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Old 07-18-2011, 04:31 PM   #1
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jabsco sea water pump advice

Yesterday I had my port side Perkins T6.3544M get hot.* I got it shut down in time.* Thank goodness for engine alarms.* I*suspect and hope that the problem is just the sea water pump giving up the ghost.** I don't know how* old the impellers are but I know I have put a tad over 100 hours of silt filled Mississippi water thru it on my trip home.

I see that there are two Jabsco replacement impellers available, neoprene and nitrile.* Nitrile is a bt more money but *I am more than willing to spend a couple more bucks for something as important as a cooling pump.

Any advice as to the difference?
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Old 07-18-2011, 06:22 PM   #2
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jabsco sea water pump advice

My Perkins are equiped with Sherwood pumps, but you should do fine with a standard impeller, as you should change them every year anyway if you have that much silt passing through them. *Did you already check the impellers for lost blades. *You may have another problem, such as plugged heat exchanger, etc.

My understanding is the nitrile impellers are for pumping petroleum products or protection from oil contaminated water, etc. *We use nitrile rubber gloves in my work, because it is resistant to ozone, mild acids and oils.


-- Edited by Edelweiss on Monday 18th of July 2011 06:29:45 PM
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Old 07-18-2011, 07:01 PM   #3
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jabsco sea water pump advice

Be advised that the pumps can wear. I suspect you have a worn cam and backplate. These are available via a rebuild kit.

*A friend with a 240 Perkins T6.3544 chased a 10 degree temp rise issue for several years. He finally bought a new pump and that solved the problem. We compared cam sizes before he installed the new pump...the old one was half gone.


-- Edited by jleonard on Tuesday 19th of July 2011 05:23:26 AM
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Old 07-18-2011, 08:14 PM   #4
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RE: jabsco sea water pump advice

Quote:
jleonard wrote:
Be advised that the pumps can wear. I suspect you have a worn cam and backplate. These are available via a rebuild kit.
*

What he says is worth considering.*

Both of my raw water pumps have neoprene impellors.* What you might want to do is go ahead and pull the back plate off and see if it is grooved which can cause loss of prime/water movement, as can a badly worn cam...* I would also pull the back plate or inspection port off of the heat exchanger to see if its plugged up....* Have you made sure that the seacock is clear as well?
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Old 07-18-2011, 11:30 PM   #5
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RE: jabsco sea water pump advice

I replaced my impellers on my 4.236's a couple years ago as part of the routine maintenance. When I put the new impeller in on one engine, it wouldn't pump water. It really had me scratching my bal...er...umm...head. Come to find out the wear plate (back plate?) on the backside of the impeller was worn. I didn't even know it was there. Only after talking with the Jabsco rep did I learn that. I had to use the smallest jewelers screwdriver tip to free the plate from the pump housing. Jabsco sent me 2 replacements, free of charge, dropped it in and then all was well.

If I had only known about those plates ahead of time, I could have saved myself a lot of time and grief.

BTW, I went nitrile and have had no problems. Not sure which will last longer, but so far it's been fine. Nitrile seems a bit softer and more pliable. No difference in operating temps from what I see on the gages.
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Old 07-19-2011, 04:02 AM   #6
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RE: jabsco sea water pump advice

I have put a tad over 100 hours of silt filled Mississippi water thru it on my trip home.

Operating in silt filled water requires the impellers to be changed fairly frequently. 100 to 400 hours is not unusual as pre filters do not seem to be much help with really fine materials.

A set of spare pumps is advisable as well as a box of impellers and gaskets.

Keel cooling would be an option of the change out of impellers becomes a chore.
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Old 07-19-2011, 08:50 AM   #7
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RE: jabsco sea water pump advice

THANK YOU TO ALL.** Tonight I'll stop by the boat to turn on the air, open the hatches and run a fan for a couple hours before I tear into it.* It is hotter than Hades in the Midwest these days.

Thankfully the Miss where I live is much cleaner than the chocolate brown stuff down south.* It was darker than a McDonald's shake, probably had more chocolate too.

Thankfully too the engines are in-line 6's not Cat 3208 V8's as there is enough room for a fat guy like me to crawl* to the port side of the port side engine.

It will be good idea to order 4 sets of rebuid parts so I have a spare set for the parts kitty.
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Old 07-19-2011, 02:16 PM   #8
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RE: jabsco sea water pump advice

By the way, what's all this "My A/C's broken", "turn on the air" stuff I keep reading

about on this*site? *

Up here in the Pacific Northwest, when your wife say it's getting a little stuffy

"turn on the air" *you just crack the window open a notch. *

*

We're still waiting for summer here!!

* * * * * * * * *Larry B
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