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Crank case suction problem
https://www.ausmini.com/forums/viewtopic.php?f=2&t=73565		 Page 1 of 1
Author:  bluewhitecoopers1968 [ Sat Oct 15, 2011 6:59 am ]
Post subject:  Crank case suction problem
Hey guys,

I run my car in hillclimbs and sprints so it gets a hammering in the engine dept. During an event the engine refused to idle and dumped an amount of oil from the back of the engine. Couldnt isolate the leak as it only seemed to happen at max revs.
Engine seems to run roughly and cough a bit, took off the oil filler cap and put my hand over it and there is suction instead of puffing out. Any ideas thoughts??
The engine is an A series 1360cc does about 80hp atw.
Author:  Lockie91 [ Sat Oct 15, 2011 7:59 am ]
Post subject: 
I'm only guessing here, but it sounds like the gearbox could be pressurized. If it is pumping alot of oil like you say out, and at high rev's this sounds like it could be. Is the oil coming out of the dipstick hole as well?

I had this once and wouldn't idle, and played silly buggers coughing and spluttering at times.

Turned out that a hose was put on the breather and it was blocked at the other end so the poor engine couldn't breathe, so was pushing it out elsewhere.
Author:  Bubbacluby [ Sat Oct 15, 2011 11:59 am ]
Post subject: 
Lockie91 wrote:
I'm only guessing here, but it sounds like the gearbox could be pressurized. If it is pumping alot of oil like you say out, and at high rev's this sounds like it could be. Is the oil coming out of the dipstick hole as well?

I had this once and wouldn't idle, and played silly buggers coughing and spluttering at times.

Turned out that a hose was put on the breather and it was blocked at the other end so the poor engine couldn't breathe, so was pushing it out elsewhere.


yeah lockie also happened to someone elses car, due to 2 lads trying to help me out :lol: :lol: :lol: :lol:
Author:  michaelb [ Sat Oct 15, 2011 1:38 pm ]
Post subject: 
Another possibility is piston blowby as the rings have worn or lost tension
Author:  mini_mad_matt [ Sat Oct 15, 2011 9:01 pm ]
Post subject: 
What engine breathers or pcv do you have on your engine?
Author:  peterb [ Sun Oct 16, 2011 9:23 am ]
Post subject: 
mini_mad_matt wrote:
What engine breathers or pcv do you have on your engine?


Yeah, if you're getting suction it has to be related to intake PCV type problem. Blown pistons, buggered rings etc, all make pressure not suction. Check the PVC valve or breathers are correct.
Author:  drmini in aust [ Sun Oct 16, 2011 10:17 am ]
Post subject: 
Maybe unrelated to your prob, but...
Even if engine is in excellent condition (sounds like it is if you have PCV suction) It will chuck heaps of oil up the flywheel housing breather at high rpm on long LH bends...
That's why I have closed mine off- I now run the PCV valve from the rocker cover on both the 1360 and the 1412.
No more James Bond 007 problem! :P No leaks, either..
Author:  Fiji [ Sun Oct 16, 2011 10:36 am ]
Post subject: 
Pcv 013 doc? Toyota type.
Author:  drmini in aust [ Sun Oct 16, 2011 10:47 am ]
Post subject: 
Fiji wrote:
Pcv 013 doc? Toyota type.

Yep, it goes into the Weber manifold.
Image

But if running an SU with the vac port on the side, no PCV valve needed.
Author:  bluewhitecoopers1968 [ Sun Oct 16, 2011 10:47 am ]
Post subject: 
drmini in aust wrote:
Maybe unrelated to your prob, but...
Even if engine is in excellent condition (sounds like it is if you have PCV suction).


Thanks for the replies peeps...so is it ok to have suction from the oil filler cap when I put my hand over it (engine at idle) of shoule there be pressure pushing out?

I don't run a PCV valve, just 2 breather, one on the clutch housing and one on the back tappet cover to a catch can. Breathers are clear, that is I can blow into them, No oil in the catch can. It dosn't blow any smoke out the exhaust so assume the rings are ok. No oil in the coolant or bubbles.
Bump?
Author:  SuperCooper [ Sun Oct 16, 2011 9:43 pm ]
Post subject: 
What oil r u running Richard?
Does it happen when engine is cold? Warm? Or only after a long thrashing? Have you done a compression test?
Changed oil...same problem?
A few ideas to look at ?
Author:  Tadhg [ Wed Oct 19, 2011 11:40 pm ]
Post subject: 
bluewhitecoopers1968 wrote:
I don't run a PCV valve, just 2 breather, one on the clutch housing and one on the back tappet cover to a catch can. Breathers are clear, that is I can blow into them, No oil in the catch can.

When you say you don't run a PCV, you run a catch can... Could you give a bit more info? :? Do you have a vented oil filler cap? You've got the breather on the clutch cover - is it vented to atmosphere (through a filter?)? :? Or is it feeding to the carby/inlet manifold..? You've got the rear breather to the catch can - is it vented to atmosphere or connected to the carby/inlet manifold..? :?

As the Doc says, cars can dump oil through the clutch cover breather after long left handers with decent revs. So that may explain the oil dump (it's the most likely exit - especially if it's not connected to anything). :? But that doesn't explain your suction. Especially given you've not said the breathers are connected - in any way - to your inlet system. You've clearly said no PCV. If there's no PCV - especially if you're connecting to the inlet manifold direct, say, off your catch can - that would explain strong suction and rough idle. :idea: If you can't hook up to your carby, but you want to plumb to your inlet manifold, you really, really do need a PCV. :wink: My $14 breather is plumbed off my catch can. :)
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