Threaded Port on Side on Motor??

AristonSpeedShop

AristonSpeedShop

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Having purchased my 3.0cs in a disassembled state, the assembly is a challenge, there is the threaded hole on the motor, rear side of block behind exhaust? Maybe it is water to feed heater? Or drain? Thanks, David
20230322_170151 (1).jpg
 
I ordered the one posted and was way to small, wrong! I stopped by local BMW dealer and that was a bust, they were clueless. It is a 20mm x 1.75 or x 2.0. No one seem to have it anywhere or know what it is. I don't know if the guy who tore the car apart I bought it from or my engine guy lost it. I am ready to JB weld a 1/2" brass NPT plug in there as this is now a $500 escapade for this part.
 
The correct plug for the block is an M14x1.5. The number sfdon posted is the right number.

There’s another plug that’s used on the left side of the motor where the return port goes above the starter. It’s much smaller than the drain plug but I doubt that’s what you received.

Don’t JB Weld anything or seal it up as you need a block drain for the cooling system. Someone must have drilled it out and re-tapped with a larger thread.
 
Well, @wkohler , looking from the pics @AristonSpeedShop provided, I am quite convinced that an M14 will not close the gap...

Something else is going with this block. The OP's block is significantly different then Oem it seems, so the immense wisdom of the group on original situation doesn't seem to apply here.

I am a bit puzzled though by the picture when comparing the std pic from Wkohler to the one from Ariston. The hole is Ariston's block should be 6 mm larger in diameter, but the flat metal ring around the hole doesn't look like it is 3 mm thinner vs the same dimension in WKohlers image.
 
Any stock M30, that M14x1.5 plug is the correct part. I completely agree that it doesn’t work for the OP’s block. I, too, was expecting a greater difference.

I cleaned up the hole in this 3.0 block I’ve got and I think we can agree that the one on the OP block has been drilled and tapped larger, if for no other reason than looking inside the hole.
 

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If, as it appears, someone went through the trouble of enlarging and retapping that obscure hole with non standard size and pitch, I would be seriously concerned about what other "improvements" this block may hide.

Your comment about "I hate putting together cars some rookie took apart" would reinforce that suspicion.
 
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I could believe that in trying to get the plug out at some time, it may have been seized in there and broken off, that would necessitate the larger hole. I thought maybe a drain plug but they are 22mm X 1.5 Maybe a drain plug from a newer engine, I think that they are smaller diameter

Thanks, Rick
 
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Well, so back to my pulling the drain plug yields no drainage thread - https://e9coupe.com/forum/threads/p...ain-plug-yields-no-drainage.18227/post-128185 - when I pulled my drain plug I was looking at a solid wall of, well, something deposited on the inside of my engine. Both sfdon and Mario Langston had seen this problem before and both recommended that I use and punch or chisel and a hammer to smash through the deposits on the inside of the block and open up enough of a hole to allow for coolant to drain. Mario also commented that he had pulled the head from an engine to address this problem. Fortunately, the hammer and punch method worked for me, although I had to hit the punch pretty hard to break though.

Before getting this recommendation, I had thought about using a drill. So, I can see where someone might have done this.
 
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