Raw water impeller question

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Interesting, wonder if Hino/Toyota built their own pump housings and didn't get the specs quite the same?

My Perkins actually has a Jabsco pump on it, driven with a Love-Joy type coupling.

My last two Globe impellers were installed in Johnson pumps with no issues. I hope my Jabsco Pump does OK with one, tomorrow I'm going to order an 8 blade unless Globe gets back to me with a reason that it makes more sense to use the 10 blade.
 
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Hino uses a Kashiyama (sp) pump, only engine maker that I've heard of that uses them.
 
My boat has them from the PO. The jury is still out. I just changed impellers. One engine went fine with finger tight and no leaks. The other needed an old paper gasket and pliers. They say no gaskets but there is an O ring that seems very fragile and doesn't seem to stay in the groove so not sure if it gets misplaced when installing. The knobs seem like a good idea, especially on the starboard engine where the pump is nearly out of reach. But you could use thumb screws or something on the traditional covers using more than four screws.
 
Back to the 8 or 10 vanes, I have a small boat (350 chev inboard, 1977 jabsco) used mostly for cold weather striper fishing that was fine with the 8 vanes in cold weather but wanted to overheat in the summer. In going through my used spare box I discovered an old 10 vane, and replaced the impeller with a new 10 vane which seems to have corrected the summer overheating problem. In checking the original jabsco part numbers, the pump originally came with a 10 vane. I also could not find any data on the pressure flow differences for the different impellers.

I have always used about any available oil as an assembly lubricant and assumed that it got "washed" off pretty quickly in use - so that water became the only lubricant. Jabsco advertises their industrial versions for slurry applications, so they are not overly sensitive to lubrication in the normal sense if you don't run them dry.

I have seen the impellers take a set when left several months without running. The issue is how closely the pump is sized for the cooling requirements which may be more a function of other things like heat exchanger fouling. My small boat is currently layed up and because I had the pump apart I chose not to put the new impeller back in it until I get ready to use it again. I would shy away from any impeller that had cracks, although I don't know that an impeller that had some set would bother me as long as the cooling was OK.
 
Use high quality thumb screws if you do. Beware of plastic knurled with SS. Do you need to know how I know this?
 
A bit hard to tell in this photo, but these screws are SS knurled allen-head screws. I find them much easier to start in the threaded hole and tighten than the phillips- or slot-head styles. This modification provides me with much of the functionality of the SpeedSeal kit at a fraction of the cost.

img_174095_0_ee0b9930179842eee2d16567f5783d77.jpg
 
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My raw water pump is not that easy to see because Yanmar thoughtfully buried it from view on my 4JH3. I pretty much have to work by feel, or use an inspection mirror. After the first impeller change, I started looking for a way to make it an easier job. I discovered Speedseal and decided to give it a try.

I am very happy with the Speedseal Life which has the enhanced end plate with replaceable bearing discs.

Welcome to Speedseal Safety Covers

Even with the extra parts, it is easy to service, and the large knurled thumbscrews make it a breeze to change.

I also purchased this impeller removal tool from Bay Shore Marine.

IMPELLER PULLER

Impeller service now takes just minutes.

As for lubes, Johnson Pump and Volvo recommend and sell glycerine exclusively. Since Johnson is OEM on so many engines, I assume this is a safe choice. That said, Jabsco, Yanmar and Mercruiser simply say to 'grease' the impeller when installing. I suspect what is most important is that the impeller is not dry when starting for the first time.

Larry
m/v Boomarang
 
IMO, the lubricant is mainly to ease installation. It would also lubricate the impeller for the first 10 seconds if it was dry, but I doubt if running dry for that period of time would do much harm.

What may be often be overlooked is the potential for a complete or partial air lock after doing any work on the cooling system.
This can interupt the raw water flow allowing the impellor to run dry intermittently, shortening impeller life.

Having a raw water cooled system, I see an immediate effect on my temperature gauge when this happens (all too often). The temperature guage is all over the place because the thermostat cant keep up with the change.

On a fresh water cooled engine, the effect on engine temperature would be much less obvious, as the heat exchanger acts as a buffer. An intermittent raw water flow may go unoticed.
 
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I have somewhat unbelievable news. I just got off the phone with an Engineer (Brian Adams) at Globe. They have NO data about ANY impeller's performance! They don't test any of them. Manufacturers give them a call wanting them to offer a Globe impeller option on a particular application and they manufacture an impeller with the same dimensions as the "stock" impeller! No testing is done! (I'm sure they test for their warranty specs though). The best I could get was that they never advise going to a lesser number on any application. He is supposed to call me back (computers down) when he can look up the drawing specs of the two and give me the difference in blade length-if any. If relatively close, I think I'm going to try a 10 blade. Time will tell.

So far as long term storage-does anyone here do the talc in an airtight ziploc bag method? I found several references to storing the impeller this way. They don't even recommend keeping them in the factory 2 piece vacuum formed package since its not airtight.
 
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OK He just called me back after going and just pulling actual units off the shelf. 8 blade body measures 1.26, 10 blade is 1.32. A difference of .06 is no biggie. Like I thought he thinks the 8 blade will flow more water due to having fewer blades taking up space in a given revolution. He has no idea why a 10 blade impeller would be better than an 8. So I queried him about a 6-nothing.

I'm curious if more blades don't offer more "smoothness" of flow esp at low speeds. Like less pulsation primarily effective on the intake side.

I'm going to order a 10 shortly. I can't see that 2 less blade's volume per revolution will diminish my overall flow enough to notice. I'll report back once installed if I can tell any difference with my application ('83 Mainship III with 200 HP Perkins T6.3544M, primarily 7-8 kt but capable of 12+)
 
Seahorse.

If device has no mfg or patent info, might consider finding shop that does 3 D printing, which can duplicate device. I know I would buy one !
 
Your Perkins should have a Sherwood pump.
Over the years I have tried both Globe & Jabsco in my 6.354 Sherwood pump. Jabsco blades are thicker and more prone to cracking at the base. My Globes (spares) were N/G right out of the box (maybe too old but spares do get old).
The Sherwoods have a much more flexible blade and a small rib on the side of each blade which contacts the pump back and cover plate reducing friction and wear.

I have Jabsco pump on my other boat but use Sherwood impellers in it also.

I don't think the number of blades makes much difference. Reminder: many people fail to apply sealant under the cam when they install it which can lead to priming delays which in turn can lead to shortened impeller life.
 
Brooksie


Please elaborate on "sealant behind cam" comment. What type sealant applied where ? Not sure I have been doing properly.
Thanks.
 
sea hag said:
Brooksie


Please elaborate on "sealant behind cam" comment. What type sealant applied where ? Not sure I have been doing properly.
Thanks.
Click to expand...

You may never have removed your cam, but given the age, maybe someone else has. The cam is the piece which turns the round chamber into an oval; it's held in by a single screw from the outside of the pump. When this is reinstalled or replaced it should have some sealant under it (silicone good) so that air can't be drawn across under it causing slow priming.

Jabsco also makes a reduced volume cam for its pumps so check for this if you are having volume problems

Lots of variables here like cam fit and distance above waterline on pump but this can be a problem.

If Sherwood make an impeller for your Jabsco pump, you will like it better and it will last longer.
 
twiisted71 said:
I have somewhat unbelievable news. I just got off the phone with an Engineer (Brian Adams) at Globe. They have NO data about ANY impeller's performance! They don't test any of them. Manufacturers give them a call wanting them to offer a Globe impeller option on a particular application and they manufacture an impeller with the same dimensions as the "stock" impeller! No testing is done! (I'm sure they test for their warranty specs though). The best I could get was that they never advise going to a lesser number on any application. He is supposed to call me back (computers down) when he can look up the drawing specs of the two and give me the difference in blade length-if any. If relatively close, I think I'm going to try a 10 blade. Time will tell.

So far as long term storage-does anyone here do the talc in an airtight ziploc bag method? I found several references to storing the impeller this way. They don't even recommend keeping them in the factory 2 piece vacuum formed package since its not airtight.
Click to expand...

Storing for anything more than 6 mos I would consider vacuum bagging slightly (not tight)...I wouldn't bother with talc although I remember old rubber snorkeling gear way always suggested to be stored in talc.

I think for 2 years or less in a ziplock or partial vacuum would be fine then used as the turnover impeller and a new spare purchased.
 
psneeld said:
Storing for anything more than 6 mos I would consider vacuum bagging slightly (not tight)...I wouldn't bother with talc although I remember old rubber snorkeling gear way always suggested to be stored in talc.

I think for 2 years or less in a ziplock or partial vacuum would be fine then used as the turnover impeller and a new spare purchased.
Click to expand...

The Globes I had trouble with were 2-3 years old but in their original bags when we went to put one to use in Granada, the vanes broke off in my hand. The Sherwoods you can run in your engine for 2-3 years... No Globes for me.
 
I put the SpeedSeal kits on both of my engines this Spring. Last week had no flow from the port engine. Changing the impeller took all of 10 minutes or so. Used the grease that came with the impeller, and lubed the O ring as well. I recommend it highly for ease of use. They also have the teflon spacer that the end plate spins on, which they claim will allow 5 minutes of dry running without eating the impeller. I know it worked for about 2 minutes this year when I accidentally started one on the hard. (oops!) Again, two big thumbs up for this product.
 
Not sure if speed seal saves that much time over a pump that regularly has it's impeller inspected, opened for winterization or replaced (meaning the machine screws come out easily) It only takes me a minute or two to get the machine screws out...it's the impeller that's either easy or the struggle.

The issues some have had with them is what concerned/prevents me from switching.

As a single owner..I'm more likely to plumb my raw water washdown into my cooling system with a quick connect or just full time so I can at least keep idling out of harms way than worry about a minute or two with a pump cover.

I might also keep a spare pump with impeller in it all ready to go...my cats it was worth it...not sur eabout the Lehman direct drive though...sometimes easier to do a few bolts than the impeller.
 
I have found that replacing the tiny screws that are hard to remove

with hex head bolts that can easily be accessed with a hex key , with feel no looking,

is the fastest way to R&R the pump cover.

There cheap so buy a dozen and dont worry , be happy , when one gets away.
 
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