Got my valvetrain noise diagnosed

I had put out a previous thread on valve clatter and Techron. It turns out that the valves all needed adjustment pretty badly but what mostly caused the clattering (and here I'm a bit fuzzy) is that sludge had developed around the rocker arms and had prevented the oil from being distributed there and/or being recirculated. The indie shop adjusted all the valves, put in a new valve cover gasket and plug and added some heavy duty oil cleaner. He told me to come back after 1000 miles and they'd change the oil. The noise is down about 50% after 50 miles on the road.

In researching my Bentley Manual (p.27, section 4.4) I see that the rocker arm shaft has little holes (oil bores). I think they were trying to tell me that these holes got plugged up with sludge and interfered with the oil flow to the rocker arms. Does that make sense?

yes, sounds plausible.

Plausible maybe, but it turned out not to be the case. After that shop put in the Swetco 502 Engine Cleaner the clatter turned into a louder rapping noise. I drove it for ~150 miles and got nervous that damage was being done. I brought it to my BMW mechanic and he diagnosed bottom end noise, probably bearing wear or a spun bearing. He cut open the oil filter and found sludge and small pieces of metal. End of story, end of engine.

Cause unknown but it must have been driven with low oil pressure and high temperatures at some point before I bought it. The previous owner (1999-2007) only used Mobil 1 so it must have happened prior to that.

Looks like I'll be buying a used engine through the BMW shop for $500 and having it installed. Damn, damn, damn! Other ideas for alternatives are welcome, but I don't see that there are any.

stevehecht: I am sorry to hear about the fate of your engine! That is really bad news! I am glad to hear that you are getting another engine for it. You have such a nice E30 it would be a shame not to fix it! Other than a used engine you could get a rebuilt unit from Korman or Metric Mechanic. Those of course will be much more expensive. BUT, if you are going to keep this car a very long time it would be worth it. And since you are replacing the motor anyways, you could go with one of their performance motors! You will have more power with not much sacrifice in drivability! They have different levels of performance modifications. Check out their websites.

http://www.metricmechanic.com/

http://www.kormanautoworks.com/

Again sorry about the ruined motor!

GR

Sorry to hear that. I'm hoping their engine cleaner did not aid in damaging your motor. I will tell you that if you plan on getting a new engine that you may wish to build yourself (or have someone) build you a nice motor for the car. A 2.7 liter 325i is a mighty nice car to drive and not all that hard to pull off. In fact, if you can find a 1988 325e or 528e motor, then you are almost there. You would only need to swap the cam, and there is really not that much power to be had by doing that, so you can simply request a 1988 "super eta" motor and be done with it if funds are a problem.

Yeah, my mechanic is pricing out the M50 swap vs. the M20 2.5L. If it's a matter of $500 or less of a difference in cost I might go with the M50.

Are there any particular reliability problems with the M50 swap? I do have a 4.10 LSD in the car and I've heard that that could be a problem with the M50. But I've also heard that it's OK.

I ran a 4.44 with an M50 in my ti for a little bit. It revs like mad, but that is with a 1:1 5th gear. Of course to do the M50 swap, you should use an M50 trans, which has a 1:1. You could sell the 4:10 for big bucks and pick up a 3.25 LS for next to nothing. The M50 swap is "easy" but they have to know their stuff.

If I'm going to swap the diff I'm trying to find out what's ideal. 3.73? 3.25? I've heard "diff"erent ideas about it. Also, I thought it's OK to keep the stock tranny for the M50 but then again I've heard otherwise. Sell the 4.10, pick up a 3.25 or 3.73 and do I still need the M50 tranny? Or keep the 4.10 and go with the M50 tranny?

As for the 325e, I don't think I'd be happy with that amount of hp. I'd prefer the M50 for that reason.

For the M50 you can use the M20 trans, but the angle is a little off and requires some work to get hte shifter right. If I remember correctly, the angle is off by maybe 5 degrees, but it is a problem that you have to deal with if you keep the M20 trans. The diff depends on you entirely, but my suggestion is that if you have the M50 trans with a 1:1 5th, get the 3.25.; That is what I have in my ti and it is a good balance between enough power torque to blow the tires away, reasonable revs on the interstate, and enough restraint to keep from always blowing the tires away. If you like spinning tires or keep the M20 trans, then go for the 3.73 or even a 4.10.

As for the 325e motor, you don't understand what I meant. Running a 2.7L bottom end with an i head means you can make more power and torque than a 325i, which has a 2.5L bottom end. With some tweaking, you can approach 200hp without breaking your wallet. The "super eta" is a 2.7L bottom end with an i head (88 only) and a special eta cam, which was not much weaker than the i cam. I milled my 325i head down 0.040" and put it on a 325e bottom end, and that car was a screamer. I finally retired the body and the bottom end (with over 60k on the head swap and lots of redline shifts) and will either build another 2.7, or go for a 2.8 or 3.0 M20. For now the head is back on a 2.5L bottom end in a different body.

No reliability problems with the swap, but make sure your suspension and driveshaft are in good shape for the extra weight and power.

Let me know if you have any questions.