Valve Adjustment for BMW M10 Motor

Article 1:

Original Author: Sam Schultz

Valve Adjustment for BMW 1602-2002 M10 Motor

The process of adjusting the valves needs to be done at every major service. This service happens every 15,000 miles or so. Failure to properly adjust the valves will cause increased wear and rob your engine of power.

Tools:

• 10-mm wrench
• 10-mm socket (optional)
• 0.008" feeler gauge
• Small allen wrench or piece of bent coathanger
• Parts tray

Parts:

• Valve cover gasket (11-12-1-734-276)

Project: With the engine cool (let it sit overnight), remove the valve cover, 6 castle nuts and 1 bolt. Remove valve cover and, depending on its condition, you should replace the old valve cover gasket as it is NOT reusable.

You can start at any cylinder you like, but just keep track of where you start! What you want to do is relieve all tension on the valve you are adjusting by rotating the motor until the valve is fully seated. If you are using the starter to rotate the engine make sure the car is out of gear, e-brake engaged and the positive coil wire is disconnected. If you are rotating the motor by the crank nut remove the spark plugs, and follow the same set up procedures as with a starter switch. My favorite way is to simply roll the car while its in gear.

To do this, use a flat spot of hard ground. Disconnect the + coil wire and put the car in 4th gear. (Optionally, you can remove all the spark plugs to make this slightly easier-- you should inspect them now anyway.) Roll the car slowly until the first rocker arm you are doing is on the backside of the cam lobe. Next, tilt the rocker pad forward until it is resting on the camshaft. Back off the lock nut slightly and slide the feeler gauge under the eccentric.

Use the small allen key or bent piece of coat hanger to rotate the eccentric until its snug on the .008" feeler gauge. Then tighten the nut. The nut should be tight but don't break or strip it! The gauge should just slide between the eccentric and the top of the valve and should grab slightly as you remove it. Make sure you hold the feeler gauge flat. Be aware that the valve spring itself may compress slightly if you turn the eccentric too much, causing the valves to be too tight when you tighten the eccentric. It is better to have the valve a little loose than tight, but if it is too loose it will cause lower performance, valve clatter and wear. Too tight will also rob power by preventing the valves from closing all the way, and also wear out the cam/rockers/etc. much more quickly, and THEN cause valve clatter...

The entire operation can be a little tricky but a novice mechanic can do the job! If you are good you can do an intake and an exhaust valve at the same time (not the same cylinder). Make sure you adjust them all, then replace the valve cover gasket and reinstall the cover. The acorn nuts should only be torqued to 8lb.ft., so don't overtighten them! This will warp the cover and cause leaks, assuming you get away with not breaking the studs themselves. Once you are finished, start the car and listen for any strange noises. Remember vintage BMWs should have some valve noise, not having enough play will cause wear to the cam shaft. The old rule is its better a hair loose than a hair tight. If all is good, then close the hood and take it for a nice run!

Article 2:

Original Author: pklym

Well, I am trying to slowly prepare my '76 02 for a late summer cross country trip. Three years ago I brought the car from Portland Oregon out to Washington DC to attend law school. With six weeks before finals I am finally getting serious about preparing the car the trip back west (will probably leave the car stored somewhere in DC area for the summer before driving it out in August if anyone has suggestions on a safe place to store the car out here). I struggled through the winter months rebuilding my heater box...a few times until it worked right but now that we just had a good rain to wipe the streets clear of snow, I am getting to some more preventative maintenance.

After reading everything I could find on adjusting the valves, I decided I would tackle this job. The valves didn't sound particularly off, but my engine does feel a little tired, so I thought I would give it a try. I'm not sure if I have ever had the valve cover off of Bridgette and have no idea when they were last adjusted (I've owned the car for four years, but other than the cross-country trip, and one from DC to Birmingham, AL, I haven't put too many miles on it). I read as much as I could but still did not completely understand the process, mostly I thought "What the hell is an eccentric?" I could not find any pictures of that. Because of my slight confusion, I thought I would try to document my process to make it easier on other first-timers.

First things first. Remove the spark plugs, and wires (and I removed the coil wire, I think this is redundant).

Then I removed the valve cover breather hose (which is vented straight out the bottom, at some point I will get a catch can and maybe reroute it back into the carb). I undid the VC bolts a little at a time working from inside out, I am not sure if this is necessary but I didn't want to accidentally warp anything.

Now I tried to get a lay of the land, I understand the cam no problem, so I looked for the lobes that were pointing straight down (as oriented to the engine, not the ground) to see which valves to mess with first. It is kind of hard to tell when the valve is completely straight down because you can't see down there, but you can tell when the lobe is not touching the rocker anymore.

After locating a valve to work on, I slid my .06/.08 go-no-go feeler gauge into the spot just above the valve. I must admit, this took me a bit of time to figure out exactly where it went, but after some trial and error it made sense. I had to bend the gauge pretty severely to work in the area.

From there I had to figure out what this eccentric thing is. In the picture below I labeled the nut you have to loosen (it's pretty tight and will move the rocker at first) with a "1" and the eccentric with a "2"

For the most part the valves seemed in good adjustment, none of them fit any feeler in higher than .08 so they did not need much adjusting. I felt like it was tough to get the resistance on the feeler exactly where I wanted, but ultimately I just relied on the go-no-go aspect of the feeler.

I was confused at how to adjust the eccentric. I knew you could use either a small allen wrench or a coat hanger, but I also read that you turn in the hole of the eccentric. I thought this meant you actually rotated some sort of nut. That's not so, you turn the eccentric along its pivot point. I marked the photo with the way the eccentric moves.

I also quickly learned that you have to keep your eccentric tool in the eccentric hole while tightening up the nut or the eccentric would close the valve gap too much. I had to switch to a piece of coat hanger from my original allen wrench tool to get a few of the eccentrics to turn properly. I snugged up the nut, but didn't tighten it too much. I hope that is right (anyone?).

After doing the two valves whose cam lobes were pointing down I got in the driver's seat and bumped the starter just a bit and would check what valves were available next, without a helper I had to head in and out of the car a few times to get the cams just right. I did try turning the motor with the fan and the alternator belt, but I could only get it to turn a bit this way, I think I may need to tighten my belt.

After checking and adjusting all the valves (a few of them didn't need any adjusting). I put a new valve cover gasket on with a couple dabs of Indian Head Shellac in the corners. I torqued the VC bolts to 96 inch lbs of torque (8 ft lbs), working inside out. This really isn't much. Gapped and inserted new spark plugs, and hooked everything back up.

Thankfully the car started back up and seems to run well. Not sure if there was any improvement, but then again they didn't seem much out of whack. I haven't taken it for a spin yet.

Next, I will be replacing all my fuel line (except the in-car hose) and sender gasket. I think my carb leaks a bit of fuel onto the intake manifold which ends up making my car hard to start without starter fluid if it has been sitting for more than a few days, unfortunately I don't think I am going to have the time to try and learn how to rebuild a carb before my trip. I would have done the fuel line today but the lady at Autozone (God I hate Autozone but its my only option nearby) threw some 5/16" VAC line in my bag instead of fuel line and I didn't notice until later.

I hope these photos help someone, and if anyone who actually knows how to adjust valves and sees anything I did wrong, please point it out!