oil pressure drop in corners: a classic I know but ...

[Miura]

Hi Guys, old and well worn topic I know, but I would like help with diagnostic confirmation please

 

The story goes:

 

freshly reassembled 1800K

wet sump, no foam

Appolo

engine being run in with mineral oil

 

good and solid pressure in the straights but in tight corners at moderate speeds, pressure drops sharply to warning levels ( but I already have 7.5 l there and the level seems to be around the max - it is difficult to check with the apolo as you know)

 

- problem with the pick-up pipe clearence with the sump

 

As I only have one day to fix the issue before my trip to France, good advice on what else to consider when I drop the sump gratefuly received.

 

[PAUL MARRIOTT]

Have you changed the guage as well, if so you might just be seeing what has always been there.

 

When I changed to SPA guages a couple of years ago I noticed the dreaded surge for the 1st time.

 

1 bar = 14.5psi which is very low!!

 

Paul M

[shn7]

Hi Thomas,

 

If I've got the right person then I would have a chat with JH as IIRC he helped build the engine and will have intimate knowledge.

 

It could also be a sender or wiring problem giving false readings of course, that's assuming the std. CC set up and not a mechanical guage.

 

Good luck.

 

 

 

Steve.

Sussex (West) AR

Not forgetting Percy the Polar Bear

[Miura]

Steve, I did that bit (reassembling pick-up/ sump etc ...)so I am the one who should know 😬

 

paul : all instruments are identical to what they were before i.e less than adequate Caterham standard issue and should be heavily damped so I am fraid ther is something there that wasn't there before

[shn7]

Aha I see. I should say I was in no way indicate JH could be to blame

 

Given the wiring to the sender will have been disturbed during the rebuild I would consider this as a cause. Cornering forces affecting a bad connection or piece of wire only holding together by a strand or two. That or the sender.

 

Steve.

Sussex (West) AR

Not forgetting Percy the Polar Bear

[PAUL MARRIOTT]

No easy answer then but I would start with checking terminals and wiring, you never know something might be stressed, before dropping your sump.

 

Paul M

[PAUL MARRIOTT]

SNAP ❗

[Miura]

Steve, oh yes I am sure he is reading 😬 😬

by the way the new engine is superb ( honnest )

 

I need to do an oil change before the RR session anyway so dropping the sump is not an issue in itself (I have one full day available to sort out deyails - i.e. for "polishing" 😬) I will check wiring first to eliminate this as a cause

[Mick Day]

Thomas

 

You need to check there is some clearance between the oil pick-up & the bottom of the sump. If you can see witness marks on the sump pan then there is not enough clearance.

 

To ensure this it helps if you give the bottom of the pick-up a few blows with a hammer & drift in between the 3 pips. I used a big screwdriver as a drift.

 

When I removed the foam I also fitted a Hellier Baffle which kept the OP above 2 bar in all conditions. However I did modify the pick-up as recomended.

 

Good luck.

 

Mick

 

Edited by - Mick Day on 9 Jun 2008 16:27:44

[Miura]

thank you all

[Willie.]

Any particular corners? Left or right handers?

 

I was getting this and removed the sump gasket. Now I don't get it. See here for the bigger explanation and the responses.

 

By all means look into electrical stuff, but I think you're being hopeful (I was hoping it was water in the sender too). It'll be surge, and it will knacker your bearings if you don't get it stopped.

 

Willie

[Mick Day]

Oh yes forgot to mention the DVA sump gasket mod! V important! Too big holes drilled into the gasket over the oil pick-up pipe.

 

Edited by - Mick Day on 9 Jun 2008 19:28:52

[Richard Price]

(that would be easy but I already have 7.5 l there and the level seems to be around the max - it is difficult to check with the apolo as you know)

 

It does sound like oil surge to me. If it were the oil pick up, then it would happen on straights as well as corners.

 

I think the oil level may well still be a little low.

Are you checking the oil level with the engine running? If not, then the oil level will look higher as the oil drains back out of the apollo tank.

 

If it's a new engine build, then it will take more oil than a simple oil change. More like 8 Litres.

I'd double check the oil level with the engine running and hot.

 

 

 

Edited by - Richard Price on 9 Jun 2008 21:46:20

[Miura]

Mick - gasket is modified already

Richard - you may well be right - I was checking hot and running (20 minutes at least) the problem is that it is very difficult to get a consistent reading : it will say full , then 3/4 full, then over filled : drives me up the wall 😬

[Colin Mill]

The "hot and running" thing drives me up the wall. I had a Jag with an auto box that required this method to check the ATF level and you could get any reading you liked. In the end I was told about the two handed technique of having someone turn off the engine and you plunge the dip stick in very briefly just as the engine comes to a stop.