Oil pressure

[Chris]

I've got a question about the oil pressure in my Rover V8, so I figured it'd be more useful to post it here than in the Spitfire section. :)

Bascially, while my oil pressure seems fine when the engine is cold, it appears to get very low when the engine is up to temperature (don't remember the exact figures off the top of my head - something like 50-60 at idle with a cold engine and 10-15 at idle with a warm engine (I assume my oil pressure gauge is in PSI, but don't remember that off the top of my head either :B)).

Is this normal? What pressure should I expect to be seeing with a warm engine?

Assuming this is too low, am I just using the wrong oil (I'm using 10W-40, as recommended by the good people at Haynes) or should I be thinking about fitting an oil cooler?

Lots of questions, I know - it just seems too low to me, and I thought it was possibly time I did something about it.  :)

Cheers,

Chris

[James]

How old is the oil?

I just changed mine and it's gone from about 25 to 50psi!

The old stuff must have been proper knackered.

[Chris]

The oil's only a couple of months old, as I had the car serviced just before its last MOT.

[Beans]

An oil cooler is always a good idea imho.
Don't know about the oil pressure for a RV8, but 10-15 psi at idle seems fairly low to me.
My Sprint engine (after being trashed for nearly 90.000 km) stll has ±45 psi at idle @ 950 rpm when hot.
That is with new oil. As James stated old oil reduces oil pressure. Same applies for bad quality oil.

[mikeyb]

Rover engines have a much lower normal oil pressure than Triumphs.  From memory, 25-30 psi hot at higher rpm is fine. 10W40 is way too thin though, the RV8 is an old pushrod engine that is basically unchanged from when Buick made it in the early 60's.  20W50 is what you should be using, it certainly won't make your oil pressure drop further!

[Chris]

So I'm using the wrong oil, and I should look into fitting an oil cooler. Cool.

Strange that Haynes would recommend using 10W-40 for an RV8 though. Ah well... :-/

Okay then, next question: If I were to change the oil myself to make sure it's got a good quality oil of the right grade, what's the recommended method of disposing of the old oil? (I know, I know - it's disgraceful that I've not changed my own oil before :P)

Cheers,

Chris

[Jason]

Pour it down the sink, I mean you pay your water rates, it's their problem  8)


OK, seriously - most "Civic Amenity" sites aka the Tip have a waste oil collection point or some councisl will actually collect it with your recycling. That way it will be back on theshelf in an Netto can in a couple of weeks :-)

[F1xa]

Agree 10-15psi is a bit on the low side although as stated the RV8 engine has never been renowned for high oil pressure- it one of the reasons it can wear badly if not looked after by regular oil changes etc.

A lot depends on the age iof the engine and the mileage it has covered. My ex-SD1 engine was fully rebuilt a few months ago and maintains between 20and 25psi when hot, using 10W40. A higher mileage engine will be lower, as will an older design (the older P6's and Range Rover engines had a smaller oil pump housing and so had lower pressure).

As a first point of call i would change the oil to a good quality branded one, and fit a good quality oil filter too. If possible may be worth checking by use of a second gauge temporarily connected, it could of course be your gauge that is reading low and engine is fine.....

Nigel

[neilnaz]

Take sump plug out. Let oil drain into oil tray (available from halfords and other car accessory places). Leave draining for 1hr. Replace sump plug. Change oil filter. Pour new oil in (after double checking that you did put in sump plug!). Pour old oil into used and empty oil container (helps to use a funnel). Take used oil down to recycling centre where they should have a specific place for dumping your oil.

I have never bothered with engine flush. There may be some benefits. From beginning to end it shouldn't take more than 2 hours including dropping the used oil off at the recycling centre (I suppose that depend on where the recycling centre is).

Neil

[F1xa]

Couple of points I would add to this sound advice:

1. Assuming you are still using standard oil filter hanging from bottom of engine, fill it as far as possible with oil before you screw it back on- will reduce the time the bearings are starved of oil on start up.

2. If you are happy your battery is strong, disconnect ignition at coil and spin over on starter (after oil and filter replaced!) for a couple of good bursts to let it circulate some oil before you start. Then reconnect and start it up, making sure oil pressure rises within a few seconds.

Hope this helps

Nigel

[James]

Engine flush would help you if you have to wait 2 hours for all the oil to drain out Neil... makes the oil like water and shoots out...

I never leave mine more than about 10 minutes (without flush)

[Chris]

Cool, thanks guys.
Next time I get a free weekend, I'll change the oil and filter and see if it helps.

:)

[TR Tony]

The RV8 does indeed run on surprisingly low oil pressure. In a good condition engine using a normal pressure relief spring you should have 35 psi or more at 2400 rpm when hot, & 12 - 15 psi at idle.

The pressure relief spring can be uprated to give higher pressure but it should not be neccessary on a road engine. A thermostatically controlled oil cooler can be a help if you like to press on on a bit!

[rob]

When you fitted the engine, did you upgrade the cooling? If you didnt then it sounds like your engine may be unable to cool itself adequatley resulting in low viscosity of the oil and thus low oil pressure. :o

This may prove fatal for your engine as what will happen after a period of time is that your big end bearings will become starved and will fail meaning an expensive bottom end rebuild. An oil cooler will go some way to helping but will not replace the cooling provided by the correct coolant radiator.

[leylandracer]

TR_Tony wrote:

The RV8 does indeed run on surprisingly low oil pressure. In a good condition engine using a normal pressure relief spring you should have 35 psi or more at 2400 rpm when hot, & 12 - 15 psi at idle.

The pressure relief spring can be uprated to give higher pressure but it should not be neccessary on a road engine. A thermostatically controlled oil cooler can be a help if you like to press on on a bit!

True, mine runs around 12-15 psi on tickover, a low idle speed will have the oil light flickering as well. V8 Developments recomended Silkolene 15-50 fully Synth, but i suppose its each to there own,

[Chris]

rob wrote:

When you fitted the engine, did you upgrade the cooling? If you didnt then it sounds like your engine may be unable to cool itself adequatley resulting in low viscosity of the oil and thus low oil pressure. :o

This may prove fatal for your engine as what will happen after a period of time is that your big end bearings will become starved and will fail meaning an expensive bottom end rebuild. An oil cooler will go some way to helping but will not replace the cooling provided by the correct coolant radiator.

I'm not trying to run a V8 on a standard Spitfire radiator, if that's what you mean. :)
The rad in my Spit was originally for a (whisper it) MGB-V8, and I've got a Pacet electric fan fitted as well - the temp gauge never goes up above half way (which admittedly could just be mean the gauge is broken, but I don't think so).

Anyway, from other replies, it sounds like the pressures I'm seeing might not be that unusual after all. I'll try just changing the oil for a good quality oil, and see how it goes from there.

Cheers.