Oil Burp

[thegoose50]

Thankfully i had fitted a catch can recently and today it was put to test, I think on the last lap of the group track session today I had a burp as pulling into the pit lane the oil light came on, when I emptied the can there was 300ish ml in it as measured it out in a empty two stroke can, I don't think the car was over filled although I did top it up yesterday, I topped up the oil (thanks Stu) drove home no issues tbh the car was going pretty well, so what causes this apart from over filling??? as all seems ok especially on the drive home.

[warpc0il]

Are you sure that the oil light and oil in the can were directly related?

Why are you convinced it was a burp?
OMP oil consumption is massive on track, so that would explain the low (level) light.
Did you check that the catch tank was empty before the session?

[thegoose50]

Yes because the catch tank was empty and I also have a sohn adapter fitted so it doesn't use engine oil

[warpc0il]

Fair enough, so I wonder what caused it?

[thegoose50]

Fair enough, so I wonder what caused it?

I did have one wen I first got the car however the young lad who had it for only 2 months couldn't get to grip with running to the beep 'oh I don't like doing that' lol so he had over filled so it burped then, I sorted that out and replaced the oil usually keeping the to the third dot on the dipstick so not had a problem, I did however top it up Friday but it seemed to be where I normally keep, what do cause oil burns other than over filling?

[warpc0il]

Rotor side seal failure can pressurise the engine case beyond the capability of the system to vent without taking oil with it, resulting in constant burps.

It's easy to check for this by removing the oil filler cap a putting your hand over with the engine running. There should be a gentle pulsing of the air and not air blowing out.

In theory it's possible to have a side seal momentarily leak e.g. if a piece of carbon breaks away, without permanent damage.

Checking the oil level too quickly after switching off, rather than waiting a few minutes, can result in an overfill sufficient to trigger a burp.

On the pre-06 cars it's easy to pour the oil into the filler too quickly resulting in oil overflowing into the breather system, even without overfilling.

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[V8 Power]

When I had a side seal failure the pressure was that great that the filler neck blew off!

[thegoose50]

When I had a side seal failure the pressure was that great that the filler neck blew off!

Certainly not had that, as I said normal road use I haven't had an issue as bad as this infact not had any oil in catch can, I have had a compression test done which ended up low fives, however it starts first time even after a spirited drive first time and still has a normal starter not a 2k one.

[warpc0il]

The side seals can leak on the intake or more commonly on the exhaust section, in either case it has no impact on measured compression or hot starting.

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[thegoose50]

The side seals can leak on the intake or more commonly on the exhaust section, in either case it has no impact on measured compression or hot starting.

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Thanks Dave I take it the only way to find out if they are leaking is a rebuild? Day to day all seems fine I suppose if I track it again double check the oil before doing a session see what happens lol?

[untakenname]

I had oilburp at Bedford twice on the same part of the track, haven't any before or since. Engine on around 7k after a rebuild.