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Hi guys, im having trouble with my 304 blowing out rear main seals. My engine builder suggested a bigger brether setup.
Currently i have 2 6mm id hoses coming off the front of the motor to a cannister with a filter on top. 1 of front of each rocker cover.
I tried a temporary set up. Keeping the original setup and adding a breather to the oil filler cap on left side rocker cover.

With that fitted the engine does not idle real well once warm and has also lost power.
If i swap back to standard cap it idles like it did and picks up the lost power.

Engine was tuned by a reputable workshop, and i have Kalmaker SP3, but on the day the tuner had to use older SP2 so im unable to view whats happening.
But i would like to hear any opinions on this as im working at being able to view the tune some how.

Maybe someone could even tell me a way to view my tune?

You should be able to use the flashtool to read the bin with generic settings. Once youve got a bin you should be able to see the timing and VE tables etc in tunerpro with the xdf from here https://pcmhacking.net/forums/view ... 542#p13542

Then you should be able to use excel to adapt the spark and VE to ose12p and run that with all the rest of the tools from here. There is an sp3 to 12p excel file I made around here somewhere, it stretches the ve and spark tables to fit 12p. I think sp2 and sp3 are probably the same size tables, so that should work for you.

what type of rear main are you running? the new type 2 peice rubber/whatever they are are crap, nothing beats the rope seal they came out with imo. mate had a 2 peice seal, put engine together, bang blown out first drive, replaced with rope seal, been fine ever since.

Thanks for the reply's. I cant remember what seal was used it was a while ago now. It is a VR block and i think he used the factory style.
The first time it was rear main, front timing cover, sump and dissy.
This time just rear main so far.

Antus, i will look into that thanks for the help!

In regards to losing power with the extra breather, could it be a mechanical proble? ie, worn rings, down on compression?
Or is the better breathing needing the tune altered to bring back to normal power?

purely the fact its blowing out seals makes me wonder how much blow by its getting, it definately sounds like theres something wrong a bit more than just a seal issue ...

Dylan wrote:Currently i have 2 6mm id hoses coming off the front of the motor to a cannister with a filter on top. 1 of front of each rocker cover.

is this then plumbed back into the inlet tract?

Dylan wrote:I tried a temporary set up. Keeping the original setup and adding a breather to the oil filler cap on left side rocker cover.

With that fitted the engine does not idle real well once warm and has also lost power.

I'd imagine the loss of power due to installing the filter/oil cap is a result of the vacuum leak that it would cause if the OEM PCV system is still connected.
The PCV hose connects to the inlet manifold after the throttle body, so it will be sucking air in through the oil cap filter, through the crank case, past the PCV valve and then into the motor, regardless of throttle position.
if that is the case the ECM will probably have a wrong manifold pressure reading, which would cause all kinds of problems...

is this then plumbed back into the inlet tract?

No, both hoses go into the canister which is vented to atmosphere