Oil Pressure

[chiffer]

Started the cobra up yesterday morning, has`nt run for a week, and the oil pressure gauge took a few seconds to respond. Normally it rises to about 65lbs and when the engine is hot settles down at 50lbs per sq. in. at 1000 rpm. It first took a few seconds to move to 20lbs, stayed for a couple of seconds then moved up to 40lbs, then after a few more seconds rose to the usual 65lbs, and from then on works fine. Is there a problem with the gauge, or something more sinister?
Thanks in advance for your replies.

[Clive]

What type of guage do you have? Is it electronic or live feed? If it is electronic check wiring earth etc. If live take off the flexi pipe and check for blockages.

[wilf]

Good question from Clive - if it is a mechanical gauge, it might simply be the fact that it has got colder, the oil in the capillary line will be more viscous, and the guage will respond more slowly.

Once it was running, did you notice anything else at all different?

Other thoughts - might be the anti drain valve in the oil filter has failed?

[mylesdw]

Sounds like simply a sticky gauge. Unless you have deliberately bled oil through the capillary (which I think would be a bad idea) the capillary will be mostly full of air so coupled with the friction within the gauge mechanism it is quite easy to imagine the reading lagging slightly behind what is really going on. Wilf's comment about the drain-back filter sounds interesting too, is the filter inverted on your engine?

[craigh]

my mechanical gauge always takes a few seconds to start creeping up when the engine is started,it likes a nice steady idle to creep up to maximum

[Purple AK]

My Electric gauge seems to take longer to register full pressure on startup since the temp has dropped. must be an oil thing

[chiffer]

Originally Posted by Clive

What type of guage do you have? Is it electronic or live feed? If it is electronic check wiring earth etc. If live take off the flexi pipe and check for blockages.

Clive.

It is electronic and sounds as if it could be a bad earth. Had a few earth problems lately.

Wilf, Mylesdw.

When the engine was fitted, the oil filter (which was replaced 200miles ago) had to be taken off the engine and replaced on the side of the body as the shassis was in the way. It is now in a vertical position.

[Clive]

The current flows from the ignition to the guage and then to the sender through which it is earthed. Check that the sender is earthed. ie there is no sealant (loctite or PTFE tape on the threads) causing insulation between the sender & the block. I don't think that there can be a problem with the engine being earthed as you would have other problems such as temp guages, ignition, starter motor.