How do you tst to see if your oil/air seperator is bad??

Reason being is that my coolant system is being pressurized by oil which is giving an intermix problem in the coolant system, not the oil system. I've tested the oil cooler already and there is no leaks. No coolant in the oil pan either. The car has had a new engine installed by porsche about 60k ago. I know of the other causes such as cracked heads, cracked block, or a sunken cylinder. So I want to test out the other causes first before the major pia ones. Any suggestions appreciated

Oh ya the car is a 1999 c2 3.4l 6spd.

http://www.renntech.org/forums/tutor...for-a-bad-aos/ But an AOS is not likely to cause intermix.

Then what causes the cooling system to become so pressurized it blows it out the coolant resivor? This isn't a small drip when it does either. It pretty much pours out the resivor.

I dodn't know why but that link doesn't work for me.

After reading a few articles. Some similar issues I have as others would be the oil in the intake plenum along with a gas smell. It also had a slight unbalanced idle. Nothing extreme but noticable. Spark plugs showed no signs of oil on them either. The car also doesn't overheat. I have the engine pulled now.

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There are not many places where high pressure oil comes in close proximity to coolant save in the heads. In fact, right off the top of my head I can't think of any other place save possibly the oil cooler. You say you have eliminated the oil cooler as a possible source of the intermix. Ok, but be sure your diagnosis the oil cooler is ok is 100% accurate. At this time all I can think of is a cracked head, with a block a rather distance second possibility. Sincerely, Macster.

I'm going to replace the oil cooler, AOS, Tstat, waterpump, update coolant cap, replace coolant resivor, replace oil cooler orings, replace I/M orings and have porsche perform a coolant flush after it is back up and running. I know of the crack issues associated with these engines but I just find it hard to believe with it having a fairly new crate motor in it by porsche. The warrenty time is expired on it. Is there a way to change the headgaskets without taking the engine out of time? I'd like to replace the headgaskets as well but really don't feel like messing with the timing just yet. If I can't I'll just wait till round two of inspection when I have the heads shipped off to be tested and repaired if need be. Thanks, Mike

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You have to register on renntech.org to see it, but basically it described how to test your crankcase vacuum to see if your AOS is bad.

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In order to replace the head gaskets the camshafts have to come out, and the engine re-timed.

From moderator "RFM" via http://www.renntech.org/forums/topic...ost__p__210285 "Oil in the coolant from a broken AOS is not possible cause lack of pressure on the oil, there is only a thick oil mist present inside the AOS where by a swirl motion and some obstacles, air and residual oil becoming separated, the air goes in to the intake manifold, the residual oil drips in a natural way in to the sump. Coolant in the oil could be theoretical possible for 996 AOS since they are heated on top by the coolant, but i've never seen that phenomenon. "

hmm maybe I should just have the heads sent out now for inspection.

To test AOS, simply remove oil cap and if the motor dies, it is dead. If it runs nearly the same, it is fine. Should have a very slight vacuum over the filler neck when working properly.

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The most pressing problem is the oil in the coolant. Throwing a new oil cooler at the symptom with new o-rings and whatever else is supposed to be replaced when the cooler is replaced makes sense to me. Replacing the coolant cap with a new(er) one is a good idea. And a good cooling system flush followed by once empty a pressure test to ensure the empty system is pressure good is what I'd do. If the thing holds pressure then have it refilled with Porsche anti-freeze and distilled water using a vacuum refill system. Then drive the car. See what happens. That is to say start the engine and let it warm up and check often for any signs of oil in the fresh coolant. Be careful, of course working around a hot engine and hot coolant under pressure. But also be careful about how you react to what you might find in the fresh coolant. Given the cooling system was contaminated with oil the flush may not remove all of this oil/coolant and there might be a few dark globules of oil floating on the new coolant which might make you believe there's a problem when there isn't one. In fact, if any oil globules did show up I'd be tempted to drain the coolant out into a clean container and remove the oil and pour the coolant back into the engine, that is ideally using a vacuum system to refill the cooling system. IOWs, I'd have to see oil globules in the coolant twice to believe these were not left over from the previous oil in the coolant episode. All of those other parts...That's a lot of parts to throw at a problem the cause of which you are not even sure of yet and some of those parts have no bearing on the problem in any case. Unless of you know the water pump needs doing, along with the coolant tank, the AOS and so on. Of course, it is your car and you can do what you want to do. A new engine can manifest a cracked head (for example) so why can't a replacement engine which is identical to the engine it replaced do the same? There's no guarantee a replacement engine can't fail, and fail in the same way the engine that it replaced failed. That the replacement engine fails at all, the probability is low, to be sure, but not zero. Do what you feel is right for you and try to nail down what is going on. It may be the oil cooler, one of its o-rings. My WAG and it is only a WAG is that the oil cooler or its o-rings accounts for more oil in coolant events that a cracked head. Sincerely, Macster.

The other parts are just preventative maintance really. A kind of while I'm in there thing. There is a lot of other items/upgrades I am installing at the same time. I just didn't mention them since they had no relation to coolant or oil. I wasn't going to worry if I say oil droplets reappear after the flush. Just worry if it stayed looking like a milkshake. I know that the cooling system is extensive in these cars. Does anyone know of a place that sells a full radiator hose kit for a good price?

For all of the hoses you can go to Suncoast, Sunset, Sonnen Porsche. There are miles of hoses in this car and that is a major job in itself to replace them all. If your coolant looks like a milkshake and you are 100% certain it's not the oil heater (cooler), then it has to be a crack in the heads. They should be removed and pressure tested otherwise you're going to be dropping the engine again in no time at all to repair the heads. Also all of the intermix residue has to be cleaned out otherwise it will continue to eat away at the hoses.

cracked head

Does anyone have pics of oil in coolant so folks know what it looks like?

Milkshake.