• Annnnnnd we're back! Got questions, suggestions, or comments, Guest? Post them here!

suitable relay for glow plug circuit M 25

Apr 22, 2011
19
Catalina 30 Watkins Glen
I have C 30 # 3619 with an M 25 diesel. I would like to use a relay to eliminate the glow plug power having to run to the cockpit panel, so I am working with heavier gauge wire, no trailer wire plugs. I have done the panel/wiring harness upgrade from Cat Direct. I am looking for a marine-suitable relay to use in this circuit. Thanks in advance.
 

Attachments

Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
I have C 30 # 3619 with an M 25 diesel. I would like to use a relay to eliminate the glow plug power having to run to the cockpit panel, so I am working with heavier gauge wire, no trailer wire plugs. I have done the panel/wiring harness upgrade from Cat Direct. I am looking for a marine-suitable relay to use in this circuit. Thanks in advance.
A standard ford starter soleniod would work great... you can also get them in a 100amp constant duty model for a few more dollars... or the evviromentally sealed units.... but any auto parts store will have the ford starter relay/solenoid
 
Jan 6, 2010
1,520
Catalina 30 Mark II John's Pass Florida
Guys,

I need some Education here. Do I assume the relay is to save battery power not having the glo plugs energized when also cranking, thus saving draw?

CR
 

Maine Sail

Moderator
Feb 6, 1998
11,016
Canadian Sailcraft 36T Casco Bay, ME
Guys,

I need some Education here. Do I assume the relay is to save battery power not having the glo plugs energized when also cranking, thus saving draw?

CR

No, the relay is simply to tap into the heavy gauge wiring so the small gauge run, that draws 45+/- amps, (in-rush is higher) does not need to carry the current all the way to the panel and then back to the glow plugs via small wire..

I use a Cole-Hersee (often the 24059) heavy duty/constant duty solenoids for this as I find they last longer than the no-name intermittent duty versions from an auto parts store...

Buy Cole-Hersee Solenoids At Sailboatowners.com
 
Dec 11, 2004
950
Catalina 30 easy living
pardon the ignorance of this hard-starting m25 owner, but what does the solenoid do and where does it go, both electrically and physically?
 
Feb 26, 2004
20,692
Catalina 34 224 Maple Bay, BC, Canada
pardon the ignorance of this hard-starting m25 owner, but what does the solenoid do and where does it go, both electrically and physically?
morty, you might want to read the link I provided, and the wiring diagram in the OP's post. They explain it pretty well.

"Hard starting" rarely has anything to do with glow plugs (unless they're not getting warm, that is) and is usually related to poor electrical connections, whether the trailer plugs or the main engine ground connection.

***************************************

Engines 101 - One of the better collections of M25 Series Universal Engine Information on the Internet, plus some M35, too :)

http://www.c34.org/wiki/index.php?title=Diesel_Engine
 
May 7, 2011
159
Catalina 30 Lake Lanier
As Stu said below, Hard Starting has multiple potential causes. The PO of our 1985 with an M25 had the starter rebuilt, a solenoid (Starter Relay) for the starter, all kinds of 'fixes' done by a 'Professional Mechanic' that did not solve the issue. Once I replaced the OEM cable and plugs we've never had an issue since. Be sure to read this link for other things to be aware of: http://c34.org/bbs/index.php/topic,5078.0.html
 
Jan 28, 2017
54
Catalina 30 Mk II Williamsburg
Just wanted to say that I recently completed the modification to the glow plug circuit on my Catalina 30/M25. Boat starts much more easily. Many thanks to all who contributed.