cg13 powered mini no oil pressure when hot
- Thread starter tommmtom
- Start date
frank
Club Member
its usually the expander for the rings tom, there are little feet on the expander that exert pressure on the rings against the cylinder wall (arrowed ^) so when 1 section of the ring wears a couple of thou more than another section, the feet are held away from the ring in either the upper or lower ring.
so you end up with the rings having only small contact points around the bore (and areas of daylight showing where they dont make contact)
i got round it by making sure the lower ring had more wear (which means the upper ring has more feet pressure) and by stretching the expander slightly, so that the piston need 6kg to move it up and down the bore (oil rings only)
OP
OP
had an interesting little development today...i put a funnel shaped piece of metal on top of the gauze on the throttle body (small hole of funnel against gauze) and then put the silicone pipe and air filter back on. It picks up from idle pretty much as is should now!! also i have less induction noise & it SEEEEMS to have more low down grunt 
I know the thread has been dormant for years but I have much the same problem as in the original post even including the install in a mini (which might be part of the problem).
Good oil pressure when cold, maybe a little high, about 70 at 3000rpm or so about 50 as it heats up further, cool oil pressure @ idle is decent @ about 20, but after a long run at freeway speeds oil pressure @ idle can be 0 on the gauge.
At these freeway speeds the rpm are @ about 3800rpm and could be for upto a couple of hours. I've upgraded the radiator as driving @ 110km/hr particularly added to how often the fan comes on and for how long. The heat and oil problems are I'm suspecting related as both would seem to be related to rpms above 3500 for extended periods, I can fang the car for a bit and it will put the rad fan light on but cool down relatively quickly.
Suspecting the engine might be tired I have tried 10W50 instead of 15W40, hot idle pressure comes up from 0 quicker with a few revs but still goes to 0, the oil light has not come on ever.
I'm thinking rpms above 3500 might be heating up the oil and the cramped engine bay and an exhaust running near the sump means the oil never gets the chance to cool as it might in a standard install.
This is effecting the cooling system as there's heat in the oil that the radiator can't effectively remove so the engine stays hot.
BTW the oil pressure sender is read from the front of the block.
Any thoughts before I look at fitting an oil cooler? I agree with comments for Tom's mini the oil pressure relief valve might be stuck open and causing similar issues.
I've got an infra-red thermometer on order so I'm going to try and get an idea on how hot the sump is getting.
What generally makes oil temperature climb?
Good oil pressure when cold, maybe a little high, about 70 at 3000rpm or so about 50 as it heats up further, cool oil pressure @ idle is decent @ about 20, but after a long run at freeway speeds oil pressure @ idle can be 0 on the gauge
.At these freeway speeds the rpm are @ about 3800rpm and could be for upto a couple of hours. I've upgraded the radiator as driving @ 110km/hr particularly added to how often the fan comes on and for how long. The heat and oil problems are I'm suspecting related as both would seem to be related to rpms above 3500 for extended periods, I can fang the car for a bit and it will put the rad fan light on but cool down relatively quickly.
Suspecting the engine might be tired I have tried 10W50 instead of 15W40, hot idle pressure comes up from 0 quicker with a few revs but still goes to 0, the oil light has not come on ever.
I'm thinking rpms above 3500 might be heating up the oil and the cramped engine bay and an exhaust running near the sump means the oil never gets the chance to cool as it might in a standard install.
This is effecting the cooling system as there's heat in the oil that the radiator can't effectively remove so the engine stays hot.
BTW the oil pressure sender is read from the front of the block.
Any thoughts before I look at fitting an oil cooler? I agree with comments for Tom's mini the oil pressure relief valve might be stuck open and causing similar issues.
I've got an infra-red thermometer on order so I'm going to try and get an idea on how hot the sump is getting.
What generally makes oil temperature climb?
Thanks frank, I agree there doesn't seem to be any downsides to fitting an oil cooler except the cost and it should make the whole thing more reliable, I'm building a CG10DE piston high comp engine so I want to look after that engine.
