Went to change the pencil zinc in the heat exchanger and the part number listed is 301068.
The issue is that on my M35AC engine, I have the "old style" exchanger. This is different from the picture in the manual, which references a "new style" exchanger.
As far as the zinc, the part number they recommend for the new style has the same threads/nut at the bottom as the "old style" but the zinc itself is too fat for the opening. The zinc for the "old style" requires the same nut but a much thinner zinc.
Has anyone run into this? Is there a different part number?
Thanks,
—
Jack
Solstice
Hull #1598
1996 MKII/TR/FK - M35AC - 3 Blade MaxProp
Lake Texoma
Jack,
I am a little confused. The "nut" on my heat exchanger is a tapered pipe thread plug with a tapped hole to accept the pencil zinc. The zinc is a stright rod with a male thread chased on one end. Since the female threaded hole in the heat exchanger is much larger than the zinc, there is no diameter issue.
BTW, we buy all our zincs in local hardware stores. They stock all the typical sizes and they are much cheaper than West Marine or getting anything shipped online.
Good luck.
Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/
I was going to touch on this last month when I changed may zincs, I too purchased generic, way cheaper but found two issues the generic was too long and could severly damage the heater core tubes if it makes contact and then is tightened. I cut mine down to the propper length with a hacksaw.
I also turned them down in a lathe as the appeared to large in diameter, larger than the base of the threads on the bolt that hold them in. I also found that as the old zinc wastes, salts and calcium build up around the hole for the zinc making it appear that the hole is much smaller than it accually is. Of course on my boat this task is done in the blind so you can not see this. I used a flat blade stubby screw driver to ream out the scale and smutz and found I had not needed to trim the diameter of the zinc as much as I had.
Cepheus dream
C36 MK I # 825
MK I Tech Editor No Mas
Jack, it is so ironic that you would post what you did re: zincs. I attempted to replace mine and when I pulled out the (supposed) replacement I too experienced the same darn thing. The zinc that the fomer owner had purchased were oversized. So, I went to WM and bought a couple of the correct size. I removed the old one, that was totally eaten up and when I attempted to plug in the new one it was clogged. So, I guessI need to disassemble the heat exchanger to clean it out.
Glenn Druhot
Carpe Diem
New Bern, NC
35* 6' 10" N / 77* 2' 30" W
2001 C36, Hull #1965
Std Rig; Wing Keel; M35B
Thanks guys for all the help and guidance. Just seemed a little strange that the threads would fit fine but the zinc had no chance of making it in there.
There are different sizes and part #s for the M35A vs. M35B.
When did the "B" model come out?
The "B" model zinc looks to be 3/8" Diameter with 1/4"NPT and the "A" Model is 1/2" diameter with 3/8"NPT.
Jack
Solstice
Hull #1598
1996 MKII/TR/FK - M35AC - 3 Blade MaxProp
Lake Texoma
www.texomasailing.org
It's a good thing to occasionally (every couple seasons???) clean out the heat exchanger...the raw water side, that is. It's easy to do, but have two gasket kits in hand before you begin. Both ends of the HX are removable, although the end with the zinc is the likeliest one to need to be cleaned. Once each of the ends comes off, REMEMBER which side of the large rubber gasket the O-ring goes on. (I think it's on the outside of the large rubber gasket, but I am not sure.) You'll probably find some old zinc smutz in there, and I just scrape it out with my finger.
Larry Brandt
S/V High Flight #2109
Pacific Northwest, PDX-based
2002 C-36 mkII SR/FK M35B
It was crud that caused the hole to shrink. Also took the cover off and found a "pebble" size piece of debris.
However, the raised lettering on the new zinc had to be filed off to get the nut to seat properly. It would catch on the interior housing and force the threads to mis-align.
Thanks again to all for the help.
Jack
Solstice
Hull #1598
1996 MKII/TR/FK - M35AC - 3 Blade MaxProp
Lake Texoma
www.texomasailing.org
The mechanic who cleaned my heat exchanger told me the next time I need my heat exchanger cleaned , which should me in a few more years, do not clean it. Replace it with a Nickel Copper heat exchanger, they do not requier zinks. Has anybody done this replacement using a nickel copper unit? My boat is 20 years old with 2000 hrs on the M35 engine.
__/)__/)__/)__Capt Mike__/)__/)__/)__
Punta Gorda Florida
1990 Std WK M35 Hull #1050