Great debate: Oberdorfer vs. Sherwood

[crieders]

So my boat started her life with the Oberdorfer
Replaced it with Sherwood that cooled well but was hard to access
Went with new Oberdorfer and in a strong headwind, against the tide on a hot day, engine gets up to 185-190. Makes me nervous
Thinking of going back to Sherwood
Any new views on this?

[KWKloeber]

So my boat started her life with the Oberdorfer
Replaced it with Sherwood that cooled well but was hard to access
Went with new Oberdorfer and in a strong headwind, against the tide on a hot day, engine gets up to 185-190. Makes me nervous
Thinking of going back to Sherwood
Any new views on this?

Yes, but first...

What's your:

Engine model?
Thermostat temp rating?  Checked it lately?
Hx size - 3"?
Location - ie, water temps?
Ob pump model?
Size of inlet hose - 5/8"?
and outlet hose?   5/8"?  (7/8" on the B engines?)


-Ken

[Roc]

My friend with a C350, same engine as C34 (M35B), converted to this Oberdorfer.  Apparently, there are different Oberdorfer pumps and you need to get the one with 1/2" fittings (-16 model).

[crieders]

I have the 25xp and yes I did check all those other items
I noticed that the Oberdorfer does hava a smaller impeller or so it appears

[KWKloeber]

I have the 25xp and yes I did check all those other items
I noticed that the Oberdorfer does hava a smaller impeller or so it appears

So what Ob pump model do you have?

Ken

[DarthOccam]

Both pumps have similar GPH ratings. If your engine is over heating, I would eliminate other possible causes first.  Are you getting a "normal" volume of discharge from the exhaust?  If not, could be clogged inlet, heat exchanger, or the impeller. All cheaper and faster to fix than a new pump.

More details on the symptoms and what you've eliminated would help.

Michael

[Ron Hill]

Cliff : You have thrown out a question to a form that 99.9% have either a Sherwood or an Oberdoffer !!

You are one of the VERY VERY FEW M25XP engine owners, that I know of that has used BOTH pumps :
1. On the same engine,
2. In the same boat
3. In the same environments,
4. With the same running RPMs.

You aught to be telling us the answer to your question - rather than asking us !?! 

My thoughts 
 

[Stu Jackson]

Cliff, Ron makes a good point!      All in good humor...

It has been repeatedly reported here that the Sherwood pumps more water.  I have also repeatedly mentioned that in the 27 years our boat has had its Oberdorfer it works just fine.  Michael is right, check the other issues first.  If you're concerned about 185-190, either 1) don't worry it's normal; or 2) put a 160 thermostat in.  Before someone says it's bad for your engine, it isn't.

[oldcatsailor]

I was running near 200* cleaned the heat exchanger and replaced tired sherwood with a  model16 1/2 inch in=outlet oberdorffer
now the temp is usually below 180.ground off some metal as per the forums instructions and it fit perfectly.220, for a new pump compared to 370. for a rebuild,

[MarkT]

I have the M25 which came to me with a Sherwood pump. Replacing it with the Oberdorfer was one of the first things I did after buying the boat. The design of the Sherwood is so unhelpful when it comes to changing impellors that there was no argument in my mind.  My heat exchanger did have the remains of several impellors in it when I cleaned it out. If you are not getting sufficent cooling then my first advice is to remove the end caps from the heat exchanger and clean it out.  Next check that there is no obstruction to the inlet. My experience has been that the Oberdorfer does a great job and pumps more than enough water for the efficent cooling of the engine.

3" heat exchanger, M25 engine on the Chesapeake bay

[crieders]

I have never opened the heat exhanger and will do that

[Stu Jackson]

I have never opened the heat exhanger and will do that

Cliff,

http://c34.org/bbs/index.php/topic,8171.msg57142.html#msg57142

You might be interested in the rest of that topic, too.