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oil psi drops
https://www.ausmini.com/forums/viewtopic.php?f=2&t=77967		 Page 1 of 2
Author:  Kennomini [ Wed Aug 08, 2012 10:20 pm ]
Post subject:  oil psi drops
This is my replacement 1100S motor.
It looks like my oil psi falls the longer I drive the mini. When cold it sits around 60psi when the engine warms up it's around 40psi but after that the gauge starts to drop worryingly to 20-15psi while driving and down to 5psi at idle :shock: . It isn't affected by engine temp at this stage (after about 30min driving) I've had the engine temp right up and right back down, the oil psi stays low.
The engine did have a oil cooler in it's previous car but i have not ran it with the cooler in my car and I'm using KMX 20-50 with 1L of castrol 20-50 although my old engine never had a problem with mixing these oils and it ran between 40 and 80.
Would refitting the cooler help?
I should add I still drive it but I feel like it's a bad thing waiting to happen, the engine seems fine and I cant tell any difference in the engine through the different psi's, the oil looks nice and clean on the dipstick, new oil & filter, the oil warning light has never come on while the engine is running.
Author:  simon k [ Wed Aug 08, 2012 10:32 pm ]
Post subject: 
that's what KMX was doing in my current motor, just didn't maintain pressure, though never went that low. I went to Fuchs Formula 60 - never drops under 50psi

but.... if it's an old & unknown motor (unknown to you, no matter how good the previous owner said it was) then maybe it's just time it had some bearings put through it
Author:  drmini in aust [ Wed Aug 08, 2012 10:41 pm ]
Post subject: 
I currently run Valvoline Classic 20W/50- on the Rylstone gig last year, my 1412 sat on 75psi all the way up there and back. No cooler. Was a fresh motor though.

What relief valve spring is in it? You could pack it out a bit (say 3mm) to see what happens, or fit a Cooper S spring (are stronger than the old common A series ones).

Could also be the relief valve plunger is worn- I use a 9/16" steel ball in my motors instead.
Author:  Kennomini [ Thu Aug 09, 2012 6:26 pm ]
Post subject: 
I might try an oil change on the week end.
Hey Doc what's involved in the stuff you suggested.
Author:  drmini in aust [ Thu Aug 09, 2012 7:16 pm ]
Post subject: 
Kennomini wrote:
I might try an oil change on the week end.
Hey Doc what's involved in the stuff you suggested.

1. Make sure the spring is straight, or get a new Cooper S one.
2. Pinch a CV ball (9/16") or go buy a new one from a bearing shop.
3. Grind a chamfer inside the best end of the spring so it sits on the ball better. I use a pointed stone in the die grinder. It's not essential if you can't do it.
4. Cut a piece of smooth 5/16" or 8.0m steel rod 40mm long, deburr the ends and put it inside the spring. This stops the spring bending and pushing the ball sideways off the seat (with instant oil pressure drop).
5. Remove the old relief valve plunger. I use a 10mm dynabolt, put it inside the plunger and then do the nut up a bit. Then you have a handle to pull the sucker out with. But sometimes they come out easy with your finger (if the right size).
6. Assemble it all into the valve, refit the cap, start engine and check pressure. If it's too high, trim 2mm or more off the outer end of the spring.
I run mine @ 70-75psi hot from 2500rpm up. Cold, it's ~90psi... :D
Author:  michaelb [ Thu Aug 09, 2012 9:28 pm ]
Post subject: 
IT does sound like you have a problem, either engine bearings or pressure relief valve is worn?
A new engine should have 75 lb when cold and during highway driving, above 3000rpm, and a minimum of 25lb at idle when hot, although my new engine is still idling with 40-50lb when warm
Author:  Irish Yobbo [ Fri Aug 10, 2012 6:44 pm ]
Post subject: 
This might be an obvious one, but it could be the oil pump too. If you've had anything break in the gearbox the swarf can make it into the pmup and wear it down. They're very robust, but they can wear out, and I have heard of the shafts breaking too.

Id say an oil change should be the first on the list.
Author:  CARTER_GT [ Sat Aug 11, 2012 12:24 am ]
Post subject: 
At hay this year I ran the last half of the Khana with less than 5psi... Between 3 drivers hahaha somehow survived! Then got a loose fanbelt and snapped the handbrake out of the floor during the heroes. Man I had alot of problems that day. Shame as when it ripped out I was infront of rid shaw who went on to win the event :wink: :lol: always next year :)
Author:  AWOODY [ Sat Aug 11, 2012 9:46 am ]
Post subject: 
got a mate who is having the same problems ! still searching for answers.
Author:  Kennomini [ Sat Aug 11, 2012 7:02 pm ]
Post subject: 
I meant to swap the oil today but didn't get a chance, I'll hopefully get it done tomorrow and see what that dose.
Author:  TheMiniMan [ Sat Aug 11, 2012 10:02 pm ]
Post subject: 
Hhhmmmm,,, doesn`t sound good kenno

yeah maybe try an oil change & the oil pressure relief valve , but im not too sure it will fix it
Author:  Kennomini [ Mon Aug 13, 2012 7:15 pm ]
Post subject: 
Changed the oil on Sunday (from KMX to Penrite HPR30) and went for a drive, it did help raise the level by 5psi when hot. Picked up a new spring this arvo so I'll try and swap that next weekend, fingers crossed it fixes the problem.
Author:  michaelb [ Mon Aug 13, 2012 7:20 pm ]
Post subject: 
I'm a bit concerned about the HPR30? I would have used 60 grade if I was trying to raise the oil pressure
Author:  drmini in aust [ Mon Aug 13, 2012 7:37 pm ]
Post subject: 
michaelb wrote:
I'm a bit concerned about the HPR30? I would have used 60 grade if I was trying to raise the oil pressure


HPR30 is a 20W/60, I think. Been years since I used it... it sludged inside my rocker cover in 1000 miles. :cry:
Yep I was right- http://www.penriteoil.com.au/products/e ... um_mineral
Author:  Kennomini [ Mon Aug 13, 2012 8:07 pm ]
Post subject: 
Yep 20/60
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