Throbin Posted October 8, 2009 Share Posted October 8, 2009 On a blat in this afternoons sunshine I noticed a fairly severe drop in oil pressure under heavy braking. The car is a K Series with a CC dry sump system with remote tank in front of the passenger footwell. My OPG is a SPA. I'm fairly sure it has enough oil in the system as some is being spat into the catch tank. Normally the pressure is around the 4.7 bar mark once warmed up, but under braking it dropped to just over 1 bar but soon picked up again. I'm realatively new to the dry sump set up so all comments appreciated. Cheers, Robin. Link to comment Share on other sites More sharing options...
Mark w Posted October 8, 2009 Share Posted October 8, 2009 Do you really mean 4.7 Bar or 4.0 bar hot ? 4.0 bar is approx 58 psi which is exactly what my CC dry sump R400 records when hot on 0W-40 Mobil 1 and measured with the Stack As for the drop to 1 bar i would say that if the engine was at anything above tickover it was either a duff reading or you have a problem ! Is it repeatable ? Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted October 8, 2009 Share Posted October 8, 2009 Is the SPA an electric or mechanical gauge ? Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted October 9, 2009 Leadership Team Share Posted October 9, 2009 Robin, my SLR (K) runs at 4.9 bar when over around 3500 rpm, so I guess similar to yours, SPA gauge also. If the pressure drops under heavy braking your oil level is too low, nothing more complex Brake hard, oil pushed to front of d/s tank, exposes exit hole to pressure pump, air sucked in, low pressure Just add some oil. Stu. Joint Area Representative MAD Sevens (Merseyside And District) www.superse7ens.co.uk..........the rebuild 😬 Link to comment Share on other sites More sharing options...
Throbin Posted October 9, 2009 Author Share Posted October 9, 2009 Guys, thanks for your comments. Mark - yes I do mean 4.7 bar but as Stu says below this is at mid to high revs, not idle. The drop in pressure was repeated several times, each time braking hard! S M25 T - um I think its electrical. There is a metal cylinder to which an oil pipe runs from the pressure take off adjacent to the filter. This then has an electrical lead that runs to the gauge. Stu - I did think it could mean I need more oil, but I thought on D/S systems you put enough in until it just about stops spitting it out into the catch tank. Is there a better method? Cheers, Robin. Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted October 9, 2009 Leadership Team Share Posted October 9, 2009 I find if I put too much in it just burns it and/or spits it out, with not enough it suffers under severe braking - and there's not much tolerance inbetween! Certainly the CC dry sump setup is not perfect, but whatever is! I'd started thinking about whether a baffle could be added to the tank to reduce the forward movement under braking but never really got anywhere with the idea. Stu. Joint Area Representative MAD Sevens (Merseyside And District) www.superse7ens.co.uk..........the rebuild 😬 Link to comment Share on other sites More sharing options...
Gavin H Posted October 9, 2009 Share Posted October 9, 2009 Robin I have had exactly the same issue, althoguh with the Caterham Bellhousing oil tank. As Stu says, a top up should sort it out. FYI I discussed it with the technical guys at Caterham at the time and they said that, as it was under braking / deceleration, and the engine was not under load, there was no reason it should cause a problem (mine returned to normal when car stopped or just coasting - pressure was fine under acceleration or blipping the throttle). It's a bit unnerving, but should be sorted with a top up. Gavin Link to comment Share on other sites More sharing options...
7 wonders of the world Posted October 9, 2009 Share Posted October 9, 2009 SFAIK the remote tabk CC use is the Pace easiclean which I also use in conjunctipon with a Pace DS set up, there is already significant baffling in his and providing the oil level is maintain at just below th baffle when running I don't see so the oil could surge that much even under severve braking as the pick up is right at th bottom of the cylinder. Too young to be old ! Link to comment Share on other sites More sharing options...
Myles Posted October 9, 2009 Share Posted October 9, 2009 1 bar is a bit of a worry as even when super-hot at idle, the norm for a wet-sump with Apollo is about 25+psi for mine. (1bar being around 15 psi for the sake of round-numbers). My wet-sump Caterham is on SPA gauges - I'd turn the bloody-thing off if I registered that low under any circumstances. My Blackbird Westie is DS'd and idles at around 20psi - although I understand the standard bike OP low light is something silly like 5psi! 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Alcester Racing 7s Ecosse™ 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Mick Day Posted October 10, 2009 Share Posted October 10, 2009 I think you should check the effectiveness of your scavenge pump. The oil level is checked at tick-over however at higher revs it could be that not enough oil is being returned to the oil tank. This is then exacerbated when braking when the oil moves to the front of the tank exposing the pick-up. Link to comment Share on other sites More sharing options...
Throbin Posted October 10, 2009 Author Share Posted October 10, 2009 Guys, thanks for all your comments. As its sunny here this morning I topped it up with just over half a litre and went for a blat. The pressure is now fine, even under severe braking, and very little was spat into the catch tank. Hopefully I have now found the optimum level for my set up. As Stu says its a fine line between too much so its spits it out and too little when pressure is lost. Cheers, Robin *wavey* Link to comment Share on other sites More sharing options...
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