205 Mi16/gti6 Oil Breather Issue.

[matty 4]

My brother has a 205 rallye with mi16 block and gti6 cylinder head. It is running very well however when cornering hard the engine seems to be breathing very heavily.

 

At the moment the oil breather setup is fairly basic with one pipe running from the block to the inner tube on the rocker cover and the outer tube on the rocker cover runs to an oil catch tank. The large pipe from the block which usually goes to the oil filler is blocked off.

 

When cornering hard the oil filling up the catch tank way too easily and then blows out in the engine bay, usually all over the exhaust manifold, which causes a little smoke! I have attached a few pics to show the current setup.

 

Any advise or help will be apreciated!!!

 

 

[kyepan 291]

ok no expert here, but i think i can see what might be going on.

 

In case you're not familiar with the standard MI setup.

 

The large oil filler hose also acts as a breather, the filler cap recirculates back up and across into the inlet after the afm as does the other hose, which t's into the filler, so in effect you have two hoses venting into the inlet to vent crank gas.

 

Mi's also hold a lot of oil in the head, so the breather coming off of the head straight into the catch tank may just be surging across full of oil and then because its breathing out of the block, it's pumping the oil that collects straight into the catch tank.

 

I would look at the standard setup again, and try to make sure the gas has somewhere to vent that won't push oil into the catch tank with it. but i've been thinking and can't come up with an answer to be honest. if you had somewhere to re-circulate back into the inlet then that would be ideal. But saying that the bodies don't have anywhere to allow entry back into the inlet.

[matty 4]

hi thanks for that. ive been thinking about how we can alter the setup, the only idea i can come up with is to try and run a 8v setup so the large oil filler pipe could be used for recirculation. i think the main problem is the gas is running into the catch tank and just pressurising the oil out again.

 

thanks ash (matty's brother)

Edited June 20, 2009 by matty

[matty 4]

the plan is to run the 8v setup somthing like this. should this breath ok?

[kyepan 291]

yer the fact it can drain from he head back into the sump has to be better than the current setup, give it a whirl and see how you get on.

[Cameron 16]

Kyepan - he has a GTi6 head, not Mi16.

 

I had major problems with this when I first built my engine (same thing, XU9J4 bottom end and RS head). I had to do a lot of experimentation with the breather routing to stop it from chucking all it's oil out. The way I found to work was:

Use the large breather pipe off the RS block to run from the large breather on the block up to one of the rocker cover stubs, there is a t-piece off this that goes to the small block breather so any oil chucked up can drain back down. The remaining rocker stub goes to the catch tank, and the catch tank vents under the car.

 

I think the problem lies in the rocker cover, there is a baffle that seals the breather sfrom the inside of the head, so any oil thrown up through the breather will collect and then be blown out the exit breather, all over the engine bay. You need to have some way of draining any oil that gets thrown up from the crankcase breathers back into the sump.

 

I hope that makes sense, I can get some pics tomorrow evening if you want.

Edited June 21, 2009 by Cameron

[matty 4]

thanks cam, ive looked through on your thread on fsc but cant see it very well. if you could get a pic up that would be great.

cheers

[Spiky 37]

i know mines a std GTI6 engine, but wouldnt he be better to keep the std setup?

 

edit to all

 

i havent even got anything on the end of mine and is fine on track

 

and put the catch tank on the end of the black pipe near where the battery tray is on mine

 

Edited June 22, 2009 by Spiky

[welshpug 1,622]

you do have that valve in place though spiky, that is quite important

[Spiky 37]

thats what i getting at, maybe if he puts one back in the system it would solve the issues

[matty 4]

ive found that black valve. im going to fit it tonight and see what happens

does it really make that much difference then?

thanks all

Edited June 22, 2009 by matty

[Cameron 16]

In my experience, no.

[Miles 331 1 Cars]

No, It's more of a flame trap