Reply
 
Thread Tools Display Modes
 
Old 01-02-2015, 03:25 PM   #1
Guru
 
CaptTom's Avatar
 
City: Southern Maine
Country: USA
Vessel Name: Cygnus
Vessel Model: Prairie 36 Coastal Cruiser
Join Date: Dec 2012
Posts: 1,373
Onan Water Pump

As a winter project, I've taken the water pump and heat exchanger off my Onan 7.5KW MDJE genset for some PM. The heat exchanger is cleaning up nicely. That's good, it's a $550-$700 part.

The water pump works, and really had no problems before I removed it. However, there's minor corrosion below the weep hole, even though I never saw any evidence of an actual leak. On the off chance the seal is leaking, I'd like to either rebuild it or buy a spare.

But, OMG they want $1,400-$1,700 for the replacement pump!

It's just a pulley-driven impeller pump. Theoretically, I could mount any old pump there, as long as the flow rate matched. I'd just have to drill and tap new mounting holes if they didn't match up.

Any reason this would be a bad idea? Anyone know a good shop on the East coast that does pump rebuilds?
__________________
Advertisement

CaptTom is offline   Reply With Quote
Old 01-02-2015, 03:44 PM   #2
Guru
 
City: gulf coast
Country: pinellas
Join Date: Jun 2014
Posts: 2,198
Depco Pump Company
__________________

bayview is offline   Reply With Quote
Old 01-02-2015, 03:47 PM   #3
Scraping Paint
 
City: -
Country: -
Join Date: Oct 2007
Posts: 13,748
Quote:
Originally Posted by CaptTom View Post
Any reason this would be a bad idea??
In your situation, I think your idea would work.

We have an MDJE in our 1973 boat. So far the only thing we've had to have fixed was the starter, which we had completely rebuilt by a local electrical shop that does this sort of thing.

It seem that MDJEs had at least two water pump configurations. On ours, the raw water pump is direct driven from the generator itself. It is mounted at the lower right corner of the control side--- injectors, intake air hot box, oil and fuel filters, etc. It is a flexible impeller pump but is hard-mounted to the generator.

There is a water pump that sits on a little platform near the top of the right side of the generator. This is a metal impeller pump, it's belt driven from the flywheel, and it's the coolant pump for the generator.

But it seems that some MDJEs have an opposite arrangement, with a metal impeller coolant pump mounted low and direct driven by the generator and the raw water pump mounted higher and belt driven from the flywhee.

If this is the arrangement you have, then I don't thing the generator's going to care what kind of pump provides the raw water as long as something does.
Marin is offline   Reply With Quote
Old 01-02-2015, 03:49 PM   #4
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 3,884
I think it is an Oberdorfer pump, can source elsewhere for around $500. Also, if bearings are good with no play or roughness, and no liquid leakage, leave it alone.

This applies to the circ pump, not the sea water pump.
Ski in NC is offline   Reply With Quote
Old 01-02-2015, 03:54 PM   #5
Scraping Paint
 
City: -
Country: -
Join Date: Oct 2007
Posts: 13,748
The owner of the marine electrical shop we use who is a long-time Onan dealer gave us a piece of advice years ago regarding the belt-driven pump on the MDJE. And that is to run the belt fairly loose. Not loose enough to come off, but just tight enough to keep the pump going. This minimizes the side load on the pump and he said the seals and bearings will last a lot longer. So this is how we've run ours the last 16 years.
Marin is offline   Reply With Quote
Old 01-02-2015, 05:00 PM   #6
Guru
 
Capt.Bill11's Avatar
 
City: Sarasota/Ft. Lauderdale
Country: USA
Join Date: Apr 2014
Posts: 5,422
Leave the old working one alone until you have to replace it. In the mean time keep your eye out for a used one that is rebuilt or one that is rebuild-able to have as a spare when the time comes to replace the old one.

The corrosion you see could have come from the front cover weeping at some point. And perhaps has nothing to do with the seal leaking.
Capt.Bill11 is offline   Reply With Quote
Old 01-02-2015, 06:40 PM   #7
Guru
 
Edelweiss's Avatar
 
City: PNW
Country: USA
Vessel Model: 1976 Californian Tricabin LRC
Join Date: May 2011
Posts: 1,834
Quote:
Originally Posted by CaptTom View Post
However, there's minor corrosion below the weep hole, even though I never saw any evidence of an actual leak. On the off chance the seal is leaking, I'd like to either rebuild it or buy a spare.
But, OMG they want $1,400-$1,700 for the replacement pump!

It's just a pulley-driven impeller pump. Theoretically, I could mount any old pump there, as long as the flow rate matched. I'd just have to drill and tap new mounting holes if they didn't match up.
The coolant pedestal pump on the platform is indeed an Oberdorfer circulation pump. Very easy to rebuild with simple tools and a vise. the rebuild kit isn't too expensive either. The pump brand new price is $600 at Pump Masters.

The Saltwater Onan gear driven pump on the side of the Onan Gen. engine is the ridiculously expensive $1500 rubber impeller pump. When it goes out consider replacing with a Jabsco pedestal impeller pump or an electric pump.

If you decide to change the Oberdorfer out with another brand of pump, keep in mind the Oberdorfer pump is a "slinger style" centrifuge pump designed to circulate hot water and not a rubber impeller pump. So a rubber impeller pump won't do! But it is far better and simpler to just rebuild it. You can order the rebuild kit on line.

If you need the Onan manuals for the MDJE, PM your email address to me and I will send them too you.
Attached Images
 
__________________
Larry B
Careful . . .I Have a Generator and I'm not afraid to use it !
Edelweiss is offline   Reply With Quote
Old 01-02-2015, 07:21 PM   #8
Guru
 
CaptTom's Avatar
 
City: Southern Maine
Country: USA
Vessel Name: Cygnus
Vessel Model: Prairie 36 Coastal Cruiser
Join Date: Dec 2012
Posts: 1,373
Quote:
Originally Posted by Edelweiss View Post
The Saltwater Onan gear driven pump on the side of the Onan Gen. engine is the ridiculously expensive $1500 rubber impeller pump. When it goes out consider replacing with a Jabsco pedestal impeller pump or an electric pump...

If you need the Onan manuals for the MDJE, PM your email address to me and I will send them too you.
I have the manuals, thank you.

I should have mentioned, it's the raw water pump, not the circulating water pump. Both are belt-driven off the flywheel.

I can't seem to find the flow rating for the existing part, Onan 170-3172, or its replacement, 131-0257.

I've seen the Depco site, I may call them Monday just to see what they say.

$1500 for a new pump is out of the question. I'm interested in the idea of an electric pump. I'm actually surprised that isn't done more, given how unreliable and problematic rubber belts and impellers seem to be.

I also think those who say to just clean it up and use it, since it's showing no other signs of failure, may be onto something.
CaptTom is offline   Reply With Quote
Old 01-02-2015, 07:45 PM   #9
Guru
 
Edelweiss's Avatar
 
City: PNW
Country: USA
Vessel Model: 1976 Californian Tricabin LRC
Join Date: May 2011
Posts: 1,834
Ok, sounds like somebody changed out the original gear driven pump then? I haven't seen a MDJE from the factory with two belt driven pedestal mounted pumps, but never say never!!

I replaced my Onan gear driven saltwater pump, so it's the same as yours is now. I removed the old Onan 3/8" pump, fashioned a cover plate and gasket to cover the hole. Then bought a standard Jabsco 3/8" output brass pedestal pump with a rubber impeller, which I mounted on the platform opposite the Oberdorfer pump, resized the belt and all was good. It actually flows a little more water than the old pump, but that doesn't seem to matter. I changed it out 5 or 6 years ago and hundreds of hours later still going strong.
__________________
Larry B
Careful . . .I Have a Generator and I'm not afraid to use it !
Edelweiss is offline   Reply With Quote
Old 01-02-2015, 08:53 PM   #10
Scraping Paint
 
City: -
Country: -
Join Date: Oct 2007
Posts: 13,748
Quote:
Originally Posted by Edelweiss View Post
Ok, sounds like somebody changed out the original gear driven pump then? I haven't seen a MDJE from the factory with two belt driven pedestal mounted pumps, but never say never!!
Our MDJE is stock and has the pump arrangement you describe. Only one belt-driven pump up above on the little platform for the engine coolant.

Quote:
......bought a standard Jabsco 3/8" output brass pedestal pump with a rubber impeller, which I mounted on the platform opposite the Oberdorfer pump, resized the belt and all was good..
Great to read your description of what you did. I'm going to write it out, print it, and stick in our Onan manual so if or when the day comes the raw water pump craps out I'll have your idea to act on. Thanks.
Marin is offline   Reply With Quote
Old 01-02-2015, 09:55 PM   #11
Guru
 
hmason's Avatar
 
City: Westport, CT
Country: USA
Vessel Name: Magic
Vessel Model: Grand Banks 46 Europa
Join Date: Aug 2013
Posts: 1,895
I second touching base with Depco Pump. I have had several pumps rebuilt by them. They are reasonable and fast. They will also sandblast the pump and paint it to match the engine paint. Great folks there. Howard
__________________
Howard
Magic, 1996 Grand Banks Europa
Westport, CT and Stuart, FL
hmason is offline   Reply With Quote
Old 06-07-2015, 07:29 PM   #12
Guru
 
CaptTom's Avatar
 
City: Southern Maine
Country: USA
Vessel Name: Cygnus
Vessel Model: Prairie 36 Coastal Cruiser
Join Date: Dec 2012
Posts: 1,373
Figured I'd post a follow-up to the saga above. Over the winter, I bought an March electric pump and installed it last weekend.

The hardest part was finding where on the genset I could take off 120VAC to power it. That solved, I lowered the sea strainer so the cover is just at or below the waterline (no losing prime), got a new belt to fit the circulating pump now that the raw water pump is gone, new hoses all around, and fired it up.

I love it! There's a good, strong flow of cooling water out the exhaust now. I test-ran it for an hour under load, no issues.

Edelweiss, thanks for the suggestion!
CaptTom is offline   Reply With Quote
Old 09-08-2015, 09:53 PM   #13
TG
Senior Member
 
TG's Avatar
 
City: Oceanside, CA
Country: USA
Vessel Name: Tera Grace
Vessel Model: Californian 42 LRC
Join Date: Oct 2012
Posts: 153
The raw water pump bearing went out on my MDJE 7.5K last week while we were at the Isthmus on Catalina Island. The pump configuration is both pumps are up top, raw water on the left and coolant on the right both driven by the same belt. Luckily the over-temp sensor shut the generator down.

Since we were staying on the island for a week I purchased a shorter belt from the island warehouse to drive just the coolant pump then I rerouted my livewell pump to the raw water strainer for the generator and plumbed the strainer direct to the heat-exchanger. I had to top of the anti-freeze since it boiled over but I keep two gallons on reserve. Sounds kind of busy but only took about an hour and we were back in business. We ran the generator as needed for 5 days under this configuration.

Now that we're back in port I need to source a new raw-water pump. I'm thinking about going with the Jabsco Pedestal with 1/2" ports but would be interested in seeing what electric pump CaptTom used.
TG is offline   Reply With Quote
Old 09-08-2015, 10:52 PM   #14
Enigma
 
RT Firefly's Avatar
 
City: Slicker?
Country: Bumpkin?
Join Date: Oct 2007
Posts: 9,995
Greetings,
Mr. TG. Impressive improvisation!
__________________
RTF
RT Firefly is offline   Reply With Quote
Old 09-09-2015, 12:56 AM   #15
Guru
 
HopCar's Avatar


 
City: Miami Florida
Vessel Name: Possum
Vessel Model: Ellis 28
Join Date: Aug 2011
Posts: 3,501
TG I think we need to rename you MacGyver. Nicely done.
If you want to go to an electric pump, I think an Oberdorfer 104 should be about right. It's not self priming so it would need to be mounted below the waterline.
__________________
Parks Masterson
www.hopkins-carter.com
HopCar is offline   Reply With Quote
Old 09-09-2015, 02:05 AM   #16
Guru
 
Xsbank's Avatar
 
City: Pender Harbour, BC
Country: Canada
Vessel Name: Gwaii Haanas
Vessel Model: Vancouver Shipyards Custom Aluminum 52
Join Date: Sep 2013
Posts: 2,447
Electric pump, no question. Runs when the generator starts, no belt issues, stops when the generator stops. Put the pump anywhere you want, in your galley if you want to watch it!
__________________
Don't believe everything that you think.
Xsbank is offline   Reply With Quote
Old 09-09-2015, 11:22 AM   #17
TG
Senior Member
 
TG's Avatar
 
City: Oceanside, CA
Country: USA
Vessel Name: Tera Grace
Vessel Model: Californian 42 LRC
Join Date: Oct 2012
Posts: 153
I just purchased a Jabsco 1673-1001 1/2 inch Pedestal mount pulley driven on ebay for $125.00. New price is around $245 on up.

There's a guy on ebay parting out never used military surplus water filtration units that incorporated these pumps.

I like the Jabsco because of the parts availability.
TG is offline   Reply With Quote
Old 09-09-2015, 04:00 PM   #18
Guru
 
CaptTom's Avatar
 
City: Southern Maine
Country: USA
Vessel Name: Cygnus
Vessel Model: Prairie 36 Coastal Cruiser
Join Date: Dec 2012
Posts: 1,373
Quote:
Originally Posted by TG View Post
Now that we're back in port I need to source a new raw-water pump. I'm thinking about going with the Jabsco Pedestal with 1/2" ports but would be interested in seeing what electric pump CaptTom used.
I used a March LC-3CP-MD pump:


Very happy with the results so far. And if it fails I can cannibalize one of the air conditioners.
CaptTom is offline   Reply With Quote
Old 09-10-2015, 12:50 AM   #19
Guru
 
Edelweiss's Avatar
 
City: PNW
Country: USA
Vessel Model: 1976 Californian Tricabin LRC
Join Date: May 2011
Posts: 1,834
Quote:
Originally Posted by TG View Post

Now that we're back in port I need to source a new raw-water pump. I'm thinking about going with the Jabsco Pedestal with 1/2" ports but would be interested in seeing what electric pump CaptTom used.
1/2" or 3/8" will work fine. I replaced mine MDJE pump with the 1/2" Jabsco long ago and it works great. But I did have to switch to a larger diameter belt pulley as it pumped a whole lot more water than the original. If I had it to do over again I would probably go with the smaller pump. The larger pump was a bit of an overkill.
__________________
Larry B
Careful . . .I Have a Generator and I'm not afraid to use it !
Edelweiss is offline   Reply With Quote
Old 08-17-2017, 06:55 PM   #20
Newbie
 
City: Babylon
Country: Usa
Join Date: Aug 2017
Posts: 3
Hi capt. Tom. I am considering converting to the same electric pump set . Can you tell me how to or Where to hook up the wires ? And if you ever bad any problems if the the water flow is to much. Thanks, for. Capt Ted
__________________

Capt. Ted is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 04:27 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012