996 Water and Oil Intermix

[1ricardo]

Dear Friends,

I have a 2000 996 with an unknown history with 90 K miles and unfortunately there is a lot of oil on the water reservoir but no water on the oil, and here is what I know about the car
- I did not make any leak/compression test
- The oil cooler was pressure tested and its ok
- The AOS was not tested
- There is a lot of oil in the water reservoir, but the oil on the deep stick is very, very clean
- I don't know if the WP was replace any time, don't have the car here with me now, to see if the gasket was cutted
- No matter what I'll put the engine/transmission out ( to try to fix this issue + IMS + Clutch +WP + OAS + Coolant Hoses + Water reservoir + Vacuum lines?! + Oil pressure sensors + wherever you guys tell me it's a good time to change)
But my questions are:
1-) Let's assume this whole problem was the OAS (not likely) could a faulty OAS cause that much oil in the coolant system?
and if yes, how can I double check this info before disassemble the heads ( which is going to be another can o worms)
2-) Now let's assume the head is cracked, how do I check for this? Is the only way to check this is but tearing down the whole thing?
3-) Once I have the heads out, how do I check if they are cracked? Sent to a machine shop or use some type of dye?
4-) Most of people say that its the head 1-3, but then again, what if it's both or bank 4-6? So my question is:
Do I remove both, no matter what?
Do I send both to the machine shop so the head that is not bad could be checked and the valves guides and seat cleaned / refitted / fixed / improved, so I can have both heads in a OK shape?
5-) Once I remove the heads, how can I check if the block/cylinders lines are not cracked as well? Is there some kind of dye to do this job or again, I'll have to ship the whole assembly to a machine shop to be checked?
6-) I heard that there are 2 kind of bolts that holds the heads on the block, where one is a elastic one the other one it's not? Is that true? If yes how can I know which one my engine use?

Thank you all for the help and I hope some of those answer could help out JIM R as well

[carlvs]

2 years ago I purchase a 99 996 with a known intermix problem. I removed both heads and sent them to Hoffman, https://newsite.hamheads.com/porsche/ and they repaired the cracks on the right head. While there I had them pressure test both heads, surface them replace the guides and grind the valves. They did an excellent job. Highley recommend!


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[1ricardo]

Dear friend

Thanks for the reply! May I ask you how you cleaned the cooling system?

[carlvs]

Sure, I “flushed it” numerous times with a strong detergent and hot water. I can’t remember the brand but i5 had been recommended by others on the forum for just this type of situation.


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[looneybin]

“Shout” is what I have heard from a certain M96 guru to use for a flush

[Jeff Alton]

Flush it all you want. Until you have stopped the oil from entering the cooling system (which it will as it operates at higher pressures than the cooling system) you are wasting your time chasing your tail. The 2000 model year has suffered more cracked head issues than any other model year. Do a quick search for that and see what comes up.. Sounds like your issue....

You need to remove the heads to check and confirm....