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Discussion Starter #1
Hey all,
2008 e70 N62 4.8 recently diagnosed with a cracked cylinder; needs a new block.
Have been looking for the e70 used engine but very $$. I noticed that the n62 4.8 (750i and 650i) block was similar and plentiful and cheap. Was thinking about rebuilding the lower engine and using just the n62 block (from the 750i or 650i) but can't find cross reference info.
Anyone have info regarding the blocks.
Any help is appreciated!!
 

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1. "cracked cylinder"? This an actual fact? or just a WAG by a semi-qualified shop/mechanic/stranger?

2. Look up part numbers. If they are different, you cant mix and match. DO you think there is some magic decoder ring where someone will say "oh, yeah- they are interchangeable but BMW tries to hide it by using different part numbers"?

3. You say used motors are too much $$ yet you are going to rebuild a motor from the block up and save $$$... really?
 

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Discussion Starter #3
Yes, actual crack in the cylinder wall.

Was just inquiring as this is my first BMW rebuild. Have done other rebuilds (SBC) and parts were interchangeable (cross reference table)

And yes. Used engine is $2800-$4500. Was going to get a used block ($450 on eBay), new rings and new bearings and take the other parts off the old engine.

just looking into options
 

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3. You say used motors are too much $$ yet you are going to rebuild a motor from the block up and save $$$... really?
My first thought too. The answer is no (unless cutting corners). And it will cost you a lot of time. It should be better than a straight "used" engine though, so if it is within your skillset to rebuild an N62, have at it.
Expect to replace all timing components, etc etc. Might as well do a little sport build on it while you're in there?
... The rest of the car is nice, right?
 

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02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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You owned the car when the cylinder was cracked? How, and what might the other damage be, caused by the same incident. Hydrolock, bent rod? I can***8217;t imagine.
 

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Discussion Starter #6
Plenty of time, honing my skills. . .

Rest of the x5 is pretty mint, no accidents, interior grade A condition.

Visually ( not that it means a lot) the blocks are very similar, gaskets are the same, bore and stroke are the same, mounting points are the same so was just making inquiries; no definitive answers so far.
Was just not trying to drop $4000 on a used engine, would rather drop a rebuild. . . .
Hanks
 

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Discussion Starter #7
The actual cylinder damage may have occurred when doing valve stems; I used the rope method when I should have used compressed air method. Could speculate for days but my thinking is the rope may have shifted the head gasket and allowed coolant in the cylinder causing hydro lock condition; not really sure.
Kinda surprised there isn't more info on the differences in the blocks.
Thanks
 

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The actual cylinder damage may have occurred when doing valve stems; I used the rope method when I should have used compressed air method. Could speculate for days but my thinking is the rope may have shifted the head gasket and allowed coolant in the cylinder causing hydro lock condition; not really sure.
Kinda surprised there isn't more info on the differences in the blocks.
Thanks
I highly doubt that the rope shifted the head gasket. There is no edge for it to catch, the head gasket is perfectly bored to the cylinder diameter and even when installing a gasket it has dowel pins for correct positioning. I'm sure anything is possible but just doubt it :dunno:
 

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Could speculate for days but my thinking is the rope may have shifted the head gasket and allowed coolant in the cylinder causing hydro lock condition; not really sure.
I would keep speculating...

The obvious thing to do here (since you want to rebuild it), is take it out and take it apart. See what it actually looks like inside, and how severe the obvious damage is.
 

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Did you have it inspected with a borescope? Do you know for sure you have a cracked cylinder wall and not a leaking head gasket?
 

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Discussion Starter #11
Yes. When I did a leak down on the cylinders, I could hear air escaping from number 3 so I pulled the head and I saw that number 3 has a piece broken off between the cylinder and coolant passage (block is shot ).

Used vs Short block. . . . .
 

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A good used engine would probably be the best option in the long run. It will be the quickest and lowest cost option to get it running again. Considering a rebuild will likely result in enough unforeseen additional expense that you'd probably be closer to the truth if you take your current estimate and double it. That has been my experience in my younger days when I had the urge to pull the engine and make it better.
 

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Plenty of time, honing my skills. . .

Rest of the x5 is pretty mint, no accidents, interior grade A condition.

Visually ( not that it means a lot) the blocks are very similar, gaskets are the same, bore and stroke are the same, mounting points are the same so was just making inquiries; no definitive answers so far.
Was just not trying to drop $4000 on a used engine, would rather drop a rebuild. . . .
Hanks
I don't know about the interchangeable aspect.
But it sounds like you have done your homework.
Having the skillset, having done rebuilds before
Seem also you're on a budget.
All these factors plays into the swap option you're suggesting. IMO

Make sure there's a back up vehicle... as this will take some time.
Worse if you encounter other issues.

Bear in mind...BMW ain't cheap.
 

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Discussion Starter #14
Hey Rusty34,
That's kinda what I was thinking too. I'm caught in that space of wanting to do a summer project and wanting to just put the bummer back on the road. Will probably settle for something in the middle; getting a used engine and rebuilding parts of it.
And it's like you stated,once you start down the rebuilding path, you don't know where it may lead you . . .
 

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Discussion Starter #15
Hey new kid,
Thanks for the advice. Was just feeling around for options and trying to get some advice.

It's like you said, BMW ain't cheap !!
 

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Discussion Starter #16
Just finished the engine swap. I was able to get a good short block off a 2007 650i and swap out some parts (oil pump and oil pans). However, I had to tap two threads for the oil cool lines on the engine block). Aside from that it was a straight swap; the blocks are the same.
 
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