Oil burps

[osman]

Hi,
Rx8 keeps having oil burps, had compression test at rr to check for side seal issues but was all fine high 5s and low 6s
Oil isn't over filled was around 1/2 mark out of ideas why
Car has got aem coils on it, bridgeported 2k miles

Any idea what could be causing it ?

[warpc0il]

What year is the car?

The breather layout was redesigned in 2006, mainly because dealers were refilling the engine oil too quickly and it was overflowing into the vent.

However the later design is also less susceptible to burps.

Are you cleaning out all the intake after a burp? Repeat burps can just be oil trapped in the resonator.

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[osman]

What year is the car?

The breather layout was redesigned in 2006, mainly because dealers were refilling the engine oil too quickly and it was overflowing into the vent.

However the later design is also less susceptible to burps.

Are you cleaning out all the intake after a burp? Repeat burps can just be oil trapped in the resonator.

Sent from my SM-G800F using Tapatalk

It's a 07 kuro and it has an aem intake so cleaning out everytime.it burps. Oils dark brown so definitely not fresh oil from being put in

Thanks for the quick response

[osman]

In that case your best bet would be to install a catch can.

It won't stop the burps but it will capture the excess.

Make sure that you're checking the oil level within 5-10 minutes of switching off a hot engine.

Any sooner or later, or cold, gives a false reading.

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[350matt]

A tweak that helps is to fit a restrictor / washer on the exit of the crankcase port before fitting the plastic inlet
this still allows oil to flow down from the filler and gas to escape it just makes the gas path a little harder so reducing the level of blow-by and oil carry-over you get making its way into the upper breather chamber

also don't fill the oil level to the top mark about 2/3rds between the two marks seems to be a happy spot

[ChrisHolmes]

Have got the breather pipe connected after the throttle body if yes then it will have to much suction.

[Ryan Rotary Performance]

Our sump does help with oil burbs and an improvement over OEM

https://www.ryanrotaryperformance.com/s ... -2003-2008

[dac69er]

How exactly do these "oil burps" happen? What normally causes them?

I always keep my oil at almost the max level and have done a couple of track days and never had any oil in the intake?

I am just curious????

[ChrisHolmes]

It's probably a combination of factors-
- the design/layout of the breather system (original vs updated)
- any changes made by the owner to the intake.
- the actual static oil level, significantly impacted by when it was measured.
- the layout of the track, the nature and direction of the turns relative to the acceleration zones.
- on the road, burps are most likely with sustained acceleration e.g. long overtake or slip-road onto motorway, particularly uphill, as this creates maximum sustained intake vacuum.

I suspect but have little evidence that moisture in the oil is also a factor.
The most common source of moisture being;
- running the engine at idle for long periods, especially in cold weather.
- lots of short journeys, again worse in cold weather

Moisture in the oil turns to vapour when the oil reaches 100C (or more under pressure).
If this happens over a short enough period of time then the steam created will massively increase the pressure above the oil in the sump and this has to blow off through the breather system.

The result is a major oil burp, leaving (often emulsified) oil in the intake, lots of smoke from the exhaust, but no indication of a mechanical problem in any follow-up investigation.

I'm now convinced that this is what happened to Ranjan's car at Three Sisters, while I was driving and Malcolm was watching the gauges. All Chris' checks found lots of evidence of a massive burp, but no other cause, and it hasn't (yet) done this again, despite some active provocation.

For road use in cold weather, the Mouse Mat mod, is a good way to allow the oil to reach above 100C as soon as possible and therefore dry-out any small amounts of moisture before they can accumulate enough to cause an issue.

Mayo on the dipstick is a sure sign of condensation moisture in the oil (not a blown head gasket ) which, while it's often considered "normal" still isn't good.

My car is an 04 and only suffered an oil burp once, a couple of weeks after an accidental over-fill back when my Dad still owned her. He was accelerating to blend into the traffic on the A12, when the view in the mirror disappeared and the engine seemed to switch into "limp mode". Green Flag recovered the car and told him "to scrap it, as the seals had gone". It was only two years old then...

[dac69er]

Ok, that would explain why I may not have had any issues.
The car is only ever used in the summer, so not much chance of condensation build up in the oil.

I'm pretty anal at keeping an eye on the oil level, so whilst it is near the max, I have never over filled it.