Quagmire Posted February 5, 2008 Share Posted February 5, 2008 Ok, so my oil pressure light has started coming on when the engine is warm and at idle. I drive 33miles to work each day and it usually comes on for the first time in a journey when i stop at the first roundabout at the end of the motorway slip road one mile from my destination. The tiniest touch of the throttle is enough to make the light go out. Because of this it was decided to lash up a pressure gauge and see what the situation is. During testing the pressure seemed to hover at 40psi when cold at idle, and peaked at around 50-55 psi when about to change gear. As the book figure (i think) is around 45-65 i thought this was on the low side but not as bad as it could be. Remedial work could wait another week... However. When driving home last night (25 miles) i maintained a steady 45-50 psi, but when coming to the first stop of the journey from 70mph, the oil pressure gauge showed the pressure drop to around 10psi!. This only went back up to around 30psi by itself, at which point a light dab of throttle brought it back up to 40ish. The bearing shells were changed recently when #4 big end came loose. At the time the crank was inspected and deemed to be ok. I did inspect the oil pump too, but admit i did not check the pressure relief valve to see if it was working correctly. The engine is running fine, no funny noises, and plenty of power. Any ideas? Oh yeah, am running 20w/50. No oil leaks. Thanks! Quote Link to comment Share on other sites More sharing options...
edwardatherton Posted February 5, 2008 Share Posted February 5, 2008 What brand of oil is it? My 2.25 used to do that if I used cheap oil from Morrisons (supermarket), but not on a branded type. Quote Link to comment Share on other sites More sharing options...
billypikey Posted February 5, 2008 Share Posted February 5, 2008 would it be the pump Quote Link to comment Share on other sites More sharing options...
Diff Posted February 5, 2008 Share Posted February 5, 2008 Ok, so my oil pressure light has started coming on when the engine is warm and at idle. I drive 33miles to work each day and it usually comes on for the first time in a journey when i stop at the first roundabout at the end of the motorway slip road one mile from my destination. The tiniest touch of the throttle is enough to make the light go out. Because of this it was decided to lash up a pressure gauge and see what the situation is. During testing the pressure seemed to hover at 40psi when cold at idle, and peaked at around 50-55 psi when about to change gear. As the book figure (i think) is around 45-65 i thought this was on the low side but not as bad as it could be. Remedial work could wait another week... However. When driving home last night (25 miles) i maintained a steady 45-50 psi, but when coming to the first stop of the journey from 70mph, the oil pressure gauge showed the pressure drop to around 10psi!. This only went back up to around 30psi by itself, at which point a light dab of throttle brought it back up to 40ish. The bearing shells were changed recently when #4 big end came loose. At the time the crank was inspected and deemed to be ok. I did inspect the oil pump too, but admit i did not check the pressure relief valve to see if it was working correctly. The engine is running fine, no funny noises, and plenty of power. Any ideas? Oh yeah, am running 20w/50. No oil leaks. Thanks! Its fine. Workshop manual says 35 to 65psi at 2000rpm on a warm engine. 10psi at idle on a warm engine is fine, plenty of engines go down to 5 psi or less at idle with no problems(Cold engine idle can easily be 40 psi. Idle pressure much lower when hot as the oil is thinner). Providing the oil light goes out as soon as the revs go above idle it should be ok. I suspect you need a new sender as I don't think the oil light up until you are down to around 5 psi anyway. Hope this helps, Regards, Diff Quote Link to comment Share on other sites More sharing options...
Quagmire Posted February 6, 2008 Author Share Posted February 6, 2008 Thanks for the replies guys, will try a new sender and see what happens! It is only Tesco cheap oil, but i have used it for years in my s2 with no problems so far. Quote Link to comment Share on other sites More sharing options...
Quagmire Posted February 25, 2008 Author Share Posted February 25, 2008 Changed the pressure switch for a new one. Light doesnt come on now at idle (but working OK) Quote Link to comment Share on other sites More sharing options...
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