overheated M54. Pictures of a complete removal, teardown, and inspection.

so im not sure if ANYONE here is interested in this, but I figured Id post it anyway.

I purchased a badly overheated E39 about 5 months back. I knew the cylinder head was toast, but rolled the dice on the rest of the engine (its pretty hard to properly diagnose without a full teardown).
I time-serted the block threads at the time as I knew the engine had been cooked not once, but twice. The owner knew it was overheating, pulled over, waited 15 minutes, then started it again and drove it until it stopped.
the head was warped enough that every fluid inside the engine (including fuel) was coming out between the block and head.

so i got the car cheap and yanked it apart. The head was warped, but repairable. There was no obvious damage to the cylinder walls, so I just said "the heck with it" and assembled it.

however, more damage was present. The engine had pretty awful piston slap from the moment it was started. The noise was very obvious when cold, would diminish, then come back with a vengeance as the engine hit operating temp.
I drove it for 4 months anyway, as it ran fine. It was just rattling pretty badly.
Finally i decided to find out exactly what else was ruined, as my first guess was piston damage.

the following are photos of my repair up until now, as Im waiting for some parts to be delivered and a little free time.

it turns out the noise is NOT from the pistons.. but rather the block itself. The deck is flat, but a few cylinder bores are royally tweaked. Number 4 in particular is out of round by .010! The piston flops around inside it like a fish.

Cylinder one and two are perfect, and the others are a little messed up but usable.
the options are to bore it, replace it, get a new engine, used engine, etc..
I dont trust used assemblies, and I dont want to invest the time/money in oversizing this block... so I searched and found a nice used bare block. They are MANY available, especially if you consider that the 2.5 block is the same as the 3.0 block.

so ill replace the block, use my rotating assembly, replace maybe one or two pistons along with misc other parts, and have a nice, quiet M54.

I shall update with other info and photos if it turns out that anyone actually cares.

Interesting! Thanks for positing this.

Interesting too how the calipers don't lie, whereas our eyes may tell you all's well. Hope you can get it all back together and have a better deal this time around!

When you say you got it cheap---I do hope you mean FREE !

Wow, amazing pictures.
It's rare to see photos of such extensive work.
Entire front end seems to be taken apart.
Are you a professional mechanic?


Do you feel this car was worth getting into?
Or do you wish you just got a normal condition E39 for $6000 or so...

Originally Posted by EconoBox

Wow, amazing pictures.
It's rare to see photos of such extensive work.
Entire front end seems to be taken apart.
Are you a professional mechanic?


Do you feel this car was worth getting into?
Or do you wish you just got a normal condition E39 for $6000 or so...

Its the easiest way to take it apart. Not the ONLY way, just the easiest assuming you have the facilities. Obviously, doing this in your garage is unlikely. You'll need a minimum of a car hoist and a large set of tools.

And yes, Im a bimmer tech.


my total invested will be approximately 3000$ (if you don't include time).

it blue-books at about 7000-7500$ (its a lower mileage 03), so yeah, Its worth it. It would have been MORE worth it had the block not been warped from the heat, because my total investment then would have been only about 2000 bucks. But whatever! Cant win 'em all.

I have a set of good used M54 3.0L pistons that you can have cheap if you're interested. I'm in the process of doing a performance build on the same motor.

Gary

I see you are in MN. Is that motorwerks? Do you work there?
Awesome to have a lift for such a task. GL

I had decided to reference only the last 50 threads in the bestlinks for people to get an idea how others resolved a badly overheated E39 engine ... so ... with that in mind, I think it's fitting to make this the fiftieth and final thread referenced in the bestlinks pointer on this topic:

- Summary advice to provide users who suspect a major engine repair due to overheating (1) (2) (3) (4) & how to test an engine for a blown head gasket, cracked heads, a warped block, stripped head bolt threads, cam seizures, contaminated bearings, coolant hydrolock, or piston, ring, or valve damage (1) (2) & what are the major factors in deciding whether to rebuild the engine, replace the engine, or sell the car (1) & a DIY for replacing the I6 M54 head gasket (1) (2) & replacing the V8 M62TU head gasket (1) & why these engines are so prone to heat-related damage in the first place (1) & welding the crack between cylinder #3 and the water jacket on the exhaust side (1) & what engine swaps are most recommended (1) (2) (3) & where to obtain a new or rebuilt head (1) replacement short block or long block (1) (2) & how to lift & remove the engine (1) & the most recent real-world results from the last 50 people faced with similar blown engine problems from which this advice came from (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (43) (44) (45) (46) (47) (48) (49) (50)

Just looking at those pictures fascinates me, I hope to be able to tackle more and more complex jobs myself on my E39. I'm interested in seeing more for sure.

I miss having the facility to do tear downs. Glad you got this issue sorted out.

Nifty thread!

Thanks for the expertise and pictures!

Thanks!
Jason

Oooh ... nice pics, Manybrews, please update as you go. Very educational.

Wondering to myself if it's possible to slap a 3.0 head/pistons on my M52TU (2.8 L) block....

Originally Posted by pleiades

Oooh ... nice pics, Manybrews, please update as you go. Very educational.

Wondering to myself if it's possible to slap a 3.0 head/pistons on my M52TU (2.8 L) block....

Dont quote me, but I'm pretty sure the m54 head is the same casting as the m52tu.

Pistons, I dunno.
The m54 blocks are the same between the 2.5 and 3.0, as are the heads.. But the crank, rod, and pistons aren't. Neither is the intake, throttle, or dme.
Externally nearly identical, though.

More pics.
not always the best, but you get the idea.

Here you will see me measuring a cylinder on the new block... and its perfect.
the same cylinder on the old block? You'll see its .010 out of round widthwise. And thats
not taking into consideration that it pulled the cylinder walls IN longitudinally .002, which makes a grand total of .012 out of round.. or 3 times the allowable.