1998 Catalina 34 M35B port side engine oil leak

gkennedy12 · May 26, 2022, 10:56:29 AM

While leaving the marina last weekend with our 1998 C34 the oil low pressure alarm came on and we stopped the engine and when the dip stick was checked it was clean. Coincidentally, the tach was not working either for first time since I've owned boat (3+ years). When back at the slip added more oil so that where the leak was coming from could be found. Leak is coming from the nearly inaccessible port side of the M35B engine up against the head (bathroom) wall. Because it was so hard to get at, could not absolutely determine where the oil leak was coming from, but it's in the area of the oil sending unit.

The oil filter was on snug and not leaking. The dip stick was not leaking. The oil drain cap was on.

Has anybody else had a similar issue? If so, how did you gain access to determine where the oil leak was coming from and how did you gain access to fix the problem? Did you have to cut access through the bathroom wall?

KWKloeber · May 26, 2022, 11:10:13 AM

On a B engine the oil pressure switch is low on the engine, on a bracket bolted to an unused engine mount hole. There's a hose that connects to the oil port on the block, which is forward of that. Seethe parts manual on the Wiki.
It could be leaking from either area (most likely the oil switch) or somewhere along the hose (my M-25 leaked from that hose that had deteriorated.)

You have the Seaward panel w/o an oil pressure gauge, not a Universal panel w/ a gauge?

gkennedy12 · May 26, 2022, 12:22:02 PM

Thank you KWKloeber, Correct. The panel does not have an oil pressure gauge. When the hose went on your M-25 was access to the hose an issue? I'm wondering if I have to cut through the bathroom wall even to get at the area of the oil leak.

KWKloeber · May 26, 2022, 12:45:53 PM

Quote from: gkennedy12 on May 26, 2022, 12:22:02 PM
Thank you KWKloeber, Correct. The panel does not have an oil pressure gauge. When the hose went on your M-25 was access to the hose an issue? I'm wondering if I have to cut through the bathroom wall even to get at the area of the oil leak.

Access was no issue at all!!! [on the C-30 we can SEE, TOUCH, and put a wrench on every part of our engines!)
well, except that unlike y'alls we can't change the oil pan w/o pulling the engine.

Ron Hill · May 26, 2022, 02:43:17 PM

All : Access is an issue on a C34 MHII with a M35BC engine !!! - that port side engine compartment panel is very close to the engine !!!

A thought

tvorgitch · May 26, 2022, 03:52:33 PM

gkennedy12,

How much oil was below the engine? Are you sure the dipstick did not show any oil? At least on the M35, you need to remove the dipstick (it will always be clean) to release the air from the dipstick tube before you can actually measure the oil.

I had a leak from my oil pressure switch which had apparently been disconnected to stop the alarm. While there was significant oil under the engine, it was lever low on the dipstick. The way these switches work is that the oil pressure pushes a rubber diaphragm to open the circuit and stop the alarm. When that diaphragm fails, the switch often starts leaking.

In my case, replacing the switch (which was not easy!) fixed the alarm and the leak. Hopefully, this will be all you need to do.

You can get a WiFi borescope on Amazon for under $30.

gkennedy12 · May 26, 2022, 07:34:24 PM

Thanks Tom, Yes the dipstick was clean. Had major oil cleanup under engine & bilge. Thanks for the tip on the scope. Good idea. What is also odd is that the tach is not working for the first time since I've owned the boat. Not sure it's related, but seems to be. Not sure of the tach wiring and it's engine access, if any.

Paulus · May 27, 2022, 03:13:31 AM

gkennedy12,
I would also check the valve cover, the casket could be leaking. Should be able to see oil on the engine making it way to the underside of the engine. Had a similar problem once.
Paul

Robert Mann · May 27, 2022, 08:00:55 AM

If you pull the woodwork from in front of the engine (step mountings etc), it is a lot easier to access the head side on the Mk II boats. It is still a PITA but a reduction in pain. It pays to get a mirror in there to look at the hose and oil pressure switch set up to see where the oil is coming from.

gkennedy12 · May 28, 2022, 06:59:03 AM

As suggested took off front wood work and could finally see the leak. Oil sensor, which yard says can probably found at napa.

gkennedy12 · May 28, 2022, 07:31:12 AM

Oil Pressure Switch 037323

KWKloeber · May 28, 2022, 09:31:30 AM

Quote from: KWKloeber on May 28, 2022, 09:15:31 AM
Barn door, but oil dye also helps pinpoint a leak (if you can access it to see the UV light)

The switch is different if a B engine has been rewired (as Ron did.)

Ron also wrote an article about JB Welding the oil sw to prevent it leaking at the plastic end. Dunno if it applies to the B switch or just the non-B switch.

Ron Hill · May 28, 2022, 03:52:52 PM

Ken and Guys : That epoxy that I put around the plastic to metal joint applies to ANY switch that has that kind of Plastic/Bakelite to metal joint!! Because my experience (autos) has been that that is the weak spot that starts leaking!

A few thoughts

gkennedy12 · May 30, 2022, 06:35:22 AM

Thank you all for your guidance and suggestions. Napa $13 oil pressure switch did it. Replaced it and motored about yesterday. Miles away at home now so do not have the napa PN.

tvorgitch · May 30, 2022, 08:31:46 AM

Glad that worked out for you. I'm amazed that the failure was bad enough to leak that much oil that quickly, but I guess it's possible it leaked without the switch actually failing, so it continued to leak without sounding the alarm until the oil pressure dropped.

If you still have the old switch, it would be interesting to see if still functions properly.