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Dodgy Oil Pressure


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#16 Dusky

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Posted 21 June 2020 - 04:29 PM

If a needle bearing was munched up, imagine how much metal went through the engine.

#17 fortythree

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Posted 21 June 2020 - 04:49 PM

Looking at what was left in the gearbox it wouldn't have been too much - all the needles were still in place but they destroyed the surfaces of the first motion and main shafts. A couple of shards may have got through the pickup sieve, though I'm hoping they were all on the end of the sump plug when I did the first oil change after the rebuild! They way things looked in there most of the shrapnel had already been through the system before I pulled the engine. Interestingly, the car ran well and there were no odd noises. The only reason I did the gearbox was because two of the sync rings were shot.

 

I do know I should have gone through the engine and cleaned out all the oil passageways. A two week job turned into six months and I just got tunnel vision :( There were so many things wrong that I should have been doing a complete resto, only I hadn't planned for it and didn't have the time. I am planning on rebuilding the engine next winter, but if it was my car I'd probably be parking it up again now and going through the engine measuring and replacing everything.



#18 Spider

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Posted 21 June 2020 - 09:01 PM

I suspect the engine itself is OK but the pump is worn here.

 

The pumps will pump more volume of oil than the engine 'needs', hence why they have an Oil Pressure Relief Valve.

 

The pressures you are seeing when it's reved seem fine to me, but at lower speeds and idle, the pump seems unable to move enough oil volume, which, to me tends to indicate a worn pump.

 

Also, as you have had gearbox issues and also rebuilt it, some of the 'loose parts' from the failure would have gone through the Pump, as that's unfiltered oil. Also, new baulk rings will shed a fair bit of material in their first 1000 miles or so, also which will run through the Pump.



#19 fortythree

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Posted 21 June 2020 - 09:20 PM

Thanks. I'm hoping the bottoming out will get better with the new valve. Then I guess I'll just have to make sure my wife keeps an eye on the light and hope it doesn't get any worse until winter.

Stupid thing is, I did think about the oil pump when I was working on the gearbox, but never got around to finding out where it's located on a mini. Live and learn I guess.

 

I did think that the problem may have actually been around before the rebuild, but just not bad enough to make the light go on. It may have gotten a bit worse due to the central pickup (slightly more flow resistance), baulk rings shedding and "rebuild debris" - my workspace can get a bit dirty, I'm usually pretty good at keeping things clean, but I do have lapses :)



#20 InnoCooperExport

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Posted 22 June 2020 - 09:20 AM

It´s on the engine, opposite side to the top of the timing cover (the other end of the cam, which drives it). 

 

P.S. I'm a big fan of your hometown, my sister did her PhD there and my other half spent some time doing Postdoctoral research there, spent many happy hours in Neckarmüller over the years. 



#21 nicklouse

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Posted 22 June 2020 - 09:24 AM

Thanks. I'm hoping the bottoming out will get better with the new valve. Then I guess I'll just have to make sure my wife keeps an eye on the light and hope it doesn't get any worse until winter.

Stupid thing is, I did think about the oil pump when I was working on the gearbox, but never got around to finding out where it's located on a mini. Live and learn I guess.

 

I did think that the problem may have actually been around before the rebuild, but just not bad enough to make the light go on. It may have gotten a bit worse due to the central pickup (slightly more flow resistance), baulk rings shedding and "rebuild debris" - my workspace can get a bit dirty, I'm usually pretty good at keeping things clean, but I do have lapses :)

Center pick up will have done a big fat Zero to this.

 

oil pump position is easily found in your Haynes manual  and you would have looked directly at it as you stripped the transfer case off when changing the gearbox.



#22 fortythree

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Posted 26 June 2020 - 08:38 PM

It´s on the engine, opposite side to the top of the timing cover (the other end of the cam, which drives it). 

 

P.S. I'm a big fan of your hometown, my sister did her PhD there and my other half spent some time doing Postdoctoral research there, spent many happy hours in Neckarmüller over the years. 

 

Thanks, I looked up where it was sometime after the engine was in the frame. 

I'm actually just a bit outside of Tübingen and don't get down there much. If your sister was doing here PhD about 15-20 years ago I may have served er a few beers though :)

 

Center pick up will have done a big fat Zero to this.

 

 

oil pump position is easily found in your Haynes manual  and you would have looked directly at it as you stripped the transfer case off when changing the gearbox.

 

 

Yeah, wasn't sure on the pickup. Technically, it will affect flow due to reduced surface area, but I didn't do the maths on how much. My thinking was maybe it was the straw that broke the camels back as far as the pressure switch was concerned. Doesn't really matter, was more of a "why is this happening now but wasn't before". I'll put it down to the initial wear of new parts in the gearbox doing the final bit of damage. 

I looked up the location of the oil pump when I was almost done. I probably did look straight at it when putting the transfer case back on, but I have only dealt with bikes before this and those oil pumps look a lot different. As said before, I just kept trying to convince myself that the engine was fine as it was running well before I pulled it. Just really didn't want to open another can of worms. Hindsight is always 20-20, now I have an unopened can of worms :(

 

Got an e-mail from minispares and the new valve is on the way. Will see if this makes a difference.


Edited by fortythree, 26 June 2020 - 08:40 PM.


#23 nicklouse

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Posted 26 June 2020 - 08:49 PM

Yeah, wasn't sure on the pickup. Technically, it will affect flow due to reduced surface area, but I didn't do the maths on how much. My thinking was maybe it was the straw that broke the camels back as far as the pressure switch was concerned. Doesn't really matter, was more of a "why is this happening now but wasn't before". I'll put it down to the initial wear of new parts in the gearbox doing the final bit of damage. 
I looked up the location of the oil pump when I was almost done. I probably did look straight at it when putting the transfer case back on, but I have only dealt with bikes before this and those oil pumps look a lot different. As said before, I just kept trying to convince myself that the engine was fine as it was running well before I pulled it. Just really didn't want to open another can of worms. Hindsight is always 20-20, now I have an unopened can of worms :(
 
Got an e-mail from minispares and the new valve is on the way. Will see if this makes a difference.


Nope it is not reduced. the pipe is the same diameter. just that in the original it was in the wrong place.



#24 MiniMadRacer

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Posted 26 June 2020 - 09:21 PM

Slightly off topic but back in the day on the racers we used a ball in place of the oil pressure relese cone but we had to cut a coil or so off the spring to stop the pressure hitting over 100 PSI



#25 fortythree

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Posted 27 June 2020 - 07:38 AM


Nope it is not reduced. the pipe is the same diameter. just that in the original it was in the wrong place.

 

 

Yeah, the pipe is the same diameter, but the screen has a lot less surface area (the mesh on the central pickup screen also seemed to be a bit tighter). I'll admit, the resistance from the screen will be small, especially when the oil is warmed up. Like I said, I thought it may have just made the difference from the oil pressure tanking to 11psi, to it tanking to 10psi and tripping the pressure switch. Not that 11psi would be any better, I just would have been blissfully unaware ;)


Edited by fortythree, 27 June 2020 - 07:43 AM.


#26 fortythree

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Posted 27 June 2020 - 07:43 AM

Slightly off topic but back in the day on the racers we used a ball in place of the oil pressure relese cone but we had to cut a coil or so off the spring to stop the pressure hitting over 100 PSI

 

Thanks, I read that method somewhere as well. Looking at Moke Spider's post linked on page 1 the newer system with the cap is definitely the better option. Thanks for the link nicklouse and thanks for the info Moke Spider!



#27 fortythree

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Posted 28 February 2021 - 01:30 PM

So, it's been a while but I thought I should follow up on this.

The mini was parked up for the winter and I needed it out of the garage so I could work on the bikes :)

I pulled the engine again last week to fix an oil leak and put a new oil pump in. Started it up today for the first time and the oil pressure problem is a lot better, but not completely gone.

I haven't had time to check the actual values but I did put a 20psi pressure switch in. The light only seems to go on after idling for a while - and only once the motor is warmed up (idle speed ~800rpm). A quick rev and the light goes off and stays of for a while (at least 1-2 minutes). I'm just going to leave it as is and keep an eye on it. Given that the pressure switch has been swapped out and the light goes off straight away when revved to about 2000-2500rpm, I'm pretty sure I won't be damaging the engine. I just hope it doesn't get too much worse when it gets warmer. 


Edited by fortythree, 28 February 2021 - 01:31 PM.


#28 sonscar

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Posted 28 February 2021 - 02:49 PM

Worn mains and big ends won't get better.Driving it may cause more serious damage.Unwelcome though it is it is really crank out time at least.You probably know this yourself.Good luck,Steve..

#29 fortythree

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Posted 28 February 2021 - 06:41 PM

Yeah, you're right - next winter ;)

I'll check the pressure with a guage, as long as I'm getting around 15psi after a minute or two at idle it'll be fine for the summer. 






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