I read the article in last December's Jibsheet by Hal Smith which also appears in this month's Mainsheet about his engine over heating problems. I had the same problem and tried everything as he did from replacing the raw water impeller to havibng the HX rodded and cleaned in muriatic acid. The cleaning did help a little, but at 2500 rpm the temperature would shoot up to 190.
The mechanic who inspected the exhaust and cleaned out the HX suggested replacing the HX with a copper nickle HX just like Hal Smith said he did. I bought a new SeaKemp, American made copper nickel HX online from Inetmarine.com for $424.85 plus shipping. It realy pays to shop around on the internet.
Now I can cruise at 2500 rpm and I have ran it to 3200 rpm for a short distance of about two minutes and the temperature stays no more than about 160. I am anxious to see what the temperature goes up to in the summer when our Florida sea water goes up to 90 degrees. The sea water is only about 65 now.
__/)__/)__/)__Capt Mike__/)__/)__/)__
Punta Gorda Florida
1990 Std WK M35 Hull #1050
Our 28 with M3-20 had a 195F thermostat in it, that was what the book said it should have. It ran at that temp all the time with no issues.
I was very surprised that the M35A had a 160F thermostat in it and that's what its book calls for. It would occasionally touch 180 the first year we had it and that bugged me since it was supposed to be at 160. Cleaned the HX and it has been at 160 since.
They say (who are they anyway?) that hotter is actually better for diesels, within reason, but each engine seemed to run fine at the spec'd temps. I just wonder why they spec different temp thermostats.
The only reason I can think of to run a diesel so cold (160 F) is to keep the fresh water heater temp down. As long as your coolant and/or water heater is not boiling you are not over heating. I routinely operate heavy equipment in the Mojave desert @ 210+ F. Diesels like the heat.
Don't worry until you get temperature spikes to 250F.
Fair Winds,
Mark Andrews
S/V Grace
86 C36 #995730
San Diego
Wow! I just read the additional maintenance items listed for my engine (M35 30hp) in the Catalina Company site. They describe the need to periodically replace the zinc that's in the heat exchanger. I wish I had read it earlier. No word of this in my Universal/Westerbeke owners manual. So I raced down to Wind Rose, found and pulled out the "Hidden" zinc. Of course there was nothing left of it but a little dab of white powder. I also noticed some corrosion around the heat exchanger's end caps. I have replacement zincs in a spares kit so I installed one immediately. And I also drained and replaced the coolant on the freshwater side. My engine runs great and nice and cool but,
What I'm afraid of is that the PO didn't know about that zinc and that its been years without one. Is there something I should do, i.e. flush the exchanger? Replace the Exchanger? Take off end caps and inspect? (I don't think I would be able to see in there without a mirror. Or if its running nice and cool, just not worry about it?
Thanks
Sam
Capt. Sam Murphy
1994 Catalina 36, Hull 1327
Shoal draft, two cabin model.
Panama City, Florida
Sam, if you have ANY questions about it, take the HX off and inspect it completely.
Stu Jackson, C34IA Secretary, C34 #224, 1986, SR/FK, M25 engine, Rocna 10 (22#)