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On The Road Again/Intermix Is Fixed


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:D Well about 11 months after I first discovered the intermix on my 2000 996 C4 Cab, and 2 ½ months after starting to drop the engine I took the first real drive today. Put about 50 miles on the car and everything seems fine. Total cost was about $2,000 in parts and repair of the cracked head (this included some misc parts unrelated to the cracked head) and a lot of hours of labor (but these days I am working pretty cheap).

I guess I will feel better after I put a couple of thousand miles on the car, but I am thrilled to be back in the driver’s seat of my 996 again. I had forgotten how much fun it is to drive this car, especially with the top down. The whole process of tearing down the engine, finding the problem and fixing it was quite an adventure, with a lot of side roads taken. But the final outcome seems to be good.

So those of you who have an intermix problem, TAKE HEART! When mine first happened I was told by many sources, on the boards and mechanics that the only fix was a new/reman engine. Well that is really not the case. I will do a longer post later recapping the whole process, but just wanted to let people know that the car is fixed and back on the road.

I also want to thank several people who helped and consulted on the project.

First, thanks to Doug Donsbach, who has a “twin” crack in the head of his car. We commiserated and he gave me help in fabricating tools, and the picture of his crack helped me find mine.

Thanks to Jake Raby at Flat 6. Jake is an incredibly nice guy, who has an unbelievable knowledge of these engines, and was extremely generous with his time and advice. I can’t say enough nice about Jake.

Also, a big thanks to 99firehawk, a tech with a lot of knowledge who was helpful in many ways. His time and help were really appreciated.

And thanks to Jeff Clark at Sunset Porsche. I have been getting my parts from Jeff/Sunset for several years and they are great.

Thanks to John Edwards/Costa Mesa R&D. They did the head repair and valve job on the 1-3 head. John knows the problem with the heads and has experience in fixing them. He was quick and very well priced to do the work.

Also thank to Rick and Ron at Valley Tool & Mold in Gilberts, IL who did the tapping and plugging of the cams. The expansion plugs on these proved to be a major challenge, but should never be a problem again.

There were a lot of others who helped and commented but I can’t name all of them.

So I AM ON THE ROAD AGAIN. If anyone else needs some help with their intermix problem I would be glad to help as much as possible, I have developed a little bit of expertise in this over the last few months.

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:D Well about 11 months after I first discovered the intermix on my 2000 996 C4 Cab, and 2 ½ months after starting to drop the engine I took the first real drive today. Put about 50 miles on the car and everything seems fine. Total cost was about $2,000 in parts and repair of the cracked head (this included some misc parts unrelated to the cracked head) and a lot of hours of labor (but these days I am working pretty cheap).

I guess I will feel better after I put a couple of thousand miles on the car, but I am thrilled to be back in the driver’s seat of my 996 again. I had forgotten how much fun it is to drive this car, especially with the top down. The whole process of tearing down the engine, finding the problem and fixing it was quite an adventure, with a lot of side roads taken. But the final outcome seems to be good.

So those of you who have an intermix problem, TAKE HEART! When mine first happened I was told by many sources, on the boards and mechanics that the only fix was a new/reman engine. Well that is really not the case. I will do a longer post later recapping the whole process, but just wanted to let people know that the car is fixed and back on the road.

I also want to thank several people who helped and consulted on the project.

First, thanks to Doug Donsbach, who has a “twin” crack in the head of his car. We commiserated and he gave me help in fabricating tools, and the picture of his crack helped me find mine.

Thanks to Jake Raby at Flat 6. Jake is an incredibly nice guy, who has an unbelievable knowledge of these engines, and was extremely generous with his time and advice. I can’t say enough nice about Jake.

Also, a big thanks to 99firehawk, a tech with a lot of knowledge who was helpful in many ways. His time and help were really appreciated.

And thanks to Jeff Clark at Sunset Porsche. I have been getting my parts from Jeff/Sunset for several years and they are great.

Thanks to John Edwards/Costa Mesa R&D. They did the head repair and valve job on the 1-3 head. John knows the problem with the heads and has experience in fixing them. He was quick and very well priced to do the work.

Also thank to Rick and Ron at Valley Tool & Mold in Gilberts, IL who did the tapping and plugging of the cams. The expansion plugs on these proved to be a major challenge, but should never be a problem again.

There were a lot of others who helped and commented but I can’t name all of them.

So I AM ON THE ROAD AGAIN. If anyone else needs some help with their intermix problem I would be glad to help as much as possible, I have developed a little bit of expertise in this over the last few months.

Glad it worked out for you -- do you have pix of the crack?

Just wait ~2k miles & you'll really be having a blast and truly be able to pat your self on the back.

good motoring,

m

Edited by txhokie4life
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Congratulations for a fellow "intermixer"

My engine is out and on the floor of my garage. Just took off transmission, and beginning some cleaning before head disassembly.

Great to hear your car running, I'm wondering if I will ever hear the same, as I'm about 8 months into my intermix ordeal.

With luck I have a repairable head as well.

Will get with you as may want my head to be repaired at same place!

OUTSTANDING!!!

I've forgotten what its like to drive my 996! :P

Tim S

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Tim - No picture, but I know what you mean about the intermix stuff, it is like pudding and is everywhere in the cooling system. I took out my radiators and had them flushed, took off almost every hose and ran rags through them, also the tubes from the front to the back of the car, and cleaned out the engine as much as possible, but could never get all of the stuff out. And the heater coil was never touched. I think the only way you could get rid of all of the pudding would be to replace the radiators, pipes hoses, heater coil and everything else. But I don't think a little of the stuff will be too much of a problem. I still have some that floats up into the coolant tank. I am going to flush the systems a few times of the next few months to get more of it out.

Now that the engine is out of the car the first thing you should do is check for the crack at cylinder #1. Here are pictures of my crack, and of the crack that Doug Donsbach has with dye on his.

post-7011-1247693738_thumb.jpgpost-7011-1247693780_thumb.jpg

These cracks are at the inner exhaust vavle spring seat extending to the spark plug chase, so the lower left hand side of the chase. You could put some dye in before you reomve the plastic tube and the plugs and might see it, if not then remove the tube and see if it is visible. If you still don't find it start with taking the cam cover and cams off, then the tappet carrier. If yours is the same crack (and lots of them are) you will be able to see it then. Hope this might be your crack/source of intermix as I know it can be fixed. Let me know.

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Tim

Thought I should give you a little more guidance before you remove the cams on your heads. When the cams are removed you need to be able to reallocate them, i.e. set the timing of the cams to each other and to the IMS shaft. This is critical in reinstalling the cams. Porsche has several special tools, including pretensioners (about $400+ per set at Sunset, have to be ordered from Germany). The manuals show how this is done and the tools required.

However, I used a “shade tree mechanic” approach which works well as long as you are not totally disassembling the engine. Allocating the cams to each other is pretty simple. Here is a link to a YouTube video that shows how this is done (If you haven’t watch this whole series of videos on rebuilding a M96 engine it is definitely worth while).

However, if you don’t remove the advance/tensioner mechanism you won’t really need to do this as the cams will not lose their position to each other.

The next issue is the relation of the cams to the IMS. This is controlled by a chain that runs from the IMS to a sprocket that bolts to the exhaust cam on each side. The manual has you set the engine to TDC and the cams in a certain position, then use “pretensioners.” As I did not have the special tools here is how I did this.

The two critical things are the relation of the sprocket to the IMS chain, and then the sprocket to the Flange on the exhaust cam. I used bright red fingernail polish to mark the items and a hard metal punch to make additional marks.

For the sprocket/chain setting, you can mark one of the teeth of the sprocket and a link on the chain that it fits into. I did this but did not really need to as I never removed the sprocket from the chain. It would actually take some effort to take the sprocket out of the chain, and I used some wire around the chain to make sure it did not come out. However, the markings are a good safeguard.

For the setting of the sprocket to the flange on the cam I put to spots of nail polish in the back/cam side of the flange and the sprocket, then also scratched a line on the flange and the sprocket with the punch. These marks show exactly how the sprocket sets to the flange on the cam.

As long as you are not disassembling the engine to the point where the IMS chain is coming off the IMS itself you can use these marks to reinstall the cams in the correct position.

Thought this might help as you try to find any crack in your heads while minimizing disassembly and hassles/challenges putting everything back together.

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Doug

Thanks for the link, I have been watching those films closely! Will go over this carefully with you before I begin head disassembly.

Will be on vacation next week. Alas, my project will have to wait.

Tim

Thought I should give you a little more guidance before you remove the cams on your heads. When the cams are removed you need to be able to reallocate them, i.e. set the timing of the cams to each other and to the IMS shaft. This is critical in reinstalling the cams. Porsche has several special tools, including pretensioners (about $400+ per set at Sunset, have to be ordered from Germany). The manuals show how this is done and the tools required.

However, I used a “shade tree mechanic” approach which works well as long as you are not totally disassembling the engine. Allocating the cams to each other is pretty simple. Here is a link to a YouTube video that shows how this is done (If you haven’t watch this whole series of videos on rebuilding a M96 engine it is definitely worth while).

However, if you don’t remove the advance/tensioner mechanism you won’t really need to do this as the cams will not lose their position to each other.

The next issue is the relation of the cams to the IMS. This is controlled by a chain that runs from the IMS to a sprocket that bolts to the exhaust cam on each side. The manual has you set the engine to TDC and the cams in a certain position, then use “pretensioners.” As I did not have the special tools here is how I did this.

The two critical things are the relation of the sprocket to the IMS chain, and then the sprocket to the Flange on the exhaust cam. I used bright red fingernail polish to mark the items and a hard metal punch to make additional marks.

For the sprocket/chain setting, you can mark one of the teeth of the sprocket and a link on the chain that it fits into. I did this but did not really need to as I never removed the sprocket from the chain. It would actually take some effort to take the sprocket out of the chain, and I used some wire around the chain to make sure it did not come out. However, the markings are a good safeguard.

For the setting of the sprocket to the flange on the cam I put to spots of nail polish in the back/cam side of the flange and the sprocket, then also scratched a line on the flange and the sprocket with the punch. These marks show exactly how the sprocket sets to the flange on the cam.

As long as you are not disassembling the engine to the point where the IMS chain is coming off the IMS itself you can use these marks to reinstall the cams in the correct position.

Thought this might help as you try to find any crack in your heads while minimizing disassembly and hassles/challenges putting everything back together.

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  • 2 years later...

How long after the intermix fix were you still getting sludge in the coolant since it seems imposible to get all the intermix out of cooling system? My mechanic who did my work has told me i just need to suck up any floating residue with a scott towel once a week for next few months. He tried his best to wash it out but it still just keeps finding more.

Is this bad for coolig system to still have this in the coolant? Its not a lot but enough to worry me. I am staying away from track for a few months since i am parahoid about this in the coolant.

I went the route of using an indie mechanic to do my work and was charged for parts and 35 hours of labor. I bought a used cylinder head at Parts Heaven for $800 and had it refurb. It cost me about $8k in total. The mechanic repalaced every single hose in engine.

Happy so far.

Miller

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Wow, a thread from my past resurrected. I did an incredible amount of cleaning . Had all the hoses off, the radiators out and flush, pulled cloths through the pipes, changed the water pump, had the one head off and drained the engine on the stand, flushed the system with distilled water , changed the coolant twice, had a hose leak that flushed more out of the system. And with all this I am willing to bet that if you analyzed my coolant you would still find traces of oil in it. The only thing I did not take apart and/or flush was the heater core. I don't think you can ever get it all out. But I have over 16,000 mile since the fix and the engine is running strong.

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