Heart removal hunt for intermix

[sehorntx]

I'm on the hunt for recurrent intermix issue. Failure is not an option. Well, if engine is toast I'm shipping the car back to Stuggart (Cash on delivery) :)

[mffarrell]

I hope you find the problem and fix it. It would be funny if people start sending their engine toast back to Porsche HQ. lol

[logray]

What work have you done so far to fix the intermix?

[sehorntx]

Have had both heads repaired for cracks in the spark plug recess of cylinder 1 and cylinder 6. after removing spark plug tubes no evidence of visible cracks like before. Diagnosis still unknown.

Plan to remove heads again send to machine shop for presssure testing, and look at block for evidence of damage/cracks.

Anyone convert to full electric vehicle? :)

[sehorntx]

Got engine out this time without losing any fingernails, I'm getting better but still an amateur!

[logray]

You can also have them x-rayed.

Perhaps they didn't go deep enough with the crack repair?

Did they heat up the heads before pressure testing?

Maybe find a used head?

Check the bores for cracks.

Maybe bad head gasket seal (were they resurfaced?, checked for warpage?)

[wvicary]

Inspect the AOS and the oil cooler.

Could you be more descriptive as to where the cylinder heads were cracked. I don't think that would case a intermix problem from what you are saying and I have never heard of a fault between the spark plug recess.

[sehorntx]

Both heads were resurfaced during last repair

Head gasket for 1-3 head looks good (just removed)

Pistons/combustion chambers 1-3 look good

Can AOS cause intermix?

Had oil cooler replaced prior to last head repair but am sending it in to machine shop for pressure testing

Cracks were visible to the eye extending from spark plug recess #1 toward the valve spring adjacent to it

[logray]

The AOS would need to crack between the coolant and oil passages, and on top of that I think it would need to have also failed (causing excessive vacuum in order for enough oil to be drawn in) because normally it contains oil mist and drained by gravity. At $100 it's cheap insurance to just replace it.

Personally, I would focus on the repaired heads, and have them re-pressure tested.

[JFP in PA]

When checking the heads, be sure to closely look at the small diameter freeze plugs under the cam covers, they can be a major source of headaches to the point that some shops are machining and threading them to accept screw in replacements.