Low oil pressure on dry sump k series

[Dave McCulloch]

I've not used my seven much since a track day last year at Oulton Park - when it ran faultlessly - until the last week's nice weather. The engine is a 1900 scholar (built by myself), dry sumped, with the standard Caterham oil pressure gauge but with a separate low pressure warning light wired in - the switch being 35psi.

 

Historically, the low pressure light would flicker at idle - more so when the oil got hot. However, the last couple of days the OP gauge has been reading noticeably lower - c. 2-3 bar at revs, dropping right down into the red at idle (oil hot). I'd put this down to another dodgy sender, but the low pressure light now seems to be on constantly at idle once the oil's warmed up (over 60 degrees). Then driving home tonight I accelerated hard and the warning light flickered on at high revs.

 

I've checked the oil level - which is fine. Any clues as to what to look for next.

 

Thanks

 

Dave

[regroo]

Have you tried to overfill the oil to make sure it is the right level? If it were me I would rip out the standard caterham guage and sender and fit a mechanical one with or without a light, at least you have a definate reading.

 

I have a stock guage and sender sitting in the garage if you want to test your current setup? For ref my std SLR reads 30PSI hot idle and 70-80 at high rpm.

[Dave McCulloch]

Cheers

 

Think I've already decided to fit an (accurate) mechanical gauge - that's now the 3rd sender that's failed / been suspect. I'll fit that first and see what pressure I'm getting, and then go from there.

 

Dave

[Rob Walker]

But if your low oil pressure warning light is coming on then you must have low oil pressure? Changing the gauge to a mechanical one will not change that, only confirm that you have falling oil pressure.

 

I would advise you to have a look at the scavenge gauze filter behind the scavenge pickup in the sump, look for any debris or tell tale signs that your bearings are falling to bits.

[Dave McCulloch]

Rob

 

Can't remember from when I installed the DS system - presume I can simply remove the scavenge hose and then withdraw the pick up complete with gauze?

 

Going to swap to mechanical gauge anyway as I don't trust the electronic one.

 

Dave

[Kevsta]

My Pace DS system does pretty much the same. At tick over when hot (after drive on track for instance) the pressure drops to around 1 bar at tick over and my light comes on. If I blip it or hold at 1500rpm then it goes up to about 2 bar. I did use to worry a lot about this, now I just get on with it as I have put it down to the oil getting thinner and so offering less resistance to moving through the engine when it is not being driven at high speed. The flow characteristics (I would hope) should still be the same as when the oil is cold and it idles at an indicated 5 bar pressure on tick over. I too will change to a mech guage soon though, electric ones are carp!

 

Interestingly, if I change the oil (type or just put new in) the pressure will change a little for the better but not for very long (one track day does it!)

 

I hve tried the comma caterham oil but it doesn't make much difference at all (not worth the expense as I change oil so much)

 

 

[Rob Walker]

If you have the Pace system the oil pressure is adjustable on the oil pump.

[Kevsta]

Rob, yes I have adjusted it but it is adjustable for pressure relief, at tick over there is no pressure for it to relieve. If I turn the pump relief down then it will run a higher pressure at revs and I don't want that as that part is fine.

 

 

[Gavin H]

Dave

 

I had a similar issue with the Caterham dry sump on my R300. I suspected the pressure relief valve was jammed open (or at least sticky) as the sender was fine (I now have a spare to prove it).

 

Had a service and CC and they said they could not see a problem... Turns out they changed the oil and then investigated - there is now no issue, and I hope it doesn't come back, but it seems to me it was probably dirt in the oil!

 

If you can get to the gauze filters then worth doing and making sure they are clear, but also an engine flush might solve it.

 

Hope you get it sorted soon.

[Dave McCulloch]

Gavin

 

My current thought process is change the oil (so I can check for any bits in it), check the gauze filters, and replace the crappy Caterham oil pressure gauge with a mechanical one - the bits from Think Automotive arrived today - but had to buy the gauge from Demon Tweaks as Think were out of stock.

 

Then I'll have my fingers crossed!

 

Dave

[Mick Day]

My Pace DS oil pump gives circa 15 psi at hot idle (1000 rpm) wheras the previous WS Rover oil pump would produce 30 psi. No worries plenty of OP at 4000 rpm: 60 psi +.

 

I think this is a function of the Pace pressure pump so I've set hot idle to be 1200 rpm when OP is 25psi.

 

Just drive it!

 

Edited by - Mick Day on 14 May 2008 22:28:41

[Rob Walker]

1 bar at idle is plenty