Replacing oil pressure switch

[mregan]

I think need to replace my oil pressure switch.  Engine buzzer stopped working.  When I put the buzzer to ground it works.  When it's connected back to the oil wire, nothing.  Wire is good, put a new one in 2 years ago but connected to about 6" of the old wire since it's in such a tight spot.  Hard to get to the switch on the engine block.  Was trying to unscrew the wire from the switch but the screw is very rusted and the wire terminal seems to have rusted to it.  When trying to unscrew the screw holding he wire, the wire spins with it.
When I remove the switch do I need to worry about oil spraying out?  Its an M25.

[KWKloeber]

When I remove the switch do I need to worry about oil spraying out?  Its an M25.

ONLY if your engine is running!!  :-)

westerbeke p/n 299964
Kubota p/n 15841-39010
Or there's many available aftermarket -
You just need a 1/8-28 ("JIS" or "British" tapered thread, not NPT) normally closed switch that opens about 8 psi.

k

[mregan]

Thanks Ken.  Thanks for all your help on everything. New tach came in today so hopefully will get that issue fixed tomorrow.

[KWKloeber]

Which tach did you get?

[KWKloeber]

 Read all the WB service bulletins.  Be cautious on the switch, you need to use a socket. If not you'll muck it up.

Verify that your switch is bad. It may very well be good but you've got a bad engine ground.   It's unlikely (although possible) that the switch will fail in the open circuit position. More likely it will fail in the closed position (it's a normally closed switch and takes pressure to overcome that.)

k

[mregan]

Got a Faria Euro tach.  0-4000.  Said it was good for diesel.

[Ron Hill]

mre : If you look in the old Mainsheet tech notes you'll find an article that I wrote on changing out the oil pressure switch!!  I believe that I also had a picture with a new switch that I improved!! 

A thought

[KWKloeber]

Got a Faria Euro tach.  0-4000.  Said it was good for diesel.

That's a great replacement Matt and Faria is reliable and has a great warranty -- that's the one I used on my last two panel refurbs.  BTW, Faria says otherwise, but there's a way to advance the hour meter if you want to match your current hours.  Unfortunately it's a one-for one -- to put on 500 hours it takes 500 hours of the HM running to do it (not engine running LOL)

Use dielectric SuperLube on the oil switch terminal screw so it doesn't corrode-in again.  If you install a British to NPT adapter, you can then use a much cheaper "American" replacement switch from your local auto parts store.

kk

[KWKloeber]

PS, if the OPS terminal is seized (a Philips driver strips it out) or the wire is seized to the terminal, use a hex socket on an extension to tighten (i.e, snap off) the terminal screw.

kk

[Ron Hill]

Guys : I believe that somewhere I recommend that you use a 1/4" SD 9/32" (?) socket - as it's tough to get a #1 Philips' on that small bolt.

A thought

[mregan]

Ron
Found your tech notes article.  I believe you mentioned 7mm socket to get the screw off.  Just picked up the new oil pressure switch so I can measure the screw size on it.  Tough to see it's hex shaped where it's located on the engine.  Mostly using a mirror to try to see the switch as I'm trying to unscrew it.

Ken
Saw an older thread on the oil pressure switch where you mentioned the original M25 had a hose from the rear of the engine with the oil pressure switch stuck in the end of the hose.  I need to look at the rear of the engine but I have a hose that comes from the rear of the engine and is just hanging by the side of the engin.  There is a snapped off fitting on the end.  Nothing has ever come out of the hose and could never find a broken fitting that would match up with the hose so I've just left it as is.  Will try to take some pictures of where it attaches to the engine.  Maybe someone will be able to figure out what it is.

[KWKloeber]

 Matt,

I I don't "believe" I ever said there was an oil pressure switch stuck in the end of the hose.

There was a machined (steel?  Aluminum?) Block where the 2 inch HX bracket was bolted. There was an oil hose (1/4? 3/8?) that ran from the engine block oil port to that point. The machined bock had two holes tapped,  JIS  thread to accommodate the Kabota switch and NPT to fit either a pressure sender or a future replacement switch.

The other end of the hose threaded into the JIS thread oil port on the engine block.

My hose deteriorated from the heat and started leaking, so I removed the Rube Goldberg and moved the switch to the engine block, just as the XPs have it.   Look at the parts manual for the M-25/XP and you'll see the Rube Goldberg.

At the same time I extended the pressure switch to where I can get at it, and added a pressure sender (and oil gauge at the panel).

[mregan]

Sorry my confusion was going off my memory of the old thread.  So if your engine had that hose, did you have to tap/thread the engine block to add the oil switch to the block? 

I was looking at the manual, mainly on the picture of both sides of the engine where it has the arrows & labels of the various parts of the engine.  Didn't see the hose in the picture and there is no mention of the oil pressure switch either on the hose or on the block.  That was throwing me for a loop originally.

[KWKloeber]

<<<<The other end of the hose threaded into the JIS thread oil port on the engine block.>>>>€

Kubota engines (and XP) have the oil Sw on that port.  Universal simply moved it to the rear and added the hose and machined block/Hx bracket etc.  I trashed the block when I changed to the 3" Hx.

Forget relying on any factory picture to accurately reflect any particular engine particulars.  Typical Westerbeke.
See the engine block (crankcase, I think) parts page and Hx page.  Learn that manual backwards and forwards!  In your sleep!

I thought the manual I uploaded was a searchable PDF. Maybe not.

kk

[Stu Jackson]

Ken,

Some years ago, a friend of mine purchased a used M25 engine to put into his Pearson 30 to replace an aging but still working A4.  He was clever: he put it on a dolly in his garage, ran  the inlet cooling water (properly) into a bucket, and the exhaust water went down his driveway! 

He decided to use the M25 primarily because of the great M25 series engine support our our C34 website.

When he got it up and running, he invited me over.  It was downright AMAZING for me to be able to see ALL sides of our engine.  FOR THE VERY FIRST TIME.  Ever.   

On our boats, Ken, one simply cannot see the aft port side of the engine.  Period.  Ever.  While your contributions here and your information is incredibly good, sometimes your lack of familiarity with our particular boat shows, and I do admire you for sometimes noting it. 

That aft port location is where, IIRC, the TRACTOR oil pressure switch was located.  Because no human being could ever get there on our boats or even the C36s, it is my understanding that they (those dreaded people you keep disparaging) moved to a dumb idiot light and buzzer.  Perhaps you can get there on your engine on your C30, dunno.

That said, my boat is 30 years old, I completed a 1500 miles (almost - 99%) all motoring passage from San Francisco to Vancouver Island last summer (165 engine hours).

Do I wish I had an oil pressure gauge?  You betcha.  I used to drive some popular English sportscar in the 1960s,, which needed one because there was usually NO oil in the engine even after you added eighteen litres!   

But I gotta say that even if those dastardly Seaward panel guys and those thoughtless Catalina engineers gave us boats without that critical piece of information (oil pressure), I some how (Gasp! ) have continued to have success with my engine.  3,275 engine hours today.

I'm on the boat this weekend without my portable hard drive with the pictures of my friend's engine on the dolly in his garage.  I'll post them when I get home on Monday.