310R Sigma engine oil pressure

[Andy Ebdon]

I race a 310R, which started life in the 2014 Caterham Academy and worked up to 310R spec from 2017 onwards. I have always changed oil very frequently using 5W30.  These days, while oil pressure at cold is 4+ bar, once she is hot and at racing revs it is about 2.5-3.0 bar.  Performance remains good, but i am concerned about how much lower to let the pressure go before taking action.  I am assuming it is a matter of bearing wear after 6 years hard racing?  Is it time for a refresh and if so what to do?  I'm not sure a new engine would be affordable.

Any thoughts gratefully received!

[TigerSuperSix]

Mine runs the same and it's only done 2,000 miles since new - I think they are all like that (also, I think the guages aren't that accurate, from what I've read).

[pgm]

Just to be on the safe side why not borrow a mechanical gauge just to confirm that your readings are correct?

Kind regards Colin

 

[Tom_Arundel]

Does a 310R have an oil cooler?

I thought 10/50 was recommended for race engines

Do you do a cooling off lap at the end of the quick ones/race?

I have come in from quick laps with very hot oil and no obvious pressure on the gauge. Its not been a problem so far but I tend to keep some revs on the engine when coming in to avoid low pressure and not sit in the pit queue at idle.

[paul richards]

Hi Andy

Oil pressure senders on the K series are notoriously unreliable and whilst on the Sigma they are not located in quite such a vulnerable position to weather and grime I suspect that they are also prone to failure. Before doing anything else I would suggest changing the sender or better still changing to a mechanical gauge. 
Paul R. (Your Silverstone C1 mechanic  )

[Andy Ebdon]

Interesting, thanks.  Seems you are right about gauge accuracy based on others experience.

[Andy Ebdon]

Hi Paul, hope you're keeping well!  Gauge still works, but accuracy is another thing.  I asked Caterham and they said as long as you have pressure showing and performance is fine that's okay?! Seems like a mechanical approach might be best for piece of mind - or i'll just stop worrying about it and carry on!

[ChrisC]

I personally believe the "sub loom" between the sensor and the chassis loom has a lot to be desired in this area.   It seems like the sensor (with sub loom) and gauge are supplied by Caerbont to Caterham.  

Under the PVC cover of the sub loom is a diode and a resistor soldered to the bare wires with little in the way of weather protection, which is in contrast to Caterhams approach of using waterproof connections (Econoseals). 

There has been a post on here showing how corroded this sub loom gets, and I suspect this has more to do with the accuracy/reliability than the sensor itself. 

For reference here is the post from "egnshane" 

https://www.lotus7.club/forum/techtalk/oil-pressure-360r

[Andy Ebdon]

Thanks Chris C, sounds like that might be worth a look.

[aerobod - near CYYC]

With 0w40 oil, 4 to 4.5 bar starting pressure on my R400D at idle when the engine is cold and ambient temp is 15C is normal. Once warmed up 3 bar is normal at idle when the engine is not pushed hard and oil temp is about 70C, with thrashing to get the oil temp up around 100C, idle pressure drops to 2.5 bar. At revs above about 4000RPM (depending on oil temperature), pressure reaches a max of just under 6 bar before the pressure relief valve intervenes. My Duratec has had this pressure profile from new to it's current 31,000km.

[Domus]

Not raced but my Sigma sender failed twice when new.  It was a pain to change so bit the bullet and went mechanical with a low pressure warning light to boot.  You know it makes sense.