Oil Catch Tank

[caldy]

There have been dozens of posts regarding the carbon build up and various recommendations as to how to prevent/minimise the build up on the inlet valves. However, it doesn't appear that anyone has yet installed a catch tank. What happened to pippyrips mod that was being trialled by MRC?

[ArthurPE]

I'm not convinced it's blow-by oil vapor
first it's got baffles in the valve covers, pretty effective
long tubes to the seperator allowing the oil to condense
plus it's got the cyclone

I did a small experiment
I took some filter gauze
stuffed/secured it into the cyclone to intake hose
after 200 miles+ no oil stains, not a tinge...

I also found out something interesting...the RS4 engine produces little vacuum
it has a diaphram pump powered by the diff press across the the TB
it also has an aux electric pump

after looking at the hoses it would be easy to install a filter canister in the cyclone to intake line ( http://www.mann-hummel.com/group/upload ... UCmOK5.pdf )

[pippyrips]

Caldy,

MRC skipped the catch-can idea and went one stage further, completely blocking off the inlet from any oil etc and fitting a VTA filter.

The positioning of the filter (had to be up high to allow drainage) was a bit of an issue as it caused fumes to enter the cabin when stationary though I quickly learnt I could combat this by switching to recirculate when coming to a stop!

The bigger issue was when she was opened up again, although the valves weren't as bad they were covered again. The only explanation they guys could think of was it must be some of blow-by coming back form the cylinder head.

Ultimately, (if you do want to keep your valves 'clean') the only option is to manually clean them every once in a while.

[caldy]

Does that mean that Arthur was right all along???

[sonny]

Iv always believe it to be blowback coming from the Cylinders, maybe the valved are opening slightly during detonation...any way.

[pippyrips]

Well the build-up was reduced and less 'gunky' so oil coming back through via the EGR system if definately a contributing factor.

Nearly all people i know of that has taken an inlet manifold off has said oil has dripped over the floor from it - it cetainly did with mine first time round. There is no way on earth this won't be being baked on when the engine is hot and switched off.

The issue(s) seem to be coming from both ends.

It

[sonny]

yes true. im so surprised how there has not been a cure for this, what about the VW lot, they have been running FSI for a few years now maybe they have the Holy Grail.

[pippyrips]

the problem is there are 2 separate issues:

1) Oil vapour coming back through the inlet via the EGR system.

2) what looks like blow-by coming back up

In theroy a catch-can or similar will solve the first issue but very little can help the 2nd.

[silverRS4]

The oil vapor through the inlet is typical of all engines. (Pippyrips - This is the crankcase ventilation system, not the EGR system). Additionally, there is no active EGR system on the RS4. Its exhaust gas recirc is done "internally" during the valve overlap. Definition of "overlap" the point in time during the exhaust stroke when the piston is moving up and BOTH the intake valves and exhaust valves are open. This is done for two reasons. Primarily, the first reason is utilize the resonant scavenging effect of the exhaust system. High speed pressure waves of the exhaust gases leaving the cylinder can actually "pull" more fresh air into the cylinder. This, of course, can only be accomplished if the intake valves are open. Secondly, for the purpose of having the intake valves open as long as possible, they are opened early. In even mild engines, the intake valves open before the exhaust valves are completely closed. And lastly, internal exhaust gas recirc (EGR) can be accomplished with a certain amount of overlap as is the case with the RS4. External EGR (with all the piping, aka A4 2.0FSI) leads to carboned up piping AND valves, while internal EGR FSI motors will result in carboned up valves. The "blow-by coming back up" Pippy is hot exhaust gases being forced into the lower areas of the intake during overlap. The hydrocarbons in this mixture is what's primarily to blame for the valve buildup. It just so happens that it also cooks any PCV oil vapors on the valves as well. So yes, Arthur is right, the PCV vapors are really not the issue. Your experience shows this as well. A catch can or even eliminating the PCV gases altogether (like you did) only eliminates a fraction of the problem. The primary issue is practically impossible to fix.

[pad125]

Guess that puts it to bed

[sonny]

So you saying we should have crank case breather filter detached from the air box, just like when a GruppeM is fitted, would it make any difference?

[caldy]

silverRS4 - another excellent summary. Good job I'm a low mileage, hands on guy who is prepared to lift the inlet every once in a while. Guess I'll just put the catch tank cash into a set of wheels.
May be a shortfall!

[sonny]

Caldy have you inspected your valves since having the manifold De-vaned?

[silverRS4]

So you saying we should have crank case breather filter detached from the air box, just like when a GruppeM is fitted, would it make any difference?

Sonny, I'm afraid that's not a filtered breather on the Gruppe M. It has nothing to do with the crankcase ventilation system. Here's a picture that shows just what that little filter on the GruppeM is for (its the fresh air inlet for the Secondary Air Injection Pump). Getting back to the crankcase vent system, Pippyrips can confirm that just venting it simply results in a stinky mess, whether its filtered of not. My earlier post reflects my opinion that the crankcase vapors are not the primary culprit of the carbon buildup anyway.

[sonny]

Good post there SilverRs4. I was misinformed so it seems.

Good picture that, very "idiot proof"