Oil jet blockage

[David Grear]

The oil pressure relief valve blows off at 22 pounds
This may be helpful

[Ruairidh Dunford]

I find I get a lot of false alarms at this time of year year due to temps being colder.

14 years ago, on the way to my stag do on Jura, my father had to stop 6 times because he was getting high readings, each time cleaning made no difference and we put that down to the outside temp.

What psi are you getting when the suspected blockage occurs Peter?

Howard, my Pearl runs at 9psi hot, I bought a later 0-20 gauge and fitted that.

[Howard Wright]

Hi

Thanks David and Ruairidh.

20 psi may be a bit high so 15 psi may be better although I may have to watch for “false alarms” in cold weather. I’ll also look out for a 20psi gauge.

I’ll be interested to hear from Peter what psi his blockages occurred.

Cheers

Howard

[Peter Naulls]

I have a 0-20 gauge. Normal pressures on my engine are 1-2 lbs on tickover, topping out at about 7-8 lbs. The blockage gives 5-6 on tickover, 15-18 lbs at 40mph. Poking the jets through restores normal readings, sometimes for the rest of the journey, sometimes just for a mile or so. The engine is well up to temperature.

[Ruairidh Dunford]

That is too much Peter - my examples above were giving readings about 4 psi above normal, which I always find terrifying!

If you do open up the front gallery plug, use a hoover with a suitably small tube taped to the end that will suck whatever is in there out, pushing it with a brush or similar won't remove it from the system.

[JonE]

Do 3 bearing engines generally have higher readings than two bearing ones? I wondered when the 20 psi gauge came in...

[Ruairidh Dunford]

Yes, the oil jet holes are smaller and this raises the pressure to aid lubrication of the centre main.

[Peter Naulls]

Ok thank you. What I find terrifying is wondering how long it took me to notice it the first time!

[Howard Wright]

Ok thank you. What I find terrifying is wondering how long it took me to notice it the first time!

Hi Peter

Thanks for the info.

Hence my idea of a warning light!

Cheers

Howard

[Peter Naulls]

Jon,

I don't think the smaller jets necessarily came in with the 3-bearing engine. Ours is Jan '37 and had a 0-10 gauge until "The Austineers" modified either the pump or jets to increase the pressure some years ago.