I have got a disco 97 3.9 v8 and I have had the light on for a couple of days I done a oil and oil filter change no luck so changed oil switch and still nothing :-(

Today on the way back home it lost power BIG time couldn't get over 2 thousand revs in 2nd gear stuck doing 20mph for about 1minute then the power kicked in again..

Can anyone help please thanks in advance
 
Did you prime the oil pump after the oil and filter change? Don't drive it with the oil light on you will damage the engine unless you are certain you have oil pressure and it is a pressure switch fault.

Have you tried replacing the relief valve, they are known to stick.
 
Yes, most likely is the pressure relief valve on the oil pump.
Probably stuck open after redlining it.

If it was just worn pump gears light would flicker at low revs

Could be faulty pressure sensor switch though

I would expect it to sound like a bag of hammers if you have driven it more than a couple of miles with no oil pressure and require an engine rebuild

But if it sounds sweet still you've got away with it. I hope so

Never drive with oil pressure light on!!!
 
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Where is the pressure release valve?
I have changed oil, oil filter and switch so next job is to take of sump and have a look I am getting oil to the top of the engine so the problem most me at the bottom ill keep you informed thanks
 
Do a search, plenty of images out there.

Its a hex sump plug 22mm ish from memory on the side of oil pump with a copper washer and a spring behind pushing valve closed (or maybe not in your case)

You don't need to remove pump or sump yet.

I am reading from your OP that the light came on before oil filter change, not after
 
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Sorted it took off sump and there is a pipe that feeds the top of the engine and one bolt had come off and it was half on half off so wasn't getting enough oil to top of engine.... If I know how to post a pick I would show you..

But all sorted now thanks every for your help

Back to the v8 power
 
Sorted it took off sump and there is a pipe that feeds the top of the engine and one bolt had come off and it was half on half off so wasn't getting enough oil to top of engine.... If I know how to post a pick I would show you..

But all sorted now thanks every for your help

Back to the v8 power

Oil strainer thingumy. Well done
 
steady on chaps this is a 3.9 serp so doesnt have pump gears or need priming

having the strainer come loose is BAD

that is the pipe that supplies the oil pump with oil

its not the top of the engine that gets left out its the whole engine

i would cross your fingers ask ask your family to do the same cos you could have done some damage :eek:

i run a mechanical pressure gauge right in front of me because i dont trust the pressure switch!
 

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