Be Wary (Maybe) of Stay Cool Pumps Impellers

[Jim Cate]

Originally Posted by bdbcat

Jim...


"Why not just change the impeller every 550 hours and skip the filter? You say it is quite reliable up to that figure!"


Well, by 600 hrs she has lost enough impeller blades that she won't pump enough water to stay cool at 90 % load. Who knows when the first blade was lost....


So even if I change at 400 or 500 hrs, I still have to disassemble the HE inlet boot to get some rubber bits out.


btw, the 600 hr figure is also specified in the service manual. I'm impressed.


Dave

Ah, I see! I misinterpreted what you meant by "reliable".

And FWIW, we get around 1000 hours before shedding fins usually... except in the example mentioned upthread with the suspected "old stock" impeller. So, I change impellers around 900 hours now.

Jim

[a64pilot]

Update, I went to cross from little harbor this morning to Spanish Wells and Wx was quite a bit rougher than we were told to expect, and the West wind wasn’t there, wind from the bow. Anyway at one point I pushed the throttle up quite high and could tell water flow was restricted so we returned to Little Harbor.
I started disassembling the cooling system and found I hope all of the blade bits in the entrance to the heat exchanger stack, and in the hose leading to it. I back flushed the oil cooler, but don’t think any was there as I think it’s a tube in a tube, so no restrictions.
Picture of what I found in the heat exchanger stack.
I didn’t measure, but my tubes I’d estimate to be not much larger than .22.

[stnick]

Im not awair of any pump or impeller that makes the claim that it will run cooler ????
i only know of two types the rubber black and the blue poly impellers.
I had the the issue of black rubber fins breaking off, and clogging . So I switched to globe blue, Who claim to be able to run dry for over a minute.
I use it because it does not break up when it drys out .
I keep several spairs aboard for my various pumps.
Depco Pump company in Clerawater fla Tells me this is a better impeller.
Yes they are more money per impeller. But not more than a break down or the hassel of finding loose fins in my system. I keep Maintance logs and change out the impellers no matter what they look like to my eyes. ! Good maintance is a on going job !

[stnick]

Hey guys Tell Me how to post a photo here ! ???????????

[erie]

Originally Posted by a64pilot

My exhaust note changed, I noticed waterflow was way down, but temp gauge was still right under 180.
Well I started with the intake screen of course, then moved onto the intake thru hull itself, cause the impeller was nearly new.
Well when I took the impeller out I found this, it has I’d guess maybe 50 hours on it, maybe a little more, but less than 100.
Attachment 182877

Was it installed right ??

[Dave9111]

Originally Posted by stnick

I replace all my jabsco pump impellers with Globe The Blue run dry impeller I purchased it from Depco Pump company in Clearwater fla. My perkins 4108 also has a Globe in the water pump !

Good Luck! I purchased two Globe Dry run impellers for my Atomic 4.. the impellers are much softer than OEM and they won't easily prime or maintain system pressure and flow. The engine ran hot. Got an OEM impeller and the problem vanished. The Globes might be ok for some applications but certainly not all!

Watch your temperature gauges and the flow out the exhausts.



Dave

[mikecambrai]

My Volvo TAMD40 has the filter mounted on the output of the Jabsco pump. This is standard apparently and can only be there to trap any breakup parts from the impeller.
I really cannot understand why these flexible impeller pumps are fitted as a standard item.
Early Perkins had a fibre meshed gear pump which never gave any problems and was self-priming.
A Centrifugal pump as fitted to a central heating system would be so much more reliable. Mine has run for at least 10 years now all winter! All you need to do is mount it below the level of the external water so that it can prime.
Anyone know why these flexible pump s are fitted always? How many times have you witnessed boats in the harbour changing the impeller?
Slow speed engines have a reciprocating pump.
Does anyone have an engine which has an alternative pump for cooling water?

[drcat]

There have been many threads here and elsewhere on raw water impellers. The discussion is never good with conversations of these lasting 1000's of hours. For comparison take the typical electric pump used in water based house heating systems. In NE you could expect the system to run 150 days per year and run maybe 15 hrs a day - so 2250 hrs per year. Can you imagine the uproar if these pumps or their impellers failed every 1000 hrs. From my perspective boaters have been too complacent. Yes it's a harsh environment and it's salt water but still.
I've read/seen only one youtube vlog - Catamaran IMPI- from 2 years ago where the owner sought to end the vicious cycle, at least for his generator, and installed a 12v magnetic drive raw water pump. I do not believe he has had any problems since. No belts to check, no seals to leak. Looking online on ebay for $55 you can purchase a 12v variable speed magnetic drive water pump putting out max 2000L/hr. And some with 10,000 hr useful life. To me this would a worthwhile alternative to the belt driven or cam driven raw water pumps found on sailboat diesel engines.

[mikecambrai]

Thanks, DRCAT for your comments. I have not been able to source a pump of 2000l/hr yet in Europe but will keep trying.
I think that I will set up a jury rig bypassing the Jabsco, and just see what happens. I need to find out if this type of pump can cope with the vagaries of my engine in the marine environment.
2000l/hr is the correct flow for a 100 HP engine.

[Buzzman]

Originally Posted by mikecambrai

Does anyone have an engine which has an alternative pump for cooling water?

My British Seagull outboards have a four blade 'impeller' that does not seal inside the pump housing, so they never wear out.

Housing is in the leg under water so is self-priming, but does not produce anything like a 'pressure' water flow from the tell tale, but then, it's a tiny engine, so doesn't need a huge amount of flow.

Well, you did ask.....



EDIT: In fairness I should point out that it produces almost no flow at idle speed, so you do need to keep a few revs up. Not good as a trolling motor....

[mikecambrai]

Wow, those Seagulls are a piece of engineering history. I am glad that you have one that is still running.
They are very simple but nowadays I don't think that they would pass the new eco laws being imposed on us all the time.
As you say the water pumps are very simple, and I suppose that a larger version could be made that would pass 2000l/hr but might be very inefficient because of the water which would leak back past the impeller, but the pump would be able to pass some rubbish through without damage.
Is that not what is used on domestic washing machines? They are certainly very reliable.
Where could I buy one that I could try? I prefer the magnetic drives because the 'motor' part is separated from the impeller part.

[a64pilot]

Originally Posted by erie

Was it installed right ??

To be honest, I’m trying to figure out how it can be installed incorrectly. I wrap a zip tie around impellers to fold the blades to install, then of course remove the zip tie as it’s going in, been doing that for awhile as it makes it way easier.
Even if you fold the blades backwards it doesn’t matter as they flip around correctly immediately, in fact it’s not uncommon at all for an engine to rotate backwards slightly on shut down and fold them backwards.

[a64pilot]

Originally Posted by mikecambrai

Thanks, DRCAT for your comments. I have not been able to source a pump of 2000l/hr yet in Europe but will keep trying.

I think that I will set up a jury rig bypassing the Jabsco, and just see what happens. I need to find out if this type of pump can cope with the vagaries of my engine in the marine environment.

2000l/hr is the correct flow for a 100 HP engine.

A few years ago I replaced the rubber impeller pump on my generator with a March electric air conditioner pump, because they run for years continuously without failure.
It works on a generator very well, because a generator is a constant speed motor, just size the pump slightly large and your good.
However a main engine of course runs at very widely different RPM, so you want a pump that will vary output with RPM so that you don’t flood the exhaust with too much water.
I considered it, all you would need to do is connect a ball valve to the throttle cable so that you would vary pump output, but never went past the concept stage.
Too many other things to do, and usually main engine pumps are nearly trouble free if you replace the impeller on schedule, I assume many like mine are below the water line, so they are never dry, not even for a second, where many generators are above water line, and run dry until the pump primes.

[sailorboy1]

Maybe people would get better life out of their sw impellers if they stopped messing with them so much.

[Buzzman]

I don't think it is correct, or wise, to say that we are "having all these eco laws inflicted on us".

Implicit in the wording of that comment is criticism of "eco laws" and criticism of govt for introducing them.

Legislation is what govt does.

They take the pulse of the available scientific opinion and, if that opinion states that oily motors are not good for the environment - and therefore not good for the planet, and therefore not good for ALL of us -*collectively* - then those are *good* laws that we should all be happy to adopt as being in our *collective* best interests.

In other words, what's good for the planet is, ipso facto, good for all of us.

Even if, right here, right now, I want to keep using my old, oily, smelly Seagull outboard and someone somewhere says I can't. That's OK. I get it. If a lake or pondage is 'paddle or electric only' then I won't insist on some imaginary 'right' to for me to be using my Seagulls there.

We, the public, should be happy to adopt any process or procedure that is better for the planet as, ultimately, this is also better for us both collectively AND individually.

Even if it may not look like that at first...

And I accept that there will be times when things we USED to be able to do freely, we no longer can, and must accept greater regulation to 'manage' - for example marine parks - where we KNOW from past history overfishing is a bad thing. So 'nursery areas', 'safe zones' and 'no fishing areas' need to be established in order to ensure ongoing growth of fish stocks.

We now known mangrove wetlands are crucial for the survivial of juvenile fish, so we accept that ripping them up for 'canal developments' is no longer a good idea. UNles you're a canal developer, of course, in which case, YMMV.

Similarly, where over-use by 4WD vehicles (or bushwalkers) leads to degradation of wildnerness areas, that also needs to be 'managed' to minimise that damage and protect the environment from further damage.

We humans are THE most destructive force on the planet - left unchecked - so at some point, some checking is required. Unfettered or unchecked exploitation will lead to a desert in which we can no longer live.

For the naysaysers or deniers, I have only two words. Montreal Protocol.

Science proved CFCs were damaging the oxone layer, which would have had a distastrous effect on ALL life had the ozone hole been allowed to keep expanding. Removing Cfcs has halted that expansion and in recent years the ozone hole has been shrinking, back towards pre-CFC levels.

Ergo, we've proven that regulation and limiting 'free access' DOES work, so it should not be contested.

Those who want to exploit *without consequence* should pick another planet - and go there!

We only have the one planet, peoples, lets look after it and not criticise or lambast those who are attempting to do so.