Jump to content


Photo
- - - - -

oil pressure


  • Please log in to reply
26 replies to this topic

#16 1976 clubamn

1976 clubamn

    1 Gold star

  • Members
  • PipPipPipPipPip
  • 467 posts
  • Location: Shrewsbury
  • Local Club: None yet

Posted 04 July 2004 - 01:27 PM

the picture below showes the lobes of an oil pump.

the check you pump you need to remove the engine, pretty bad if you are not planing to take it out anyway. as has already been said, check your presure with a guage befor you consider an engine out job.

Attached Files



#17 pierce

pierce

    Mini Mad

  • Members
  • PipPipPipPip
  • 170 posts

Posted 04 July 2004 - 01:27 PM

put a new sensor in still the same so how much is an oil pump

#18 Purple Tom

Purple Tom

    Up Into Fourth

  • TMF+ Member
  • PipPipPipPipPipPipPipPipPip
  • 4,921 posts
  • Location: Derbyshire
  • Local Club: TMF

Posted 04 July 2004 - 04:09 PM

they start at about £13 up to about £30, the one for my 1275 is £15. They are easy enough to fit, but getting at them is the trickier bit, you need to have the flywheel/clutch assembly off, then the transfer gear casing (ie big ally casting on the left hand side of the engine as you look at it, which houses the flywheel, clutch and engine-box transfer gears). Once you have this off the oil pump is a circular object at the top left of the block under the head with either 3 or 4 bolts holding it in, and is driven directly from the camshaft by a variety of drives, could be pin, spade, slot or star drive depending on your engine and its age. Its easy to remove and replace, but you will need the right gasket (thin material) when you replace it. I had to make one for my 1098, but its not hard. Fill the new pump with oil and replace it. Some pumps have lock washers fitted, but some don't, depends on the engine again. Then just put everything back together and its job done.

#19 pierce

pierce

    Mini Mad

  • Members
  • PipPipPipPip
  • 170 posts

Posted 04 July 2004 - 06:14 PM

where can I get a spring for the oil pressure relief valve

#20 Sfanatic

Sfanatic

    Learner Driver

  • Noobies
  • PipPip
  • 11 posts

Posted 05 July 2004 - 05:06 PM

To get to the oil pump:
Engine out and flywheel off, then flywheel cover casting off and that gives access to the oil pump.
I think if I was going that far I would change the oil pump for a Metro Turbo pump, change the big end and main bearings and thrust bearings and just check over everything. Also check that the relief valve is not stuck. I had that with a Cooper 'S' unit once just after a rebuild. A small bit of swarf got under the valve and made it jam slightly open. So when it was hot the pressure dropped until I really revved it, then it came back up again. It's worth a good look at this.
As for oil, I never like using 10w40 oil as I don't think it's right for the gearbox or oil pump. A really good oil is the 15w50 from Morris Oils of Shrewsbury. It's called 'MultiVis' and I use it in my rally cars. It's API 'SJ' quality.
The other really good oil for a Mini is Valvoline Racing 20w50.

#21 pierce

pierce

    Mini Mad

  • Members
  • PipPipPipPip
  • 170 posts

Posted 05 July 2004 - 07:22 PM

fitted a pressure gauge the pressure when I start it up from cold is about 50 psi then drops as it warms up but if I rev it it goes right down to virtually nothin

#22 Cooperman

Cooperman

    Uncle Cooperman, Voted Mr TMF 2011

  • TMF+ Member
  • PipPipPipPipPipPipPipPipPipPipPip
  • 23,014 posts
  • Location: Cambs.
  • Local Club: MCR, HAMOC, Chelmsford M.C.

Posted 05 July 2004 - 10:15 PM

Hi Pierce,

Sorry to be alarmist, but I think you've got a problem either with the oil pump and/or, more likely, the bottom end bearings. My advice is don't run it until you've stripped it out and had someone who knows about the insides of 'A-Series' engines have a look at it and do some measurements. If it is a bearing problem you will just damage the crank some more by running it with really low pressure. Remember, on a standard engine the oil light comes on at about 7 psi. To run it at that low a pressure will just cause more and more damage.
Where do you live? I would be happy to come over and take a look if you live in Hertfordshire or East Cambridgeshire, once the engine is out of the car.
Sfanatic is right about the oil. A 20w50 is always right for a Mini. Change it every 3000 miles as well if you want the engine and box to last. New filter every time as well.
I hope this helps.

Peter V.

#23 pierce

pierce

    Mini Mad

  • Members
  • PipPipPipPip
  • 170 posts

Posted 06 July 2004 - 07:24 PM

how much would it be to have a engine recond

#24 pierce

pierce

    Mini Mad

  • Members
  • PipPipPipPip
  • 170 posts

Posted 10 July 2004 - 11:45 AM

put another engine in oil pressure is fine until you rev it then it starts to fall till gets to nothin turn it of leave it for about 30 secs and start it again and the pressure is fine till you rev it again

#25 dklawson

dklawson

    Moved Into The Garage

  • TMF+ Member
  • PipPipPipPipPipPipPipPipPipPipPip
  • 10,923 posts
  • Name: Doug
  • Location: Durham, NC - USA
  • Local Club: none

Posted 11 July 2004 - 02:17 PM

Pierce... I don't understand your last post at all. Are you saying you installed a new engine or a new sending unit? If I understand you correctly, your oil pressure "drops" when you rev the engine? This really is strange behavior. For most engines the oil pressure responds in the opposite manner to what you're describing. The pressure is usually high when the engine is cold and drops when the engine warms. Re-starting has no effect on this until the engine cools sufficiently. Reving the engine increases the pressure until it reaches the set point for the relief valve (which then opens) and the pressure stabilizes.

As others have mentioned, check the relief valve, change to 20W-50 oil, and install a mechanical pressure gauge (at least for a while). Do a Google search for +"Mini" +"oil pressure" +"conversion" and you should find links discussing the "ball bearing" relief valve conversion. Basically the ball bearing out of a CV joint is used to replace the bullet shaped standard relief valve. This virtually prevents swarf from causing the valve to hang open. You need a ball, a new spring, and something to cut the spring to length with. There are additional web sites that will talk about how to make this setup adjustable so you can "dial in" your oil pressure. Be advised that you can not use the adjustable oil pressure relief valve to compensate for engine wear.

Were I you, I'd start by cleaning up the existing relief valve (including using a stone to polish its OD), and I'd install a mechanical oil pressure gauge so I could see what's really going on. If the mechanical gauge shows the pressure is really dropping off toward zero... I would NOT drive the car anywhere until the engine is torn down and inspected.

#26 Dan

Dan

    On Sabbatical

  • TMF+ Member
  • PipPipPipPipPipPipPipPipPipPipPip
  • 21,354 posts

Posted 12 July 2004 - 09:40 AM

Have to agree that it sounds as though your bottom end is worn and could do with an overhaul. Whats the mileage on the unit? Wouldn't try driving it with low oil pressure as has been said. Can't remember if you said what type of block it is, but if it runs with no cam bearings then the cam will chew up the block in seconds with no oil pressure, and then the whole thing is scrap.

Don't put a turbo oil pump in a non turbo engine. They pump a massive amount of oil which normal motors don't need (turbo's barely do). About 60% of oil from a normal pump goes through the relief valve straight back to the sump anyway. If you put in a turbo pump, then most of its capacity will be wasted and that just wastes horsepower pumping oil you aren't using.

If you're going to use a ball bearing relief valve, get the kit from Avonbar Racing. It comes with a genuine Cooper S spec spring (which will still need shortening for a regular motor, you don't need Monte Carlo Rally type oil pressure, but only clip off about 1 1/2 coils.) The correct size ball and a seating cup. The cup is quite an important OE part, as without it the ball rattles about in the oilway quite alot and starts to mark the walls of the valve seat. Eventually the seat is quite useless, and the ball can never seal. Then it starts to take a few seconds to get oil pressure at start up and the motor starts to sound like a Triumph Straight Six.

Personally I always change an oil pump any chance I get. They are dirt cheap really and if you have the engine out, you may as well do it as they are a pain in the arse if they fail shortly after you put the lump back in. Minispares pumps are good, and any pump you buy make sure it's in good order before fitting it. I have had a couple that were siezed solid from the factory.

#27 pierce

pierce

    Mini Mad

  • Members
  • PipPipPipPip
  • 170 posts

Posted 12 July 2004 - 04:41 PM

its ok now dont know what it was the pressure is at 50 psi when I rev it goes up to just over 60 until the engine is really hot then the pressure is at 50ish psi




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users