faulty pressure gauge?

[Guest]

Ive got a problem on my oil pressure gauge, when I turn the ignition lights on the needle shoots straight to the top past 5 till it hits the max pin and stays there, even when I start the engine it dosent move,when I turn the engine off it goes back down again after a couple of seconds. I dont beleive theres anything wrong with the engine as it was rebuilt about 6k ago and runs fine,so its either the gauge or the switch,could anyone please tell me how if possible I can check the gauge or the pressure switch to see which is at fault and also where the pressure switch is located on the engine please.

 

[bones]

Sounds like a break in the connection from the sender to the gauge or the sender has a fault , I think it's unlikely to be the gauge as this is a common problem as 911s get older. To the right of the engine bay fan is a 1 1/2" round brass cylinder which is the oil pressure sender. Remove the terminals if one isn't already broken off, clean and refit. If the situation isn't improved I'd say replace the sender. From memory I think the top terminal is pressure and the bottom temperature. If you can get a wiring diagram and decide which is which, trace it back to the clock and test for continuity, if you have continuity, it has to be sender or gauge my bet is on the sender. If you don't the wire has broken somewhere and you'll have to run another one fronm gauge to sender but this is unlikely. 10 minute job to fit a sender.

 

[Beaky]

I concur with Pete, sounds very much like either a bad conection at the sender (known problem) or a faulty pressure gauge.
To test the former just take the top connection off, give it a good clean, then replace an see what happens, if this doesn't address the issue then a new sender unit may be required which is a 20 minute DIY job - a bit tricky to get enough leverage to undo the retaining nuts without damaging the pipe.

I had my sender unit go without any prior notice a couple of months - my heart sank when I first saw my gauge thinking terminal enginer failure, but Chris Turner was nearly 99% certain it was the unit as the engine was still running sweetly, so he put a new one on and all is well again[]

 

[Guest]

Hi Beaky,

I have the same problem with my guage fluctuating massively, usually over the 5. Not being massively practical, would you mind if I asked how much the new one was?

This is something I have lived with for 2 years now and I know the engine is fine because it was rebuilt with new pistons & cylinders!

Cheers,
Simon

 

[Beaky]

Cost me £85 fitted, in the end got my local specialise to do it