Heavy breather.

[FATGTS-R]

Got a frustrating prob with my car at the moment.

It is breathing a significant amount of oil from the breather. If I nail it all the way through 2nd, 3rd and 4th ( RB20 - 225rwkw ) it will spew out approx. 5 tablespoons worth of oil.

Now before I am told the rings etc are gone and I need a rebuild etc a compression and a leak down test were carried out with the results not pointing to a stuffed cylinder instantly.

Compression was on average 150 with no other cylinder more than 5 away and the worst leakage was on cylinder 6 with 19%.

The mechanic told me that 19% isnt the best but should in no way let that much oil get out.

Is it possible that a cylinder with 19% leakage can let that much oil get through and indeed a do need a rebuild?

Or could it be something else?

I have been given two other possibilities as to the cause ( not from mechanics ):

The gauze that is meant to be under the breather hole has been removed at some time causing an excessive amount of oil to get in or the oil drainage from the rockers has partially blocked over time meaning the oil is getting up there fine but it cant drain back fast enough and its getting sucked up through the breather?

Any help on this matter would be much appreciated.

Thanks

[awurth]

My friend had the same problem, his breather was like a kettle blowing, even went to the extent of making it harded for air to get out to his catch can by altering his cam covers, piston number six was stuffed. He never did a compression test though. you got to remember that with the compression test nothing is firing, so you have 19% difference. imagine how much gas get's blown by when the piston fires and then when your nailing it on boost! gas travels from the sump area blowing all oil up with it. if it was a serious wrecked valve stem seal you should see allot more smoke on start up.

[FATGTS-R]

No,not 19% difference.

Besides having the compression test done I also had a leak down test performed and the worst leakage was 19%. Not a 19% difference between cylinders on the comp test. The biggest difference between cylinders on the comp test was about 3%.

[Ben101]

Are you using more fuel? If you are it could be your oxygen sensor gone which puts more fuel in as it thinks the engine is running lean this then washes the oil off the bore which gives you blow by as theres no sealing effect from the oil

[FATGTS-R]

Interesting Ben101. At present my fuel economy is ridiculous. Approx. 18L/100km on CRUISE!

I have recently had an ecu fitted up and obviously it needs to go back as not much attention was paid to cruising mixtures.

I would be a happy chappy indeed if all the problem was is a rich tune, but honestly I had never heard of rich mixtures causing excessive blowby but it sounds feasible.

[awurth]

The biggest difference between cylinders on the comp test was about 3%.

Hmmm, got my little mechanical mind stumped then. The only reason I can think of oil blowing out your breather is your getting allot of gas in your motor which would come from the piston. Has anyone ever had a valve stem seal let exhaust gas through blowing a heap of air into the cam journal? You should have smoke on statrt up then. Don't know my friend!

[Ben101]

To tell if its worn rings smoke will appear through out the driving range and idle if its valve stem seals you will only blow smoke under vacuum eg giving the car some but you have good compersion it sounds like the fuel economy is way to rich the ecu needs to be re tuned to much fuel going in can wash the bores down which then washes the oil away and will wreck your hone pattern on the bores which will lead to more problems down the road

[FATGTS-R]

It seems as though the problem is solved so I thought I would post this up to help out anybody in the future.

On advice from another forum member (from NSW I think ) I checked the pcv for the prob as I was told if it was not shutting properley it could blow boosted air into the head.

I removed the hose to it and took the car out for a spirited drive to come back to find not a single drop of oil had breathed out.

I repeated this test several times and same outcome everytime, no oil at all.

So once again, SAU forums has saved me some money and I learnt something at the same time.

Thumbs up!