Elan fitted with a dry sump -advice needed!

[paul356]

A week ago I became the proud new owner of a 1971 Elan S4....the car is fitted with a dry sump and has had some other mods (all about 15 years old and I think carried out by Cosworth). The car has been off the road for a while but had a shiny new MOT (I was a little nieve!).

Ive used the car a fair bit in the last few weeks and it runs well at low speeds but after prolonged (15mins+) motorway use it seems to start burning oil and blowing it down the road....

The oil pressure is running at about 110 psi consistently, I'm wondering if the engine isn't venting properly or if the oil is not returning and as a consequence is running at too higher pressure. Its difficult to work out where all the oil is coming from (Im thinking maybe rear oil seal on crank as the underneath of the car got covered when it did it yesterday).

Has anyone got any experience of twin cams fitted with dry sumps or even know any professionals who do? I obviously don't want to keep running the car as is and would appreciate advice before I strip the system down.

I'm also considering converting it back to a wet sump...any thoughts?

Cheers and happy lotus motoring

P

[elans3]

Hello Paul, sounds like the pressure relief valve isn't working, 110 psi is almost 3 times what the pressure should be (38 - 40 psi). There's no wonder it's all over the underside of the car. Sounds like it's blown the rear crank oilseal, and probably a few more sels / gaskets too.
People even have trouble with the "standard" h/p pump which is rated at 60 psi, in fact I had problems with a car that had such. I changed the pump back to a std one and eureka, most of the leaks stopped.
Check the relief valve, but I would also consider going back to a wet sump, especially if you're not going to use the car in hard competition.
Was this the car that was on Ebay a week or two ago ?
Regards

[types26/36]

Hello Paul, sounds like the pressure relief valve isn't working, 110 psi is almost 3 times what the pressure should be (38 - 40 psi). There's no wonder it's all over the underside of the car. Sounds like it's blown the rear crank oilseal, and probably a few more sels / gaskets too.
People even have trouble with the "standard" h/p pump which is rated at 60 psi, in fact I had problems with a car that had such. I changed the pump back to a std one and eureka, most of the leaks stopped.
Check the relief valve, but I would also consider going back to a wet sump, especially if you're not going to use the car in hard competition.
Regards

While I agree with most of what elans3 says the seals and gaskets are not under direct oil pump pressure (except for the head gasket were the oil is fed to the cylinder head) the oil pump pressure should not be causing the oil leaks, I would suspect blow by on the rings to be pressurising the crankcase and causeing leaks or just normal gasket failure, the rubber oil return tube (head to block) is also a usual place to leak and run down giving the impression the rear crank seal is leaking.

[types26/36]

Just an after thought, IIRC some dry sump pumps have a device to adjust the relief valve in order to set the oil pressure.

[paul356]

Thanks everybody...I will be checking the pressure relief valve over the next few days! It is indeed the car which was on ebay!

P

[elj221c]

Cosworth spec sheet for Mk 12, 13 and 15 dry sump twincams states 60 - 70 psi. The original pumps had an adjuster below the outlet to the tank and beside the outlet to the cooler and filter.

Roy
'65S2

[paul356]

Roy,

Thanks for this, unfortunately I have discovered more horrors so haven't yet been able to fiddle with oil problem! See latest posting under 'rotten chassis'!

Will try just as soon as I sort the suspension turret (new chassis me thinks)!

P