Duratec 2.3 Oil Pressure

[Hedgetrimmer]

I recently purchased a 2.3 Duratec Caterham that's running a Raceline wet sump.

The oil pressure reads around 40psi - 45psi at higher revs and 20psi on idle when up to temps. The readings are from a Racetech mechanical gauge so should be accurate. The oil pressure also seems to oscillate from time to time when at steady revs.

Can anyone confirm whether 40-45psi seems correct?

Also anyone experience pressure oscillations on a mechanical gauge? r

Cheers

Carl

Edited by Hedgetrimmer on Wednesday 30th September 12:53

[DCL]

That's probably on the lower side of what I'd like to see, but, if it has always been like that, I'd not be too concerned about it. There can be quite a variation between Duratec engines - particularly if they are fitted with the standard oil pump and relief valve. It is the volume of oil being pumped around that is important and not necessarily the pressure.

The oscillation is something I've seen too. I'm not 100% sure what causes it but I suspect it may be air pockets in the oil galleries that are interacting with the little jets that squirt the bores and causing them cycle on and off.

[edit to add: It is not unknown for some builders to adjust OP relief valves down to reduce power loss]

Edited by DCL on Wednesday 30th September 14:10

[Hedgetrimmer]

Thanks. I managed to speak to Raceline and they confirmed that the 2.3 is very sensitive to shell clearances and can vary on oil pressure, and therefore my readings are ok. They also mentioned that the oe oil pump is massive and the fluctuations are due to oil pressure relief and the volume of oil the pump can scavenge.

[Hedgetrimmer]

Thanks. I managed to speak to Raceline and they confirmed that the 2.3 is very sensitive to shell clearances and can vary on oil pressure, and therefore my readings are ok. They also mentioned that the oe oil pump is massive and the fluctuations are due to oil pressure relief and the volume of oil the pump can scavenge.

[Hedgetrimmer]

I am now not convinced as i went for a longer drive and the pressure settled at circa 38 psi at lowest when holding revs at 4500 but was moving around more than normal under hard acceleration. I thought the oil pressure relief valve might be stuck open so I unscrewed the relief valve bolt and there wasn't a spring!

Therefore:
Should there be one on a duratec raceline sump?
I assume the spring couldn't be injested beyond the pump valve?

The problem is bugging me so your wisdomn is much appreciated.

[DCL]

Any chance you can post a picture of the bolt you undid? The wet sump uses the oe pump and that has the relief valve pressed in - unless the 2.3 is different?

Edited by DCL on Sunday 4th October 22:09

[Hedgetrimmer]

Thanks I'll take a picture later but the bolt is accessible from the outside of the engine at the front on the drivers side just before the engine mount.

[DCL]

Hedgetrimmer said:

Thanks I'll take a picture later but the bolt is accessible from the outside of the engine at the front on the drivers side just before the engine mount.

Sounds like the bolt for the TDC timing peg to me. IIRC, there are no oil galleries on the the right hand side of the engine.

[Hedgetrimmer]

Hi apologies for the delay. You are right, the bolt had nothing to do with oil pressure! I now need to get the sump off and find out whether there is a leak in the pick up pipe or whether the valve needs replacing. The engine is generating some high pressures under acceleration but they drop of when revs are held so I think there must be a problem with oil getting dumped back in the sump. I am not overly concerned as the pressures are still well within tolerance but it's disconcerting.

[BertBert]

I think I would be concerned somewhat if I have understood the symptoms.

you get 38psi at static 4.5 k but lots more at that revs if you accelerate?

How much more? Is it acceleration or when you rev the engine with the car static?

[DCL]

The running oil capacity on the Duratec can be high as the oil galleries that return the oil to the sump hold significant amount of oil in high G situations. But if you are getting to that point with your driving, you should really be fitting a dry sump.

This picture show the the galleries at the top - large and far from 'G' friendly. It really needs all the 6+ L.

[Hedgetrimmer]

Max pressure is 65 psi so not too high when revving to around 7k. I get around 50 psi when the oil is hot when I first lift the revs to 4.5k then it drops back down to 40 psi after a couple seconds if I hold the same revs. It feels like the initial increase in revs generates enough flow to outweigh the pressure valve then the valve kicks in and the valve drains oil back to them dump.

Is the valve a replacement item? I think this or a leak in the pick up pipe could cause the symptoms as there is 65 psi at times indicating that the pump itself and the bearings must be ok.

[DCL]

The relief vavle is pressed in. I've never taken one to bits - just usually replace the whole pump. There's no pick-up pipe as such, the raceline sump connects to the pump with a 'top hat' and angled adapter with a couple of 'o' rings. I believe the 2.3 and 2.0 L Duratec is different angle, so it is worth checking you have the right one fitted.

The Caterham engine (CPT) was fitted with an awful botched adapter wedge and this one caused problems on one of my engines. The Titan version was much better. I would hope yours will be fitted with one very similar.

[BertBert]

Hedgetrimmer said:

Max pressure is 65 psi so not too high when revving to around 7k. I get around 50 psi when the oil is hot when I first lift the revs to 4.5k then it drops back down to 40 psi after a couple seconds if I hold the same revs. It feels like the initial increase in revs generates enough flow to outweigh the pressure valve then the valve kicks in and the valve drains oil back to them dump.

Is the valve a replacement item? I think this or a leak in the pick up pipe could cause the symptoms as there is 65 psi at times indicating that the pump itself and the bearings must be ok.

That seems very odd behaviour. I can't see how a valve would behave to produce that effect.

[Hedgetrimmer]

On further investigation it looks like the Cosworth oil pump may be defective. The engine builder confirmed there was a batch of Cosworth pumps that were built which ended up with defective seals. Overall oil pressure has been fine and the bearings are unmarked.

As the engine is coming out for a new pump I am going to take the plunge and convert to dry sump and sell the current Raceline wet sump set up.

What's the general consensus on which dry sump kit to go for?

Edited by Hedgetrimmer on Thursday 5th November 08:44

[Mitch911]

I went for Raceline on mine, came recommended from Team Leos who know their stuff on these engines

[DCL]

Unless you are a serious racer needing multiple scavenging, I think the Raceline is the sensible choice these days.

[Hedgetrimmer]

Thanks. Raceline DS was high up the list as it is good value and the pump is integral. I always worried about the belt coming off on my R500k.

[Seven Smiles]

The pressures in my Minister wet sump 2.3 are a lot higher, at one time they went over 100 when cold (mechanical gauge) and I still regularly see over 80. It also oscillates quite alarmingly. Both used to worry me but having driven it 25,000 miles I've come to accept that that's how it is and content myself with the thought that if I just had a warning light I'd be none the wiser.

I noted the numbers after I'd driven a few miles
30 PSI idle
50 PSI 2000 RPM
90 PSI 4000 RPM

Mine has the wedge adapter between the engine and the sump, I think that may be the reason for the fluctuation. I didn't know there was an alternative - is it a straight replacement?

Edited by Seven Smiles on Sunday 8th November 13:01