Oil Pressure Switch

[SeaFever]

Background:

I have just transferred my engine (M25) panel gauges from the standard panel to the EnginePod made by Ocean Equipment that mounts on the Pedestal. I also changed the ammeter to a voltmeter based on the suggestion from this forum. I rewired the gauges and tested the new Panel with the engine (still in my garage). Everything worked fine except for the fact that the red lamp for Low Oil Pressure was continuously ON even when the engine was running with proper oil pressure. Also the alarm for low oil pressure kept going even while the engine was running. Note that in the my old panel both the alarm lights were not wired hence I don't know how to connect them, hence it seems I had connected them incorrectly. The engine Oil pressure gauge would also read Max at this time.

Investigation:

I disconnected both the low pressure red light and the low pressure alarm and the Oil pressure meter then reads OK. I also read some of the other messages on this forum about the oil pressure switch (which I think is separate from the Oil pressure sender). On checking the engine I find that I have a oil pressure sender connected to the crankcase that feeds the Oil pressure meter. However I don't have a Oil pressure switch. At least I can't see it.

Questions:

1. The oil pressure switch (on/off) is separate from the Oil pressure sender, correct?
2. Does anyone have the Oil pressure meter as well as the Low oil pressure light/alarm working? If yes, can you confirm that you have both the pressure switch as well as the sender?
3. If the answer the above questions is yes then where are are both the sender as well as the switch mounted? At two different places or in one place using a mechanical 'Y' kind of a connection? I can easily get the Oil pressure sender, Kubota part number 15841-39010, from tractor smart. I just need to understand how to connect the pressure switch in addition to the pressure sender.

Other than that I am almost ready to replace my A4 with the M25...:-)

Thanks.

[pablosgirl]

The M25 came with a oil pressure switch (on/off).  I believe that the threshold pressure is 5-8 PSI.  In order to get both oil alarm and oil pressure you will need to install a "T" fitting in the block between the oil pressure switch so that you will have another connection for the oil pressure sending unit.  The "T" fitting is readily available at most auto parts stores.  You may also need to buy a short nipple pipe to connect the "T" to the engine block.  Should be 1/4" NTP.  The standard panel on the older C34's did not come with a separate oil pressure gauge.  I have added one and installed it by the engine box down below.  Good luck with the engine refit.

Paul Shields, pablo's girl C34 #551

[SeaFever]

Hi Paul,

Thanks for the quick response. I am attaching a picture of my Oil Pressure sender connected to the crankcase.

This connection seems similar to what you suggest with a short nipple pipe connecting the pressure sender to the crankcase. However if the M25 came with the pressure switch, I cannot find it. Perhaps PO took it out...?

It would be great of you had a picture of yours with the pressure switch and the pressure sender...:-)

Thanks again.

[pablosgirl]

The previous install of your M25 engine may not have had the pressure switch and just the pressure sending unit, relying on the operator to notice a low oil pressure situation visually.  OK for a car since you are constantly scanning the dash for the speedometer anyway, but not so good for a boat where the instrument panel may not be in your constant line of sight.  I will try to take a picture this weekend and post it, but it is pretty tight in there and may not get a good shot.  I have an 1988 MK I, and it has the Seaward panel mounted into the port side of the cockpit.  The engine instrument panel did not come with an oil pressure gauge, just the oil alarm and light which operated off the oil pressure switch screwed into the engine block.  I believe that the oil pressure gauge was added when the engine instrument panel was moved to the engine pod mounted to the steering pedestal in the newer models.  So maybe there is a MK II owner out there who can contribute some insight (and a picture too!) into the connection of their oil sending and switch units.  I added the oil pressure gauge when I was troubleshooting a condition where I was getting the oil light but not the alarm after startup.  In addition, my oil pressure gage is mechanical and not electrical like yours.  I have a small line connecting the "T" to the oil gauge.  The gauge does give you more info about the health of your diesel.  The plus side to this type is that I do not have to worry about matching the sending unit to the gauge or electrical failure.  But a break in that line will lead to oil loss.

[pablosgirl]

OPPS!  I just read the "Seward Products engine Control Panel" posting here on the message board and in post #6 there is a picture of the engine pod without a oil pressure gauge from a 2003 MK II C34.  the Ocean Equipment panel must be different from the Seaward products panel.  So that won't help.  You will have to install a "T" to be able to install the oil pressure switch.  If you do a search on the site for "oil pressure switch" on of the hits lists where you can obtain a compatible switch from.

Paul

[Ron Hill]

Mah : As Paul mentioned you'll need a "T" off your engine block so that your light can be connected to a switch and your pressure gage can be connected to a sender.
 
I know of no C34 that came from the factory with BOTH an oil presssure sender(gage) and a switch(light)!!  They have always had only an oil pressure switch to a light in the standard engine instrument panel. 
I wrote a short bit (Mainsheet tech notes) on wiring in a sounder to the oil pressure light so you could also have a double alarm - one that you can See and also Hear!!
 
A few thoughts

[SeaFever]

Ron and Paul,

Thanks for your quick responses and suggestions. I successfully completed the mini project. Here is a brief summary:

Parts used:

1/8" NPT brass nipple pipe, 4" - $3 at Ace Hardware
1/8" NPT brass 90 deg ELL - $3 at Ace Hardware
1/8" NPT 'TEE' brass - $5 at Napa
1/8" NPT brass nipple, 1" - $2 at Napa
Low Pressure switch (Model 8606 from Cole Hearse) - $7 at Svendsens

Time to set up and fit on engine - 30 mins.

This was an easy mini project. I tested the EnginePod after connecting the pressure switch and pressure sender (this I already had). It worked great!

Attached are a picture of the final assembly.

Thanks again for your help. Tomorrow I am taking the engine to the Yard so we can put the A4 and then the M25 on the jig that they (the yard) have to understand the changes needed to the stringers.

[Ron Hill]

Mah : Nice fix to get the oil pressure send and switch in place.

In the picture I also noted that on your exhaust system you have a galvanized pipe fitting.  You'd better keep an eye on it as galvanized pipe is a NO NO in an exhaust system. 
Boat builders always use Black Pipe and black pipe fittings, because the exhaust+saltwater will errode it in a much shorter period than black pipe.  A thought

[Stu Jackson]

Ron, that's just a temporary arrangement.  The engine is on a dolly in his garage!

[Ron Hill]

Mah : Sorry, didn't know the engine was still under test in your garage.

I still think that you're going to regret not moving that oil drain to the back of the oil pan (rather than the front where it is now) while you had the chance !!  A thought

[SeaFever]

Thanks Guys.

Re-power Status update: The A4 is out and the diesel is out of my garage and in the shop. The diesel is being compared with the A4 in the shop for changes required to the stringers. It is extremely close based on first blush measurements and it seems that with the K75s there is not much room left for adjustment as the aft bolts will need to be almost down to the metal cover of the bolt. It is possible that the diesel may go in this week... Although if we have to cut the stringers it might be another week . I have also just ordered a PSS shaft seal so Sea Fever is going 'drip-less' 

Ron,

I tried to move the oil drain to the back by turning it 180 deg but as I mentioned on another post the holes won't match up. I have already removed the dip stick tube from the oil pan and am using the Kubota dipstick on the Port side so that was not going to be an issue. Since I am going to be changing oil regularly I did not think it was worthwhile to take the oil pan to the shop and drilling and welding another outlet. When I inspected the welding inside the current drain plug, I found that it was a specialized welding, perhaps done by a robotic welding machine. In any case I thought that all that effort to get some more of the oil out was not worth it given the fact that I can change the oil at twice the normal rate, easily.

BTW on the current subject,

My yard mechanic (who is very experienced who I respect a lot) suggested that I change out the bronze 1/8" NPT pipe used in the pressure switch modification to the flexible tube that was there originally. He indicated that in the long run the metal tube may cause issues owing to the vibration and the flex tube will be preferable. I can put the T fitting and the pressure switch/sender after the flexible tube without issues.

I think that is a wise suggestion. What do you guys think?

Regards.

[Ron Hill]

Mah : I know what your mechanic is talking about on the flexible tube for the oil pressure switch and sender. However, with such a short nipple and if you have the wires connected to each have some slack - I believe that you shouldn't have a problem.
What he's concerned about is the sender and switch weight causing a moment, that the engine vibration will cause the nipple to crack and break. 

I would have put my thoughts in a differant order, but this damn cut/paste won't work the way it should!!!    

[SeaFever]

Thanks Ron.

Note that the nipple is 4" long. Although I tried, I could not use a shorter one as I had to clear the exhaust manifold in order to mount the pressure switch.

Do you see any disadvantage of putting the flexible tube back and attaching the "T" after that? It would be the same as it was before except that there will now be a T and a pressure switch in addition to the pressure sender at the end of the T. I can 'tie-wrap this duo around the coolant hose going to the HE.

[Stu Jackson]

Good support would make that viable, but I suggest to not use the coolant hose to do so.  Once "out of sight out of mind" any rubbing on that hose could cause a failure and loss of coolant and your brand new engine.  Our hot water heater hose disintegrated underneath the galley sole, not pretty to see an overheating engine without any visible reason.

[Ron Hill]

I agree with Stu, that if you are going to support that 4" nipple with a switch & sender - it needs to be supported to the engine itself NOT to a hose.  You mechanic is probably correct as a 4" nipple will probably break.

What Westerbeke is showing for the M25XPB and M35BC engines is an oil hose coming out of the engine block to a bracket that has the sender&switch, but that bracket attaches to an engine block threaded hole under the starter.  I'm afraid that you'll never be able to get to the switch/sender once the engine is installed in  the boat!  Check to see if any of those 4 threaded holes under the starter are accessable?

I believe that your best bet might be to support that nipple with a home made bracket that attaches to the reservoir or block where you can get to it!  (Even if you had to drill and tap a hole in the reservoir!)

A few thoughts.