Oil pressure bouncing around

[Brownie]

First post after 2 years with my Griff! Several with my previous Tuscan...

For the last 2 years the oil pressure guage has been sitting very consistently at 30 during all weather and driving conditions. However the guage is now bouncing between 0 and 30 at different revs (no pattern between revs and pressure reading).

In reading different views as to the potential cause I have come up with the following list:

faulty sender unit
faulty pressure unit
faulty oil pump

Any thoughts/advice on the best process for diagnosing the problem prior to going out and buying new parts in a trial and error (expensive) basis?

PS - the oil level did drop dangerously low at one time before this started happening.

Cheers - Mark

[Doc Toad]

Had a similar problem - not fun

Suggest checking the sender and its wiring first - TVR item expensive, but got mine on ebay, (search item=270851281864) Works fine.

I also took mine down to the local garage and got them to put a proper gauge on it - rock solid 15 at idle and 30 over 2000rpm.

Quite a relief!

[J400GED]

You could try, at the sender, taking off the wire (I'm assuming you have only 1 wire at the sender - with the sender casing acting as the earth)that goes from the pressure sender to the guage and short it to earth with the ignition on but engine not running and if the guage goes full deflection it is the sender.

HTH

Ged

[Brownie]

Thanks guys. Am travelling for a couple of weeks now but will have a go at the sender when I get back and let you know how I get on. You are right about it not being fun - sitting on the M25 about 70 miles from home on zero pressure thinking I know there is oil in there but do I gamble it being an electrical problem as opposed to a pump problem. Anyway I got home but it was a nervous drive!

[Doc Toad]

...just remember, if the worst happens its the perfect excuse for a rebuild and a few mods at the same time..?

[bomb]

I had the same symptoms and it was a loose wire, at the connection of the wire to the spade connector on the oil sender unit.

Reterminated it, and it was fine.

Driving the car with an oil pressure at zero does nothing for your blood pressure !!

[Chimpabollics]

Worth a read............

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[WOO5IE]

It is most probably the sender.
If it was the pump or no pressure then the oil pressure LED would be on

You can get the sender on PH Classified for £28 . Supposed to be originals as well.

I did and they work very well.

Could be just a dirty connection at the sender as well

http://www.pistonheads.com/sales/3423942.htm

Edited by WOO5IE on Monday 21st November 12:44

[Brownie]

Thanks for your advice guys. The fault was the sender unit - this was obvious when I finally managed to get underneath and had a good look. The male connector coming out of the sender and the plastic gromment holding the connector in place was loose and was obviously vibrating around causing the variation in the oil pressure. Got a new replacement unit and works perfectly - and more importantly consistently! Smiling again :-)