Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 02-11-2014, 08:52   #1
Registered User

Join Date: Dec 2009
Location: aboard Akka, currently in San Francisco Bay
Boat: Stevens Custom 50
Posts: 70
Oil-pressure switch keeps giving out

We have an engine-driven refrigeration system (we have a 12V system in parallel, but that's another story). The compressor clutch excitation line runs through a manual switch and an oil-pressure switch, in series. That way, the clutch circuit is disabled whenever we want it to be or when the engine isn't running.

We live aboard, almost always at sea or at anchor, and use the engine-driven fridge system almost daily. The oil pressure switch gives out regularly. Not every month, but more often than once a year.

We actually have three oil-pressure switches aboard, one for each alternator and the one for the fridge. The two alternator switches have worked fine for decades, without replacement. Any idea why the compressor clutch circuit is different? The only thing I can think of is current -- the other two circuits are sensing only, no real load.

And what is the solution? These switches are hard to find, at least in the more developed parts of the world. They have two poles and screw into an oil pressure manifold. It turns out (I have a lot of experience with this) that there are two thread pitches. Ours is more common, and in some places (Morocco, Panama) our switch is widely available -- just walk into 3 or 4 little family-run stores and ask for one, and one of the stores will have it. I can't find them at all in the US, having visited just about every chain auto parts store there is (Napa, CarQuest, Pep Boy etc.). Of course, I'm hampered by not having a car model to give the clerk -- amazingly, none of their databases can be searched by part type. But eventually the clerk goes back into the shelving and looks for anything that appears to be similar to the old switch I've brought along. This is the one quest I've found easier to carry out in Spanish or French than English!

Anyway, suggestions are welcome. Meanwhile, I can simply short across the switch and we have to remember to turn the fridge off manually. Otherwise, we'll burn the clutch out in short order (been there, done that).
__________________

__________________
Akka is offline   Reply With Quote
Old 02-11-2014, 09:21   #2
Registered User

Join Date: Jan 2012
Location: Full time cruisers
Boat: Krogen 42
Posts: 252
Re: Oil-pressure switch keeps giving out

You may want to try a small relay. An auto parts store would have the kind that are used for a starter motor.
__________________

__________________
meridian28 is offline   Reply With Quote
Old 05-11-2014, 09:45   #3
Registered User

Join Date: Dec 2009
Location: aboard Akka, currently in San Francisco Bay
Boat: Stevens Custom 50
Posts: 70
Re: Oil-pressure switch keeps giving out

Thanks, Meridian!
__________________
Akka is offline   Reply With Quote
Old 05-11-2014, 09:56   #4
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,365
Re: Oil-pressure switch keeps giving out

Are you talking about a switch for engine oil pressure that disconnects the refridge if low pressure? Do you have a low pressure alarm on the engine? IF so why not eliminate the various pressure switches?
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 05-11-2014, 10:23   #5
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2007
Location: Santa Cruz
Boat: Boatless Again
Posts: 4,330
Re: Oil-pressure switch keeps giving out

Quote:
Originally Posted by meridian28 View Post
You may want to try a small relay. An auto parts store would have the kind that are used for a starter motor.
+1 ---you have too much current going through the switch.
__________________
donradcliffe is offline   Reply With Quote
Old 05-11-2014, 16:34   #6
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,055
Re: Oil-pressure switch keeps giving out

If I was going to the auto store, I'd get a relay for the airconditioner clutch, not the big starter one
__________________
a64pilot is offline   Reply With Quote
Old 07-11-2014, 16:04   #7
Registered User
 
MBWhite's Avatar

Join Date: Apr 2012
Location: Illinois
Boat: Hurley Alacrity
Posts: 370
Re: Oil-pressure switch keeps giving out

I agree with the above posters.

Additionally, I would ask for a "Bosch Style" or "Ice Cube Style" relay:



These things are universal all over the world. They are a universal style so if you get one from a different manufacturer I wouldn't worry about it. Also get a "Relay Harness"


So you can swap out relays if one ever goes bad. I'd get a spare to have on hand as they are only a couple dollars. Actually, I'd get as spare harness too and then you not only have spares but you can always use it for a completely separate application too if needed at some point.
__________________
MBWhite is offline   Reply With Quote
Old 07-11-2014, 17:29   #8
cruiser

Join Date: Feb 2008
Location: North Charleston, SC
Boat: Camano Troll
Posts: 4,669
Re: Oil-pressure switch keeps giving out

Quote:
Originally Posted by meridian28 View Post
You may want to try a small relay. An auto parts store would have the kind that are used for a starter motor.
Yes. I suspect you are attempting to switch too much current through the oil pressure switch. I doubt you would need a starter motor relay. You can get relays at auto parts stores that are rated for extra driving lights or horns. These should be rated for 20 amps or so and have the same spade terminals often found on boat wiring and a mounting leg.

I use one to power my depth sounder so I can leave the GPS (and anchor alarm) on overnight without the additional current draw of the depth sounder.
__________________

__________________
rwidman is offline   Reply With Quote
Reply

Tags
oil

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Old and New Isotherm water heater pressure valve keeps opening TacomaSailor Plumbing Systems and Fixtures 0 26-10-2014 23:56
Water pressure pump keeps running boating2go Plumbing Systems and Fixtures 6 19-01-2014 23:48
Westerbeke 7.6: BTD Oil Pressure Switch R_C Engines and Propulsion Systems 6 08-06-2011 20:15
Defective Oil Pressure Switch Charging Concerns wind rose ll Electrical: Batteries, Generators & Solar 3 12-07-2010 07:00



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 19:11.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.