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Oil out breather
https://www.ausmini.com/forums/viewtopic.php?f=2&t=95190		 Page 1 of 1
Author:  carter [ Sun Apr 09, 2017 7:24 pm ]
Post subject:  Oil out breather
G'day all! I have a dilemma with a newly built motor. I went for its first drive today and it's spewing oil out the rocker cover breather. It is an 1100 s motor with only that one single breather. If I buy a timing cover with a breather will this fix my situation ???? Cheers
Author:  peterb [ Sun Apr 09, 2017 8:09 pm ]
Post subject:  Re: Oil out breather
There's also the clutch housing breather.
Author:  Phil 850 [ Sun Apr 09, 2017 8:33 pm ]
Post subject:  Re: Oil out breather
I have an 1100S and it only has the breather out of the rocker cover and there is not a sniff of oil that comes out.
Now prior to this, it spewed oil like there's no tomorrow, but it was due to one of the cam bearings being fitted the wrong way around. When this happens you get full oil flow into the rocker cover and at speed the rocker cover fills up faster than it can drain back into the sump.
Author:  carter [ Sun Apr 09, 2017 9:20 pm ]
Post subject:  Re: Oil out breather
thanks for the reply...... I didn't fit the cam bearings I had a mechanic fit them. He removed the old and pressed the new ones in. They new ones were all pressed in the same way... is there a way I can fix this ? I do notice it takes a while (or I should say I did) for the oil to drain down to the sump when I filled it for the first time the rocker stayed full of oil and slowly drained down slower, it seemed, than the small bore I had in previously. How would I know if a cam bearing is wrong? And how can I rectify it?
Author:  36 [ Sun Apr 09, 2017 10:29 pm ]
Post subject:  Re: Oil out breather
If it is the cam bearing, you can fix it by putting a piece of feeler gauge with a tiny hole in it under the number 1 rocker post. This restricts the oil flow up and will fix your issue.
Author:  carter [ Sun Apr 09, 2017 10:37 pm ]
Post subject:  Re: Oil out breather
Ok. Is there any way of knowing if it is a cam bearing? Could it possibly be a breather issue?
Author:  drmini in aust [ Mon Apr 10, 2017 7:23 am ]
Post subject:  Re: Oil out breather
My 1100S motor only runs a single breather on the rocker cover with no problem. It has a pcv valve into the manifold.
Note that the common Chinese alloy covers have a spot for a breather hose directly above a pushrod. Not a good idea as it will toss oil up it.
Drill a hole above the rocker post instead.
Author:  1071 S [ Mon Apr 10, 2017 9:02 am ]
Post subject:  Re: Oil out breather
Before attempting a fix you need to know what's going wrong... (doh!)

Go for run to cause the problem to occur. Stop and check the rocker cover... full of oil??? OK, try the shim under the rocker post. Fixing the cam bearing means another complete strip down ....

The bad news is that I had a similar problem. Turned out that they stuffed up the rebore and I had piston to bore clearance that the rings couldn't handle which resulted in huge blow by. A drive of about 150 kms pumped virtually all the oil out of the sump.

The only solution was another rebuild (rebore/new pistons etc etc :( :(

Cheers, Ian
Author:  carter [ Mon Apr 10, 2017 9:13 am ]
Post subject:  Re: Oil out breather
Ok cheers Ian will do. It's rainy today so will have to do it tomorrow. Blowby is pressure out the tapper cover yea? Because I have next to none of that.......
Author:  DavidE [ Mon Apr 10, 2017 9:43 am ]
Post subject:  Re: Oil out breather
carter wrote:
Ok cheers Ian will do. It's rainy today so will have to do it tomorrow. Blowby is pressure out the tapper cover yea? Because I have next to none of that.......


Blow-by can also emerge from the dipstick hole.
Author:  Phil 850 [ Mon Apr 10, 2017 8:42 pm ]
Post subject:  Re: Oil out breather
When I ran down the freeway the rocker cover would fill up. The breather was originally connected inti the inlet manifold and the freeway would disappear in a cloud of smoke.
I took it to Grieg and he diagnosed the problem.
He loaned me a fuel pump adapter that had a tube welded to it. I modified a rocker cover with a tube out of the corner as low as possible and connected the two with a rubber hose.
The oil drained back into the sump faster than the pump could push it into the rocker cover.
Eventually had new cam bearings fitted and Grieg has the parts back for the next unfortunate mini enthusiast.
Author:  1071 S [ Tue Apr 11, 2017 11:46 am ]
Post subject:  Re: Oil out breather
carter wrote:
Ok cheers Ian will do. It's rainy today so will have to do it tomorrow. Blowby is pressure out the tapper cover yea? Because I have next to none of that.......


UUUmmmm but you complain about "..and it's spewing oil out the rocker cover breather..." ????

So , lots of liquid oil being blown out ... but no vapour??????

Blow by is combustion pressure escaping past the rings which pressurises the engine block. The block is full of oil vapour/droplets that will be forced out of any vent available... or past seals if insufficient vents exist to release the pressure.. All vents on the engine..tappet cover/rocker cover/drop gear case/dipstick (not forgetting the rear main seal and timing case seal) are all connected to the same space..

Cheers, Ian
Author:  carter [ Tue Apr 11, 2017 5:25 pm ]
Post subject:  Re: Oil out breather
Ok fellas I'm pretty sure I have found the problem..... my timing chain cover is bent to the point where it was pouring oil out somehow finding its way onto the harmonic balancer and fan and throwing it up onto the well everywhere. So once I fix that it should be fine :-).... thanks everyone for your help and advice as always it is greatly appreciated
Author:  minimans [ Wed Apr 12, 2017 4:08 pm ]
Post subject:  Re: Oil out breather
carter wrote:
Ok fellas I'm pretty sure I have found the problem..... my timing chain cover is bent to the point where it was pouring oil out somehow finding its way onto the harmonic balancer and fan and throwing it up onto the well everywhere. So once I fix that it should be fine :-).... thanks everyone for your help and advice as always it is greatly appreciated

Make sure the oil flinger plate is fitted to the crank behind the seal!!
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