Oberdorfer Raw water pump

[David Comando]

Let me set the stage: currently my raw water pump is not working. Every 2 years I replace the impeller although I regret doing it as I take out a working one in very good shape and replace it with a $58 new one that currently is not working. (This has happened before.)
I take out the pump shaft with the impeller, remove the snap ring, install new impeller, replace snap ring. I lightly sand the inside of the pump, sand and polish the face plate, install new paper gasket, remove o-ring on pump, polish the face of the pump, reinstall the old o-ring.( i spent 2 hours trying to find a new one, no luck).
Tighten the 4 screws evenly, open the thru-hull, bleed the air out of the pump, and when I start the engine it seems to be pumping at 50%, but maintaining the 158 degree engine temp. I go sailing and when I start the engine to return to the dock, it is not pumping. I make it to the dock before the engine  temp exceeds 180.
The last time it was this bad I replaced the entire water pump, as it was also weeping. This pump is less than 10 years old, not weeping and had been through 4 successful impeller changes.  What is going on? 

[Jon W]

I may have read your post wrong. Are you using both a paper gasket and the o-ring on the cover?

[waughoo]

I may have read your post wrong. Are you using both a paper gasket and the o-ring on the cover?

I noted this as well.  The paper gasket could cause a problem if there is also an O ring.

[David Comando]

Thanks. I read the Oberdorfer descriptions on Catalina Direct about the o-ring replacing the paper gasket. I did order an o-ring from them to replace the older one.
On my way to the boat to try again.

[Jim Hardesty]

take out a working one in very good shape and replace it with a $58 new one that currently is not working. (This has happened before.)

Happened to me also.  The two impeller failures I've had have both been with recently changed "new" impellers.  My theory is old stock.  FWIW  I now buy only from distributer online.
Jim

[scgunner]

David,

I change my impeller as part of the 100hr service, it's better to change a good impeller than a bad one, I consider it cheap insurance. I recently had a new impeller fail, the bond between the brass sleeve and the rubber failed so the brass sleeve was just spinning inside the rubber vanes and not moving water. I'd check that first, apparently the Chinese are now making repops. Generally any problems I've had with new replacement for any vehicle parts is because they're made in China. I'd recommend whenever possible you take a little extra time to source OEM parts.

[KWKloeber]

The paper gasket for the old style (202M pump) doesn't FIT the o-ring pump (N202M pump).
The bodies and bolt pattern were revised to accommodate the o-ring improvement, which sits on the pump side. There is a cover available that converts the old style 202M into an o-ringed pump (the o-ring sits on the cover side.)

Oberdorfer did have a bad batch of impellers where the rubber detached from the center hub. Also there have been issues with knock-off impellers not sealing against the cover and body.  Always make sure you are getting genuine Oberdorfer impellers.

[KWKloeber]

>>> I take out the pump shaft with the impeller, remove the snap ring, install new impeller, replace snap ring.<<<

Next time throw away the clip.  Read why on the TechWiki.

You might try extending it to 3 years, it just depends on how much you use the engine and (if you annually lay up) removing it to avoid the fins developing a set to them.  Careful replacing the shaft - use SuperLube on the end and rotate it while inserting to avoid nicking the seals.  Dab SuperLube on the shaft to help prevent the brass hub from seizing onto it.

I wouldn't be sanding the body of the pump - why? Do you have some sort of build up annually?  The wiping fins should keep it clean.

[Ron Hill]

Dave : Inspect the old impeller.  Bend each blade and look for cracking where it joins the center.  No cracking, I'd give it a shot of silicone and reinstall it.

What I always did was to take the impeller out over winter layup and put it in a cup under the engine with a shot of silicone.  In the spring I would reinstall it just opposite of the last season so the blades bent in the other direction.

A few thoughts

[David Comando]

Thanks for all the input. I did remove and discard the paper gasket, re-polished the face plate, removed and inspected new impeller, reinstalled. I noticed that I didn't install the inside washer on the impeller, so I did. Used glycerin as a lubricant. I noticed that when I opened the thru-hull, the  pump wasn't filling with water. So I removed the raw water hose and filled it with water, then reinstalled it. when I opened the thru-hull, water slowly came out of the bleeder.
It took a few seconds for water to pump after I started, but it was pumping well at low speed, faster at 2000 rpm. Engine temp leveled out at 158 degrees and all was well for 15 minutes.
I appreciate all the suggestions. I will purchase OEM parts next time as a kit, impeller and o-ring. I really don't put many hours on the engine seasonally, I work at burning a tank of fuel so I don't have old fuel in the tank.
I think I'll go 3 years next time!
I go sailing Wednesday, that will be the final test.

[Ron Hill]

Guys : The best easy lube I found for a new impeller is - liquid dishwashing soap!!

A thought

[KWKloeber]

Dave

The KIT used to come w/ an impeller, o-ring AND paper gasket (as such it was universal for an old-type or new-type pump.)  The latest dealer info is that Ingersoll Rand (who swallowed up Gardner Denver (who earlier swallowed up Oberdorfer)) decided to discontinue the kit after moving manufacturing out of NY to home base in Milwaukee.) 
Of course, that decision could change at any time!

ipso, the
impeller is p/n 6593
o-ring is p/n 9797-034B
paper gasket is p/n 6599

[Noah]

They still sell the kits on Amazon that includes an impeller, a paper gasket AND an O-ring together. It is an outfit called Stay Cool Pumps. I bought one back in August.  So that combo kit may contribute to the confusion of using both O-ring snd gasket on the same pump.

[KWKloeber]

[edited]

They still sell the kits on Amazon that includes an impeller, a paper gasket AND an O-ring together. It is an outfit called Stay Cool Pumps. I bought one back in August.  So that combo kit may contribute to the confusion of using both O-ring snd gasket on the same pump.

Be cautious.  Very, very cautious.
"They" selling it is not Oberdorfer selling it. 

The Ob kit (p/n 6593K) was discontinued (Depco still offers one as a "build to suit" item (put together in-house, not from Ob.))  But it's a wa$te -- you pay more to include what you don't need anyway.   I lobbied to the marine manager @ Depco for 5 years that he stop duping owners into buying something that is more expensive, just to throw away part of it.

I would be very wary of any seller not stating that it's GENUINE Oberdorfer (is a "Cool Pump" brand.)
LQQks to be an across-the-pond knockoff because the total kit is le$$ than my dealer COST for an impeller alone.

Possibly the source of the non-working setup (w/ gasket) was a knockoff?

-k


[edit]
https://www.cruisersforum.com/forums/f54/be-wary-maybe-of-stay-cool-pumps-impellers-211889.html



Question:Who is the manufacturer of this?
Answer:It is an aftermarket kit. I use quality parts aand package the kits myself.
Thank you,
StayCoolPumps

staycoolpumps Seller · June 2, 2020

[Ron Hill]

Guys : If there are problems with black Oberdoffer impellers, go to Defender and buy a blue Globe impeller!! 

That's what I have used for many years!!

A thought