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"slow" Oil Pressure

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#16 RooBoonix

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Posted 27 March 2017 - 06:29 PM

I can recall some Triumphs needing a certain brand of filter to prevent it draining, and have vague recollection of something similar on a B series, but it "should" not be a major problem on an A series with vertical filter bowl that stays full.



I think you're referencing filters with a non-return valve, and I believe some older Volkswagens used to use them (maybe they still do?) but my Dad said unless you got a VW filter then the aftermarket equivalents never had this valve in them. But as you say, the A-Series doesn't need this. I recently replaced the oil and filter on a Mk3 Golf me and Dad have, this had a non-return valve and I soon found this out after trying to fill the filter with oil (and not looking properly!) but found my hand to be covered in most of this oil instead.

Good luck with finding the problem, hopefully it's nothing too serious.

Cam.

#17 need4speed

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Posted 08 April 2017 - 11:27 AM

Update. This morning I removed the pressure switch and attached a test gauge. I started the engine and for a few seconds the gauge read zero then it immediately went to 60psi at a fast idle then at a normal (almost stalling) idle it reads 50psi. I conclude the oil pump is OK. I haven't yet looked at the relief valve.

 

Any suggestions as to what's going on here?



#18 nicklouse

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Posted 08 April 2017 - 01:50 PM

to be honest it sounds normalish.

But maybe the pump is not holding oil as it should when not running.

Which position is the oil filter in? Normal or later inverted screw direct to the block?

#19 need4speed

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Posted 08 April 2017 - 03:32 PM

to be honest it sounds normalish.

But maybe the pump is not holding oil as it should when not running.

Which position is the oil filter in? Normal or later inverted screw direct to the block?

The behaviour is, to me, as if the pump is draining back every time the engine is switched off so, effectively, it has to prime itself. There's not a non-return valve in the oil pick-up, is there?

The filter is what I would call normal in its installation - below the filter head with it axis vertical.

 

The point now is that I know I have enough oil pressure to warm the engine up to normal temperature and give it some revs - something it last had 7 years ago!


Edited by need4speed, 08 April 2017 - 03:32 PM.


#20 need4speed

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Posted 09 April 2017 - 12:09 PM

I took the pressure relief valve out this morning - the spring length is perfect but the plunger won't come out. I even tried turning over the engine to shift it with a bit of oil pressure. Any suggestions as to how to pull it out (arf arf!)



#21 nicklouse

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Posted 09 April 2017 - 12:33 PM

Right it sounds like the relief valve is your problem.

It should come out quite easily.

Now how to get it out.

First buy a replacement. Then you will see what size of tool/drill/tap you will need to use to pull it out. You will need to fit the replacement as it sounds like yours is worn.

#22 need4speed

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Posted 09 April 2017 - 03:31 PM

I got the plunger/cup out and it is quite badly scored.oilvalve.jpg


Edited by need4speed, 09 April 2017 - 04:53 PM.


#23 need4speed

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Posted 24 April 2017 - 12:10 PM

I finally got the new relief valve installed today and there is no difference in how quickly the oil pressure comes up. I am at a complete loss.



#24 GraemeC

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Posted 24 April 2017 - 12:38 PM

I'd agree with your summary that the suction side is draining back.  There was recently an issue with new pumps not having sufficient gasket sealing surface that were giving this exact symptom, but as your pump hasn't been replaced then it can't be that.

Has the engine & 'box been apart?  I would suspect a blown gasket either on the pump or on the pick up pipe.  Or the O-ring seal between block and 'box has failed (less likely if its not been disturbed).



#25 need4speed

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Posted 25 April 2017 - 02:35 PM

As far as I know the engine has never been off the box. This car has had the same owner virtually from new and he's not aware of the engine ever being removed. I ran the engine up to full temperature for at least 15 minutes today and if I switch off and immediately start up again the pressure is slow coming up. Once the pressure is up then it's a solid 60psi. It's an awful lot of work to strip it all to check a gasket on the pump and in over 40 years of mini, I've never met such a failure. Having said that I do agree with your logic.



#26 nicklouse

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Posted 25 April 2017 - 02:49 PM

note the gasket and pump issue is within the last 5 years.

 

I would put it down to a worn pump by looking at the relief valve.

 

just think each bit of metal that made each scratch on it has passed through the pump.



#27 need4speed

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Posted 25 April 2017 - 03:28 PM

It could be worn pump but I've never met a worn pump that produced correct pressure once it got around to it. I haven't tried this, but I suspect that starting the engine and not touching the throttle might never result in oil pressure at all! Basically I'm trying everything to avoid taking out an engine that's just gone back in. :ohno:



#28 nicklouse

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Posted 25 April 2017 - 03:32 PM

don't forget the pump produces more than needed as standard.

the relief valve kicks in at about 60.

 

so it can still be worn and still provide enough oil to keep 60 but as there is wear in the internals it is not holding as much oil as a "new" one.

 

I am still not really concerned.



#29 need4speed

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Posted 25 April 2017 - 03:37 PM

This isn't just a crap oil issue is it. Supermarket quality 15/40. Not my car, I didn't buy the oil.



#30 Dusky

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Posted 25 April 2017 - 04:35 PM

20-50 Will leak out a tad slower, but that's it





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