads we have here.
Even overtightening of the belt doesn't have the significance some might think. BTW. We have much smaller bearings in the alternator, which is driven by the same belt on some cars, like my Euro car.
If the bearings would have been underdimensioned, it would probably be the outer bearing which failed first. But most pumps I had so far had a bad inner bearing.
On my own first pump with big bearings the inner bearing did actually miss its cage. I found small brass pieces of it inside the pump.
On this pump the outer bearing would have been good for many more miles, but the inner one was dry and completely seized.
I would not hesitate to try such an upgraded small bearing pump on my own car now for testing purposes, but I have none.

Best Regards
Martin

 

O.k.,
so let's hope, that the bearings got also better after 40 years. At least the bearing data of those SKF Explorer bearings I use, differs significantly from the data of the same size bearings from 1982, I still have data sheets from back then.
So far I had luck to rely on these data sheets. Otherwise I would have experienced catastrophic results in my job.

The really interesting thing would be finding a plausible explanation for these bearing failures.

Best Regards
Martin

 

Hi Andy,

sorry, but no. Not with these modern one piece seals. I have one of these converted pumps in my own car, and it lost not one single drop through the drain holes since 2011.
When you see water coming out of the holes, the pump is on its way going south.

Best Regards
Martin

 

yes, it should only be no more, than a tiny amount, that it evaporates. Those seals, I use, are still basically two discs sprung agains each other, but no more carbon / ceramics, but silicon-carbide / silicon-carbide.

Best
Martin

 

Basically you are both correct. Before choosing the seal I now use for my rebuilds and conversions I had extensive discussions with the german seal manufacturer.
With the latest material silicon-carbide for both surfaces they actually aimed for surfaces, which need NO lubrication . What they need is cooling and dry-running is critical, because of lack of cooling.
If they run dry and exceed temperatures of 350 centigrade, they will get damaged. But not because the seal rings get damaged, but because this excessive heat damages the rubber bellow.
The old carbon-ceramkcs seals did stand this slightly longer, because it takes a little bit longer to produce these temperatures but also not for prolonged periods.
We also discussed rim speed, what's also not critical with our Ferrari engines. They allow rim speed for these seals of 15m/sec. as opposed to 10 m/sec. of the old carbon-ceramics seals.
They also recommend this seal for truck applications and state a life-span of 3 million kilometers.

Best Regards
Martin

 

Happy to discuss via PM or e-mail.

Best Martin

 

Brian,
I'm curious to learn about how long the average or min./max. durability (in miles) was, for these small bearing pumps back then.

Best Regards and thanks
Martin

 

Thanks.
Maybe a different thing in the U.S?, but over here in Europe, there were quite a few mundane daily drivers with an otherwise great reputation of reliability, always 'except the waterpump'. The 70s cars from Opel (a GM marque), for example, with engines good for 250.000 kms and often much more, were especially infamous for their waterpumps. But it was widely accepted as 'god-given', that the cars needed a new waterpump with each big service.

Best Regards from Germany
Martin

 

Hello together,

while cleaning up my harddrives I just dug out a 3D CAD model I got some time ago from the manufacturer and refined it a bit regarding showing components in different colors and a cross section.
It shows that one piece seal I use for these old - new conversions.
Just thought it might suit this thread.

Best Regards
Martin
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The seal is a press fit on the shaft and in the housing.
You need a proper tool for pressing in the seal. Which acts on the outer seal housing and on the shaft portion simultaneously.
Like this:

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All other attempts are a risk regarding the brittle carbon ring.

Best from Germany

Sorry for the pictures. Something must have gone wrong during the big FC update in 2017. As well with the link to my other w/p thread. Here it is again:

https://www.ferrarichat.com/forum/threads/308-w-pump-altering-design-old-to-new.328021/#post-140610396