polcan

Hello 1988 Porsche 928 S4 auto
Before and after i did full intake refresh, my S4 blows cloud of smoke on start up.
It is oil burning smell ,that i.m sure but it goes away after a couple of seconds . When i took my intake off i had about an ounce of oil in throttle body . The only option was to try to filter breathers air going to throttle body . To my surprise
valve cover breathers on passenger side ( S4 ) pulls " air in"(vacuum) not out .
On the other hand" nipple" on the side of oil filler neck has a lot if vacuum (pulls air from crank case out ) and goes in throttle body on driver side .Thats how oil is getting in
to the intake .
I put air oil separator on that line and i can see oil collecting in
container that normally would end up in intake and burned in engine.



Now the question?
Did i connected something backwards ?

FredR

Your assessment sounds about spot on and why many of us have modified the breather system on S4's and GTS's- systems that appear to vary from poor to downright awful and indeed the problem seems to vary from example to example with some suggesting [somewhat surprisingly] no oil ingestion issues at all. My experience with the S4 motor was that at some rpm level the problem got noticeably worse and presumably the "bads boys" had much more of a problem.

The connection on the passenger side appears to be bi-directional [depending on the throttle position] but the jury is s till out on that one.

Most modifications involve the fitting of an external separator such as the Provent 200 with some variations to the supporting plumbing. In my case I have a 1 inch vent from the filler neck in which I fitted a baffle pack that John Kuhn fabricated for me.

There are some good threads on breathing the S4/GTS motor- I am still evaluating my mods but so far promising. The big mistake I made on my S4 motor was to try to convert the breather system from S4 style to GTS style as I wanted my motor to visually appear like a GTS- a big mistake that just made oil consumption worse or so I experienced.

Rgds

Fred

worf928

Search for threads containing the word Provent for examples of solutions.

GlenL

I'll suggest that your approach to the problem is not right. Improvements in the breather system (like a separator) will reduce oil going into the intake; that is true. But I don't think your symptoms match that problem and you didn't find "a lot" of oil in the intake by 928 standards.

Oil smoke on start-up is usually oil dripping down the valve stems and into the cylinders when the engine is sitting. You burn it off and it's fine.

A breather system is really needed when you've got smoke during hard acceleration. This is a common problem when driving the cars on the track.

Then again, it could be anitfreeze on start-up which would indicate a failed head gasket. Check fluid levels and the color and smell of the smoke.

If it is a touch of oil smoke on start-up, I'd be tempted to do nothing.

jcorenman

The best explanation of how the S4 breather system works is Mike Schmidt's write-up some years ago. Herman K posted a copy here:
https://rennlist.com/forums/928-foru...ml#post9519300

Polcan, how many km's on this car?

polcan

Thanks for replay all.
My 1988 S4 shows only 120.000km on odometer ,if it is true mileage ,who knows right.
Engine runs smooth after intake refresh .Never had problems with start ups.
Installed air separator last night for first time and had engine run for about 10 min.
This morning started engine ,fired right up ,there was smoke but normal one ,smell of rich fuel.Please
mind it was -24 C outside and probably -5C in the garage ,cold start up .No stinky oily smell .Is that a fix for oil consumption ,dont know ,will not drive the beast till April but maybe is something to consider
Pictures below (plz dont judge ) it is just temporary testing set up .Plan is to connect and drain oil from container right in oil pan.



temporary set up just for testing





note amount of oil in container that would end up in intake

jcorenman

If this was from idling then something is very wrong.

Are you sure that the hoses are all routed correctly?

Have you run a compression test? And a leakdown test?

MjRocket

As a side note/question..What is that resivor from?

I like the look of it.

Thanks

Cosmo Kramer

When you did your refresh, there are two connections on the oil filler neck. One has a one way valve and the other doesn't if memory serves me correctly the spigot with the one way valve goes to the throttle body and the other one goes to the passenger side cam cover. Maybe you have them mixed up?

polcan

Neg. hoses are connected properly ,that im sure .One with check valve to tb.
My oil filler neck has buffer plate on the bottom .Oil that little nipple sucks from top of oil filler neck
comes from crankshaft splashing oil in crank case right bellow filler port
.Next step will be stuff filler neck
with stainless or copper mesh to prevent oil from reaching top of filler neck port but allowing air to circulate .
Should have gone this route ,link bellow
http://www.kuhnperformance.com/model...r-oil-scrubber

GregBBRD

Very, very wrong!

polcan

Now thats sound like trouble Greg ,i hope it is not worn piston rings creating a lot of pressure in crank case

GregBBRD

One end of that hose (that you installed the filter into) connects to the filler neck, another end hooks to the bottom of the intake manifold, and the third end hooks to the solenoid which draws fuel vapor from the charcoal canister.

Check these attachment points, as you originally said one end went to the throttle body, which is incorrect, but I assumed was just a typo.

If these are hooked up to the proper location, somehow huge amounts of oil are getting up into the filler neck....at idle.

While where the filler neck bolts onto the block is a direct path to the crankshaft and this area tends to get packed with oil at higher rpms, there should not be any oil up this high at idle.

Is the engine overfilled with oil?

polcan

neg . oil is at bottom level . 3 way hose is also connected properly ,i.m sure of it .
I might put filler neck buffer upside dawn ? little wings were facing dawn when i installed it.
I used 20W50 oil on last change ,I started again today and again no oily,blueish smoke at all but i can see oil separating in air separator hmmmmmmmmmmmm

GregBBRD

Well, if everything is correct with the hoses and the oil isn't overfilled....there's definitely Sum Ting Wong.

There simply can't be oil pushed up into the filler neck at idle.