What to lubricate rubber impeller with?

[oldbilbo]

Let me relay a point made by a skilled marine engineer at Newlyn, who came to the boat to fix a series of impeller problems and who had 'the nouse' in depth. It seems that 'our' impeller failed initially in the axial 'shaft-to-rubber' bond. The chap explained that such a failure mode used to be quite common, and it was caused by the use of a rubber compound that was degraded/corroded by petroleum products. He further explained that, in oily waters such as were found in commercial harbours such as Newlyn or Falmouth/Pendennis, a yacht cooling pump could readily suck up water well-contaminated with diesel spill. This pollutant would coat the impeller, which would be stopped for hours or even days while alongside or in a nearby marina. The 'rubber rot' would, like rusting of steel, continue once started.....

The solution was, he recommended, always to use an impeller made of petroleum-resistant Nitrile rubber.

I cannot attest to the 'right' of this story, but it is plausible and could explain the failure we experienced.

 

[Spirit of Glenans]

I have heard KY jelly is a good water based lubricant

Yes, it's used by body piercers when inserting new piercings.

 

[Trundlebug]

Just to clarify another point that seems to have been misunderstood in the thread so far.

Initial lubrication of the impeller actually serves two purposes.

1. To lubricate the impeller for the first few seconds whilst it is turning dry until it has primed. Thereafter it doesn't need lubricating at all.
2. To help seal the impeller to aid priming. The lubricant seals any minor imperfections along the blade tips and also at the ends. Once it has primed and there is water all the way through the cooling system, it'll work just fine with no lubrication or additional sealing. This initial sealing function becomes more important as the pump, end caps or impeller get older.

 

[Robert Wilson]

on the first revolution the blades will have sorted themselves out. dont worry

That's what I thought, and hoped !! Thanks

 

[Daydream believer]

So why did the impeller I removed last month have a vane pointing the wrong way?

Possibly when stopping the engine it hit compression & turned back a part turn
Depends on the type of engine of course

 

[ghostlymoron]

I can't see how any lubricant is going to survive for long inside a water pump with a significant flow through it. It's water lubricated but needs something initially to lube while it primes.

 

[Trundlebug]

I can't see how any lubricant is going to survive for long inside a water pump with a significant flow through it. It's water lubricated but needs something initially to lube while it primes.

..Er I think I just said that. See #43

 

[ghostlymoron]

..Er I think I just said that. See #43

Yes. I agree with you.

 

[NickC]

I can't see how any lubricant is going to survive for long inside a water pump with a significant flow through it. It's water lubricated but needs something initially to lube while it primes.

Interestingly the impeller I have just removed from the small Yamaha F2.5 which might possibly have been in for the last nine years was still coated in something which looked and felt like some sort of translucent vaseline type grease.

That also had one blade pointing the wrong way. Which way does the impeller normally turn clockwise or anticlockwise? Guess I could always push the prop back on, put it in gear and work out which way from there.

Nick

 

[[2574]]

Any tips for removing an impellor? I'm thinking this year that I might lubricate the old one with something to ease the removal process. Previously it has been a devil to remove. I've heard stories of applying a lubricant and then turning the engine over with the pump cover off in the hope that the impellor will spin out. Any tips?

 

[Daydream believer]

Any tips for removing an impellor? I'm thinking this year that I might lubricate the old one with something to ease the removal process. Previously it has been a devil to remove. I've heard stories of applying a lubricant and then turning the engine over with the pump cover off in the hope that the impellor will spin out. Any tips?

You can purchase long nosed pliers with turned in ends. I think they are for wire stripping
If you have a pair they may grip the rubber to let you pull it out
A lot depends on the impellor. Some are rather large & an impellor removing tool would do the job
Normally a couple of screwdrivers will suffice

 

[kelmark2590]

Anything that is slippery and washes off in water should do. I would suggest silicon on rubber parts. In my marine school, they used Mercury Quicksilver 2-4-C. Here is the link:

http://www.partspak.com/productcart...W-LUBE-2-4-C-Boat-Marine-Parts-3771p15986.htm

 

[DaveS]

Any tips for removing an impellor? I'm thinking this year that I might lubricate the old one with something to ease the removal process. Previously it has been a devil to remove. I've heard stories of applying a lubricant and then turning the engine over with the pump cover off in the hope that the impellor will spin out. Any tips?

The easiest tool to use for this is "water pump pliers" - the clue's in the name. They're quite cheap, and handy for other jobs too. Messing about with screwdrivers risks scoring the pump body.

 

[NormanS]

Used with some common sense, two screwdrivers will lever the impeller out with no problem. They shouldn't be anywhere near the pump "body". Also as others have said, it doesn't matter which way the vanes lie when fitting. They will be correct as soon as the shaft turns.

 

[kelmark2590]

Here are some options for impeller pullers. These will work on water pumps that are inside the boat.

http://www.partspak.com/productcart...nt=10&keyword=impeller+puller&submit=GO+>>+++

 

[ghostlymoron]

Used with some common sense, two screwdrivers will lever the impeller out with no problem. They shouldn't be anywhere near the pump "body". Also as others have said, it doesn't matter which way the vanes lie when fitting. They will be correct as soon as the shaft turns.

Unless you permanently lubricated the impeller when they'll skid around and stay inverted.

 

[ghostlymoron]

Interestingly the impeller I have just removed from the small Yamaha F2.5 which might possibly have been in for the last nine years was still coated in something which looked and felt like some sort of translucent vaseline type grease.

That also had one blade pointing the wrong way. Which way does the impeller normally turn clockwise or anticlockwise? Guess I could always push the prop back on, put it in gear and work out which way from there.

Nick

Remarkable !

 

[earlybird]

To remove a reluctant impeller, with the fairly poor access to the front of my engine, I find a toolmaker's clamp effective. I happen to have various sizes anyway, but they're quite cheap, with little chance of damaging the impeller or pump body.

 

[temptress]

You do not need ANY lubricant for the impeller but you do need a gasket, thin paper cut to fit can be used, to seal the housing.

 

[Daydream believer]

Unless you permanently lubricated the impeller when they'll skid around and stay inverted.

At one point in the rotation there is less bending pressure due to the shape of the body
At that point it will flick over to the correct angle. That is assuming it is a decent impellor & not an old one where the material has started to perish & gone stiff, or been stored distorted. If so it is ready to crack & break
I suspect It would not pump properly bent the wrong way
I suggest that people who think the lubrication stays on the vanes may be mistaking lubricant for the sludge that collects on the vanes from the water. This is more obvious when the engine has been left unoperated for a while.
I do not lubricate mine but have noticed this " sludge", for want of a better word, at the end of the season