Oberdorfer N202M15 on M25XP

[Mike McDonald]

Hi all,
I'm having trouble getting the Oberdorfer water pump on my engine to pump water through. I changed the impeller and gasket, cleaned the sea water strainer, sucttioned the water through the pump inlet hose and reattached to the pump, started the engine and nothing coming out the exhaust. Removed the pump outlet hose from the heat exchanger and little or nothing coming out with the engine running. It won't seem to prime. I removed the sea strainer lubed the gasket/o-ring and re-tightened, suctioned the water through the pump inlet hose again, re-attached the hose again, and still nothing.

Is there a way to determine if the pump itself is bad, other than what I have already done?

Engine over heated on last trip out which prompted all of this. (Bad impeller after 2 seasons) I always change the impeller every season. This time I tried to get more time out of the impeller.

Any ideas would be appreciated! Thanks
Mike......

[KWKloeber]

Mike

Checked for blockage on the intake thru hull?
Is the impeller turning?
Is the face plate worn?
Is the pump body worn?
Correct cover o-ring?
Prime thru the pipe plug?
An impeller vane from overheating caught in the outlet hose?
Bypass everything. Try the intake hose in a bucket (of water of course.)
Try lubing the inside faces of the pump body w/SuperLube for a better seal against the impeller faces.
Posted previously - there were some prior issues w/impellers. Is it brand new? From?  Ob brand or a knock off?  Try a different one?
Is it a M-15 or M-16?

[Ron Hill]

Mike : Check all the items that Ken has recommended !!
Broken impeller blades usually get trapped in the output (lower) brass elbow and clog things up.

A few thoughts

[Mike McDonald]

Hi Ken,
Just saw your reply. Thanks. Tried all of those things, then tried a second new impeller. The first new one from today was Oberdorfer, This one is from StayCoolPumps.com.
Still would not pump. This time the pump has water leaking from the opening on the bottom of the pump near the back. I'm guessing that's a good indication of a bad pump. I may have missed the water dripping before I put in the second new impeller.

I have a spare used pump from a previous owner, that appears to be rebuilt with new impeller inside. I don't have a gasket for mounting it to the engine, I'll have to locate one and give it a try. Will also have to transfer the 90 degree inlet/outlet fittings from the old pump to the backup.

If that makes sense, anything to watch out for when removing the old and installing the new pump? Tips/cautions?
Thanks,
Mike.....

Ron,
Your reply came in while I was typing. Yes I did find pieces in the elbow and removed. Also checked the heat exchanger, but did not find any there.
Thanks,
Mike

[KWKloeber]

Mike

That was intended to be "Try lubing the inside faces of the pump body w/SuperLube for a better seal against the impeller faces."  Damn autocomplete.

The StayCoolPumps impeller is an offshore knock-off.  I don't recommend using them, but.....

If you have a Kubota dealer near you use the Kb gasket (part # 15296-88130); it's a better gasket than the Westerbeke (part # 298485.)

If the water seal is leaking the pump **should** still be pumping water to the Hx (if it's leaking that means water is being drawn to the pump.)  Strange - it seems there's something else wrong -- but a boat is a boat -- you never know, especially when you *know* the cause.  Really strange that you have zero out the outlet hose.

Again I'd bypass all the other variables until you solve the no-pumping problem.

Make sure the pump flange and engine land are very clean and flat, not worn or corroded.  If one is pitted, you can adhere the gasket (to one side only) with a smear of hi-temp RTV meant for forming gaskets or non-hardening Permatex.

You said you tried everything -- you saw the impeller turning?  I know an owner whose camshaft had a broken-off fork so there was nothing to drive the pump shaft.  Similar to below, but on the older engines, not XPB.

[Mike McDonald]

Hi Ken,
Haven't been able to locate the Kubota gasket nearby, but have a few on order. The places I called said the gasket was for an hour meter. Does that sound right? The pump is N202M15 and my engine is an XP.

I did not actually see the impeller turning, I was going by the fact that the flat on the shaft was in a different position each time I removed the cover. Maybe I'l turn the engine over with the cover off briefly to actually see it turning. If it is, I'll try the water in the bucket again with a shorter hose. I was going from a tee off the hose after the thru hull and strainer. Thanks again!
Mike....

[KWKloeber]

Yes that's the gasket. I'd send you a few but no doubt across the border who knows how many months that would involve.

[Noah]

Mike, maybe I am "all wet", and I am certainly not a mechanic, but earlier you mentioned "I changed the gasket/o-ring..." I believe depending on the age of the pump, it uses a gasket OR an O-ring— NOT BOTH.

[Ron Hill]

Mike : On my old M25XP engine I must have changed pumps or had the pump off 20/30 times and NEVER put on a new pump to engine gasket!!  The old one stayed in place!!

If you have water coming out of the weep hole (about center of pump body) you need a new water lip seal.  Look in WiKi for the "how to" did that very many times.

A few thoughts, good luck

[Stu Jackson]

Hi Ken,
Haven't been able to locate the Kubota gasket nearby, but have a few on order. The places I called said the gasket was for an hour meter. Does that sound right? The pump is N202M15 and my engine is an XP.

..........................
........................................

Yes, it is.  If you look in the wiki, you will find the TRACTOR manual for your engine.  Where the rw pump is on our marinized engines, the tractor had an hour meter.

I did this a couple of years ago and wrote it up in a tech note.  Same gasket.

[KWKloeber]

you mentioned "I changed the gasket/o-ring..."

That was RE: the strainer — but Mike said "gasket" on the pump, so good point - the N202M-15 uses an o-ring.  Maybe that's what he meant?

[Mike McDonald]

Sorry about the gasket and o-ring confusion. The strainer I mentioned has an o-ring.

The pump currently on the engine uses a paper gasket. The spare pump has a groove for an o-ring on the pump. The cover plate goes over the o-ring. That appears to be the only difference between the 2 pumps. The spare pump has a small metal plate attached over the cover plate with one of the 4 cover plate screws. It says Oberdorfer and has N202M 15 stamped into the plate. The cover plate itself has Oberdorfer Pumps 6597 stamped into it. The 2 pumps have identical mounting bases and hole configurations.

As far as the pump mounting gasket goes, I wanted to be sure to have a new one on hand in case I needed it when mounting the spare.

I really appreciate all of the support from everyone. Probably can't get back to the boat for a day or 2. I'll further investigate/test a few things, based on all of your comments, prior to swapping the spare pump. Still hoping the spare is a good pump. It was on the boat when I bought it. Looks like it may have been rebuilt. We'll see. Thanks again!
Mike......

[Stu Jackson]

.............
.................
....................


Still hoping the spare is a good pump. It was on the boat when I bought it. Looks like it may have been rebuilt. We'll see. Thanks again!

Mike, the way "to see" is to look inside with a bright light, and perhaps even take photos.  If it has actually been rebuilt and never used, the cleanliness and shininess of the new seals should be quite evident.

Like this:

Oberdorfer Pump Rebuild 101 - http://c34.org/bbs/index.php/topic,6766.0.html

[KWKloeber]

[edited]
P.S.: Remove the impeller and lube the shaft w/ SuperLube/Lanacote, TefGel, etc. to help keep the impeller hub from binding onto the shaft/flat.  AND permanently deep-six the cir-clip while you have it off (it has absolutely no function on an installed pump, except to make an impeller switch-out more difficult in an emergency.)

If you are uncertain of the spare condition, slide out the impeller/shaft, inspect for any scoring or wear (at the location of the seals.)  It would be a shame to install a leaky shaft.  Lube up the tip and CAREFULLY insert the shaft while SLOWLY TURNING it so the tip doesn't knick a rubber seal. I had *perfectly good* seals but a scored shaft that leaked -- a millwright buddy turned the shaft to take out the score and it lasted me another 5 years.

Thx for the clarification, Mike!

The pump on there is a 202M-??, the spare is a N202M-15
6597 is the cover plate part no. (there  have been various flavors, 6597, B-6597, 6598-B; thick embossed cast bronze, thin cast bronze, stamped brass for the newest N models.)

It's slightly odd that you have a 202M-15 (3/8" NPT inlet/outlet) pump.  I thought the 34s had mostly the 202M-16 (the 1/2" NPT version.)  Before you mount the spare make sure that the one on there isn't the 1/2" version as obviously the hose elbows are not interchangeable.

Just FYI some things I have done to these pumps over the years to increase flow are:

   * increase water TO the pump;  the -15 and -16 have the same pump body and theoretically have the same flow rating, but I changed some supply hoses from 5/8" to 3/4".  I figure if you reduce the losses getting water TO a pump, then you get at least an even chance for better output (and maybe more likely to retain prime, I dunno?)

   * switch the 90 hose elbows for straight in/out hose barbs - again less restriction = greater water to and out of the pump.  At least a sweep 90 instead of a tight 90 if one of them MUST be an elbow.

   * switch to longer barb fittings so it can be double-clamped (some surveyors will ding owners if below waterline hoses are not double-clamped, even though ABYC doesn't require that.)

   * switch from the brass (not approved for the use) to glass-reinforced plastic or stainless hose barbs.

Good luck on the spare switch in.

-ken


   

[Ron Hill]

Mike : Have you blown out BOTH lines from the Obd. pump?  After running the engine is there any evidence of water in the pump?

Remove the inlet hose and Try to suck water up to the pump - does the water stay in the hose? or disappear? or some flow out?

A few thoughts