logray

That looks bad. I would be surprised if the oil cooler caused this. If it's not a crack in the head, it would be a miracle.

Yes. The entire 6 miles and 6 gallons of hoses and radiators and heater core has to be removed and cleaned and/or flushed out.

Dharn55

Not nearly as bad as mine was. I would drain the oil and take a look at it. Mine was like a chocolate shake and when drained there was visible green coolant that would float to the top.

The only things I did not take off and clean were the heater core and the hoses leading to it.

Flat6 Innovations

The heat exchanger is always what people go to first.. The multitude of cars that come to us "in a box" after other shops give up on them have had the heat exchanger replaced.. Thats a sucky job and isn't cheap.

I have never had one of those scenarios play out to actually be the heat exchanger.. The same goes with head gaskets that NEVER blow. Fact is the cylinder heads are weaker than the heat exchanger or head gaskets.

Thats heavy intermix.. Very heavy and its kiling your coolant hoses as this post is being read.

jsoderbe

Hi,

Today I had the time to dive into the engine work again.

Once again I am very impressed with how simple the car is to work with, especially with the help of this forum. I'm all the way in to the AOS with under 3 hours of work, and with an additional 45 minutes I succesfully removed the oil cooler. You would not belive that, looking under the engine lid....

Anyway, I quickly noticed the main cause to my coolant leak:



There was a severe crack in the coolant hose from the tank to the top of the oil cooler! Impossible to see without removing the intake.

Jake, is this what you were expecting in regards to hoses breaking from the intermix? The hose is all sticky and feels more flexible than it should.

The oil cooler itself was easy to remove, and it looked terrible!



I'm pretty sure coolant was leaking from the o-rings too, who actually looked more like flat gaskets. They are very very dry, and looked horrible:



There is a large amount of oil on top of the engine, mostly around the oil filler tube and the oil cooler. There is a severe oil leak where oil is dripping (or pouring) down the engine block just beneath the oil cooler. Theses two things make me pretty sure that the o-rings for the oil was leaking too.

Unfortunately, I could not see any obvious signs of intermix over the o-rings:



I am taking the cooler over to the Porsche shop tomorrow, and let them pressure test it, just to be safe. I do hope the cooler is the reason for the intermix, but I am realistic about the heads being the root cause.

Is 4 bar enough to pressure test an oil cooler? They claimed so, but I would have thought oil pressure up to 7-8 bar is possible?

The AOS looked really good, but I am replacing it anyway while I'm in there. There was no obvious signs of either oil or coolant leaking from it.

Any thoughs?


Regards,

Johan

jsoderbe

Btw, if anyone has the o-ring sizes, please let me know! I am guessing Porsche doesnt have hem in stock.

In millimeter, preferably...

Johan

logray

Certainly Porsche has them in stock.

qty 2 99970740940 26mm X 3mm
qty 2 99970738940 35mm X 4mm

Flat6 Innovations

That hose is just a sample of what happens when an engine is ran with intermix in the system... It attacks the hoses fast.

jsoderbe

I got an interesting voice mail earlier today; the Porsche dealership Service Manager said that they had tested my oil cooler, and it was leaking like nothing they've seen before. Unfortunately they closed before I could return their call, so I couldn't confirm it was the actual cooler or just the gaskets that was leaking.

I am cautiosly optimistic, since he asked if I wanted them to order a new cooler. But, it still sounds to good to be true, so I'm waiting with the champange until can get it confirmed....

Thanks,

Johan

speed rII

Hope that the cause is really the cooler

Flat6 Innovations

Sounds like you might have gotten seriously lucky... If thats what it really is I suggest that you immediately buy a couple hundred bucks worth of lottery tickets...

jsoderbe

Hi,

now I've talked to the dealership, and apparently I am on plus Karma-wise....

They say that the oil cooler leaks severely both internally and from the gaskets. Of course they can't rule out that there is a problem with the heads too, but it seems unlikely.

On a note they say that to them it seems like the oil cooler often isn't tested properly when trying to diagnose intermix. They have built a really clever test rig, that allow them to test it with the o-rings, fastened like it is on the engine.

They can test oil and coolant passages independently, testing every possibility for leaks. Also, they can test with pressure up to the max of their compressor, around 10 bars. That is very important since many coolers are tight up to a few bars pressure.

I find it very interesting that they claim to have replaced more oil coolers than diagnosed cracked cylinders and heads. Looking at this web site it looks like 50 % cracked cylinders, 49 % cracked heads, and 1 % leaking oil coolers. And I am that 1 %....

I'm just saying, if you have intermix, make sure they pressure test the oil cooler properly before you replace the engine!

Unfortunately I am going back to the US for a month now, so I won't be able to put the car back together until I'm back here. Be sure I will post an update when it is running again! And please keep your fingers crossed for me.

I asked them to keep the cooler for me, and when I am back I'll go by a metal work shop and ask them to cut it in half for me. The porsche tech said the leak most likely is too small to see, but I want to see the internals anyway. I'll be back!


Thanks,

Johan

Flat6 Innovations

Every car that we see with intermix that has been delivered here from another shop has the heat exchanger replaced.. Not once, not ever has it been the root of the intermix issue.

You are that lucky. Exceptions to the rule always occur, but don't get your hopes up until they have cleaned the entire system and you have driven 500 perfect miles with zero mysterious oil or coolant loss with zero signs of intermix.

We also have a device that we made for testing the heat exchangers; your dealership must be outstanding because generally at that level unless the book tells someone exactly what to do they can't do it... Most have to have the book do their thinking for them, because in technical school all they are selected from is how well they perform on written tests...

logray

We also heard of user Sumflow replacing his 97 986 "oil heater" last month which apparently corrected his intermix issue... and I think that he has put plenty of clean miles since.

porschesal

you should ck the oil seperator i can help if you are in the ny area . silverton2@optonline.net

logray

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. "