The Lotus Grand Tourers

As mentioned elsewhere my oil pressure appears to be very very low. The engine is newly rebuilt but showing zero pressure at idle. When the throttle is blipped, the needle moved to the top of the red and then drops down with the RPM. Oil is getting round the engine as when I initially started it there was a demonstration of the inlet cam cover not having been properly tightened down, thus it seems the pump is pumping oil, and if the flow from the cover was anything to go by a reasonable flow rate at least (while not chucking it out it was visibly leaking!) So while I await delivery of an oil pressure test gauge to screw in I am wondering about the pressure relief valve, if this stuck partially open that may also be a potential cause, but the service notes make no mention of it, and I would be very surprised if there was not one. So where is it? can it be got at? The oil pump drawings show a spring in the centre of the shaft but that makes no sense at all, I am wondering if it's under the big brass bung in the oil gallery that goes to the pressure sensor.

Using the search part of the site reveals this link that might be useful
viewtopic.php?f=7&t=11022&start=30

Bash

OK, I have decided to move this to here as my other thread has drifted way off from the original topic.
I have taken the oil pump off, and note two things, the oil pressure relief valve can be opened using pressure from one finger, as it is supposed to stay shut till 80 PSI, I feel that's not right.
The other thing about it I noticed is that there is a lip on the inside outer edge of the annulus, not a great amount but it's there, other than that it looks pretty much consistent with every other oil pump I have looked at on other cars that has been used but was still working just fine. I am thinking I may just replace the whole lot as its in bits and the rotor and annulus are not that expensive from QED

I'm planning to build a jig to mount the oil pump housing on to enable the pressure at which the relief valve opens to be assessed - it won't be for a while yet though. Perhaps you could do the same?

Pete

Having got the rotor off, is it’s supposed to be a very very tight fit on the shaft? I’d rather not take the aux housing off to put the new one on!

I have recently dismantled the oil pump and pressure relief valve.
I was first unsure where the valve is and concerned about using a press to get access to the valve.
Being used to pressing bearings on and off I found that to remove the oil pressure valve the internal spring takes the inertia without moving the retaining cap. I then realised that by compressing the spring to coil bind-up it is a simple job to continue the pressing until the cap releases.
All of this was done simply with my bench vice, using a short rod on the inside of the valve and a socket over the cap to allow this to move outwards.
Very little load is needed as the cap is held mainly by the O-ring, the distributor base once fitted ensures the cap cannot displace outwards.
I replaced the valve spring, very cheap, and noticed it was somewhat stronger than the old one.
Tim Engle has mentioned that if you want more pressure you can insert washers between the spring and end cap.

After all this, I have read somewhere that our engine is designed to run at LOW pressure and high flow, as the manual Rev/pressure rates indicate.
Also I do not know how modern oils perform in our engine.


Dave the cog.

Hi Dave, I have done much the same with mine and now have it apart. Where did you get the new spring from?
I have noticed the witness line round the valve does not go full circle which is a little concerning as that would indicate it is not seating correctly I do have a photo but need to find where the microscope software has put it on the ipad,

The oil pump rotor has to be pressed off the shaft after removing the circlip - you need to remove it from the auxiliary housing to do this. If you decide to remove the shaft make sure there are no burrs around the end of the shaft after removing the pulley - especially where the woodruff key fits - or it will score the housing/bearing as you withdraw it.

Pete

I got the rotor off using a hide mallet and then a puller…seems to have worked, the aux housing is still in place on the engine. Not overly sure how to get it back on, as the woodruff key looks a tight fit..

I obtained the spring from SJS for 6.78 p.s. A907E1323F.

Dave the cog.

As I have my pressure relive valve apart, is the valve seal supposed to fall out with the rest of it? I would have expected it to be an interfraenace fit within the pump body but mine is a very loose fit and doe not hold in place at all. The other think is the witness line of the valve is not continuous leading me to think there is some seating issue. And finally which way round does the sleeve go? (There is a ring of larger holes one end and one smaller on at the other and when it all dropped out I did not see how it was orentated!)

Yep - all the parts come out together. The large holes in the sleeve go at the bottom - nearest the pointy end of the valve.

Pete

Try this one. The parts are as normally located in the housing.

Dave the cog

So the valve seat is not supposed to come out with the rest? (I have 5 parts, not 4!) this is not encouraging, but I guess there is some locktite that will fix the valve seat back in. I have a new rotor and anulus to go in, and a spring on its way along with an olive, gaskets and o-rings for the distributor and relief valve plug. hopfully when that lot is in the oil pressure will exist!