84 OMC 2.5 Low/No Oil Pressure

[cubbo]

Let me start by saying....I am a new forum member, kind of new boat owner, and very appreciative of all the support and advice found on the forum.

I have a 1984 Glassport with a 1984 OMC Sterndrive 2.5L (252STHRCRA).

Looking for some help troubleshooting oil pressure. I recently did a quick ignition tune-up (points, cap, condenser, plugs, rotor, coil, battery), what used to be a hard to start motor, just fires up and purrs. This is in the driveway on muffs, I noticed that temp is holding around 160, battery is showing 14ish on gauge, idle seems good, but oil pressure gauge showing very low or no pressure, I tapped it a bit and it seemed to move up a bit.

My question is...how long should it take for oil pressure to build and show on gauge? How to troubleshoot gauge and or sending unit? Test actual pressure?

I just ordered a SELOC book for this and waiting for it to ship. I can't seem to find the OEM manual....any ideas?

Thanks, jt

 

[Bondo]

My question is...how long should it take for oil pressure to build and show on gauge? How to troubleshoot gauge and or sending unit? Test actual pressure?

Ayuh,..... Welcome Aboard,..... Take the wire off the sender, with the key "On", touch ground with the wire,.... The gauge should Peg, Max,...

The sender can be metered for ohm's at various pressures,....

"T" in a mechanical gauge to cross-check the electric gauge,.....

If ya have no oil pressure, the motor would be knockin' in a minute,....
I'd expect gauge movement in well under 15 seconds on a cold start,....

 

[cubbo]

No knocking what so ever, I will test in the morning and post results.

 

[Scott Danforth]

Use a mechanical pressure gauge. The factory electrical gauges are a suggestion at best

 

[cubbo]

You suggesting run a hose up to dash and mount gauge? Could I use a T fitting and use the sending unit and a mechanical gauge? Was thinking if I am going to hook up a mech. gauge to test maybe just use a T and have both? I could always have the mechanical gauge to make sure the dash gauge is true. Is this ok to do or will it mess with the pressure reading??

 

[Scott Danforth]

No, I suggest a mechanical test gauge to verify your real pressure for your peace of mind. Then if you feel you need to fix you electrical issue with your gauge and sender, then do so

 

[cubbo]

ok, wire off the sender, key on, gauge pegs when grounded. is there a reference chart for ohms and various pressures? how does this test work? also going to find a mechanical gauge to test for peace of mind. may also need the sender. what next?

 

[Bondo]

Ayuh,.... Ohm the sender on the motor, note the ohms,.... start it, 'n repeat,.... donno the numbers yer lookin' for, somebody might,....

 

[cubbo]

Will try on Wednesday, tomorrow is wife's b-day, no working on boat! I have a new sender beings delivered on Wednesday. I will ohm the sender as you said and note the readings, I will also install the new one and do the same. I will post the two sets of readings and status. Thanks for the support

 

[cubbo]

Sorry it took so long to get back.....so I put a mechanical gauge on and tested good, about 36psi. I went ahead and installed the new sender and I am good to go. It is reading pretty close to the same. If run it at about 2000 rpm, I am seeing 40 on the dash! Now on to tilt motor problem....this just discovered. I will start a new thread. thanks for all the support!!