Oberdorfer rebuild.

[rickinnj]

Just rebuilt my Oberdorfer. What a pita getting those old seals out! I got a chuckle outta Don's comments in the directions pertaining to how fairly easily the seals could be pried out. I think mine were tig welded in place.

My grease cup fitting didn't have a check valve in the nipple, nor did it appear to have any provisions for ever having one. There was water in the cup when I disassembled it but there was no grease in it either... I'll keep an eye on it and probably install either a new cup assembly or a remote zirc system later if deemed necessary.

The real eye opener was just how thin the old removeable cam plate was compared to the new one supplied with the kit! It was barely 1/3 the thickness of the new one!

I'm still not sure as to the cause of my initial raw water pump failure last weekend. The impeller was brand new from Moyer and had an hour on it. I figure the second impeller failed after installed in the seaway because some dumb a^% didn't reopen the seacock when he was finished the job. Other than the aforementioned man-made obstruction, the raw water inlet is clear. I had what I considered to be good flow out of the exhaust (this is my first inboard).

I'll install the rebuilt pump and proceed from there.

[ndutton]

How does the thickness of the new impeller compare to that of the old impeller and to the pump cavity depth?

[ArtJ]

There is a version of the Oberdorfer pump that has Glass sealed bearings.
They are impossible to field swap out without ruining the Pump. I think
it was the salt water pump PTO. This pump was created specially to
eliminate the grease cup. If anyone has one of these send it to oberdorfer
for seal replacements. I think it was a early attempt which may have
later evolved to become the MMI Pump.

Regards

[rickinnj]

How does the thickness of the new impeller compare to that of the old impeller and to the pump cavity depth?

Everything else seemed the same as original. Except that the seals were metal cased.

[sastanley]

Rick...if you think the Oberdorfer is a PITA, try rebuilding the mechanical fuel pump...compared to that, the water pump is child's play...but if you got it working well....good on ya!

I will agree though that I had a little trouble with the seals...I think my impeller was old enough stock from a local marina that I am not having the clearance issues some others are seeing now...but my impeller is coming up on 24 months old, so it will need inspection soon.

[ndutton]

Everything else seemed the same as original.

There have been instances of 0.005" difference in impeller thickness causing a no pumping condition, certainly smaller than can be seen. My recent experience was much greater, like 0.020" and it was difficult to see with the naked eye. There was no mistaking a dry exhaust though and the calipers told the tale.

[rickinnj]

Neil,

I am assuming the thickness you refer to was .005 too small allowing for excess bypass flow on the impeller. If that's the case, that might have been the culprit in my case. Thinking back, I couldn't source any oil paper for the cover gasket so I used some gasket material a little thicker.

It took about an hour for flow to deteriorate...I don't know.

As an aside, I was troubled by the way the water temp fluctuated between 130F and 190F the entire time. I was talking to Maurice on the phone last week (real class act, Mo!) and he seems to think, and I agree, that that was the thermostat and that I should remove it. With the 80F Chessy Bay water I'm in, I think we can do without it.

[rickinnj]

Shawn,

I rebuilt my fuel pump this winter and didn't have half the trouble I did with the water pump! I was in and out of the fuel pump in under an hour... the oberdorfer took over two hours and a screwdriver gouge in the palm of my hand!

[ndutton]

Yeah Rick, the thickness of the home made gasket could have been the issue or at least a contributor. If the impeller doesn't rub on the faceplate there's sure to be trouble.

Next time you're in need of a gasket in a pinch, use a dollar bill. It's about the right thickness and is made of the most waterproof paper you can find.

[rickinnj]

Dollar bill! Sweet idea. And if I borrow it from one of the crew, it's a free gasket! Thanx.

[sastanley]

At $3 per gasket, you are saving money by literally cutting it up!

[ndutton]

Disclaimer:

The suggestion was intended as a temporary jury-rig, not an alternative to a proper gasket.

[Mo]

Only a buck "eh" !

Nice one Neil...I'll store that in the back of my tiny little mind.

[hanleyclifford]

At $3 per gasket, you are saving money by literally cutting it up!

I think we could make money melting down pennies, too!

[ndutton]

Not me again

Nice one Neil...I'll store that in the back of my tiny little mind.

Can't take the credit (again). I'm just regurgitating the experience of others. And so as to maintain my reputation as a cheap-o scrounger, one dollar yields two gaskets. $0.50 apiece.

Please, please - this is a get-home measure only.