'07 44 DB Generator Raw Water strainer prob

The Sherwood/Hypro pumps used on the 4 cylinder Onan generators are self priming and pump about 10 gallons/minute. Given the pump is located near the water line, I don't get the priming advice.... There is a height they won't self prime but that would probably be like... 100 feet in the air? (guess) If the system is tight, then it should prime. If it doesn't, then you have a bad pump/impeller, a blockage, or are sucking in air from a hose that is above the waterline.

You may want to check out this post:

http://clubsearay.com/forum/showpost.php?p=50348&postcount=4

The blockage caused the generator to shut down when I got on plane but the generator would run fine off plane. Remember that when you are on plane, the orifice (I finally got to use that word) on the bottom of the boat has water going tangentially to it causing low pressure (suction) on the raw water circuit. Any blockage in the raw water circuit or a failing impeller can shut the generator down because the low pressure stops the water flow on a limping system. As a side note, that's why you need to have the sea cock closed on the sewage tank as the low pressure can/will suck the sewage right out of the holding tank without the discharge pump running.

So... when I see the symptom of "it'll run standing still and not on plane", I think the raw water impeller is missing a few vanes, there's crap in the heat exchanger, or there is a blockage in a hose....

My 2 cents...
 
One other thing I'll throw out there is make sure you have reinforced hoses from the sea cock all the way to the suction side of the water pump on the generator. Sea Ray installed a non-reinforced hose on the suction side of the raw water pump and it took me a year to trace that down because when the hose would warm up and have any suction on it, it would collapse hence shutting off the water flow. As soon as the engine stopped, it would "re-inflate". Again... it always shut off on plane probably because more suction pressure was introduced into the system as I discussed above... I didn't find that one until I was hanging out in the engine room going down the river on plane... how fun is that...
 
Well boys....the truth will set you free!! Or set some bills out of your wallet free... Any way,
Make sure you have your insurance agent's phone number handy in case you can't get the hose back on that is essentially below the water line.
__________________
Gary
2003 480 Sedan Bridge/QSM-11 Diesels

No insurance agents needed Gary. I just started pulling hose sections off one by one and openning the seacock at each point to check flow. Damn good thing I could always shut it!! Crazy thing is I told Festivus that I thought my impeller and pump were on the back right (or aft starboard corner..bitch of a place), but actually on the Onan 9KW that I have, the hose comes out of seacock, runs across the front and toward the back right corner and enter the cabinet there; then it just passes through the cabinet wall only to run under the center of the genset back to the front side and up to a bronze little 3 bolt "housing" entering at the bottom of the housing and exiting at the top with the next hose. When I pull the hose to the inlet side of this housing and open the seacock, first thing out is practically an entire blade! That was it. I thought it odd to be in that section as I thought any "parts" would be downstream of the pump (which there still could be..). I couldn't tell, (& maybe you guys know) if that bronze kinda' skinny housing is where the impeller goes. Had to stop as I realized all the frickin' bolts are metric and all my damn tools were standard so tool shopping was fun. Anyone know if you can get the impellers any place other than an Onan dealer? Found a Onan dealer an hour away and will probably get them there in a couple of days if no other alternatives. Plus, also getting service manuals. Nobody has a breakdown of this thing or knows for sure if that's the housing huh? Anyway, I should be into it on Wednesday, and then checking downstream for parts before cranking her up.

Four Suns Blog: http://foursuns.blogspot.com
 
Well... I'm glad you found it. As I said earlier, the suction created while on plane can make the water stop flowing if the impeller is bad (or a blockage). If you want to have fun, you can do a back of the envelope calculation and going 30 mph creates about 13 PSI of suction on the system so if a blade or two of the impeller are missing, you can be hosed... get it? "hosed.".. You also need to make sure you find all the pieces/blades that fell off. The heat exchanger should have one bolt on the end cap that removes it so you can clean out the parts. However, it may be behind the oil filter and so... you may be changing the oil at the same time.

The pump is a Sherwood pump... Print this out:

http://www.sherwoodpumpsdistributio...arine-Distribution/en-us/MPG_3022_ENGLISH.pdf

On page 12 you can match up your old impeller. Take that impeller part number and order it from... well... I can't say... go to my blog... it's listed at the bottom on my links.

Your other pumps on your mains are also Sherwood... You should also carry extra impellers for those as well.
 
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Gary,
THANKS A MILLION !!!! I had just finished visiting your blog site and was going to tell you how cool it was that you had your "supply" sites down there for ready reference. Much appreciated Capt. I didn't think about needed an impeller removal tool or "pulley puller" basically. Don't know if my model will require it or not, but now I know what to expect. Do you change your main engines each season or 100 hrs or so? On the heat exchanger, you're right there is a bolt/cap "on each end" of this thing. Would I just remove both sides to clean it out well? Is it just a series of "channels" in there like a radiator? Thanks again man!:smt038
 
I don't use an impeller puller on the generator even though I have one. I have a tool that looks like an ice pick with the tip bent over 90 degrees and that usually does the trick. Do not use a screwdriver and pry it out as you can damage the rim of the pump and the cover won't seal properly then.

You only need to clean the entrance to the heat exchanger. The exit just blows out to the muffler. Make sure you get the stuff out of the brass elbow between the water pump and the heat exchanger as that can hold a lot of impeller pieces and block water flow. Those ice pick tools come in handy for that. (You can get a 4-pack at Lowes... mine are made by Kobalt).

I change main engine impellers every season. Some people go a few years but it isn't worth the risk for me. I don't want to discover a cooling problem 3 hours from an inlet. I see you have QSC 8.3 engines so you probably have a sherwood 1700 series pump (17000 impeller). I started getting my engine impellers from these guys:

http://www.sbmar.com

They are better quality than the sherwood brand. They only make the bigger impellers though so you can't get them for your generator.
 
Hey Gary.
I'm not too sure about the "green balls" thing you guys mention periodically, but if it has anything to do with helpful diagnosis, hell you get a damn dozen of them!! Pulled the impeller and I literally had 1 BLADE LEFT on it!! I was going to post some pics of it for the fun of it, but the hurricane kinda kept me busy. Anywho, I used the "ice pic tool" from Sears and it was a breeze to change. Fished out about 7 blades total from the heat ex....i guess the rest blew through. The only bitch of reassembly was keeping the oring in place on the housing. The soapy water wasn't terribly effective. Suggestions for next time?? Just straight soap? Second question is re: the impellers for the big boys....since my QSC's are still under warranty, i thought i'd stay with Cummins for the impellers and those boogers were almost $200 each!! Is that what they run from the Sbmar.com site more or less?? I kept looking for something else in the box because the diff btwn the $31 for the genset impeller, and the $200 main engine impeller didn't seem to be much other than peso's. Again, Thanks A MILLION for the help!
 
Hugo,
You have the same generator I do, I believe. When you reinstall your impeller it is much easier to remove the entire water pump assembly from the generator and install the impeller with the pump on a workbench (or in your lap in the ER, in my case). Trying to shoe horn the impeller in while the pump is mounted is an exercise in frustration. Pulling the water pump is a simple two hose clamp-two bolt drill.

regards
Skip
 
Skip said:
Hugo,
You have the same generator I do, I believe. When you reinstall your impeller it is much easier to remove the entire water pump assembly from the generator and install the impeller with the pump on a workbench (or in your lap in the ER, in my case). Trying to shoe horn the impeller in while the pump is mounted is an exercise in frustration. Pulling the water pump is a simple two hose clamp-two bolt drill.

regards
Skip
Click to expand...
Skip-
I too have the same genny--- I tried your approach (removing the pump entirely), but couldn't get the damn hoses off. Is there a trick to getting the hoses loose? Fortunately, I was able to get the impeller aligned/installed on the first try. Beginners luck I guess!

And before you ask, yes, I removed the hose clamps!
 
Tim,
Sea Ray uses a 3M adhesive, colloquially referred to as 'Gorilla Snot."
on the hoses at the factory.

It eases the installation because it acts like a lubricant up until the moment it hardens up, then you have to struggle like hell to get the hoses off again. Ever. Again.

I know this because I replaced every raw water intake hose on the mains and gen set in the grand and glorious summer of 2006 after I bought the boat. The connection on the starboard main at the Sherwood pump was especially enjoyable to remove.

I got a tube of Gorilla Snot from my local SR dealer and used it to reinstall all the new hoses.

There is no really good answer here besides brute strength and the liberal (hate that word) utilization of curse words. I don't have the boys in the ER when I am doing this sort of work. Better they learn to curse from Mom, like when I mention to her the notion of perhaps buying a 52DB with MANs next year.

I guess you could score the hose with a cutting tool-that might help get them off, but then you are doing hose and impeller replacement.


Skip
 
I've never put stuff on my hoses... I like to be able to take them off for maintenance of the items they are attached to...
 
Thanks for the great ideas guys. I, like Gary, haven't ever put anything on other than maybe some soapy water on an inlet before replacing a hose simply to not have a major hassle in removing it for maintenance. What about the cost on the impellers for the main engines? Is that pretty much the norm ($200/impeller) or am I gettin' bent over by Cummins?? I do like using OEM while under warranty, but just curious if anybody has found anything better.
 
Jus' Chillin said:
Is that pretty much the norm ($200/impeller) or am I gettin' bent over by Cummins?? I do like using OEM while under warranty, but just curious if anybody has found anything better.
Click to expand...

Go to http://www.sbmar.com/ and get the main impellers from them... You are getting bent over by Cummins. Cummins doesn't make impellers....

http://sbmar.com/Products/Impellers.cfm

$75 each or $130/pair for the 17000 series which I believe is what you have. Call them to verify.
 
Skip said:
Better they learn to curse from Mom, like when I mention to her the notion of perhaps buying a 52DB with MANs next year.
Click to expand...

Come on Skip, we'll have you guys over and she will go for it, I will bring a contract to Urbana...

On topic... I had to replace my impeller in my ONAN at about 170 hours also... not a bad job, and found all the blades...
 
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Thanks Gary! I'm sending this $800 box of rubber back Monday! They don't even send you any vaseline for $800 frickin bucks:smt013. Thanks for the help!:grin:
 
By the way, in the Service Manual, it calls for changing/checking the zinc bolts on heat exchanger and gear oil something or other (which must all be removed to get the water out of the system prior to changing impellers). How often do you guys change out the zinc bolts?? Where to get those bolts?? Cummins??
 
3m adhesive on the hoses??? nice touch by SR but overkill. double clamps would do just fine.

correct me if i'm wrong, but arent all raw water pumps with rubber impellers self priming? i know your typical air condx pump utilizes a hard plastic impeller and we've all had problems with those things losing prime.
 
I have been away for a few days and just got around to reading this thread. I have seen this before and I am wondering if the intake itself is clogged. The last one I saw had drawn up what looked like a tampon and the owner could not figure out why the unit was not drawing water. He burned up an impeller trying to get it to draw.

A simple check is to close the seacock, pull the top of the strainer and open the seacock. Water should overflow the top of the strainer at a rate consistent with a garden hose. If it doesn't you have found the problem.

If that is the problem, you must remove the hose from the seacock and use a half inch wooden dowel to push thru the seacock (it has to be open) and out the bottom of the boat. Yes water will come pouring in when you do this procedure but it is easily managed by the seacock.

-John
 
Running a generator while on the hook sometimes causes it to suck up debris such as fish. Two times this year my generator has sucked up debris. The easiest way to correct this is to take the inlet hose of the strainer (first close sea cock) and run a garden hose from the spigot in the engine room into the hose that came of the strainer.
This always clears the blockage.

Just an FYI since if the genny shuts down (reason being that it is not drawing water), its always either the impeller or a blockage.
 
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