Oil pressure gage leak

[tommarchall]

Hi there,

I’ve looked at other posts on this topic and I think I have a different issue. Many rightly say that the leaks are where the T connects to the engine just ahead of the carb. I had a leak there before and the yard mechanic replaced it. All was well but now I’m getting a leak around the seal where the arrow is in the photo. It’s not a lot, but it’s enough that it smells and drips. Note there is no oil in the photo. I took this after I wiped it, but the lip fills with oil and it spills out.

Thanks in advance!
Tom

[Dave Neptune]

CAUTION

Tom, first welcome to the MMI Forum.

That is just a sensor that can be ordered and replaced easily with a wrench and hooking the wire back up. You will need to identify the make of gage to order the correct one.

I also see an OPSS (oil pressure safety switch) that is not hooked up. If you still are running an electric fuel pump you need that switch for SAFETY!! It is dangerous to run an electric pump without one due to a possible KA-BOOM . It is a standard part available from our host and can also be replaced with a wrench. The wiring will need to be hooked back up too, again not difficult. If you are now using a mechanical pump the OPSS is not needed.

Dave Neptune

[PPin]

Quick side question Dave.

What exactly is the purpose of the oil pressure safety switch when you have an electric fuel pump? I know it shuts off the pump when the pressure gets too low? I installed my electric pump this weekend finally (bought it last year) and the motor starts with a roar now! (in a good way I think!..)

[Dave Neptune]

It shuts down the engine if the oil pressure drops so you don't kill the engine.

Many have installed a "priming button switch" to prime the carb before starting for an easier start if a lot of fuel has evaporated out of the carb.

It is also required by the USCG as a safety precaution.

Dave Neptune

[PPin]

Gotcha, thank you!

[Dave Neptune]

The OPSS keeps electricity from getting to the fuel pump IE shutting it down unless you have adequate oil pressure to operate the engine.

Dave Neptune

[joe_db]

Saving the engine from low oil is a secondary effect. The intended purpose is to prevent the fuel pump from working when the engine is not running. Imagine forgetting the ignition is on and the pump runs all night and the needle valve is not 100% perfect.

[tommarchall]

Hi Dave,

Thanks so much for this. So it’s possible oil is just leaking from this sensor?

I have a manual fuel pump, so not sure I need the OPSS?

Thanks again!
Tom

Tom, first welcome to the MMI Forum.

That is just a sensor that can be ordered and replaced easily with a wrench and hooking the wire back up. You will need to identify the make of gage to order the correct one.

I also see an OPSS (oil pressure safety switch) that is not hooked up. If you still are running an electric fuel pump you need that switch for SAFETY!! It is dangerous to run an electric pump without one due to a possible KA-BOOM . It is a standard part available from our host and can also be replaced with a wrench. The wiring will need to be hooked back up too, again not difficult. If you are now using a mechanical pump the OPSS is not needed.

Dave Neptune

[Dave Neptune]

Tom, the OPSS is not needed with a mechanical pump.

Dave Neptune

[TimBSmith]

Pressure sensor replacement

I began a pressure sensor replacement last season. A couple of comments.

-Make sure the resistance scale of your sensor matches up with your gauge. I rushed sensor selection and found out only when my gauge was spiked to max pressure after sensor replacement.

-Take the time to test your gauge over the resistance range that it is supposed to translate into a pressure reading. There were some great suggestions in old threads on how to do this. At a minimum make sure that your gauge is responsive to resistance test at ground.

-Oil pressure manifolds. I started to copy another contributor's oil pressure manifold approach. Replacing a "T" fitting that the OPSS and sensor use. I am planning to have my OPSS, an analog gauge, and my sending pressure sensor on a manifold attached to engine compartment side wall. So easy access to the three oil pressure sensing devices on one manifold served by a short extension of pressure safe hose. Using the same tapped access point the oil pressure sensor uses.

-All the best with the project. Following.

p.s.
It looks to me like your PO was planning for electric fuel pump, else why rough in the OPSS?
The manifold gives me a great quick validation of sensor value and easier and safer access to OPSS when testing my Facet pump or fuel feed lines.

[jageryager]

YES. oil pressure safety switches can leak..

I had this exact problem last night on my 1979 Pearson 30.

The oil was drizzling out of the molded plastic from around the electrical tabs. Apparently the plastic or diaphragm material meant to keep the oil in has broken down. That oil is coming right out around those tabs and dripping off my wires that plug to to the tabs on the switch switch. This leak was extreme and caused my engine to lose enough oil over the course of about 1 hour of motoring that the engine shut down due to low oil pressure.

I I know the timeline of about an hour because I had mopped my cabin sole, and pulled the bilge covers off and actually wiped some of the dust and dirt that had come underneath the bilge covers out of the bilge. So I know the bills was oil free then. 18 hours, but only 1 hours of motoring later, my bilge has quarts of black engine oil in it, and my engine has no oil pressure and is shutting off.

In your picture, there is a tee, and going vertical up from that tee there's a round sensor with two electrical tabs and only one wire hooked to it. That is the oil pressure safety switch. Since there's only one wire hooked to it, it obviously is not in service. This can be removed, and a 1/8 inch MPT plug can be put in its place.

Some other posterers on this thread are talking about a sending unit for an oil pressure gauge also, that is a different thing. I don't know if you have one of those. My 1979 Pearson 30 does not have an electrical oil pressure gauge, it has a thin metal tube that runs all the way from the engine up to the gauge that feeds that gauge the pressure.

I hope this helps,

Kevin

[joe_db]

You can replace the unused OPS with a low oil pressure sensor and have a low oil alarm and/or light.

[Sam]

I had this exact problem last night on my 1979 Pearson 30.

The oil was drizzling out of the molded plastic from around the electrical tabs. Apparently the plastic or diaphragm material meant to keep the oil in has broken down. That oil is coming right out around those tabs and dripping off my wires that plug to to the tabs on the switch switch. This leak was extreme and caused my engine to lose enough oil over the course of about 1 hour of motoring that the engine shut down due to low oil pressure.

I I know the timeline of about an hour because I had mopped my cabin sole, and pulled the bilge covers off and actually wiped some of the dust and dirt that had come underneath the bilge covers out of the bilge. So I know the bills was oil free then. 18 hours, but only 1 hours of motoring later, my bilge has quarts of black engine oil in it, and my engine has no oil pressure and is shutting off.

In your picture, there is a tee, and going vertical up from that tee there's a round sensor with two electrical tabs and only one wire hooked to it. That is the oil pressure safety switch. Since there's only one wire hooked to it, it obviously is not in service. This can be removed, and a 1/8 inch MPT plug can be put in its place.

Some other posterers on this thread are talking about a sending unit for an oil pressure gauge also, that is a different thing. I don't know if you have one of those. My 1979 Pearson 30 does not have an electrical oil pressure gauge, it has a thin metal tube that runs all the way from the engine up to the gauge that feeds that gauge the pressure.

I hope this helps,

Kevin

Fyi - similar to my 1966 Morgan you have "mechanical gauges" maybe one for temperature as well. Little harder to find replacements but still being made. My setup has the cooper oil pressure line going to a "mechanical pressure switch first then to the gauge.