oil pressure/gauge fault diagnosis

[Dave_EH]

Hello,

I have just installed a set of speco gauges.

Having just spent the day upsidedown on my head under the dash, I now have a few problems!

• Oil pressure (mechanical) for red six is showing 30psi @idle and 35 psi @ 2000rpm - I believe this should be 15 and 45 as per factory specs.  Is there a way to test - can engine mods make a difference?
• I am running the power for the volts gauge off the same ignition wire that I am running my tacho off.  I tested volts without tacho wired up and it worked.  Now when tacho is wired the volts drop when motor is reved - alternator is new.

Thank you for your ongoing help

Dave

[Glenn 'Stinky' Stankevicius]

The oil pressure on my modded 202 only varies about 5psi from idle to operating, about 45 to 50 psi, fitted with a HV oil pump.

HTH

[Dave_EH]

Hi Stinky,

Is it possible for gauges to be faulty?

Whent here is a problem with an oil pump do they usually jsut not work?

Is there some other way to test a pump other than a second gauge?

Could gunk in the pick up be a problem?

Could it be worth trying an oil flush product and oil change?  Is there some order of diagnosis I could follow?

Dave

[smithy]

hi dave, just out of curiosty have you bled the air from the oil pres gauge, i have a set of speco mechanical gauges and first time i set up the oil pres there was a large amount of air travelling through the line.

my readings are about the same as stinky's. i am also running a HP pump.

dean

[Dave_EH]

No Smithy I haven't, and that seems like a valid point.

Whats the process?  Would you have to disconenct at gauge end, then point oil line away from car and anything important and crank the motor a few times?

I guess you wouldn't want to run the engine or it would spurt oil everywhere.

It seems to make sense that if the line has air in it and you make a perfect seal that it won't work properly.

It will be the first thing to try.

Cheers
Dave

[craiga]

Dave,

The gauge is a bourden type and should be bled to obtain correct readings. Inside the gauge is a flattened tube bent in an arc. This tube moves slightly when pressure builds in the line, it is then connected to a sector gear to which the needle is attached.

Get a syringe, fill it with oil, and squirt it up the connection tube from the engine side fitting. This will ensure that the gauge is bled. You may have to slightly loosen the connection at the gauge end to get all the air out.

Oil pressure will vary slightly between engines because engine bearing tolerances and other components differ.

From memory the figure already given of 45 PSI running is typical/correct.

Cheers,

Craig.

[Dave_EH]

Thank you very much Craig, as usual you have been a great help and hopefully saved me time and money!

Are you an instrument fitter by trade?

Thanks  
Dave

[craiga]

No problems at all Dave. Glad to be of some assistance.

Well picked on the trade   - Scientific Instrument Maker to be exact, but spent 10 years working as an electronics tech fixing automotive test equipment.

Spent many hours calibrating bourdon tube gauges with a dead weight tester. Boring as bat sh*t!!!

Cheers,

Craig.

[Fast_Eddie]

Don't sell yourself short Craig.

Folks, although he professes to know about scientific instruments, his real speciality is drag links.

Give him an old greasy drag link, a kero bath and a can of black enamel, and he's away!