Oil Gauge Mystery

[Steve Jones]

The only issue we had with our SWB Saloon during our recent holiday was that the oil gauge started flicking rapidly. For a pressure of 10psi it would flick wildly between 5psi and 15psi. Did this from our second day. Standard David Harcourt 20psi gauge. Drove for 200 miles or so like that with no ill effects on the engine to the point I ignored it after a while. Decided I should have a look this afternoon so, doing the simple things first, I substituted the gauge from the Trials Chummy. Steady oil pressure, no flicking at all. So, looks like the DH gauge but to check, fitted it to the Chummy. Worked perfectly with a steady needle. Fitted the DH gauge back in the Saloon and it now works perfectly in there as well. 

Don't believe in self repairing components so ask if anyone has any ideas.

Steve

[bob46320]

Bad pipe connection, air in the pipe, water in the pipe boiling off (improbable) ???

[Chris Garner]

Steve,

Could it be a speck of dirt in the quadrant area intermittently fouling the gear?

[Alan]

My guess would be air in the pipe, or lack of it. I spent hours watching gauges on engine test beds, but I really can’t remember which. Still, a man who gets his picture on the cover of the VSCC newsletter shouldn’t be worrying about it. I wouldn’t.

[Howard Wright]

Hi Steve

I had just this problem with my previous special.  Turned out to be a leak on the pipe to gauge union.  

Cheers

Howard

[Ruairidh Dunford]

The Chummy does this from time to time, my thoughts are that it is air in the pipe.

[Steve Jones]

Thanks chaps. I think the air lock suggestion fits with the symptoms and given that the car did something like 180 miles like this with no issues says it's not much of a problem. Anyway, it appears to have been fixed by removing and refitting the gauge so I'll see how it goes. 

I shouldn't mention the picture, Alan, but seeing as you have, have a look at: 

https://www.classicandcompetitioncar.com/wp-content/uploads/2020/09/CCC120.pdf

Scroll down to Page 75 and you'll see what happened a few minutes later where I'm probably rather less relaxed than on the front of the VSCC Newsletter

Steve

[Alan]

Hmmm I reckon you’ve placed it about an inch out.

[Tony Griffiths]

Scroll down to Page 75 and you'll see what happened a few minutes later where I'm probably rather less relaxed than on the front of the VSCC Newsletter

Steve

Go for it!

[Mark McKibbin]

I have found that air in the line just makes the gauge a bit slow to react as the air needs to compress before the gauge starts moving.