Oil Pressure

I have just fitted a High Capacity oil pump from Burton Power. From cold I get 30 psi but this drops to 10 psi when the car is at idle (80 deg C) after being driven. While driving the pressure stays at 30 -35 psi. I am hoping that I don’t need to change the mains and big end bearings, as there is no mechanical noise to indicate any problem. :unsure:

I have read somewhere that some cars will drop as low as 10 psi on idle, but does anyone else see a drop like this. What does your car run at when hot and then again at idle?

Not sure what oil the previous owner had used, but has anyone noticed any big changes in pressure with a change of oil?

Regards Jack.

Jack,
Most oil warning light switches work on a oil pressure of 5-7lbs (this puts the oil warning light off as long as it maintains this pressure at idle) A T.Cam engine is quite happy with an oil pressure of 30-40 lbs at 3000rpm and 10psi at idle is fine.
I note you have fitted a “high capacity” pump and not a “high pressure” so in my opinion you do not have a problem.
Both my Elans and my Europa drop to approx 9-10lbs at idle (hot)
my Seven on the other hand never drops below 50lbs@ 3000rpm and 15lbs @ idle but this has a modified pump.
I have never noticed great changes with of pressure with oil changes but I have never bothered to experiment with verious types of oil, I am quite sure someone else will tell you “Brand XXX will double your oil pressure” but some of these modern super oils carry a high price and the T.C. engine is after a 40 year old design.
Regards Brian. :rolleyes:

If you are using a modern synthetic oil like Mobil 1 0W40 you will find it is a bit too runny for the old twinc and oil pressure will drop off. You should try to stay with a thicker oil. I use Castrol 15W40 Magnatec and have not problems at all :smiley:

I concur, 39 psi is where one of mine has run at speed for years (and I have to lightly thump the gauge to get it up to that.) Idles “around” 12. I use Castrol GTX 20 w 50.

Thanks for the replies, thats just made me feel a lot better. I will give it an oil and filter change next weekend.

Does the longer Lotus style oil filter make any difference?

Regards Jack.

I’ve had the longer lotus style filter and the shorter one (fram I think). Doesn’t seem to make any difference.

Before I had my S4 in for a re-build it was running an oil pressure in the renge of 40 pounds when warm on regular 10W40. (The re-build had nothing to do with the oil pressure, only the leaks.) In any case, when I added 20W50 the pressure was off the high enmd of the scale when cold.

Several books I looked at specifically noted not to use a thicker oil because this tended to cause leaks.

I expect to get the car back in a couple of weeks and it will be run on 10W30 Mobil One. This will have enough pressure for the engine, while it’s superior lubrication, whichj, after all, is what the oil is used for, will satisfy any of the TC’s oil needs.

Steve B.

[b]QUOTE[/b] (1964 S1 @ Apr 5 2004, 02:13 AM)
I concur, 39 psi is where one of mine has run at speed for years (and I have to lightly thump the gauge to get it up to that.) Idles "around" 12. I use Castrol GTX 20 w 50.

[/quote]
Regarding oil. This last weekend I looked hard to find Castrol GTX in anything other than 15W40. I found Duckhams Q classic 20W50. Do Castrol still do a GTX in 20W50. The only one I found was the Merit which looked a liitle budget.

Mike

I’d be interested in using a castrol oil too. I’ve been using millers classic oil, which seems to be pretty good stuff, but it’s not always easy to find.

You can get Castrol 20W50 with a modern twist - Castrol still make this stuff but with modern additives http://www.castrolclassicoils.co.uk/

Duckhams 20W50 was always good oil and is still available at a reasonable price which is a bonus.

I can’t remember what oil Lotus used to recommend but I bet it was a 20W50. The twink is based on the old pre crossflow Kent engine after all.

Aren’t the modern oils more suited to modern engines which tend to run at much closer tolerances and are also usually oil tight?

John

I’ve been using Valvoline 20W50 Racing. Seems to thin out much less than many of the others I have tried. Started using it in my Esprit S1, much better idle oil pressure (read: more than near 0 that I had with Castrol and others), so I use it in my Elan.

Mike Geiger
66 S3 Coupe’… in Florida where a car spends most of it’s time idling in 90+ F heat.

Hello miked, I’m in the states and can pick up the Castrol in any car parts store, however, Duckhams seems unavailable. I doubt the Lotus would know the difference and they look the same on the driveway…

[b]QUOTE[/b] (1964 S1 @ Apr 7 2004, 02:38 AM)
Hello miked, I'm in the states and can pick up the Castrol in any car parts store, however, Duckhams seems unavailable. I doubt the Lotus would know the difference and they look the same on the driveway...

[/quote]
:laughing:

You’ve hit the nail on the head there.

Thanks for the advice all, I’ll keep a look out for the Castrol and Duckhams 20W 50.

thanks for the advice. I can get Duckhams for ?8.99 so will use this as it is 20W50 and available. I change it very often and believe it has an API rating of SF which exceeded its spec’ in its day anyway. Dont think i will catch much harm. This all started with my friend comenting on GTX and its modern 15w40 rating. I had not noticed it had changed. silly me!

Mike

Hi all, what a mine of information & a good read over the past few months.
Took a Lotus for a test drive, standard twin cam that had a head rebuild in '03, oil pressure showing about 30psi hot running & near zero at idle, didn’t see the oil light come on & didn’t check the oil level, Doh.
What’s the general opinion on oil pressures & suitable oils these days.
Also what is the average price for a bottom end rebuild, stripping & re-assembling it myself, if I need to allow for that.
Any opinions grateful.
Regards
Nick

A standard Elan has no oil light so not surprising you did not see it come on!!!

A typical, hot, well used twin cam will show 30 psi at 3000 rpm and around 10 to 15 psi at idle with a standard 20W50 mineral oil. Below this and its getting time for a bottom end rebuild.

A good synthetic will keep the pressure a little higher when hot and redline polyolester synthetic oil will keep it higher again when very hot but the standard pump relief valve is set at 40 psi show you should not see more than 40 psi.

A bottom end rebuild for a standard Elan is easy and relatively cheap as it is pretty much standard Ford. Its just the add ons that suck you in and cost the money e.g. new water pump rebuild, head rebuild once you pull it off as the head wears quicker than the bottom end etc etc. And then off course when ever you rebuild a twink you are always tempted with the question - how much could a little more power cost :smiley:

cheers
Rohan

Thanks Rohan, guess my eyes are ok, just my mind thats going.
So how about in the UK, anyone done a bottom end rebuild lately?
Nick

Nick I am currently rebuilding a bottom end if I can help let me know.

Hi Richard, thanks for reply, how’s your rebuild going?
I did a full rebuild on a Europa big valve about 20 years ago, with Miles Wilkins having the machining work done & rebuilding the head for me. I then assembled the whole lot with new Dellortos & Lumenition ignition (NAD 191M if anyone knows of its whereabouts), so I would be ok with the practical side of things, its the length of the proverbial piece of string that I need to find out, to factor it into a sensible offer for the car.
Any info greatly appreciated.
Nick