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Discussion Starter #1
Want to start rebuilding my overheated M54 and trying to start somewhere. Engine overheated but no warpage, just sipping pressure into cooling system through the gasket.

I am trying to arrange o-ringing tool from isky to go along with new 1mm gasket (required for oringing), so figured extra clamping force by switching to m11 would go well in a long run.

Only concern is doing this, re-tapping the thread, on overheated block. Could someone else chime in?

Note: Please don't go too far off-topic; I know that o-ringing and M11 is overkill if I am not boosting the engine. Only on-topic please
 

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After I did hot tank for my engine block , it felt like threads loosened up and i stripped every single one of them , then i retapped it with timeserts and still stripped it , apparently hot tanking aluminum block is not a good idea , it softened aluminum a lot , so i had to put 12 mm timeserts made by hand for 10 mm bolt ) So im just saying that if youre threads are good , 10mm will be fine , the ring gasket i heard bad reviews on it but its for you to decide)
 

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Discussion Starter #3
After I did hot tank for my engine block , it felt like threads loosened up and i stripped every single one of them , then i retapped it with timeserts and still stripped it , apparently hot tanking aluminum block is not a good idea , it softened aluminum a lot , so i had to put 12 mm timeserts made by hand for 10 mm bolt ) So im just saying that if youre threads are good , 10mm will be fine , the ring gasket i heard bad reviews on it but its for you to decide)
Wow talk about bad luck. I have read and heard numerous things about head bolt threads after engine overheats. Some say they get softer, others strip threads when re-installing. Figured retapping thread will take care of possible issues with threads and going up a size will get more clamping force.

So as for the gasket, are you talking about head gasket with cutting ring (or whatever it is called)? If so, yeah I am not going that route. Read good and bad things about it so going with simple 1mm MLS gasket. However, I am o-ringing the block with tool from isky. Basically making a small grove in a block around all of the cylinders. Then copper wire goes into the grove and gets squished when head is installed. Cheaper than that special cut ring head gasket and much better feedback.
 

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The block is made from A356 aluminium. It takes 160 degrees C for 4 hours to anneal the aluminium to dead soft. It will naturally age harden back to within 90% of maximum strength sitting at ambient room temp for 30 days.

The new MLS type head gaskets can't be improved upon, even when adding cut rings. The Stainless steel they are made from will outlast cut ring even when under boost. The biggest weakness is not the head gasket itself, but the head remaining clamped against the block. The one benefit of MLS is that it takes a lot to blow a hole between cylinders. They just need an almost perfect flat and smooth surface to bond to. Better than 0.001" is needed as the glue can only take up 0.001" max.
 

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Discussion Starter #5 (Edited)
The block is made from A356 aluminium. It takes 160 degrees C for 4 hours to anneal the aluminium to dead soft. It will naturally age harden back to within 90% of maximum strength sitting at ambient room temp for 30 days.

The new MLS type head gaskets can't be improved upon, even when adding cut rings. The Stainless steel they are made from will outlast cut ring even when under boost. The biggest weakness is not the head gasket itself, but the head remaining clamped against the block. The one benefit of MLS is that it takes a lot to blow a hole between cylinders. They just need an almost perfect flat and smooth surface to bond to. Better than 0.001" is needed as the glue can only take up 0.001" max.
Would the block reach anywhere near those temperatures during the hot tanking procedure? I wanted to give the head and block for cleaning but rather not to for extra savings. Now I may have another reason not to do it and just apply more elbow grease.

Btw, I don't know if you are referring the the other post or we are confusing two things. This is what I meant by o-ringing https://www.bimmerforums.com/forum/showthread.php?1532029-ORings-The-consolidated-thread
 

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The block is made from A356 aluminium. It takes 160 degrees C for 4 hours to anneal the aluminium to dead soft. It will naturally age harden back to within 90% of maximum strength sitting at ambient room temp for 30 days.

The new MLS type head gaskets can't be improved upon, even when adding cut rings. The Stainless steel they are made from will outlast cut ring even when under boost. The biggest weakness is not the head gasket itself, but the head remaining clamped against the block. The one benefit of MLS is that it takes a lot to blow a hole between cylinders. They just need an almost perfect flat and smooth surface to bond to. Better than 0.001" is needed as the glue can only take up 0.001" max.
Interesting I met a guy who fixes up m54s and e46s and e39s as a hobby and side job. Has a whole yard full of cars. I was talking to him about rebuilds and he said three times he's tried retapping and using timeserts. All three times threads either stripped or a piece of the block near the threads chipped up. He then took the block to a shop where they told him that tapping the m54 is a waste of time and they'll fail. Didn't told me why though.
 

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That sounds like a bad block to start with. Could be porosity, impurities or a shifted core. It takes a lot to tear a piece of the block near the thread. This is the aluminium block with the threads starting 5mm below the deck? yes?
 

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Discussion Starter #8
That sounds like a bad block to start with. Could be porosity, impurities or a shifted core. It takes a lot to tear a piece of the block near the thread. This is the aluminium block with the threads starting 5mm below the deck? yes?
Yup, 5mm or something like that.
 

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Discussion Starter #9
Bumping the thread with hope to get some more input. I am going with M11 head studs, just don't know which yet. What I don't know is if I want to take my chances with just re-tapping M10 into M11 or doing M11 time-sert. This is what I need input on. Also does anyone know if raceware has a part number for M11 head studs that will work with M54 or are they custom made per request?
 
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