Intermittent Oil Pressure Warning

[Tdaddy2000]

Hello All,
Recently began hearing the low oil pressure warning alarm. This is occurring at 2000 rpm intermittently and shuts off when I back down to 1500 rpms. Started shortly after my oil change done less than 10 engine hours ago. Universal m25xpb...help!
Thanks,
Anthony

 

[markwbird]

Sounds like an oil pump issue.

 

[Skipper]

I'll assume you checked the level.

This symptom would first be diagnosed by testing or replacing the sending unit.

Oil filter failure is less common but also on the list.

I would not suspect an oil circulation issue with the engine itself, unless it has major hours on it and/or has previously exhibited other wear-symptoms; ie: smoke, odd noises, loss of power, hard starting, etc.

Edit: what brand and weight of oil was used?

 

[LeslieTroyer]

I'm of the type who wants more information than idiot lights/alarms provide. I replaced the oil switch with a dual switch/gage version (same size) - I now see the actual oil pressure on my instruments. You can tell a lot from the pressure at various RPM's -- BTW I wouldn't be surprised if it was the oil switch or bypass valve being the problem rather than low oil pressure caused by the pump or bearings - but only the gage will tell.

 

[Tdaddy2000]

Hello Skipper,
Thanks a million for the advice. Yes, oil level is good. Chevron Delo 400 LE SAE 15W-4 and Fram PH3593A. Less than 300 hours on this engine. Any other advice?
Thank you,
Anthony

 

[Skipper]

Hello Skipper,
Thanks a million for the advice. Yes, oil level is good. Chevron Delo 400 LE SAE 15W-4 and Fram PH3593A. Less than 300 hours on this engine. Any other advice?
Thank you,
Anthony

Change the oil filter. It's the cheaper check.
Test.
Still sounding, replace the sending unit.
I'd bet a buck that'll solve it.

 

[Tdaddy2000]

Ok! I'm on it! I'll let you know the results. Happy sailing, Best, Anthony

 

[BrianRobin]

Most car/truck people despise Fram filters, I have personally used them for years without any problems, although most filters do have a pressure relief valve built-in ,could be the cause of the problem

 

[marchem]

I'm of the type who wants more information than idiot lights/alarms provide. I replaced the oil switch with a dual switch/gage version (same size) - I now see the actual oil pressure on my instruments. You can tell a lot from the pressure at various RPM's -- BTW I wouldn't be surprised if it was the oil switch or bypass valve being the problem rather than low oil pressure caused by the pump or bearings - but only the gage will tell.

Leslie, do you have part #s for the replacements you installed? I agree that would be good info to have available.

 

[alexco38]

I never had any problem until last summer when I filled the oil to the top marker of the dip stick because I had a pint left in the can.
While running away from a menacing storm, the oil light came on. Only go off when I reduce the speed. Later on just out of curiosity I remove some oil until it fits between the top and bottom marker. The oil light never came back on.

I believe it's because the pitching and rolling with prolonged high speed, must have foamed up the oil. Remember, oil expands when heated up. So the top mark at cold means higher when hot.

 

[Tdaddy2000]

Hello All, thanks for the input. I'm going to begin with filter, removing a small amount of oil (oil at max fill line cold) and if that doesent work, switch. Skipper, when you say sending unit, do you mean "switch"? Looking at my parts manual and see oil pressure "switch" as part #037333 (m25xpb). See image below. Am I approaching this correctly? I'll utube the repair as soon as I have a moment. Thanks again.
Anthony

 

[Witzend]

Check the wiring, if it's open the warning will come on. does you buzzer sound when you first turn the switch to the on pos with the engine not running?

 

[Tdaddy2000]

Hello Witzend,
No, no buzzing with ignition on. Occurs after engine has been running, sometimes hours later. Only at around 2000 rpms. Any advice appreciated.
Thank you

 

[Justin_NSA]

I've tested cars in the past by installing a tee fitting on the block to accommodate the original sensor and also a mechanical gauge. Then compared the warning with the actual reading.

 

[SimiSAilor]

Witzend is correct. You should have a horn with key on and no oil pressure. If you do not get the horn you probably are not going to hear the click click of the lift pump either. The original oil pressure switch has spade connectors that do vibrate loose. The switch is on the port side of the engine, almost under the starter, of coarse the side with limited access.
I installed a switch with ring terminals to eliminate this issue.
Let us know.
Jeff

 

[Skipper]

Hello All, thanks for the input. I'm going to begin with filter, removing a small amount of oil (oil at max fill line cold) and if that doesent work, switch. Skipper, when you say sending unit, do you mean "switch"? Looking at my parts manual and see oil pressure "switch" as part #037333 (m25xpb). See image below. Am I approaching this correctly? I'll utube the repair as soon as I have a moment. Thanks again.
Anthony

Yes, oil pressure switch.

There is always current present at the oil pressure switch. When there is pressure, the plunger moves to unground the circuit. With no pressure, the circuit is grounded and sounds the alarm.

 

[Tdaddy2000]

Hello all, correction. There is buzzing with ignition on prior to engine start. Once the engine has started, the buzzer turns off. Buzzer activated after an hour plus or minus of motoring and only at about 2000 RPMs. Any advice would be helpful and thank you again. Best, Anthony

 

[SimiSAilor]

A bad water temp switch will also activate the same horn.

 

[Tdaddy2000]

Checked the panel, only the oil warning light is on when warning sound activates

 

[Albanach]

Had a similar problem over quite some time: The Alarm seemed to just start ‘croaking’ intermittently at about 2000 rpm. Checked the connections to/from oil pressure switch, to fuel pump and exciter on the alternator, which provides initial ground (incidentally, the Catalina wiring diagram does not seem to show this connection correctly) with a multimeter. Eventually I replaced the pressure switch with one calibrated at 15-24psi and installed a very cheap 12V truck reverse alarm buzzer, which has two different alarm tones-same as the replaced buzzer.

The latter seems to have finally fixed the problem. The old buzzer was actually designed for 24V. Not sure, whether that contributed towards the problem.