DavidF

So, over this past weekend (+1 day) I performed repairs to the three all too common V-8 issues on my '04 545i: Leaking valve stem seals, coolant transfer pipe and plugged secondary air ports. Let me first say that these repairs are NOT for the faint at heart or occasional DIY'er. It was a royal PITA and very difficult (I consider myself a very accomplished DIY'er). I started Saturday morning and did not finish until Monday evening. Working 12-14 hour days. So all total, it took me at least 36 hours of actual labor time. All this in 100 degree or so Houston heat and humidity. I won't go through all the steps required as that has been documented elsewhere. Also, I used all All German Auto parts and tools with a total price tag of about $2600 if I remember correctly.

So, in the end, I could not get bank 2 air ports cleared/open with the AGA cleaning kit. I will still have to purchase their pick tool which requires removing the exhaust manifold...oh joy, can't wait

The valve stem seal replacement is by far the most tedious automotive repair task I have ever attempted. Sure, it worked, but holy crud what a job. By the time I got the process worked out, it took about 20 minutes per valve. But, doing this 32 times requires lots of rest and dread. And the rear valves take longer as the space is tight in the engine bay. I will say that the tool worked well. Total time to change the seals was about 16-18 hours not counting valve cover removal or any other part removal/installation to get to the seals. 16 hours just to change the seals. Be prepared.

And finally, the coolant transfer pipe. This repair is fairly straight forward and not too terribly difficult. Mine was not leaking, but the pipe pulled out of the front of the engine easily, so at 125k miles it was soon to start leaking. I changed the pipe as preventative maintenance since I was so far into the top of the engine already.

Oh, and those valve covers....holy you know what! Not fun either. Getting the bottom edge aligned with the head sealing surface so that it seats properly and you can start the nuts in the rubber grommets all the while trying not to break the cam timing sensor is a not fun.

So, got it all back together and the engine started right up with a terrible stumble/roughness. No funny noises, so I believe the rocker arms were reinstalled properly. But, I am too tired to investigate right now. My instincts tell me I have a coil or two not working. And, you should have seen the spark plugs after 125k miles on them...worn to a nub. Even with a severe miss/stumble, my fuel mileage improved by 2.5 mpg or so on drive from Houston to Austin.

So, anyone have any comments/suggestions on the roughness issue? Yes, I still need to connect my computer to the car and read the fault codes, just too tired still.....

H F

Wow , , talk about rolling up your sleeves and getting in there ,, good job you got allota stuff done .. About the rough idle , check for a vacume leak and the CCV's hopefully it's something simple like a coil pack ..

AutohausAZ-Mike

Good job for taking the job head on!
Definitely labor intensive.

DavidF

I thought about a vacuum leak and then realized that my engine has valvetronic so it doesn't really create its own vacuum and thus a leak should have no bearing on the engine performance. The vacuum (pump) is only for brake booster. Since the engine does not have a throttle plate, any small amount of vacuum leaking could only fool the MAF sensor. Such a small amount would affect drivability but certainly not the rough stumbling problem I have right now. The OBD diagnostics immediately recognized the problem which tells me coil/spark to one cylinder or more.

Feel free to shoot holes in my analysis, if you want to.

H F

After I changed my valve cover gaskets , started up the car and the car went crazy . The idle was irratic and the engine was shaking violently . I was ready to cry like a new born . But once I look under the hood I heard a mean vacume leak . Turns out I accidently cracked the vacume hose to the driver side CCV . I got some electrical tape and wrapped both vacume hoses . You know what after a quick fix ,, it purred like a kitten . So fist hand I can tell u that a vacume leak can cause a rough idle .. Also a cracked CCV diaphragm .
A faulty DISA valve can also cause a rough idle .. Something you should look into if coils , CCV and a vacume leak are ruled out ...

DavidF

Thanks HF, I certainly will check it out. I actually forgot about the CCV valves connected directly to intake manifold...that would let in a lot of unmetered air. My '04 does not have the DISA valve...I think that was added in '05 (could be wrong). Waiting for the weekend to be able to work on it in cooler morning air. 100 degrees every day now in Austin, TX when I get home from work....too hot.

Update: Listened to the engine carefully at lunch with a/c off (therefore no fan noise) and I could hear bank 1 CCV valve squeal rhythmically. So, somehow while handling the valve cover, I must have damaged the CCV (maybe due be storing upside down) or I cracked the tubing feeding the valve. Will investigate more Sat morning.

H F

Good find ,, thats an easy fix .. Your 04 by the way ,,, does has a Disa Valve .. All n62's have a motorized disa valve ...

DavidF

Yep, I was thinking of the disa on my E46 (M52) that is way different than the larger motorized version (variable intake runner length motor) on the back of the intake manifold on the N62. My bad.

DavidF

Solved: it was the #1 and #3 coils. Swapped around and one cleared, the other moved positions. Contact cleaner and both are now working fine. Engine smooth again, no smoke after idle and no coolant lose. Idle is smoother than before and generally the car runs great. Also, the CCV valve stopped squealing once the misfiring was corrected.