What I do when not riding (Mechanical Content)

[Bigred455]

As some of you know I am a mechanic by trade and as a hobby I like to buy broken cars, fix, drive for awhile, sell and repeat. This is one of my latest projects, a 2002 BMW M-Z3 with a lower end engine knock, these engines (S54) are known for having rod bearing issues. When I first got this thing I pulled the engine apart and inspected. Once apart I found the #3 rod bearing spun, but the crank was found to be in great shape and the rod looked not half bad. When a rod bearing spins it will actually cause the big end of the rod to oval, increasing the veritcal (with the small end pointing up) diameter while decreasing the horizontal diameter. If the big end is not resized or made round again the new bearing will surely fail. So with this in mind I did my best to measure the horizontal diameter and compare it to one of the other rods. This is a particularly difficult task as the rods are still installed in the engine which is still installed in the car. Not to mention the rods are split at the big end by the "fracture" method meaning there is not a straight line seperating the rod from the cap. With using a simple dial caliper I measured the failed #3 and compared it to the good #4, the difference as best I could determine was less than .001." Keep in mind this is a not very accurate method of determination, but I decided to install new bearings and see what happens as the new bearings only cost me $150.

The plan was to thoroughly torture test the engine and then before I went to sell it I would I pull the pan back off and check the bearing condition. This lasted for 1500 miles before the engine started to knock again. At this point I decided to do it properly. This includes a rebuild consisting of all bearings, rings and gaskets along with another set of rods and lastly the necessary machine work to make the engine as good as new. I decided to document the engine rebuild for the future owner. I thought being gearheads this project would be of interest to yall here. The engine is running as of yesterday and I am starting the arduous BMW recommended 1200 mile breakin consisting of 1200 miles below 5500rpm and 109mph.

To start off here is the engine removal and tear down to long block status.

Failed #3 Bearing




For BMW engines I like to remove the engine and transmission with the front suspension as unit. In doing so the exhaust, driveshaft, fan, air intake and wiring is removed. Here is the engine just before lowering.






Dropping the engine is made quite simple with the use of a lift and a table, our table has wheels to maneuver and can be raised and lowered.

[Bigred455]

Next the engine accessories are removed to allow the long block to be removed from the subframe and installed on the engine stand.

Here you can see the exhaust manifolds are gone along with some of the wiring and coils






Next, the intake, throttle bodies and electronics are gone.








I had to install the suspension back into the car to be able to move it, so while pressed for time I had to ditch the engine off the suspension and get that stuffed back in the car. Future resting place for the engine until I can get it on the engine stand.




And finally the empty suspension getting ready to be uploaded back into the car.

[1100s nut]

Wow, that's huge. I am and always will be a gear head, even though I am stuck wearing a tie most of the time, I still like wrenching. One question, why did they have a tendency to spin bearings? My biggest job in many years was in may this year, a montronic sleeve on my 530i. It was the first big maintenance job on this car, not bad for 220,000 miles. But it was not fun using jack stands. I have never owned a car that I enjoy driving as much as this car, that does everything pretty good.

Thanks for sharing!
Lane

[tm1100s]

Wasn't there some TSBs or recalls for some 2001-2002 S54 engines with the end result being explosive disassembly? Rod bearings, oil supply or something. I have pics of this phenomenon, might take a while to find them.

[Bigred455]

Yes, the early S54's (and really all years) are affected by potential bearing failure. The original cause was blamed on faulty bearings, but I have seen newer engines with them spun too. This was a severe enough problem that BMW had two service actions for replacement, but the Z3's were to be exempt due to their slightly lower hp rating and lower RPM redline, but clearly that didn't stop mine from spinning, haha. I don't know the real cause but I'd expect the cause more to be with rod journal size, Max RPM and oil as this things spin 8k RPM and uses a 10w60 oil.

Lane in Tx that would be amazing to get 220k out of the original sleeve. Was yours original, did it have orange o-rings?

[dee jones]

George, nice work! When you get caught up less talk about over hauling my motor on the 77R100RS! I think it will be simpler. Good luck.

[Martin Glasser]

Hey bGe4orge let me know when the "under 109mph"breakin phase is done, I can stop byAustin to help with the over 109 breakin phase..

[1100s nut]

George, yep, but IIRC, they were green on the replacement. One question, on a X3, to replace a starter, do you go from below or up top, looks like a PIA either way. I need to do this on my wifes x3. I thought about going in above and replacing all the pcv stuff.

Thanks,
Lane

[nail24fac]

PM'd you George.

[Bigred455]

Dee, We'd have to wait until I get my shop built, but definitely!

Martin, I really dont like driving this car at speed, maybe its the tires, but it feels like it needs more caster as it wonders a fair bit when you are trying to keep it straight.

Lane, I assume your replacement is an aftermarket one then as all I have ever seen are black. I'd guess your X3 is a pre-'06? With the crankcase vent valve out of the way (including the throttle body) I'd imagine you would have plenty of room to get it out the top. It really depends on a case by case basis for me as to whether I pull them out the top or bottom but generally they come out the bottom.

[1100s nut]

Thanks George. It is a 2004. We love the car...have had in deep snow and have climbed some pretty steep dirt hills...hauls cargo and our 5 dogs and with the versi- haul plugged in carries my ktm. Still undecided on the starter...the bendex has been sticking for a while. I wish I could get a couple of drops of oil on it....did that on my RT...never stuck again. Must have been blk. O rings...bought the part from BMW.

Be safe,
Lane

[Bigred455]

Sticks in the extended position or retracted? My last Z4 had it stick extended and then shorted internally. It cranked the engine until I got the battery disconnected, lol.

[1100s nut]

Extended...makes the screeetch sound for a couple of seconds after the engines lights off.

Lane

[Bigred455]

With The engine on the stand the fun begins











Next The Valve Cover comes off

[Bigred455]

Then the variable camshaft timing unit (Vanos)







Then the gears and timing chain







Then the camshafts







Valvetrain laid out on the table

[Bigred455]

The the head










Next the rods and pistons

[Bigred455]

Finally the crankshaft






Main Bearings look good




Damage to the crank, which is really nothing at all. The speckling you see is material transfered from the bearing. The crank was good to go with just a simple polish job.




Parts bagged and boxed awaiting return of the parts from the machine shop.

[andrisport]

Ha and I was thinking I'm a "bad ass" replacing head gasket on my girlfriend's bmw few month ago $50 on parts and 3 days of fun

[tm1100s]

Interesting pics of the S54 M3 type failure. No longer have the pics of the bits and pieces that came flying out of the pan.

[dee jones]

George, that's a nice sanitary job!

After you get it sorted out you should reward yourself with a nice long ride!