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AD41 fluctuating oil pressure buzzer

T

theo

New member
"Have a 1994 Wellcraft 2700 fi

"Have a 1994 Wellcraft 2700 fitted with AD41 200HP engine. Currently have 630 hours.
Last year at 580 hours after cruising for at least 20 minutes, when throtling back to idle,
at 600rpm, the oil warning lamp and buzzer would come on.Oil pressure meter would read about 1.5 bar.By increasing revs to 1000 for one minute the light buzzer would go off and engine idling at 600 rpm, oil pressure meter reading almost 2 bar.Volvo mechanic suggested that we change
some springs(Volvo Kit) in the oil sensor/pump.
Those were changed, as a result the cold start oil pressure has increased to about 6-7 bar instead of 4-5 and the hot engine crusing oil pressure is about 5.The oil warning light/buzzer would still come on when idling after hard driving for about 20 minutes again been resolved by going to neutral and increasing revs to 1000 rps for one minute. Now the buzzer/light require more than 1500 rpm to stop and do not stop after even two minutes of keeping the revs there. I entered the marina in idle speed buzzing all the way to my berth...Engine does not consume any oil. How do I fix this? Note that we installed an oil pressure dial directly to the engine and compared the readings with the Volvo dial and they are slightly better. So the oil pressure switch works but the oil warning light and buzzer
still sing! What do you think is the problem? Faulty oil buzzer/light sensor OR...."
 
If I am reading the right manu

If I am reading the right manual the correct oil pressures for a hot engine are 31 - 42 psi when idling (call that 2 - 3 bar) and 59 -71 psi at max revs (call that 4 - 4.7 bar) So your oil pressure now seems to be OK at high speed. You don't say what your hot idling pressure now is but if that is in the range 2-3 bar I would definitely be suspecting the sensor for the warning light and buzzer. I don't have any figures for the pressure at which it should sound the buzzer though. As it is a relatively inexpensive item and hopefully easy to change I would do that.
Provided you see a reading on the pressure gauge and that it is correct at max speed the buzzer is just annoying so it is not an urgent job
 
"sounds like you have the same

"sounds like you have the same problem i had, try changing the two pressure relief valve plungers in the block behind the oil filter. My plungers looked OK but the replacements cured the alarm on tickover.
Good Luck"
 
"Dear Terry,
Thanks for your

"Dear Terry,
Thanks for your post. What you mention was changed in the first phase without solving the problem, just the idling and full pressure readings have risen. We have now removed the plug
(wiring) of the buzzer sensor (next to the dipstick)so that it does not annoyingly buzz.
We have found that one of the two cable pins is corroded, thus giving incorrect reading. We have also ordered a new sensor. Will let you know after installation what happened.
Best Regards,
Theo"
 
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