How do I remove the oil pressure switch?

[TortolaTim]

Ken, yeah I was wondering about that hose. I looked it up on WB's website and it's 70 bucks, just for the hose! Add in the other bits and I think one is in for a couple hundred, easy. I wonder if some hi temp fuel line attached to a barb on either end would be sufficient. Then, of course the length would be customizable. Any thoughts?

[KWKloeber]

Tim

McMaster has many configurations of oil hoses on the shelf if you can find one the correct length in either a 1/8" or 1/4" NPT thread.
https://www.mcmaster.com/Oil-Hose
There's also a stainless braid hose that can be made to length w/ 1/8" NPT ends.

I had also thought that copper tubing with compression fittings would work. There's vibration but zero relative movement between the two points on the engine block at either end of the tubing.

As far as the other end it wouldn't be a big deal to cut out n drill a small 1/8" plate that bolts to the unused engine mount land holes, and have a tee brazed to it.  That's all Wb does (then paints it red.). The one I ordered was just a brass tee (flat faces) brazed to the plate.

[tvorgitch]

First of all, thanks for all your help. You people are amazing.
I was finally able to remove the old switch. I had purchased a 1 1/16 deep socket and a crows foot wrench, both of which were not useful. There just was not enough room between the exhaust manifold and the starter.

I then purchased a 1-1/16-Inch Extra Thin Wall Wheel Protector Impact Socket https://www.amazon.com/dp/B006L23AQ2 that almost worked.

On my next visit I came prepared with tools to completely remove the heat exchanged, but I tried loosening the nuts first. I was then able to get the socket partially on and after a few taps with a hammer I had enough grip to turn it with a breaker bar and I was able to remove the switch!

I had already purchased a replacement switch, but it also needed a 1 1/16 socket. I went to a couple of marine shops and everything they had also used a 1 1/16 socket. I went to an autoparts store and a very helpful woman let me look at a few switches. I ended up selecting a MasterPro 2-8000 switch as it only used a 7/8 inch socket.

Since it's used for Honda and Nissan, I assume it's the proper thread.

The only other difference was that the MasterPro used a bullet connector. It was easy to install using the 7/8 socket and the alarm sounded properly when I turn the key. Once the engine started, the light and alarm when out. 

I took the old switch home and put a ohm meter on it and sure enough it was always open. I had tested the first switch I bought by blowing compressed air into switch to confirm it would open under pressure.

I tried it with the old switch and of course it never closed, but a considerable amount of oil came out, so I'm hoping the switch was the primary source of my oil leak.

I have no idea what pressure is required to open this switch, but when I shut the engine down, the alarm goes off instantly, so it seems sensitive enough. Either way, it's better than a disconnected switch. All told, I spent about $50 on various tools and $10 each for the two switches.

Here a look a the defective switch. Does anyone know if this is the standard switch for the M35? I suspect it's not.



Thanks again for all the help!

[KWKloeber]

PS: the OEM switch is below (thanks to Ron.). Turn you phone or computer monitor 90 degrees to the left to see the Phillips slots on the hex-head machine screw terminal.  Ron said it's 7mm hex.

TV,

The old switch is not OEM Kubota, it had been replaced before. The Kubota switch has a hex head/Philips screw so it uses a ring terminal.  It opens around 5-9 psi.  It takes a 15/16" socket (per Ron.)  Did you compare the old to the Kubota switch?  Perhaps the non OEM switch caused the issue?

The MasterPro 2-8000 switch is 1/8" NPT (27/inch pitch)  The engine block is 1/8" JIS/BSPT thread (28/inch pitch.). So there was a better choice.

Note there's a Universal service bulletin cautioning that using other than a socket made for an oil switch may damage the switch and cause a leak.

[tvorgitch]

KWKloeber,

Thanks. I had no idea my monitor could do that! 

I was hoping the MasterPro was JIS/BSPT, but I guess it's not. Of course I don't know if the previous switch was JIS/BSPT, but I may try and measure it. Either way, the current switch is not leaking and appears to be functioning well. Since the "official" one is $50, I'm going to stick with what I have but I will pick up a spare as well as some 1/8 BSPT Male to 1/8 Female NPT adapters.

Given the design of the oil pressure switch the risk of a catastrophic is very low, even if I did not use a special socket. Given the design of the bullet connection I'm confident I didn't put any pressure on the back of the switch.

[KWKloeber]

TV

If there's a number on the old switch I may be able to find out its thread pitch.  There are many aftermarket switches that are JIS/BSPT, ISO, and other threads.

On the new one, it depends on what you want to call "official"  - it's an "official" Kubota engine so the official one switch a Kb 15841-39013, half the Wb cost
https://www.amazon.com/Kubota-Switch-OEM-Part-Oil/dp/B07B8C5T9J

(these have REALLY gone up - the last cost I have on them was Kb-$18 and WB-$24.   
There's aftermarket ones sold for about half the cost.

[tvorgitch]

The number on the old switch is 07317.

[Ron Hill]

tvor : I thought the M35 oil pressure switch was a 2 prong switch just like the M35BC & M25XPB engines?!?

My thought

[KWKloeber]

The 35 is the same switch/wiring as the 25 and XP. 
The 35A is 2-prong (same convoluted wiring as the 25XPA, 25XPB.)

[Ron Hill]

Ken : Thanks, as I know that some 1992 C34s that have a M35A engine!  Thought that all the 1992/93 C34s all had the same engine?  Guess that Catalina slipped in a few M35s - installed what the factory had!!

A thought

[KWKloeber]

Ron

I'm highly unqualified to know which 34 model years had which engines,    but understand that the first A engines that Wb produced (25XPA/3-20A/35A, etc.) were in March 1993 (source TOAD universal model history which info I'd imagine came from Wb?)  Before then (1990-1993) I'd guess that Wb was still turning out "non A" Universals??

So I'd guess that 93 model yr boats (that would typically have come off the line in 92) that have an A engine, would need to be a late model 93 (off the line after March 93 but before the 93-94 model year switch-over)??  Would that be how you read it?

My understanding is also that all those with the Wb wiring standard (A engines, since that's what the A designates) had the 2-prong switch (since they have the "new, improved, convoluted" fuel pump wiring carried over from the Westerbeke Propulsion Engines) and also on all the As the switch was mounted remotely (although I suppose on some very early As there might have been some bastardization on that particular aspect?)

[Ron Hill]

Ken : The 30hp engine was (as I recall) an option in the 1991 C34 production and standard in the 1992/93 production.  I wonder if there isn't a mixture of Medalist and Westerbeke M35 series engines in that time frame!!
That was about the time that Oshkosh (Medalist) was bought out by Westerbeke??

A thought

[KWKloeber]

Ron

I understood that Wb purchased UM in 1990, but am unaware if Wb ran the division in Oshkosh for some period of time or if Wb closed it down ASAP and moved the division/line to Avon.   Even if the latter, both locations could have been operating for some period of time while any stock/Kb engines/marine parts were used up.  After buying UM it would take some time but not too long (i.e., months not years?) to start producing the A engines (since the difference was basically just a different harness and a handful of bolt-on components (circuit breaker and solenoid, fuel pump, oil hose and bracket for the remote oil switch.)   Maybe Wb just continued to produce the non-A engines until at some point it got the "better idea" (an epiphany in 1992? to convolute the wiring) which then came out in March 1993?   
Again when specifically relating to what got married into the c34 -- you are the expert there!

Ken

[TortolaTim]

I have a post script for the OP's question. I replaced my oil pressure switch yesterday. I used a 1/2' drive 11/16 short socket => 1/2 to 3/8 adapter => short 3/8 drive extension to a 3/8 ratchet. I reached it from the little access door in the lav. Very easy, took about 10 minutes. I got the switch at a kubota dealer, $25 bucks. Westerbeke wanted $50! My alarm hadn't been working since I bought the boat, finally got around to really troubleshooting it. It was the switch. Working like a charm now. Thanks to all who post all the great knowledge here! I'll eventually add the gauge as discussed above, but I really wanted the alarm working properly for the time being.

[tvorgitch]

Tim,

Glad that worked out for you. I expected my fix to be on the order of 10 minutes, but it's a boat so expectations don't mean much!

Was your defective switch connected or disconnected? Was it leaking? Since mine had been disconnected to silence the alarm it makes sense to me know why it was leaking. Since it was leaking it could not hold enough pressure to short out the switch.