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Hi. 2000 C4 Cab. Started smoking heavily out of exhaust and intermix (both oil in coolant and vice versa). Took to local shop who is comfortable working on it. They talked to a Porsche mechanic who said more than likely the oil cooler. Replaced oil cooler and AOS. Flushed coolant system several times and replaced oil several times after running a couple of minutes. Now I am still getting oil in the coolant. Never a CEL and car has always ran fine. Common answer I see is cracked head. Could a cracked head put that much oil in the coolant (20 miles) and still run fine.

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Hi. 2000 C4 Cab. Started smoking heavily out of exhaust and intermix (both oil in coolant and vice versa). Took to local shop who is comfortable working on it. They talked to a Porsche mechanic who said more than likely the oil cooler. Replaced oil cooler and AOS. Flushed coolant system several times and replaced oil several times after running a couple of minutes. Now I am still getting oil in the coolant. Never a CEL and car has always ran fine. Common answer I see is cracked head. Could a cracked head put that much oil in the coolant (20 miles) and still run fine.

Unfortunately, yes. There are only a few pathways for oil to enter the coolant on the 996; the oil cooler and AOS are common. If that did not address the issue, your next step should be to have the coolant system pressure tested, looking for signs of leakage. I would also pull all the spark plugs, looking for one or more that seem unusually clean. If you find that, I would either bore scope and/or run a leak down on those cylinders, looking for signs of a cracked head.

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Most common cause for intermix in 3.4ltr seems to be cracked head. These can be fixed. Also change your water pump while you are repairing the head. *Dharn55 was the first to post a successful fix on Rennlist.com

MORE INFO HERE:

http://forums.rennlist.com/rennforums/996-forum/712349-cracked-head-2.html

From another thread:

*

"OK I will jump in now having suffered and fixed an intermix. Talking with Flat 6 is not a bad idea and I have great respect for Jake Raby. The challenge is that the best option if cost is not an issue will be a Flat 6 engine, there probably are no better engines out there. However they start at over $18,000 and quickly go up from there, plus you have to transport the car there and back. So we are talking about spending $20,000+++ to put an engine is a car that is worth about $20,000 and won't be worth that much more when the work is done. For many people that just does not make sense.

I think jake is also fixing cracked heads now, but it is still expensive with the shipping, etc., and probably not his recommended approach.

Probably the first thing to do is to determine what the source of the intermix is. You can check the oil cooler, they can crack and I certainly checked mine, but it is almost never the source of the problem.

As for the AOS, I guess it could cause a intermix, but I have never heard of this being the source of this kind of a problem.

It could be a D chunk and you might see this with a boroscope, or by taking the head(s) off but I think the most common source of this problem is a cracked head. If you check the threads on my repair you will see lots of information and pictures. It is probably a crack at the inner exhaust valve spring seat on cylinder #1 or # 6, mostly likely #1. If you remove the engine and the cam cover, cams and lifter body you can usually see the crack, start with the 1-3 head.

These cracks can usually be fixed. I spent $500 including a valve job on that head, but that was a few years ago so the price is probably higher now. I also have a new in the box 1-3 head that I will sell for $1,600, at the dealer they are over $3,000.

It took me about 40 hours or so to do the work, and this was in my garage with no prior experience on the M96 engine. If I had to do it again I would guess about $15-20 hours. You need some special tools, either make them or buy a set. I can also rent you the tools you need. I spent another $800+ on parts directly related to the crack, and more to replace other things while I was in there (coils, plugs, tubes, AOS,etc.).

Now some question whether an engine with intermix can be saved or is worth saving due to damage to bearings etc. I will tell you that my intermix was really bad. The coolant was the consistency of pudding, and the oil was like a milkshake, and I don't know how long it was like this. I discovered the problem when the coolant light started flashing. And when this happened in 1998 the dealer,my Indy and Jake all told me had no choice but to put in a new engine. At that time Jake said that cracked heads could not be fixed, but now we all know that in many cases they can be. I am sure that the bearings, rings, etc. on my car are not as good as they would be if I had never had the intermix. But I have good oil pressure and compression and spent my time and about $1,500 and now have almost 23,000 on the car since the fix, it runs strong ad I am happy. If it had required a new engine the car would be in a junk yard now. I could not have afforded a new engine and would have questioned spending what the car was worth on an engine.

I have now worked with many others on fixing their cars with intermix problems and it is being done on a regular basis.

If you want more I formation, etc., let me know, I would be glad to help if I can.

__________________

Doug

Current: 2000 996 C4 Cab, Ocean Blue w/Savannah Beige"

post-30824-0-93760800-1376794303_thumb.j

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  • 6 years later...

Doug, how can i contact you? I am a new Porsche owner ,one year roughly. My coolant light flashed this morning i check it and there was some brow slurry stuff at the bottom of tge empty reservoir. I refilled with coolant. I checked my dipstick and it was fine do I'm confused how oil can be in me coolant and yet i have no coolant in my oil.

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8 minutes ago, Sarc1218 said:

Doug, how can i contact you? I am a new Porsche owner ,one year roughly. My coolant light flashed this morning i check it and there was some brow slurry stuff at the bottom of tge empty reservoir. I refilled with coolant. I checked my dipstick and it was fine do I'm confused how oil can be in me coolant and yet i have no coolant in my oil.

 

Simple:  The cooling system operates at 18 PSIG; the oil system runs 50-70 PSIG; which way do you thing the fluid would move?

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49 minutes ago, JFP in PA said:

 

Simple:  The cooling system operates at 18 PSIG; the oil system runs 50-70 PSIG; which way do you thing the fluid would move?

True. Update... i actually do have some coolant in my oil i removes the fill cap and the is some beige spotches on the inside of the cap and in the fill tube should i assume its the cylinder head at this point? Or perhaps my engune is toast?

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57 minutes ago, Sarc1218 said:

True. Update... i actually do have some coolant in my oil i removes the fill cap and the is some beige spotches on the inside of the cap and in the fill tube should i assume its the cylinder head at this point? Or perhaps my engune is toast?

 

Some “mayonnaise” like build up on the oil cap is normal and not necessarily a sign of anything.  Before giving the car a Viking funeral, do some diagnostics first, such as pressure test the cooling system and leak down the cylinders.  You could just have a cracked cylinder head, which is not uncommon and a relatively easy fix.  You need more data before making any decisions. 

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