oil pressure on start up?

[johntom]

I 've just bought a 1985 350i with under 30000 miles from new. How much oil pressure should i have once the engine has started ie cold tickover and how much when warm, ie motorway at a steady 70mph?
Also i changed the oil and filter (valvoline racing 20/50) two days ago, when i started the car today (first time since) i noticed that the oil pressure light showed for the first 5 seconds of running, is this normal, i didnt rev the car and it sounded fine?
thanks

[odyssey2200]

Rover V8s always had low oil pressure on idle.
My SD1 oil light used to just glow on idle.
There used to me mods available to increase the pump output and/or alter the pressure releif valve settings.

[GreenV8S]

For reference, when you change the filter you should refit the new one promptly after removing the old one, and start the engine reasonably soon afterwards, ideally minutes rather than hours. When you take the filter off you let air into the pump (an oil out, obviously). If enough oil drains out then you will have difficulty getting the pump to prime afterwards. The less time you leave for the pump to drain, the better your chances.

[johntom]

Hi
sorry to mislead, i changed the oil /filter on Saturday and had the car running to circulate the oil straight afterwards to check for leaks etc. I meant that i haven't started the car since then, until today. Being new to the car/s i hadn't noticed what it was like before as i have only driven it home after buying it last wednesday and then parked it up until Saturday.
thanks for the reply

[honourablepickle]

if it's any use to you , when i fitted a new pump recently i got oil pressure of around 20psi at 1000rpm
this is on a 80k engine
rover motors don't seem to need lots of oil pressure
hp

[johntom]

Re priming the pump ?
once i have started and run the car after changing the oil / filter (having waited 5 seconds for the oil pressure light to go off) should the pump then be primed so i get pressure straight away next time i start, or does this depend how long i leave the car after shutting off ?

[andymadmak]

TADTS! Don't get yourself into a froth about this. It sounds like the engine is fine.
The RV8 survives on flow rather than pressure. I was once told by an ex Repco mechanic that they used to see 8psi on the race engines and all was fine so long as the flow was there. As people have often said, its not uncommon to see the oil pressure light on on RV8 engined cars at idle when hot (although mine does not do this) and its not always bad news
My running oil pressure cold is between 25 and 50 psi, falling to about 10 psi at idle when hot.
Max hot pressure I see is about 35psi at 4000rpm + . This is the same as it was before the rebuilt upgraded at 50k miles. (now 60k) When the engine was stripped there was no appreciable wear anywhere. even the cam was OK ish, but we replaced all shells, new cam, etc and the oil pressures are the same now as before.
I use 15w 50 fully synth in mine and I get a light rattle on start up from the cam, it lasts for a couple of seconds. Oil light goes out after 3or 4. Always been the same way. I do my own oil changes and I've never had to prime the pump ( I do it quickly! ) and my only concession to a long lay up is to spin the engine over for about 20 - 30 secs with the imobiliser engaged so as to get oil to the important little places. Like I said, it's never been a problem for me, and I've suffered no premature wear problems. I was told to avoid playing with relief valve springs, tadpoles and other such paraphenalia as they can cause as many problems as the solve.

Andy

Edited by andymadmak on Tuesday 29th May 10:23

[Trickie Dickie]

I'm sure I read somewhere(probably SH Bible) that the
Oil pressure should be 28psi at 2000 rpm
My 1989 350i always seems about right at that
(and I am also running Valvoline Oil)

Hope that helps

Richard