M-25XPB Engine

[Sagehen]

Wanted to express my appreciation for this Forum
Had been in a 2005 C310 partnership in Gig Harbor, WA, but just purchased an older C36 repowered with the infamous M-25XPB. If anything, it rumbles around even more than the one we have in the C310.
I'll be following this forum for more advice on the engine/drivetrain and general interest posts. The information has been very worthwhile. Like myself, I believe there are a lot of us out there who do not have much to say, but have greatly benefited from the experience of others and willingness to share their expertise. I found the "occasional" divergence of opinion to be most informative.
My sincere thanks to all the regular contributors, especially PaulJ, whose photos have been truely outstanding.
Anyone interested in a C310 partnership in Gig Harbor can find the ads on Craig's List, 48 North in March and this site.
Again, thank you all very much. Keep up the good work.
Jack Heaston (sagehen)

 

[Stu Jackson]

Jack,

Don't know if you "discovered" my posts on the C310 Forum on this message board.

We have lots of M25 series engine information on our C34 tech wiki.

http://www.c34.org/wiki/index.php?title=Diesel_Engine

 

[gpd955]

I hear ya Jack! Don't know where I'd be without this site. Had someone even talk me through a repair while out on the water using my blackberry. The guys and gals on this site are second to none!

 

[Sagehen]

Jack,

Don't know if you "discovered" my posts on the C310 Forum on this message board.

We have lots of M25 series engine information on our C34 tech wiki.

http://www.c34.org/wiki/index.php?title=Diesel_Engine

Stu
Yes, I have read several of your links to the C34 Owners site. Very informative. Thanks.
I think the C34s may have gone from the M-25xp to the M-30, while bypassing the M-25xpb. The latter has the unfortunate reputation for low RPM vibrations along with (in my limited observation) that POS backwards installed Sherwood raw water pump face, which requires one to remove the water hoses to change the impeller. Even then, it's not a lot of fun. On our C310, one has to remove a water hose to change the engine belt. How's that for thoughtful engineering?
I once had a pre-Westerbeke M-25xp without noticeable vibration and an easiily accessed raw water pump face. Everything changes.
Thanks again for you participation on this Forum and I'm looking forward to more of your links.
Jack

 

[Stu Jackson]

Jack, so a few hundred $$ you could swap out the Sherwood for an Oberdorfer pump.

 

[rpwillia]

Trade Offs

Jack, so a few hundred $$ you could swap out the Sherwood for an Oberdorfer pump.

I looked into that, but the Sherwood provides much better water flow over the Oberdorfer, so I decided to stick with the inconvenience of the backwards bolts.

BTW, What is the big difference between the M25XP and the M25XPB and why does the XPB have such vibration? Is there any cure besides us just running our idle rpms higher?

 

[Sagehen]

Re: Trade Offs

Thanks for the interesting info on the difference in water flow. Any idea on how much less the Oberdorfer puts out? Our Puget Sound water temperatures are in the mid 50 degree F range year around. Does that lessen the concern about water volume through the pump? Also notice that our M25-XPB runs at 160 degrees (if the gauge is accurate) at cruise RPM, which is on the lower end of how warm a diesel likes to be.

Has anyone actually replaced the Sherwood with the Oberdorfer on the M25-XPB?

I see that Catalina Direct has a $247 "Water Pump Replacement or Retrofit" on its website that shows the Oberdorfer pump. The M25-XP is specifically listed, but not the XPB. Not sure if it requires an adapter plate or other engine modification. It's a special order item and not returnable, so one would want to be pretty sure it was going to work.
There is also an ominous procedure for realigning the pump shaft with the engine should one yank the shaft out while changing the impeller. I always changed the impeller on the Oberdorfer while holding the shaft in with a 1/4" dowel, but that won't be much help in changing the pump.
Just curious if someone's already changed from one to the other and if they're glad they did.

As regards the vibration in the XPB versus the XP, I have no information on that, except that the conventional wisdom seems to not operate the XPB under 1000 RPM. Ours likes 1150 even better. The book says the idle is between 1000 and 1200.

Thanks
Jack

 

[paulj]

http://shop.torresen.com/marine_die...on=universal&contentname=engine&engine=M25XPB

 

[Stu Jackson]

1. Thanks for the interesting info on the difference in water flow. Any idea on how much less the Oberdorfer puts out? ...Also notice that our M25-XPB runs at 160 degrees (if the gauge is accurate) at cruise RPM, which is on the lower end of how warm a diesel likes to be.

2 Has anyone actually replaced the Sherwood with the Oberdorfer on the M25-XPB?

3. I see that Catalina Direct has a $247 "Water Pump Replacement or Retrofit" on its website that shows the Oberdorfer pump. The M25-XP is specifically listed, but not the XPB. Not sure if it requires an adapter plate or other engine modification. It's a special order item and not returnable, so one would want to be pretty sure it was going to work.

4. There is also an ominous procedure for realigning the pump shaft with the engine should one yank the shaft out while changing the impeller. I always changed the impeller on the Oberdorfer while holding the shaft in with a 1/4" dowel, but that won't be much help in changing the pump.
Just curious if someone's already changed from one to the other and if they're glad they did.

Jack,

1. Water flow and temp - kinda an urban myth, but true, the Sherwoods do put out more water, but the "less" flow from an Oberdorfer is not an issue. There are Os on my little M25 as well as the larger M35s. Temp is dependent on the thermostat.

2. I don't know. I'd call Torreson and CD.

3. Yup. Cover that when you call them.

4. That's another urban myth that stopped being true once they started making the inside end of the pump's shaft properly, with a male end, instead of the older female type inboard end. I, too, worried about this when we first got our boat, but did research on the pump blow up diagrams and a lot of reading. Unless your boat (and engine) was built before 1985 or so, the pumps all have male ends. I took mine out and it is NO problem putting it back in.

 

[rpwillia]

More thoughts

Any idea on how much less the Oberdorfer puts out? Our Puget Sound water temperatures are in the mid 50 degree F range year around. Does that lessen the concern about water volume through the pump?

Has anyone actually replaced the Sherwood with the Oberdorfer on the M25-XPB?

I see that Catalina Direct has a $247 "Water Pump Replacement or Retrofit" on its website that shows the Oberdorfer pump. The M25-XP is specifically listed, but not the XPB.

conventional wisdom seems to not operate the XPB under 1000 RPM. Ours likes 1150 even better. The book says the idle is between 1000 and 1200.

Jack, You are on the right track.I think you would be OK with the Oberdorfer. I read somewhere it was around a 1/3 less flow, not a big deal. The Catalina Direct on should work. After seeing the flow and the price I decided the extra minute to backout the reverse bolts was worth it and left well enough alone.

The idea about the rpms is pretty true, although it seems crazy to have to run the rpms that high. Mine now likes around 1150 as well. Seems like shifting in and out at the higher rpms would add more wear to the transmission over time. I keep holding out for PaulJ to find a magical mod.

 

[Sagehen]

Thanks for the replies

Stu and rpwillia
Thanks for taking the time to craft thoughtful replies.
I very much appreciate it.
Jack

 

[rpwillia]

Saw this on the Ask All Sailors Forum

"Ray: Given that oil color is affected by injection timing, and that I have observed a change, do you think that I should check/adjust the timing? My mid/late 70's designed Yanmar certainly will be very low tech compared the Cummings engines you refer to. I had been thinking about checking the injection timing at some point since I have read that out of spec injection timing can also cause an engine to shake more than normal on its engine mounts. The 2QM20 supposedly is prone to vibration, which certainly mine does. But at select rpm ranges, the engine movement does settle down. So there hasn't been a pressing need to check the timing."

Could some of the vibration we see on our engines be injector timing?