oil pressure light

[alarmman49]

Hi everyone,

 

Can anyone help me with a mystifying problem on my 1981 Spitfire 1500 ?? On start up the oil pressure light extinguishes and I get a healthy oil pressure around 90/100 psi. However when I pull away for the first time, on a slight bend or straight within the first 200/300 yards the pressure drops to zero and the oil light comes on. After a few heart stopping moments (5 to 10 seconds) the pressure recovers and I get no further problems. I have replaced the pressure relief valve and spring for new but can't think of any other reason why this happens, any ideas ?? Running oil pressure is 50 psi when hot down to 2 bar on tickover ? with no oil light.

[Clive]

Odd one. My thoughts are that with that huge oil pressure (try another gauge?? or is it exceptionally thick oil when cold??) the oil is not returning to the sump quickly enough until it has warmed a little??

 

Assumption is that the oil level is correct??

[Pete Lewis]

is this electric gauge or piped ??

 

 

electric would indicate a wiring fault.

 

if piped then like Clive whats the sump level

 

does it have the right dipstick, how much goes in for a refill,  when drained  add 4 litres should be around the low mark  add the last litre and should be on full mark , 

 

there could be a suction tube fault here as you corner or brake the slop moves the level lower than normal and you suck air not oil

 

if adding a litre of oil as a test improves things then its sump off and look inside

 

Pete

[alarmman49]

Thanks guys,

The oil is quality 20/50 from Moss Bristol........... the gauge is a plastic piped type with an adaptor split at the oil pressure switch, levels are correct as I check regularly, I assume dipstick is original..............on last 3 oil changes it didn't take all 5 litres but I think it was pretty close so again assume oil amount correct, suction tube problem seems to be the place to go.................... unless anyone got any other ideas ??

 

Thanks for the replies so far..........................

[dougbgt6]

I have the same high oil pressure at start up, 90/100, but I don't have this problem. The gauges aren't particularly accurate and I wouldn't worry about a high reading. I think the 1500 oil filter is a canister? The one way valve on this is quite crude and I have heard of similar problems, so I would try changing the filter.

[KevinR]

Sounds like a suction tube problem to me.

Could the sump be full of sludge that blocks it when cold ?

[Pete Lewis]

dont think this will be filter related the drain back valve is  a crude  attempt stopping the thing emptying when parked for a while,  when running it has no effect

 

think its time to lower the rack, drop the sump off,  if you need to lift the engine watch for stretched hoses and fans fouling the radiator core.

 

its a lot easier on a 4 pot than the 6 pot which is a right fiddle

 

Pete