Knurled nobs on impeller lid

TiggerToo

TiggerToo

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The thread about the demise of the SpeedySeal got me thinking. One of the nice things about SSl was the introduction of the knurled knobs, to replace the impeller cap screws. Is there anything which speaks against using these of a "normal" i.e. non-SSl cap?
 
Plum said:
Very worthwhile on the standard cover plate. Search for stainless thumb screws https://www.ebay.co.uk/itm/182019943325?hash=item2a613beb9d:g:I04AAOSw5Ylb7qhe

www.solocoastalsailing.co.uk
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Alternatively, if the pump is in an awkward place, screw into pump body short lengths of stainless studding with some locktight and then use thumb nuts Stainless Knurled Thumb Nut Normal/High Type Grip Knob DIN 466 M2,3,4,5,6,8,10 | eBay . This makes it easy to slide the cover plate onto the ring of studs so it stays there while you screw on the thumb nuts.

www.solocoastalsailing.co.uk
 
Plum said:
Alternatively, if the pump is in an awkward place, screw into pump body short lengths of stainless studding with some locktight and then use thumb nuts Stainless Knurled Thumb Nut Normal/High Type Grip Knob DIN 466 M2,3,4,5,6,8,10 | eBay . This makes it easy to slide the cover plate onto the ring of studs so it stays there while you screw on the thumb nuts.

www.solocoastalsailing.co.uk
Click to expand...
Yes, that's good. I have a spare pump on board for which I bought a purpos-made kit that comprised 4 bronze studs and 4 wing nuts.
 
TiggerToo said:
The thread about the demise of the SpeedySeal got me thinking. One of the nice things about SSl was the introduction of the knurled knobs, to replace the impeller cap screws. Is there anything which speaks against using these of a "normal" i.e. non-SSl cap?
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No.
In my experience the knurled screws were the only decent part of the Speedseal kit. In the past I've had two water pumps which I modified with Speedseals. Both pumps suffered a high degree of wear of the brass Speedseal disc. They wore eccentrically, significantly affecting the performance of the pumps. IMHO the Speedseal was an overcomplex solution to a problem that never really existed. I finished up by discarding the Speedseal components and reverting to the original cover plate and gasket. I did however retain the knurled screws but used six rather than four to reduce the possibilty of leakage.

Mike
 
mikegunn said:
No.
In my experience the knurled screws were the only decent part of the Speedseal kit. In the past I've had two water pumps which I modified with Speedseals. Both pumps suffered a high degree of wear of the brass Speedseal disc. They wore eccentrically, significantly affecting the performance of the pumps. IMHO the Speedseal was an overcomplex solution to a problem that never really existed. I finished up by discarding the Speedseal components and reverting to the original cover plate and gasket. I did however retain the knurled screws but used six rather than four to reduce the possibilty of leakage.

Mike
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Exactly what I did, apart from increasing the number of screws.
 
Bearing in mind that the demand on (my) pump is only to provide cooling water for the heat exchanger and exhaust, and not at any great pressure, I deliberately use a thicker joint than the standard one, which saves wear on the impeller and the end cover. IIRC the present one which has lasted for years, is made of corn flakes packet. (Other cereals are available). I do have knurled screws.
 
Interlude said:
Does anyone recall the thread size? I know I can have a look, but easier to ask!
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I have a manufacturer 's detailed drawing of the Johnson FB35-9 impeller pump as used on my BUKH engine and I expect that shows the thread size.

If no one else answers your question before tomorrow I'll look it up.

Come to think of it, I have a spare pump in my workshop and I can check that.

M4 x 8mm
 
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After an initial encounter with the 6 'rubbish' slotted-head bress screws fitted as OEM on my last boat, I ditched them and installed s/s knurled head jobs.

That's the way forward for me - but I'll keep a couple of spares in with the spare impellers 'cos I have been known to drop wee things like those into the deep bilge.... and that's further than my arm will reach.
 
It really makes you wonder why the original manufactures haven't gotten around to this upgrade.
They continue making the same old thing and wonder what happens when they are overtaken by a savvy competitor.

gary
 
garymalmgren said:
It really makes you wonder why the original manufactures haven't gotten around to this upgrade.
They continue making the same old thing and wonder what happens when they are overtaken by a savvy competitor.

gary
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Except the ‘savvy’ competitor has closed, (sadly due to ill health) so the original manufactures still don’t have to do anything.
 
garymalmgren said:
It really makes you wonder why the original manufactures haven't gotten around to this upgrade.
They continue making the same old thing and wonder what happens when they are overtaken by a savvy competitor.

gary
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I expect they would come up with the usual response "There's no call for it"!

And there probably isn't, at least not enough to make it worthwhile offering it.
 
I like the hex head bolt option supplied by many manufacturers, but the SS ones, not brass. Just a personal view.

It is my view that the pan head slotted ones supplied by the pump manufacturers are evidently there to cause someone a great deal of stress at the least convenient moment :ROFLMAO:
 
One of the original brass screws lost its head on my engine.
I replaced it with a stainless button head screw that I happened to have spare . That was a few years ago.
Don't recall the diameter but they were from Screwfix.
A2 stainless but seem fine.
1637878857968.pngd
 
Poignard said:
I have a manufacturer 's detailed drawing of the Johnson FB35-9 impeller pump as used on my BUKH engine and I expect that shows the thread size.

If no one else answers your question before tomorrow I'll look it up.

Come to think of it, I have a spare pump in my workshop and I can check that.

M4 x 8mm
Click to expand...
Thankyou, I will get a set.
 
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