A.M.H

Can anyone here tell me what the exact purpose of the oil filler hose (#2 in this diagram http://www.944online.com/cgi-bin/ASI...599546+9442+oi...) function is?

I have replaced the O-rings to the filler tube, and I am still getting oil all the way up in the throttle body, and in my mind, that just cant be good. Can I just delete the hose, cap off both ends of where the hose runs to/from, and call it good?

I just dont understand the purpose of it. To cycle/return oil blow-by? Why would it be routed into the air intake system, and before the TB?

Im about to rebuild my TB, and every time I pull my J-boot off, I notice oil that has accumulated and pooled up in the grooves of the J-boot, and in the TB before the TB butterfly. Im tired of seeing that, and knowing that it is mixing in with my fuel and air, it has to have a negative side effect on runability. I aim to fix it of this problem, because my OCD is driving me insane over it, and I dont want this to continue to happen once I get all fresh new seals and o-rings in my TB.

Thanks

odurandina

do you remember the changover from open valve cover breathers to pcv valve/return lines to reduce emissions from hot crankcase oil fumes? well, this is simply how it's done on your **** 4 cylinder engine....... in the process of relieving pressure, it's far better to send the smog right back into the super hot combustion chamber where most of those hydrocarbons will be burned – than allow them to escape into the atmosphere.

mel_t_vin

That hose [#2] is there to vent crankcase fumes, after they've been separated in the AOS [air/oil separator, #10], back to the intake tract.

I would not "cap off both ends...and call it good". Where would any pent up pressure in the crankcase [movement of air due to internal reciprocating parts, combustion blow-by] vent to? If you did, I suspect your engine's weakest links would probably "blow" in short order, starting with the dipstick/o-rings, then the AOS/o-rings, and possibly the head gasket.

A.M.H

Thanks for the replies. To touch base on the AOS o-rings. Those are the o-rings I replaced once already, earlier this year when I rebuilt my engine. Im thinking that maybe I need to buy a new AOS/oil fill tube to remedy this problem, because it is obviously not doing its job properly, and you cant buy the parts needed to repair the internals of the AOS.

mel_t_vin

When you re-built your engine, did you replace the rings and make sure the pistons/bores were in spec?

Where, on the dipstick, do you run your oil level? Where is your car located and what weight oil do you use?

A.M.H

So, when I rebuilt my engine, I did make sure that all my cylinders were with in spec. Even my factory rings were still with in spec gap's all the way across, and all my oil ring lands were in great shape on the pistons.

As far as your other questions. I run my oil level right at the topped off mark according to the dipstick. I run AMSoil High Zinc formula 10W-40 and I live in Marysville, Washington. So just a couple hundred feet above sea level.

Van

You could also be getting oil into the intake manifold from bad valve guides/seals.

What is your normal oil consumption?

V2Rocket

You don't need to replace the AOS unless it is damaged - there is literally nothing inside of it.
It is a big plastic hollow can that does its job of air-oil separation simply by its shape. Oil vapors come in one port and spin around on the inside of the tube which separates heavier drops which drain to the sump from lighter ones which go to the J-boot.

The engine then burns these light-oil vapors for clean emissions. Also, having this constant suction on the crankcase helps the rings seal better and helps the pistons move around easier (they don't have to compress as much air when they do their down stroke).

So oil in the j boot is normal, but there is a certain amount which becomes worrisome that indicates worn engine parts.

A.M.H

Van, when I rebuilt my engine, which cause was due to TB tensioner pulley blowing up at higher rpm, inevitably, every one of my valves made contact with the pistons. There was some impact marring on the tops of the pistons, but only to the valve relief cuts in the pistons. Was able to have them cleaned up. No signs of worrisome damage.

Anyways, I had a new head built and sent to me from R7 Racing. Coming from a man I trust very much so, and a highly successful business dedicated to 944's, everything was new on the head.

So, being I could have just given you the short and sweet answer to your question, the answer is, my valve guide seals are good. Valve seats are good. Oil consumption has been almost non existent. In fact, I just went and checked my oil level between the last sentence and this sentence, and it is still at the topped off line. Its been about 1500 miles or so, rough estimate, since my last oil change.

A.M.H

And to V2 Rocket. Thanks for clarifying to me about the AOS. I have never taken one apart, and looking inside of it is pretty much impossible with out pulling the top off. I didnt know it was just simply hollow. Thanks.

Brentb1

I would think if your oil consumption is very low, you do not have anything to worry about. The reason is, if you do not notice a low oil level there cannot be enough oil in the intake boot that would raise a red flag. From what you describe and from what I have been told, you are experiencing the normal amount of oil in the boot. Now if you are going through more than 1 quart of oil per oil change "3000 miles" then I would start to worry.

V2Rocket

Porsche's normal oil consumption spec for the 944 is 1 liter/1000km or about 1 QT every 600 miles.
So I wouldn't worry too much

mel_t_vin

So, when you rebuilt your engine, you did not install new rings?

Re: trace oil in your intake tract...here's a theory, open for discussion.

Have you been flogging/tossing your car around in the twisties recently? Running thin, 10w-40 synthetic oil, at the full mark on the stick, and pulling a few G's may have sent some of it splashing against the crank, causing it to be aerated and sucked out of the case into the AOS/intake. Simple test...see if running a little less oil resolves your irritation.

FWIW, I've run my car between half and three-quarters on the stick for 15 years with no oiling issues, to date, that I'm aware of.

A.M.H

I did install new rings. Before I began gaping my new rings, I took measurements of the factory ones and compared them to factory specs. All of them were right in the nominal range. So, when I gaped my new rings, I gaped them right to nominal range. This told me that my cylinders were still in spec. Plus, the Alusil coating to the cylinders was still in great condition.

As far as flogging/tossing my car around. Yes, I do flog it, and more frequently than not. Here in the Puget Sound region, we have tons of incredible foothills and woods with the most desirably driven roads, where the 944 is at home on. So, maybe you have a solid point/theory about that being the cause for some excess oil getting in the intake.

I will see about running a little lower oil level for a little bit, and see if I can notice a difference.

Thanks again for all the suggestions and facts from everyone. It does not go unappreciated :-)

odonnell

FWIW, I have zero oil in my J-boot (have it sitting on my desk, pulled off car a few days ago) and I have about ~11k miles on the build. Car consumes less than half a quart every 5k miles with 5W50 and 15W50 oil.

Try filling up with an SAE 50 multigrade and see if it slows down, that might help differentiate between a tolerance problem and a vacuum problem.

Have you checked for vacuum leaks? Perhaps an abnormal pressure gradient is contributing.