Just installed new oil sender on fresh M28/16 4.5L rebuild. Everything is working as adverstised with no leaks on first runup, but the oil pressure goes from 0 to 5 bar instantly after the engine fires

Shouldn't the idle range be around 3 or so and work itself up to 5 with increased rpm? Could it be a bad sender or wiring issue? We are using Valvoline Racing oil 30 wt organic for the run in.

We are going to hook up an external oil pressure gauge to check for sure tomorrow. Thanks.

 

It seems normal operation. On my cars the oil pressure gauge is pegged at 5 on start up and until the car and oil reaches operating temp, then it comes down. After that it will increase or decrease with engine rpms.

 

Just as Bilal said it is perfectly normal. It will go down as the engine oil warms up. Nothing to worry about, if it was at 3 or lower at start up then I would be worried.

 

Unless the sender is wired backwards, then it will stay at 5 bar.

 

Thanks, will check for backward wiring tomorrow before hooking up external gauge.

 

You can always empty the oil and start it and see if the opposite happens!

 

It takes about 15 minutes of driving to get the oil really up to temp.....

 

Like Bilal said.

Should go up to 5 at start up when cold. Idle or not.
Then goes down to about 3 at idle when it reaches operating temperature.
And should go to 5 again as soon as it is over about 1500 rpm.

 

NOTE if the sender is miswired.

THEN when the key is turned onto the run position,
the gauge will peg at 5 bar without the engine running

 

What Bilal and Mrmerlin said.
If it pegs with the key on and not running, could be a bad or crossed connection. Happened to mine when the insulation decided to call it a day. Easy fix.

 

Im still trying to trace mine. Its PITA!! Its never worked

 

Sometimes the sender itself gives up the ghost...have you tried replacing just that bit? (A little fussy to get to, but not a total PITA type fix...)