Widely fluctuating oil pressure - 3.4 pontiac

[malc_p]

Just an addendum to the original message - the fluctuations only happen once it's warmed up, pressure is 45psi and steady for 5 minutes before it starts going haywire. Hmmm - pressure relief valve sticky?

Hi
Had my oil changed on a regular service a couple months back ago (5w-30) and last week I noticed my pressure gauge was moving a heck of a lot during driving.
At idle it flickers rapidly between 30 and 40, when I move off it goes up to over 80psi at 2000rpm and by 3000 it drops back to 50 or so.
The 'low oil' light has been on and off for about three months even though there's been oil to the right level on the dipstick all that time, but it's only since the oil change that the pressure has been anywhere but rock-solid at 40. Oh yeah I did have the filter changed at the same time!
I have a light tick from one or two tappets but the engine has 160000 miles on it so I imagine that's usual.

Clues?

Cheers
Malc

[3.4orNothing]

Re: Widely fluctuating oil pressure - 3.4 pontiac

wel,,,,it happend to me too,but it was the oil pressure sending unit that was bad,as for the low oil light,check it could be that you have the good amout of oil but the pump not working ok.

[Rob Bell]

Re: Widely fluctuating oil pressure - 3.4 pontiac

You need to hook up a mechanical oil pressure gauge to determine what the engine is actually doing. If it shows that the oil pressure is normal, then you know the sending unit is bad.