Oil Pressure Light/Buzzer

[Hedgehog]

I know this is a common fault on T25`s. We bought it last summer and it was ok for a while then we had a problem with overheating as the fan thermoswitch wasn`t working. This has now been replaced. We have had the engine out over winter and replaced a broken valve.(As well as many other unrelated items!) Oil Pressure gauge was attached when idle and that read ok. Wiring to Buzzer etc was a bit suspect so had a mate check that out and it seemed better. But just occasionally and intermitantly the buzzer/alarm sounds then just as quickly it goes quiet again. The Water temperature is fine and the engine sounds perfect. Can`t make a pattern of when and why. Been told by a few to ignore it/bypass it as the wiring behind dashboard is poor and causes this problem. Just a bit worried in case we damage the engine. Anyone else got any idea`s how we can confirm if it`s electrical or actually the oil pressure? - Hedgehog

[AngeloEvs]

The warning system can be misleading with various faults in the electrical system that can cause erratic behaviour but if you want to definitely link the erratic behavious to the wiring then I would suggest you have the oil pressure tested at a local garage. They need to establish that the oil pressure is OK when the engine is at normal operating temperature and running at above 2000 rpm. Apart from the connector that links all the wiring to the speedo housing I would also check that the oil pressure switch near the water pump is closing when you start the engine and that the wire and connection to it are in good condition. As a temporary measure you could permantly earth this wire and see if the fault continues. If you still have the same symptoms then its a fault with the wiring. If the fault disappears then you must check this switch operates correctly (closes or connects to chassis) when the engine is at normal temperature. On a healthy engine at normal operating temperature this switch will connect to earth at around 1000/1200 rpm or just above. It does sound like a wiring fault given that you normally have to switch the engine off to reset the buzzer but sods law can prevail and its not worth assuming that this is definitley a wiring fault in the system.

[Hedgehog]

Thanks for that. I`m fairly good at the mechanics but I`m wary with electrics. I have a mate who`s not too bad at it so I`ll ask him to give me a hand with the earthing etc. I`m considering getting rid of the buzzer system and installing a gauge. Sounds like it`s far more trustworthy! We`re hoping to try it out next weekend so it`ll be make or break I guess!!