Oil Pressure And More

[Scooter]

Kaju, ain't done much work on a-series mini engines for a long while but here's a couple of thoughts:

Ya seem to have 2 issues - oil leaks, low oil pressure.

1. OIl Leaks

The good news is that virtually all mini engines leak and the even better news is that that is why front sub-frames don't rot out but rear ones do. Main mini leaks come from front of crankshaft, rear of crankshaft, rocker cover, and also out the back of the gear-shift extension.

Looking at your pics it looks like your big leak could be out of the crankshaft rear seal. This can be confirmed by cleaning up the bottom of the clutch housing and leaving it for a while to see if oil emerges from that housing. If oil emerges, its the rear cranskshaft seal crapped out. Very common problem. Flywheel has to come off to get to the seal. Can be done with engine in car but ya have to loosen clutch side engine mount, jack the engine over (need pulling the radiator out),and it's all very fiddly. More good news is that pulling the flywheel gets you into the oil pump area., the pumps driven off the end of the cam shaft. Bad news is that if the oil is leaking from the crankshaft rear seal, it's likely that your clutch is stuffed or is soon going to be stuffed because of oil contamination. so don't delay the investigation.

2. Low oil pressure

Few points, on the Mini oil pressure is a balance between the oil pump output, the pressure relief valve operation, and the clearance on bearings. And I'm assuming here that you've got a nice new filter and a sump of 20w-50 in place.

You're getting a flickering oil light? Don't mess about, get a t-piece and a cheap oil pressure gauge. Stick the t-piece into the block's oil sender holder hole, screw the electric pressure switch into one side and the capillary/sender for the oil pressure gauge into the other. Now you've got two things. a shiny new gauge on the dash that the ladies will really admire and love, and a genuine reading/understanding as to what's happening inside that donk of yours.

What should you see on the gauge ? From memory and In ppsi language and with an older engine, at cold idle about 60ish, at hot idle about 50ish, and when you're running along the road about 60ish.

If you don't get round those sort of figures, first place to look is your oil pressure relief valve. It may be jammed or stuck open and thus allowing high pressure oil to flow back into the sump. Screw it out (I think you have to pull the starter motor off to get to that part of the block, can't just remember) , clean up the plunger and the spring. Pop it back in. (Very common problem on the Mini.)

If that doesn't bring the oil pressure up then you could have a worn oil pump, worn engine bearings or both. The Mini oilpump set-up is real crude as it sucks strained but unfiltered oil and thus can wear rapidly when oil has degraded. Problem is that the pump is behind the flywheel. Once you're there it's easy to replace, though.

However, IMHO, once you get to the stage of replacing oil pumps, you might as well bite the bullet, pull the motor, strip it down and do a quick rebuild with new bearings, rings and pump, You might not even have to do any machining.

Gotta face it, old cars are always going to be on going projects of love.

[miniace]

On a separate note, Is it normal on a mini to have the engine still idling even after it's switched of from the ignition? (I don't have a turbo )

Almost all the time the engine stops 1 to 2 seconds after I've switched off from the ignition. Sometimes even longer.

Two main reasons for that. Either carbon deposit build up in combustion space or advanced ignition timings. (or maybe both). First try the ignition timing by adjusting the dizzy.

MINIACE

[Scooter]

Blimey, mate, what HAVE you bought??? As Miniace says+make sure you don't have spark plugs with extended noses. The a-series engines do not like these, tend to lead to preignition.

Retard the ignition a little bit and see what that does.

Also, what's your idle speed. Too high (above, say 1000rpm), can assist preignition.

Looking at your pics, that's a bash plate under the motor? Found my Minis with plates ran hot cos airflow across sump was diminished and they really liked having an oil-cooler....just something else to think about!

[kaju]

@Sylvi: Thanks.

Two main reasons for that. Either carbon deposit build up in combustion space or advanced ignition timings. (or maybe both). First try the ignition timing by adjusting the dizzy. MINIACE

Thanks will try that with some help.

Blimey, mate, what HAVE you bought??? As Miniace says+make sure you don't have spark plugs with extended noses. The a-series engines do not like these, tend to lead to preignition. Retard the ignition a little bit and see what that does. Also, what's your idle speed. Too high (above, say 1000rpm), can assist preignition. Looking at your pics, that's a bash plate under the motor? Found my Minis with plates ran hot cos airflow across sump was diminished and they really liked having an oil-cooler....just something else to think about!

Scooter thanks for the previous post and this, will try and get a look at the oil leak like you have mentioned. I tried cleaning in the area which I can see but couldn't figure anything out.

The spark plugs being used are Denso K16R-U11 put in recently. The idle speed is somewhere around 800-900 from what I can see. Is that too high? I saw Sylvi also mentioning that it was too high.

Is there any space in the engine bay to put in an oil cooler as well?

Edited May 7, 2012 by kaju