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Old 06-02-2020, 14:21   #16
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Re: Raw water pump on genset not pumping.

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Originally Posted by Apollo366 View Post
How much water comes out of your genset exhaust? Small, nirn, goodly amount?

I had a similar prob & it was the exch cooling jacket & elbow being clogged with carbon buildup.

Capt Wayne
Plenty of water........ Now.
Like I said IT'S THE PUMP
Its not the exhaust, heat exchanger, strainer, skin fitting, ball valve, pipes etc etc
IT'S THE PUMP
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Old 06-02-2020, 14:49   #17
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Re: Raw water pump on genset not pumping.

Try this, disconnect the hose at the Hx and plug the Hx cap, I use a wine cork. Place the hose in a bucket and crank the engine. If you get water, great. If not reconnect and move back to the raw water pump. Turn off the raw water to the strainer and disconnect the hose going to the raw water pump. Fill the bucket with water and turn the engine. If it doesnít draw water, its the pump or clogged lines between strainer and Hx. If it draws water, then it is a clog on the strainer side or air leaking in, maybe at the strainer cover.
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Old 06-02-2020, 14:56   #18
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Re: Raw water pump on genset not pumping.

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Try this, disconnect the hose at the Hx and plug the Hx cap, I use a wine cork. Place the hose in a bucket and crank the engine. If you get water, great. If not reconnect and move back to the raw water pump. Turn off the raw water to the strainer and disconnect the hose going to the raw water pump. Fill the bucket with water and turn the engine. If it doesn’t draw water, its the pump or clogged lines between strainer and Hx. If it draws water, then it is a clog on the strainer side or air leaking in, maybe at the strainer cover.
If you had read the post you will see I have essentially done all of that.

The simple fact that the electric pump has water flowing perfectly is proof that its not the pipes, strainer, heat exchanger etc etc etc
Once more in big letters, red ones this time for those that don't get it..........

IT'S THE PUMP
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Old 06-02-2020, 15:21   #19
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Re: Raw water pump on genset not pumping.

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Plenty of through hull flow, plenty of flow through HE (I did say pulled and checked)

No pieces of impeller, old impeller fine but replaced anyway, all hoses clear.

ITS THE PUMP but what?
If the pump was removed from its location to replace the impeller... was it reinstalled properly? Second, I am sure you lubed the impeller when you replaced it. If all is good, I would check the flow at a hose to check the output... What make is the gen set and pump?
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Old 06-02-2020, 16:55   #20
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Re: Raw water pump on genset not pumping.

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If the pump was removed from its location to replace the impeller... was it reinstalled properly?
Yes

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Second, I am sure you lubed the impeller when you replaced it.
Of course

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If all is good, I would check the flow at a hose to check the output...
Slightly more squirt than what we used to get


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What make is the gen set and pump?
Kubota/Diecon not that it matters
And pump is unknown, no markings, I think its a sherwood but maybe not
bought all impellers for it based on measurements
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Old 06-02-2020, 17:21   #21
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Re: Raw water pump on genset not pumping.

Iím working on one of those Diecon gensets at the moment and it has two jabscoís, one for raw water and the other ..... on the aft end of the injector pump for coolant. The raw water pump had bits of impeller in both the inlet and outlet ports and the restriction had reduced the flow by a lot. Next job is the coolant jabsco and it seems to be a case of removing the pump because of the access ( lack of). On your pump , check the length of the impeller too, there are differences in lengths between same diameter impellers.
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Old 06-02-2020, 17:50   #22
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Re: Raw water pump on genset not pumping.

Impeller is identical, same supplier, same order as the last 2 that worked perfectly........until they didn't.
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Old 06-02-2020, 21:02   #23
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Re: Raw water pump on genset not pumping.

Time for a competent professional to step in. . On a genset the raw water pump is one of the most common maintenance items and is of critical importance as you know. At this point sounds like pump should be entirely removed and inspected for wearing at lipseal and bearings. The coverplate, strike plate, and inner brass checked for scaring. Correct gasket thickness? Are you using a soft Neoprene or Buna N impeller for raw water? Nitrile impeller will lower you output and can damage brass housing if not a correct match. Just because the dimensions match doesn't necessarily mean it's the correct impeller. Some have weep holes on the hub or raised dots on the side of the blade. Find out what pump you have. Pumps are expensive. Sometimes it pays to hire an insuranced pro who has to know these things.. just my 2 cents.
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Old 06-02-2020, 21:06   #24
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Re: Raw water pump on genset not pumping.

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At this point sounds like pump should be entirely removed .
Post #1

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To get us out of a pickle I plumbed in a 240v 22lpm centrifugal pump and we are away again seemingly better than ever and I will very likely set this up properly when the weather gets sunny again due to the near impossible location of the impeller pump.
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Old 09-02-2020, 16:38   #25
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Re: Raw water pump on genset not pumping.

I know Simi is confident it's the pump. Given his experience, I have no doubt. For many, it might be the heat exchanger. I found an interesting YouTube video on cleaning a heat exchanger using Barnacle Buster. Have seen others that use muriatic acid mixed with water. Worth a watch and something to add to your maintenance repertoire for over-heating.

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Old 09-02-2020, 17:20   #26
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Re: Raw water pump on genset not pumping.

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I know Simi is confident it's the pump. Given his experience, I have no doubt. For many, it might be the heat exchanger. I found an interesting YouTube video on cleaning a heat exchanger using Barnacle Buster. Have seen others that use muriatic acid mixed with water. Worth a watch and something to add to your maintenance repertoire for over-heating.
Definitely pump.
Genset has been running like a champ, plenty of water flow and a few degrees cooler at the exhaust elbow than usual.

Old one off this morning and hole blanked off.


Barnacle buster
Active ingrediant is heavily diluted phosphoric acid and water.
Salt water swimming pool filter cleaner is very nearly the same for considerablt less
Or
You can get 80% phosphoric cheaper again and add your own water to bring it down to around 40%
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Old 10-02-2020, 03:25   #27
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Re: Raw water pump on genset not pumping.

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Doesn't matter, they reset in the correct direction as soon as the motor turns over.
Try it yourself next time you change an impeller.

Well, that certainly wasnít my experience with the large, stiff impeller on my Ď76 Grand Banks with an American Marine marinized John Deere tractor engine with a belt-driven raw water pump. I forgot to take into account that the port engine runs in the opposite direction from the starboard engine and set the impeller incorrectly. I shut down pretty quickly when I noticed that no water was coming out the exhaust. Fortunately I had used copious amounts of impeller installation lube and the impeller hadnít toasted itself to self-destruction despite getting rather warm.

So, perhaps your statement may be true for some types and materials of impeller but from potentially very expensive personal experience I know that it isnít universally true.
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Old 10-02-2020, 05:16   #28
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Re: Raw water pump on genset not pumping.

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Well, that certainly wasnít my experience with the large, stiff impeller on my Ď76 Grand Banks with an American Marine marinized John Deere tractor engine with a belt-driven raw water pump. I forgot to take into account that the port engine runs in the opposite direction from the starboard engine and set the impeller incorrectly. I shut down pretty quickly when I noticed that no water was coming out the exhaust. Fortunately I had used copious amounts of impeller installation lube and the impeller hadnít toasted itself to self-destruction despite getting rather warm.

So, perhaps your statement may be true for some types and materials of impeller but from potentially very expensive personal experience I know that it isnít universally true.
Well we are talking about a toy impeller on a 21hp genset.

Saying that, we run a 14 litre 855 Cummins and when I have replaced impellers you can turn the pulley manually and see them reset in the other direction.

Does the same on our Jabsco pump and the JMP version of the same.
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