Engine Oil Pressure - Springs!!!!

[carinatauk]

I was reading some interesting facts on the Cerbera forum ref oil pump relief spring. One big Q is will this help my low oil pressures to same extent? well not quite as well as 80 psi, i'd be happy with 50 psi

Thanks in advance

>>> Edited by carinatauk on Tuesday 27th July 21:41

[tahiti450]

I take it you are referring to the Rover engine now not the AJP8. If so it might save a lot of correspondence I direct you to the thread "oil pressure" (johnny bravo) on 21/7/04, which pretty much covers this issue.

>> Edited by tahiti450 on Tuesday 27th July 21:43

[carinatauk]

Burger!!, will have to be more observant. Thanks will have a look!!

Edited to say: Nope!! didn't address the question, will the pressure increase if I was to change the oil pressure relief valve?

>> Edited by carinatauk on Tuesday 27th July 21:50

[tahiti450]

Incidentally I used to play around with the spring on my P6, and yes you can inflence the pressure quite a bit by packing the spring to increase the pressure on the relief valve. If you do it enough (as i did) you can get the gauge to hit the stop, and generate enough pressure to pump all the tappets up so all the valve stay open (a bit) and the engine promptly stops ! Additionally the more pressure you force the pump to produce the greater the load you put on the oil pump drive gears, which just happen to be about the weakest part of the whole engine (if its a pre-serp at least), greatly accelerating wear and risking failure . Apart from that you are wasting power producing oil pressure that would be better empolyed driving the rear wheels! All that just to see the needle on the gauge sit a bit higher.... PS the bibble covers this (like most things !)

[tahiti450]

Oh, didnt see your reply, the bibble (sorry bible)doesnt cover it eh??? I shall have to see this !


Dear me i'm confusing myself you didnt mean the bible because i referred to that in the subsequent message DUUH. You meant the thread and your'e right it didnt cover that, was just meant as some background info (esp my contributions ). :
>> Edited by tahiti450 on Tuesday 27th July 21:57

>> Edited by tahiti450 on Tuesday 27th July 22:08

[carinatauk]

Got me there Alan, do not have a copy of the bible so relying on good advice. Any thoughts would be ever so useful!! and no, not hoping to cause any probs for my serp engine and as its done >100k just want to improve its chances

Double burger!!! please don't beat me on those edits!!

>> Edited by carinatauk on Tuesday 27th July 22:17

[tahiti450]

ok got you now, its a serp engine so the oil pump loading problems probably aren't so much of an issue. But, it is still the venerable old Rover unit, and high oil pressures really aren't the holy grail that they might be in some engines (if ever they are). The lubrication system is designed to give high flow, rather than high pressure (a bit like the modern paint spray guns, HVLP type - high volume / low presssure).

One of the things I dont understand about the Rover engined TVRs is that they insist on using an oil pressure gauge calibrated to 100PSI, whereas on the original Rover applications like the P6 the gauge tops out at 60PSI at full deflection. This means that a good oil pressure of say 38PSI looks nice and reassuring on the P6 (as it should) but a bit thin on the TVR. The same thing happened on early MK 1 Jags with the XK engine, started production with 100PSI gauges, but then after lots of worried owners were harrassing them they changed it to a 60 PSI unit, problem solved..!

High oil pressures can in fact be the enemy of bottom-ends (I think, due to the increased tendency to cavitation), and the main purpose (I suppose) of higher oil pressures is to feed distant regions with small oil-ways like overhead cams and valve gear. I think I'm right in saying (read it somewhere) that the AJP8 engine actually has a separate low-pressure feed for oil to the crank.

I have over the years adjusted my expectations of oil pressure in the Rover engine to take into account its design intentions, and not to get too preoccupied by relatively low values.

Incidentally what spec oil are you using ? 0w-40, would tend to be a bit thin and exacerbate the low pressure, most people seem to agree that a 15w/50 is better suited.

[carinatauk]

Thanks, just a thought really but not surprised about the answer! thanks for the reply.

Oil I believe is 15-50 or similar; Offords do the service and, touch wood, I don't experience the need to top up between services

>> Edited by carinatauk on Wednesday 28th July 19:17

[tahiti450]

No worries, hope to have been of help. Did you say , "done over 100K" ! I wonder if it might be worth having a new set of shells in the bottom end anyway at this point or at least dropping the sump and doing a quick inspection ( i think I would). Mind you good servicing and synthetic oils should reduce wear to a minimum. Could check compression as well, and i would want to have a look at the cam (could just get the rocker covers off and measure the valve lifts with a dial gauge if you want to avoid removing the inlet manifold / injection). Might sound like a lot, but nothing difficult there and would tell you a lot about the condition of the motor.