Lotus Elan

Low Oil pressure.

PostPost by: rgh0 » Fri Apr 10, 2020 1:20 am

gjz30075 wrote:
rgh0 wrote:
Now if I do change a pump in the car I disconnected the carb side mount and jack up the engine far enough to do it

cheers
Rohan


Does the end plate still have to come off?


If you remove the mount and jack the engine the pump end plate can stay on

cheers
Rohan
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PostPost by: billwill » Fri Apr 10, 2020 2:40 pm

On a RHS car, if you jack up the carb side of the engine will the oil pump removal be obstructed by the steering column?

Having looked at the diagram, I don't think I quite understand how the relief valve can be jiggled with a screwdriver, as it appears to be horizontal in the exploded diagram.

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PostPost by: Craven » Fri Apr 10, 2020 4:47 pm

Has the idea of a stuck open relief valve been well thought through, for this to be the cause zero oil pressure the bypass must equal or exceed the capacity of the delivery side of the pump. In normal operation the pump will flow sufficient oil to raise the pressure to 40 psi with the relief valve open.
Perhaps removing the spark plugs to get a better pump speed on the starter may provide more information, very unlikely to cause any damage.
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PostPost by: nmauduit » Fri Apr 10, 2020 6:06 pm

Craven wrote:Has the idea of a stuck open relief valve been well thought through, for this to be the cause zero oil pressure the bypass must equal or exceed the capacity of the delivery side of the pump. In normal operation the pump will flow sufficient oil to raise the pressure to 40 psi with the relief valve open.
Perhaps removing the spark plugs to get a better pump speed on the starter may provide more information, very unlikely to cause any damage.


The relief valve should be initially closed, and it only opens at or above 40 psi, then closes again as soon as the oil pressure drops below 40 psi (it does not take long for the pressure to drop when the releif valve opens).
I suppose one may attempt to touch/jiggle the cylinder from its inside area, since the spring is pushing a little something holding it could be dislodged by that - but I would be worried afterwards still (where does the bit come from, what is it made of, did some damage result from this...).
In any case, once the filter has been changed and every easy checks performed, making sure there is pressure or not while cranking without plugs (gauge, at least oil flow to the camshafts) would be my first step.
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PostPost by: billwill » Sat Apr 11, 2020 1:16 pm

Craven wrote:Has the idea of a stuck open relief valve been well thought through, for this to be the cause zero oil pressure the bypass must equal or exceed the capacity of the delivery side of the pump. In normal operation the pump will flow sufficient oil to raise the pressure to 40 psi with the relief valve open.
Perhaps removing the spark plugs to get a better pump speed on the starter may provide more information, very unlikely to cause any damage.


I see I had not really answered this point.

Yes indeed I will do a plugs out spin to get new oil circulating later, but it's not relevant to testing because the engine was running when the pressure went down to zero, so with bursts it was doing at least 1800 RPM, far higher than a plug-less spin would achieve, yet it was showing no pressure on the gauge. As I said above, I hastily turned it off.

Yes indeed I will use a new oil filter when I put it back together, I would do that anyway as a matter-of-course after going to all the trouble of changing the oil.

My understanding from something I read long ago is that the relief valve is designed to be fully capable of dumping ALL of its output back into the sump if the pressure is above the relief setting. The close proximity of the pressure gauge take off to the useful output of the pump, essentially means that a blockage further along the 'pipeline' (such as the cross drilling or the other side gallery) would show the pressure gauge at its relief setting 40psi, not zero. Hence my suspicion that the most likely problem is that the relief valve has stuck in the open position, the spring is not closing it. It's either that or no oil is reaching the input of the oil pump, such as the pickup has fallen off. Checking the relief valve is marginally easier than getting the engine out to take off the sump to check the input oil pipe. :o

The S1,S2 Lotus maintenance manual has a much better diagram (in colour) of the oil pathways than the actual S3, S4 manual.

Meanwhile, because of the virus lockdown, I wait for delivery of parts and flushing oil, before I can really start to do anything on this. The only item that has arrived so far for this car activity is that required last in the activity: 5 ltrs of Millers Classic Sport 20w/50 from Q.E.D. Thank you QED.



~~~~~~~~~~~~~~~~~
Edited... The italic portion added above.
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PostPost by: 512BB » Sat Apr 11, 2020 1:28 pm

Bill Williams' car is a complete car with a possible oil pump problem. Alan Barker says just remove 2 carb side bolts and drop / raise the engine. But a +2 chassis is wider at that point, so is irrelevant.

Perhaps I should have explained better, the circumstances in which I was replacing the oil pump.

The car was a 22k mile from new, 2 owner Sprint, that had just undergone a complete restoration. It needed to be restored because the paint had all cracked and the car had not turned a wheel,for 30 years.

The car had been driven for some 500 miles after the restoration, but low oil pressure, 30 psi., was noted. This was not acceptable, as the car was being sold, so after checking various things, the oil pump was identified as the culprit.

So to those that can carry out an oil pump change on a Sprint without removing a single bolt, I say good for you. And to those who can change a pump on a Sprint by only removing the 2 engine mount bolts on the carb side, leaving the LH bolts done up, I say good for you to. The same with removing the end plate of the pump.

It has been stated that engine mounts can withstand the rigors of the engine being jacked up, and down, without bolts being removed and all the other computations you care for. Well I can tell you, that old stock, Quinton Hazel mounts that were used on the car, stamped with the correct part number, cannot. The rubber used in them is stiff as a board, and the centre plate has virtually NO give at all, compared to modern repro ones, where you can press the centre plate with your thumbs and deflect it a distance. That is why engines fitted with old stock QH mounts rock minimally when reved. So therefore, I prefer to remove bolts, mounts etc, to avoid stressing quality mounts which are hard to find now.

I would also be interested to learn pharriso, how you can jack up, or lower an engine with the original setup of a hard line into a rubber hose for the clutch, without bending the copper pipe. So I undo the pipe from the master. Maybe you don't have an original setup, or maybe you did not have that connected either :roll:

Would I jack or lower the engine with the hoses, choke cable etc. connected? No I wouldn't. The car was restored at that point and no chances were being taken of damaging anything. The radiator was drained and removed. My time is my own, and I do not care how long a job takes, but it is done properly.

At the end of the day, folk will do a job how they see fit.

The car was sold within 2 days of it being on the market, for £57,500, which was a bit disappointing considering the quality of the work.

If I were you Bill, I would pump some oil into the oil galleries from the take off before spinning it over any more. Simple enough to do.

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PostPost by: benymazz » Sat Apr 11, 2020 1:54 pm

billwill wrote: My understanding from something I read long ago is that the relief valve is designed to be fully capable of dumping ALL of its output back into the sump if the pressure is above the relief setting.


This has been my experience... mostly. When I was using conventional oil (Castrol GTX 20W50) on cold mornings (under 40 F), for the first couple minutes or so if I got above 3,000rpm the oil pressure would go above 40- the highest I ever saw was around 60 I think. This, to me, indicates that the relief valve was struggling to keep up. But when the engine warmed up a little this went away.

Since I switched to redline synthetic 20w50 this hasn’t happened. My garage was 25 F last week and I went for a drive and even when the oil was cold my oil pressure never went above 40. There is another variable as well though which is that when I switched to synthetic I also switched oil pumps (engine rebuild). My old pump was the type that I believe is being discussed here, with the paper element that fits in the metal canister. My new oil pump is the newer type that accepts screw on filters. It is possible that the relief mechanism/channel in the old style pump is smaller and doesn’t allow as much flow.

Not that this matters much - I don’t know if the OP is in a warm or cold climate (I’m typing this on my phone which doesn’t slow locations of posters) - and even if they were in a cold climate I doubt they would want to rev the engine (or even start it) with 0 oil pressure. I wouldn’t do it.

As for oil pump removal in situ, I tried last year and I couldn’t do it with the engine bolted in on my S2. It came really, really close but it just wasn’t having it. If you unbolt both engine mounts it should come out with relative ease.

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PostPost by: alan.barker » Sat Apr 11, 2020 1:56 pm

Hi Leslie have a nice Easter,
thanks for the reply and as you say i removed the Oil Pump on a 1970 +2S. I don't know if a +2 Chassis is wider at that point. I sold the last +2 i had a few years ago that was a 1973+2S130 so i can't measure both to compare.
Maybe there is someone who owns an Elan and an Elan +2 who can compare the width of the two Chassis in the area of the Oil Pump.
The difference could well be why we are getting different stories.
To be honest i don't fancy crawling under my Baby Sprint to see if it's possible like i know it is on a +2.
I prefer to sip some good French red Wine + Cheese for Easter(Pâques). :mrgreen:
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PostPost by: pharriso » Sat Apr 11, 2020 3:35 pm

512BB wrote:I would also be interested to learn pharriso, how you can jack up, or lower an engine with the original setup of a hard line into a rubber hose for the clutch, without bending the copper pipe. So I undo the pipe from the master. Maybe you don't have an original setup, or maybe you did not have that connected either :roll:


Leslie

Why do you think the Rubber hose is there Leslie? Answer to allow relative motion between objects that move, like body to engine/transmission assembly. The hard lines are between points that do not move & were not strained by jacking the engine up on the RHS.

Back to BillWill's issue, I've read on here (from people sharing information on how to solve issues, not telling others what can't be done...) that you can remove the pump end plate, pack with petroleum jelly & then the pump will prime. Worth a go?

When I changed my oil pump it did take a while to create pressure & made me nervous... maybe as someone else has suggested remove the plugs & try spinning it over fast?
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PostPost by: joe7 » Sat Apr 11, 2020 5:39 pm

Not to sound like a dolt but doesn't everyone fill the filter before installing it?
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PostPost by: The Veg » Sat Apr 11, 2020 6:46 pm

alan.barker wrote:I don't know if a +2 Chassis is wider at that point.


I don't either, but in my Plus 2 I had to nudge the engine aside by an inch or so to get the pump out.
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PostPost by: vxah » Sat Apr 11, 2020 11:04 pm

I was just thinking, to rule out that the pickup pipe has fallen out. Pop out the spark plugs and spin it over with no filter fitted, it should lubricate your shoes nicely meaning it’s pulling oil up from sump..
I just rebuilt a YB engine and was able to get oil coming out of the gauge take off just by turning it with a spanner on the front pulley!
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PostPost by: billwill » Sat Apr 11, 2020 11:19 pm

512BB wrote:
If I were you Bill, I would pump some oil into the oil galleries from the take off before spinning it over any more. Simple enough to do.

Leslie


Good idea, I'll do that when the time comes. It will be a bit tricky as the only tool I have to do anything like that is an old-fashioned trigger-pump oil can.

This sort of thingy:
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PostPost by: billwill » Sat Apr 11, 2020 11:21 pm

vxah wrote:I was just thinking, to rule out that the pickup pipe has fallen out. Pop out the spark plugs and spin it over with no filter fitted, it should lubricate your shoes nicely meaning it’s pulling oil up from sump..
I just rebuilt a YB engine and was able to get oil coming out of the gauge take off just by turning it with a spanner on the front pulley!


Good idea. I'll put some old sandals on for this :D
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PostPost by: alanr » Sun Apr 12, 2020 1:37 am

Thoughts..
I haven't seen anywhere in this long rambling thread where the engine oil pressure has been double checked and confirmed that the oil pressure is actually low or non-existant. Just relying on what the gauge in the car tells you is not good enough for analysis of the problem.
I would take the gauge sender switch on the block out and connect up a mechanical hand held gauge and start the engine and definitely confirm that you do have an oil pressure problem before going any further!

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