M25 Universal troubles - need advice

Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
This simple problem has become more complicated that launching a Saturn rocket:facepalm:.

Is it an actual loss of oil pressure or is it an oil alarm problem ? ? ? ? Water pumps don't affect oil pressure. Oil drips don't affect oil pressure.

You don't know what the oil pressure is.
You need to know what the oil pressure is before you go to any next step.
An oil pressure gauge will tell you much more than I or anyone else on here can.
@garymalmgren posted the best solution but unfortunately fitting a pressure gauge on to your oil system can be a bugger if the threads are not compatible with an NPT gauge. Re-threading, avoiding getting cuttings into the oil system as the next stop is the bearings. Problematic.

In terms of money and effort, RPM is your first check. If that's not the problem, a new pressure sensor (switch) would be the next logical choice AFTER insuring that you do not have an intermittant ground in your alarm system.

Either start with the most basic approaches previously suggested or just ignore the alarm and see if your engine seizes up. Then you've got proof it was an actual pressure problem:poke:.

This COVID-19 isolation is really taking a toll :soapbox:.

 
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May 29, 2018
457
Canel 25 foot Shiogama, japan
Hi Ralph. I agree with your comment completely.
"fitting a pressure gauge on to your oil system can be a bugger if the threads are not compatible with an NPT gauge."

BUT.

Click the link on the oil pressure gauge that I posted.
I was really surprised to find it.
It comes with 10 different fittings with quick connecting couplings for $30. A killer!

The flexible hose means you can rig it up and leave it on for a while with out the gauge rattling itself apart.

gary
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Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
It comes with 10 different fittings with quick connecting couplings for $30. A killer!
Just goes to show what you can find if you dig deep enough. I had to tap into my Yanmar 2GM20F to install an electric pressure transmitter. I removed the threaded plug from the oil passage and finally gave up trying to match it to an NPT, NPS, or any other threaded fitting in the 3 mm range. Finally re-threaded the hole with a 1/8" NPT tap while slowly wiping, cleaning, and polishing the inside as I cut into the old hole. Finally wiped it out with half a dozen Q tips coated in heavy grease and didn't get any metal cuttings. The image of OCD :eek:.

For the OP's problem, yes, this is the ultimate solution as it's not too inexpensive, easy install and answers the problem once and for all.

I still got my one nickel and two dimes riding on a problem with the alarm system :thumbup:.
 
Aug 1, 2020
5
Catalina C30 Midland
I had the oil pressure checked and it drops from 50 to 25 over a 45 minute span. The alarm is set for 20. I have switched to 40 weight oil and I'm still getting the alarm. A pressure switch is on order and should go in sometime next week. Hopefully that is all it is.
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
I had the oil pressure checked and it drops from 50 to 25 over a 45 minute span. The alarm is set for 20. I have switched to 40 weight oil and I'm still getting the alarm. A pressure switch is on order and should go in sometime next week. Hopefully that is all it is.
Why would you think it's the pressure switch? Sounds to me like it's 50 when the oil is cold, and as the oil warms up and thins out, the pressure drops. This is probably due to worn-out main bearings, or a worn-out oil pump.
 
Aug 1, 2020
5
Catalina C30 Midland
Why would you think it's the pressure switch? Sounds to me like it's 50 when the oil is cold, and as the oil warms up and thins out, the pressure drops. This is probably due to worn-out main bearings, or a worn-out oil pump.
I'm just moving from lowest cost fix to highest cost. It's probably the oil pump and/or a rebuild is in order.