19 replies to this topic

[Richard e]

Hi, 998 cc 1985 City E - original engine, 75k miles, had no work, owned car from new. 180 psi all four cylinders - just checked - drives fine, decent power and not losing water or burning oil. But … it’s spitting oil out of the dipstick hole with dipstick in. I’ve cleaned the crankcase breather and fitted a new rocker cap. I tried a pipe from the dipstick hole to a container placed on the bulkhead- it collects a fair bit of oil, more after a high speed drive. Is it as simple as no effective seal on the dipstick - it’s a fairly loose fit but the plastic seal is intact, or is this excessive pressure forcing oil out (but compression test is good) or am I effectively siphoning oil out by attaching a pipe to confirm that oil is not coming out from somewhere else? Apart from dripping / loosing driveability suggests I am a few more miles from a rebuild. Ta in advance. Richard

[nicklouse]

How are you breathers connected to the carb?

[Richard e]

Pipe into air filter - as factory- out of canister on right off tapet cover - no obvious blockage

[Cooperman]

If you have crankcase breathers and they are not blocked, then the oil coming from the dipstick hole is due to there being no seal where the dipstick enters the hole.

It's not unusual and the best cure is to first of all fit an O-ring onto the dipstick, then make up a small bracket from the lower alternator mounting bracket and fit a spring to the dipstick to hold the stick in tightly. I always do this on performance engines and it works every time.

[Richard e]

 IMG_0016.jpeg   80.4K   27 downloads

[Richard e]

Okay thanks for suggesting- I was bothered that I’d be trapping pressure causing leaks elsewhere.

[Cooperman]

Okay thanks for suggesting- I was bothered that I’d be trapping pressure causing leaks elsewhere.

No, the dipstick hole is not supposed to be any part of the breather system. The dipstick does need to be sealed with an O-ring or rubber washer.

[68+86auto]

IMG_0016.jpeg

 

That fitting on the air filter probably doesn't actually have a hole drilled so you may have blocked the breather. Are you sure it was originally connected that way?

Edited by 68+86auto, 30 August 2024 - 12:09 AM.

[imack]

That breather pipe should be connected to the appropriate port on the carb, not the air filter box. As previously mentioned, the pipe on the airbox is probably blanked off anyway.

[Lplus]

That breather pipe should be connected to the appropriate port on the carb, not the air filter box. As previously mentioned, the pipe on the airbox is probably blanked off anyway.

This - Leyland went away from airbox breather connections long before '85.   The carb should have a pipe set into the body just beffore the butterfly.

[Spider]

Your Mini should have a CCV Crankcase Breather arrangement. When I can get Imgur working again, I'll post a diagram.

Also, how old is the Oil Filler Cap ? There are vented (allowing fresh air in). These do need to be changed periodically.

[Steam]

Most if not all Mini engines need negative pressure in the crankcase which is provided by the carb. It also needs a vented filler cap to allow air in. Blowby and the rotational throw of the crank causes pressure in the crankcase and the easiest way out is the dipstick. There was an attempt to make the dipstick tube hold onto the dipstick tighter to stop this but it was rather like peeing in thw wind.
It doesn't need much, the small vacuum pressure from the carb is enough.

Edited by Steam, 30 August 2024 - 09:43 AM.

[Richard e]

Thanks for comments. Let me look at this again. The pipe into the air filter is open - not blanked off. The crankcase breather comes off the right tappet cove. It’s as factory [bought new] except maniflow exhaust fitted - perhaps they attached the pipe from the crankcase filter which is defo factory to the air filter box in error. I changed the rocker cover cap last weekend. I’ll look tonight.

[Richard e]

Okay I had a good look this evening - yep the pipe into the air filter is a dummy - like a chump I’ve been attaching it to a blank off hole! The pipe on the cab that the breather pipe should attach to was blanked off. I un-blanked it and connected the breather pipe as it should be. Of course the engine then would not run - stalls / won’t tick over and lumpy without revs. I re-blank the carb pipe and it runs fine as before. For some reason the garage that fitted the stage 1 kit deliberately blanked off the carb pipe and tuned the engine in that state - and it runs absolutely fine. I am only pursuing this because of the oil leak issue. So … does any of this make sense and why would the garage do this ( very reputable and not doubting their wisdom).

[lsto]

If the breather is already piped into the air box I'd be tempted just to drill out the blank.
Alot of people blank off the breather tube in the carb for that very reason, it can change the mixture and cause poor running. You could plumb it in then get the fuelling set up. Or keep it as is and drill the air box. Failing that just put a filter on your breather and just have it open to atmosphere, this would be the easiest option although not the best.
Good luck.