Oil (not) Pressure

[oliver90owner]

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This lead to a common modification to install pre-oiler pumps. Run an electrical pump for 20-30 seconds to lubricate the cylinders before starting.

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Standard practice on heavy machinery. In the earlier days, large bearings, supporting slow turning shafts, were oiled by ‘oil rings’ which dipped in the lubricant and were rotated by the shaft. Operators manually spun the rings before starting the machines to prime the lubrication for the bearings.

First high pressure pumps, at the factory where I worked, were fitted for a ball mill, which weighed over 300 tonnes (at least). Low pressure pumps took over the lube-duty once the mill had started. That was in ‘75/‘76.

[Nickol]

A"search" brought me to this topic which i would like to latch onto.

My 1098 1969 Traveller gets summer usage and hibernates during the winter months - it gets quite cold sometimes here in the hills at 600m up. Anyway, I did have some trouble starting it a week or so ago - it just would not fire up and the starter ( recently replaced in another topic!) would spin and stall, as if the engine wanted to fire but could not. I left it for a week as, like you in the UK, it got cold again.

Today in the warmth of 12°, had another go and after cleaning some dampness from inside the Distributor cap, it finally roared into life , idling like a purring cat. Went for a 10km drive around to test everything and for the last 3 or 4 km or so, the oil pressure from the warmed up engine was only reading 20psi at about 60km/hr.

Before, last year, the gauge would read about 60 psi after a cold start ( which it did at foirst this time too) and upon warming up show about 35psi. I have asked about this on the forum before because I know this is not ideal and the consensus of opinion was to carry on but maybe sometime soon, rebuild the engine.

Having read the comments in this thread, perhaps I should replace the oil filter? Are there other items worth checking? There do not seem to be any oil leaks and the oil level is indeed full.

[philthehill]

Check that the oil pressure relief valve is not sticking.

[Nickol]

Thankyou - I will check.

[Nickol]

Oh dear,

Before removing the oil pressure relief valve to have a look inside, I went for a short drive . The oil pressure warning light extinguishes itself quite normally very quickly upon starting the engine. The gauge measured about 20psi and despite reving the engine up a bit, did not climb any higher. Perhaps the gauge has become faulty I thought? No such luck. Indeed it measured less and less at time went on. After about 15km at traffic lights the oil pressure warning light itself came on and stayed on.
I stopped the car and switched off the engine for 2 minutes or so before restarting it. There was no light so I nursed it home, stopping a couple of times when the light did come on again.

I have just removed the oil pressure release valve as suggested and measured the length of the spring. It is 71,5mm. The manual says it should be no less than 73mm. I cannot imagine that this 1,5mm discrepency is the culprit.

I am wondering what the significance is of stopping the engine to allow the oil back into the sump which in turn at least gave a minimal pressure, albeit not nearly enough. Oil pump failure? How can this be checked?

[oliver90owner]

Oh dear,

Before removing the oil pressure relief valve to have a look inside, I went for a short drive . The oil pressure warning light extinguishes itself quite normally very quickly upon starting the engine. The gauge measured about 20psi and despite reving the engine up a bit, did not climb any higher. Perhaps the gauge has become faulty I thought? No such luck. Indeed it measured less and less at time went on. After about 15km at traffic lights the oil pressure warning light itself came on and stayed on.
I stopped the car and switched off the engine for 2 minutes or so before restarting it. There was no light so I nursed it home, stopping a couple of times when the light did come on again.

I have just removed the oil pressure release valve as suggested and measured the length of the spring. It is 71,5mm. The manual says it should be no less than 73mm. I cannot imagine that this 1,5mm discrepency is the culprit.

I am wondering what the significance is of stopping the engine to allow the oil back into the sump which in turn at least gave a minimal pressure, albeit not nearly enough. Oil pump failure? How can this be checked?

If a leaking PRV, I would expect the pressure to rise when revving the engine with cold oil. Therefore, my immediate diagnosis would be the oil pump. I don’t know how (or even if) it can be checked in situ.

Likely engine out, check crank bearings and change the pump (if nothing else is found awry). Once primed a new pump should provide plenty of pressure at cranking speed (with the spark plugs removed).

Plain bearings are generally safe as long as the pressure remains above 5psi. The oil warning light is likely extinguished (or lit up) at around 7psi (0.5Bar). Once the light comes on the pressure could be anything between 7psi and zilch, of course

[philthehill]

You have removed the oil pressure relief valve and checked the length of the spring. Was there any scoring on the valve? If there was that could cause the valve to stick in the open position. The oil pressure relief valve is prone to sticking and that is why many choose to fit a ball valve in place of the factory fitted valve. Calvert recommends drilling some holes in the valve cup to reduce the chances of sticking.
As regards checking the serviceability of the oil pump you can only check the oil pressure not the flow. The oil pressure will give some indication of the condition of the pump but will not tell the whole story.
There has been reports of oil pump to block gasket failure which would give the symptoms you are experiencing.
Also there have been cases of the oil pump rotor/impellor coming loose on the drive shaft. Latterly rotors/impellors are interference fitted on the drive shaft. I always recommend that oil pump rotors/impellors which are fixed to the drive shaft with Woodruff keys are if possible obtained and fitted.

oil spring.JPG (97.83 KiB) Viewed 3182 times

You may have to take a coil or two of the spring when fitting the ball. The benefit of fitting the ball is that it does not and cannot stick.

[Nickol]

Not good news for me.

I took out the oil pressure relief valve and cleaned it up. There was no evidence as far as I could see of any scoring, only a shiny section on the plunger where it had obviously been rubbing against the housing.

Putting it all back was a challenge as there is hardly any room to get a hand around the plug to thread it in. It took many attempts, after having removed a bolt on the starter motor to allow a socket to sit square on.

All in vain however - no change to the oil pressure. Still hardly any. Tja, I think the engine has to come out.....

[Nickol]

some further thoughts.

1. Is it possible after a 6 month lay off, that the oil pump needs repriming? I suppose I can do this for what it is worth.

2. When the car went into its annual winter hibernation, the oil pressure was not optimal but acceptable. i.e 35 - 40 psi @ 70 -80 kmh. Can it be that quasi overnight, the pressure has gone? I would expect only a gradual reduction over time/usage

I can take the engine out of the car and theoretically strip it down to check components but in truth I really do not know what I am doing and items like the camschaft, crankshaft and pistons ( and perhaps a rebore as well) replacement can be problematical getting spares from UK due to the Brexit restrictions. It would be better, thinking aloud for the moment, to come over to England and pick up an exchange unit already assembled.
Are there reliable people doing this apart from the excellent ESM?

[philthehill]

As you have oil pressure of sorts shows that the oil pump does not need priming.
That said you can prime the oil pump to be absolutely certain.
To prime the pump I would take out the banjo bolt of the oil transfer pipe (between block and filter head) and fill the pump through the banjo bolt hole. If you can turn the engine backwards whilst putting oil down the hole so much the better. Once you have put sufficient oil down the banjo bolt hole refit the banjo bolt not forgetting the copper washers and then spin the engine over with the spark plugs removed and see what the oil pressure is. All you can do is try.
If you feel that your skills in stripping and rebuilding your 1098cc 'A' Series then I think you are right to consider a ready to fit reconditioned unit.
I would try ESM first.
You may feel competent enough to purchase a reconditioned short motor (block. pistons, conrods, camshaft etc) and rebuild the motor from there.
https://www.morrisminorspares.com/engin ... y-p1238990
https://www.morrisminorspares.com/engin ... s-p1238974
https://www.morrisminorspares.com/engin ... it-p830266
https://www.morrisminorspares.com/engin ... s-p1238983
Rebuilding a short motor is not difficult and can be done over a weekend. Just make sure that you have the workshop manual, gaskets and other parts required to hand before rebuilding. When you strip the engine you will soon see what new parts are required to rebuild the engine.
If you do rebuild a short motor you will look back and ask yourself what all the fuss was about. Do not forget we are here to help with any problems you come across.
Phil

[Nickol]

Thankyou Phil for spending the time to give me such a detailed answer.

I did do a partial rebuild on my Triumph Herald engine 3 or 4 years ago, although essentially it was just replacing the crankshaft. I do still have the engine crane and engine stand from then. Always my concern however, when looking at Youtube videos of people with nice workshops, tools and experience, is not doing the work properly through inexpereince (or incompetence ) and/or finding I need some special parts in a hurry Thus , my tendency for the moment is to use a completed short motor and perhaps get a new head for lead free fuel as well.

This will have to wait for a bit. Have some other things to do first.

[Nickol]

I thought I had a spare oil filter in my store but no. It is my last resort/attempt before having to remove the engine from the car to examine it.

Have ordered a new filter locally but am not expecting any miracles once I change it. Even if the the pressure is restored, which I am doubtful of, the engine will come out anyway, albeit later this year rather than now.

The plan is, as Phil has suggested, to dismantle and examine the block myself. The crankshaft can be measured for ovality, which I have done before on the Triumph. This may be reground locally or through the normal UK suppliers as an exchange unit. A replacement camshaft would seem like a good idea as a matter of course whilst the engine is out. Only the pistons are new ground for me. They may have already been subject to a rebore, I do not know yet: in which case , if they are already + 0,040, there will be a problem.

I will report on a new thread when the time comes.

[Nickol]

I would be grateful for an explanation.......

The replacement Mann oil filter arrived at the weekend and I have just taken the old one off ( spin on type) . Even though the oil as shown on the dipstick is relatively clear, the old oil filter oil was black, very black. I screwed the new one in and started the engine.



I have got oil pressure again! 60psi on fast tick over on a cold engine; just like it always was. Why? How? Bin überglücklich.

[StillGotMy1stCar]

I’d be cutting the old filter open, to have a look inside for the clue/blockage.
Please post a photo of what you find.

Regards John

[geoberni]

I’d be cutting the old filter open, to have a look inside for the clue/blockage.
Please post a photo of what you find.

Regards John

I would too. Sounds like a filter blockage.

[svenedin]

The fact the old filter was full of very black oil suggests it was doing its job very well. Perhaps the filter then became blocked allowing oil to bypass the filter. Presumably the spin on filter has some kind of bypass? The original Purolator does. So the oil pressure would rise too high due to the restriction of the blocked filter and then bypass opens and the oil pressure is then too low? Or the bypass valve was permanently stuck open. I'm guessing really!

Stephen

[Nickol]

full of crud, which means I have not changed it for ages. Cannot remember why not as the oilis regulary changed.

IMG_1457.JPG (432.82 KiB) Viewed 1590 times

[Nickol]

The fact the old filter was full of very black oil suggests it was doing its job very well. Perhaps the filter then became blocked allowing oil to bypass the filter. Presumably the spin on filter has some kind of bypass? The original Purolator does. So the oil pressure would rise too high due to the restriction of the blocked filter and then bypass opens and the oil pressure is then too low? Or the bypass valve was permanently stuck open. I'm guessing really!

Stephen

Yes, I would like to know that too.

[svenedin]

full of crud, which means I have not changed it for ages. Cannot remember why not as the oilis regulary changed. IMG_1457.JPG

Very naughty! Especially as changing a spin-on is so easy! Perhaps you changed the oil but not the filter because you did not have the spare you thought that you had and you had intended to order one?

Stephen

[Nickol]

Very naughty! Especially as changing a spin-on is so easy!

Stephen
[/quote]

Getting it off can sometimes be a problem. But yes, very remiss of me. I really cannot remember why it never got changed. Probably due to spares.