OMC vacuum cut out switch ?

[joecb]

I finally tracked down the cause of a poor idle and missing on a newly acquired, very nice 1958 Gale 25 hp. When I disconnect the electrical connections from the Vacuum switch everything is good. I tested the switch, it took only 3 "Hg to close. The engine runs at 3 to 4 " Hg. No wonder that the switch was cutting out a cylinder. Tested three other switches that I had on hand , all close at 5 " Hg. Took the "bad" switch apart and all looked like new, the spring and diaphragm. So , is there a factory spec on the vacuum required to close ? And/or are there different spec switches for different size motors?

Joe B

[fleetwin]

OK Joe, I’ll bite. First, feel good about remembering that this pesky switch is part of the ignition system and needs to be considered when troubleshooting ignition problems, too many of us just overlook the vacuum switch/wiring and waste a lot of time chasing other problems.
I looked in three different OMC service manuals, none posted an actual vacuum gage test/spec for these switches. The manuals just spoke about alternating vacuum and pressure signals to the switch while watching a test light. Please know that I do not have/did not consult the actual service manual for the 1958 Gale 25hp though. You mentioned that your switch seemed fine/un-molested when you dis-assembled it. Perhaps someone installed a switch from a different engine that was incorrect, which would support your theory of different vacuum specs for different engines/switches. Are there any numbers stamped on your bad switch?
I’m assuming the engine works OK now with one of your other vacuum switches installed.
Maybe someone with more in depth knowledge of the history of these systems will chime in.
Don

[joecb]

No identification of any kind on this switch, however I am 99.99% confident that it is original to the motor. The design is "cup shaped" , made of two cup shaped castings screwed together ( 4 screws). The other three switches that I tested were of a different design, single cup with a flat plastic back cover. I don’t know if there is supposed to be any functional difference as they all are intended to perform the same function on the motors… at least as far as I know???

Joe B

[Mumbles]

I seem to remember reading a factory bulletin about upgrading the spring to a heavier one to prevent the motor from missing at certain speeds.

[cajuncook1]

Joe here a link to Richard’s Viking site. Here is the owner manual with parts diagram and some information regarding the Gale/Viking 1957 25hp motor. Page 10 has some information about cut out switches.

http://richardlpaquette.ca/25DE15V.PDF

Right mouse click on the attachment and select view image and then you can enlarge it for better viewing.

Here is a link to download a comprehensive Gale Service Manual. It has information regarding Gale 25hp and 35hp motors with cut out switches. Page 355 of that download manual.

http://richardlpaquette.ca/GaleProducts1951-1963ServiceManual.pdf

Right mouse click on the attachment and select view image and then you can enlarge it for better viewing.

[cajuncook1]

Just in case the attachments could not be viewed.

first attachment (Page 10) from Viking/Gale 25hp owner manual

second attachment from the Comprehensive Gale Service manual of the 25hp and 35hp cut switch service bulletin. (page 355)

[fleetwin]

OK, funny how the Gale manual gives you an actual vacuum reading to check for and states there ARE different vacuum switches for the different engines.
So, maybe your engine has the wrong switch from the factory, or perhaps someone installed an incorrect switch.

[joecb]

Your guys are great detectives. THANKS Cajun and Mumbles. The Viking motor appears to be the exact same as the Gale, except mine is manual start. The Vacuum switch specs confirm that mine has the correct switch, although by my vacuum gage my switch falls at the lower limit of acceptable range. Converting the spec to inch of mercury, the spec is 3.1 to 3.4 "Hg. My switch checks at 3 on my gage.
Now, Mumbles may have uncovered the real issue if in fact there was a service bulletin to increase the spring pressure. I’ll post a specific question to that effect. Hope Gary or one of the other OMC tech chimes in.
Thanks,

Joe B

[Author]

Posts