Universal M35B, the dreaded Sherwood G908 and its Oberdorfer replacement

[mlaver]

This follows a thread I posted to the (wonderful) Catalina 34 list last fall. The background is that I noticed steam coming out my exhaust after swapping my Sherwood G908 raw water pump with the Oberdorfer "drop in" replacement N202M-908. This can - and probably does - mean not enough water is being injected into the exhaust riser. If I swap the Sherwood back in the problem goes away. There is no argument that the Oberdorfer pumps less water than the Sherwood, but it only seems to be a problem with the M35B. Many M25XP and M35 owners have had no issues.
I *did* get a response from an M35B owner in Puget Sound who said he had no problems with steam and the Oberdorfer, but I contend with 51 F deg. water coming in the heat exchanger is going to be a LOT more efficient and cooler raw water will be passed to the riser, compared to the 66 -76 F deg water we've been seeing in San Diego and n. Baja lately. Hence the question to this more heterogeneous group. Has anyone else in warmer water been using the Oberdorfer N202M with an M35B and not seeing steam? (And are you sure?)
The engine has never come close to overheating, and the Oberdorfer is SUCH a superior pump (quality and serviceability) that the steam may just be an annoyance, but I find it disconcerting.
Mick Laver
1999 Catalina 34 Mk II
San Diego, CA.

 

[whatfiero]

I would be concerned with steam leaving the exhaust mostly at the water lift muffler because with no water it could get extremely hot feel it next time your out

 

[Stu Jackson]

Mick,

In addition to this fine forum, why not ask on our C34 forum, too?

"THE" Oberdorfer swap to the M35 is, as you most likely already know, written up in the C34 tech wiki, under engines. I don't recall if it was an M35 or an M35B. I am no expert on those engines.

You may also consider posting your ? on the C36 forum, too.

Good luck.