VDO oil pressure gauge and sender

[Bruce Tuncks]

The gauge just did not move , staying on its bottom reading.

 

Now I have been inside the panel working on the EGT stuff, so I may have done something like pull a connection from the sender.

 

But the Jabiru setup has the sender directly screwed into the block, and so the senders have a shorter life than if they used a rubber hose attachment. I have had a sender fail before, but last time there was more warning with intermittent readings first.

 

So I took off the sender, and tried it with an ohm meter. 4.4 ohms.

 

Then I used a clip-lead to short the wire to the block. No response from the gauge.

 

So the gauge, with master on, does not show a response to open circuit or earthed on the single input wire.

 

What is going on here? Is the gauge faulty or disconnected somehow?

 

 

[Old Koreelah]

Bruce mine has recently shown a pressure increase, which is worth investigating in case my hydraulic tappets pump up solid. It might by a result of fitting a non- standard oil filter, but maybe the sender is faulty.

 

To get an independent reading I bought a mechanical Guage with fittings at Bearfast Tamworth for $37.

 

 

[Bruce Tuncks]

Thanks Old K.

 

Today I found that the sender showed 11 ohms with no pressure and then when I applied compressed air ( just held a blow nozzle against the sender inlet) it went to 200 ohms. So I decided the sender was ok and instead of replacing the sender I took off the instrument panel and found a disconnected spade terminal.

 

I like your idea of a mechanical gauge to see if the electrical one is accurate.

 

 

[Old Koreelah]

Thanks Old K.Today I found that the sender showed 11 ohms with no pressure and then when I applied compressed air ( just held a blow nozzle against the sender inlet) it went to 200 ohms. So I decided the sender was ok and instead of replacing the sender I took off the instrument panel and found a disconnected spade terminal.

I like your idea of a mechanical gauge to see if the electrical one is accurate.

Good outcome, Bruce. I can't take credit for the mechanical oil pressure idea. Someone on this forum suggested it.

 

 

[jetjr]

I have a simple low pressure switch with dash light fitted to lower port (below other sender)

 

Light is on before start and at shutdown, should give confidence if the main one plays up. Its reading pressure AFTER gallery unlike the main one which reads before engine, filter and cooler so is going to pick up problems pretty fast.

 

Ive had two Jab supplied ones which just started to show lowering pressure, few more revs all ok, then slowly dropping - not a nice feeling. New sender fixed the issue.

 

Be careful with mechanical types and running oil line into cockpit gauge, not sure its allowed or smart. Getting pressurized hot oil on your legs wouldnt be fun.

 

 

[Old Koreelah]

...Be careful with mechanical types and running oil line into cockpit gauge, not sure its allowed or smart. Getting pressurized hot oil on your legs wouldnt be fun.

Mine will be mounted on the engine (cowl off after engine is warmed up) for some ground running. A minute or so should show any serious difference from electric guage. I've heard of others permanently mounted just on top of the cowl.

 

 

[jetjr]

Yep old race cars did the same, they still make pods for doing this

 

You can get test gauges on a flexible hose- I bought one many years ago and used once - from ryco etc just for this use.