Noticed recently that the oil pressure alarm was intermittently going off with the engine running for about a day until eventually it was on all the time. While I trouble shooting I found no indication of any problem and it hasn't lost/consumed a drop of oil. I did find that the tang for the quick connect on the OPS had completely corroded and actually broke off when I touched the wire. Having locating the obvious source of the problem I want to change it as soon as possible and found a local ship store that stocks the universal replacement part. I'm familiar with all the issues this can cause with fuel pump shutdown, etc, so looking to replace ASAP.
There are many useful threads on here about this, which helped me troubleshoot and confirm the issue, however I had a few questions that I couldn't seem to find on the forum or service manual or were otherwise conflicting.
- Will oil leak excessively during replacement of this part? Just want to know if this is something I need to do quickly or will have oil draining all over the galley. I assume no, but wanted to confirm.
- According to the service manual the threads of the switch should have teflon sealant applied before installation. However, according to info on catalinadirect the switch modulates the connection to ground by way of engine block and insulating the threads will stop it from functioning. Has anybody made this repair and can tell me the correct way to do so?
This seems like a simple enough replacement, but as I've never done it before want to make sure it isn't maybe more technical than I'm assuming it will be.
Erik
Chicago, IL
C-36 MK II #2106
Will much oil spill, no, but have a few paper towels ready.
Will tape isolate the ground, since there are 2 wires on it, that is not a problem. I use pipe thread paste available at most hardware stores.
You are going to need a special socket to install it. The supplier may have the correct tool.
The switch is normally open and closed when pressure develops.
Sail La Vie 1999 Catalina 36 MKII, M35B-17031, Coyote Point, San Mateo, CA
About Sail La Vie
We swapped the switch also recently due to failure and it is simple and straight forward job.
There is almost no oil leaking when changing this switch.
You don't need to use any sealant on the threads as it is stated also in the instructions form CD. The thread is tapered shape.
Durk Nijdam
S/V "SILER"
Catalina 36MKII - 2001 / hullnr. 2013
Stavoren - Holland
Thank you for the quick responses. Anyone have a link or PN for the special socket to install? I'm nervous that won't be an easy find on short notice. I was hoping maybe a large spark plug socket would fit...
Erik
Chicago, IL
C-36 MK II #2106
When you use an adjustable spanner it is OK.
Not too tight else the sensor will break.
Well "hand-tight" is sufficient.
Durk Nijdam
S/V "SILER"
Catalina 36MKII - 2001 / hullnr. 2013
Stavoren - Holland
Relatively new to my 36, #1778/ 675hrs. Is the oil pressure shutdown switch an item that should be changed proactively, or at least have a spare onboard? If so, any suggestion on interval (engine hrs, age)?
Thanks for the help guys, this seemed to go fine. A little trickier than I had thought; had to remove the garbage can & unsecure the battery cables running through the area in order to wield the large 1/2 inch driver required to accommodate the large deep socket that fits the switch. I did not put any sealant on it, but saw no leaking after 20 minutes of running and of course the alarm no longer sounds when running. I was hoping that perhaps this would fix another issue I have, wherein the key is on at the panel but the engine is off the OP alarm only sounds intermittently as opposed to every time as the circuit is wired to do. I think is also a common problem, and from reading the forum I thought that this OP switch was sometime at the heart of the issue, but I guess not in my case.
Envision - I certainly wouldn't consider this a maintenance item per se, but having a spare is probably a good idea. It is under $30 and there were only 5 of them in the whole city of Chicago, so if you need it in a pinch it will probably be hard to find and it technically turns your boat into a patio if it fails since it shuts off the fuel pump (although the engine will run without the lift pump if the tank is full enough).
Erik
Chicago, IL
C-36 MK II #2106
Seabird, there is a 1000 ohms resistor near the lift pump that is part of this circuit. Check if there are loose wires there.
You can test if the oil pressure sensor is at fault by disconnecting both wires and turning on the ignition, should hear the alarm, shorting them to each other turns off the alarm. This allows you to look for loose connections wherever it may be without running the engine.
Sail La Vie 1999 Catalina 36 MKII, M35B-17031, Coyote Point, San Mateo, CA
About Sail La Vie
Interesting timing. I'm also having my oil pressure light come on and the alarm sometimes sounding and sometimes not. Actually it sounds like it's dying sometimes. Oil light stays on all the time though. Oil level is fine, no oil leaks and engine seems to run fine. Figuring it was the oil pressure switch I bought a new one. However, before I made the change I decided to test the system by running a jumper wire between the two leads going into the switch. Unfortunately the oil light still came on with the jumper wire attached. Glad I did this before working on the oil switch, but anyone have ideas what this may be? Engine has no problem starting and continuing to run, but know the fuel lift pump may turn off with the the potential of shutting down the engine. My next step is to check out the connections back at the wheel, but if they are ok I'm really stuck as what to do. Any suggestions at helping me trace this down would be great.
Tom Runiewicz
ObLaDi ObLaDa
Catalina 36 MkII, Wing Keel, Tall Rig
Hull #1998
North East, MD
Please visit my earlier post on the oil pressure switch that includes images and electrical wiring diagram at this website
https://www.catalina36.org/forum/technical-discussion/36-mkii-oil-pressu...
Wiring Diagram https://www.catalina36.org/sites/default/files/forum/WiringDiag_OilPress...
Haro
Sail La Vie 1999 Catalina 36 MKII, M35B-17031, Coyote Point, San Mateo, CA
About Sail La Vie
Where is that 1/2 watt resistor?
Tom Runiewicz
ObLaDi ObLaDa
Catalina 36 MkII, Wing Keel, Tall Rig
Hull #1998
North East, MD
it is a tiny resistor and hard to see - near the lift-pump and well protected by a shrinkage sleeve, just thicker than the cable.
Durk Nijdam
S/V "SILER"
Catalina 36MKII - 2001 / hullnr. 2013
Stavoren - Holland
Several years back, I was singlehanding and anchored in foggy, howling Drake's Bay...the only boat there, and I was glad to get the motor off and hook down. Only thing was, the oil alarm did not sound when I turned the engine off (ignition still on). Next morning, she did not start immediately, as she usually does...and I could not hear the fuel pump. Luckily, I have a second fuel pump arrangement for bleeding and backup, so I turned that on and she fired right up.
Later that day I traced the whole problem to that exact tiny resistor Haro/Sail La Vie is referring to. It had become disconnected inside its little casing. I kludged it back together with some electrical tape and things were back to normal.
Jubilee has always had one little anomaly, one of the alarms chatters very lightly at one very specific RPM and not at any others. Could it be that same transistor?
Al Fricke
S/V Jubilee San Francisco Bay
Catalina 36' MkII #1867
Universal 35-B
Al, the alarm you hear at some resonant RPM is caused by engine vibration. It is the high water alarm temperature bimetal strip that is inside this detector that is located at the top of the engine. You can test that by temporarily disconnecting its wire. It took me 2 years to figure that out. The cause of the excessive engine vibration was cracked alternator bracket which completely broke on a long hours of engining. Check your alternator bracket. My engine is M35B.
Sail La Vie 1999 Catalina 36 MKII, M35B-17031, Coyote Point, San Mateo, CA
About Sail La Vie
Wow, seems to be the time for oil pressure switches to bomb out. My alarm went off when I came in this evening and after checking the engine, found one of the terminals had broken off on the oil pressure switch. Thanks for all the insight on the symptoms and how to replace it.
David Robinson
Wind Surfer 2001 36 H/N 1947