Oil warning light & buzzer

[Bawnboy1]

Since changing oil & filters recently my 85 1.6 turbo diesel JX engine has the oil light & buzzer coming on when engine heats up .
I have had the oil switches replaced and the sump has been removed and oil strainer cleaned but no change . I was told oil pressure was low so I had that replaced but still the oil light & buzzer comes on when engine heats up . If I Rev the engine both go out for a time or if I drive at a constant 50 mph there is no noise or light . Oil and oil filter replaced again last week but still same . Any thoughts please

[Aidan]

You need to do a wet test with a oil pressure gauge to find out what's going on, local garage should be able to help or put up your location in case anyone local has one

[937carrera]

What oil grade are you using now, do you know what you were using before ?

Same for the oil filter

[Bawnboy1]

Thank you for your help . I spent some time today trying to get an oil pressure switch out , the one closest to oil filter which is hard to get to . I discovered that it was a different size to the other one ,which made me suspicious . I got it out eventually , put an old switch back in , took it for a long drive and problem solved - wrong switch .

[937carrera]

Glad you got it sorted

There are three different switches with different pressure settings (all the same size)

https://www.brickwerks.co.uk/brickwerks ... -switches/

Out of interest, which one went off and what are you using now

[Bawnboy1]

I only know of 2 switches on this engine - am not a mechanic . I changed the black one which is close to the oil filter ( hard to get access to it ) . The mechanic had left the old black switch in the vehicle so I swapped it over to see what would happen and. ' Hey Presto '

[937carrera]

There are 3 switches available for the DOPS switch, one for the low pressure switch.

As you have swapped black for black, and assuming the switches followed the right colour scheme it seems like the new switch was broken when fittted or it was the wrong normally closed type

Black should be the middle 1.4 bar trigger setting.

I'm glad you asked the garage to change the switch .............. unless the old one was actually faulty and the new one is good, so you are really best off getting a wet oil pressure test done, or get another new switch to confirm that the pressure is OK and the old switch isn't faulty.

When the garage said the "oil pressure was low", how did they know, and if a wet test what was the reading when the engine was up to temperature / at 2000 rpm - that's how the pressure should be tested

Loads more thoughts I know, but engine rebuilds are expensive