Sunday, May 20, 2007

I learn how to do a Valve Lash Adjustment on Maria (updated)

Temps in the high 70s to low 80s, humid, sunny and hot.

As Maria went over 30,000 miles, it was time for the 30k service which includes checking the valve lash clearance. In preparation, I had watched a co-worker demonstrate how to do it on his Kawasaki Concours motorcycle. Not exactly the same but the concept of "too loose", "too tight", "feels right" were what I learned that day.

Today, a fellow coloradobeemers member, Mike came over all the way from Broomfield to show me how to do it on Maria herself! He brought the feeler gauges, the newtons/meter torque wrench and a wealth of experience and knowledge. I consider myself very fortunate that Mike deigned to help a neophyte like me. Thanks Mike!

So, in preparation for Mike's arrival so I would not take up too much of his free time today, I took off Maria's tupperware, engine guards and was standing by when Mike arrived right on time at 1030. He showed me the reference materials he'd printed out from the Internet, the tools, and we talked a bit about the whole operation before we began.

Notice the road rash from the two times I've dropped her.

Mike did the right side first, methodically showing me how to find TDC or Top Dead Center which is where the valves need to be in order to do the adjustment. He talked about the BMW approved way of manipulating the valves through the removal of the front alternator cover and moving a nut which rotates the engine. We did not do it that way.

Mike talked about, and showed another way to do TDC, that is to rotate the rear wheel with the transmission in 6th gear. He pointed out the cover to the viewing port one would use to look for alignment marks. We did not do that either.

What we ended up doing is rotating the wheel as mentioned before, with him holding a long screwdriver in the hole where the spark plug is located and watching the shaft of the screwdriver go in and out as the wheel rotated, causing the valves to move in and out of TDC. Once we figured it was at TDC, he showed me how to look for an arrow marking on the gear holding the timing chain. As long as it's pointed 90 degrees out wards, you're close enough to TDC and can proceed to do the adjustment!

Pic from second linked doc at end of posting clearly showing the arrow

See link at the end of this post for the full procedure. I am just going to mention some of the tips he imparted, and some stuff we ran into.

1. The spark plug wire covers, simply pop off. Easy.

2. The spark plug removal tool that came with the BMW toolkit was flimsy, Mike had a heck of a time removing the right-side plug with it. I failed to remove the left side plug with it, ended up gripping the cap with vise grips and pulling it out. Good seal on these plugs! I then used the spark plug removal tool to remove both spark plugs which were in good condition.

3. Rotating the rear wheel to get the valves you're working on to TDC was proving hard to do with just one spark plug removed, we ended up removing the second one as well to eliminate fighting against engine compression.

4. After showing to me the BMW approved way of checking/adjusting the valve lash as shown below.

Feeler Gauges on Exhaust Valves, notice strap securing center stand to front wheel for safety.

Mike showed me the Anton Method where one slides the appropriate feeler gauge into both valves at same time, see below.

Another pic from second linked doc

This second method was a lot faster and easier and will probably be the one I use in 6000 miles when this check is due again.

5. Next time, must remember to drain ALL the oil from the valve covers before putting them back on, as well as wiping up all accessible oil from bottom of valve cover housing. Some dripped out of the left side cover after we'd put the covers back on, caused smoke and concern after we turned the engine on. We removed the left side valve cover, double checked, wiped better this time, and the second time appeared to be clean. No smoke. As Mike said, resist the temptation to torque down the cover more if there's leaks! You will strip the mouting holes. Instead, replace the plastic gasket!

So, now a trip to Sears in order to procure the right newton/meters torque wrench, same one as the one Mike showed me if possible. It made the job of torquing down the mounting screws on the valve covers easy and accurate, preventing the apparently easy mistake of overtightening which leads to strips threads and costly repairs.

This valve lash check/adjustment operation had seemed intimidating to me at first when I started looking into it. I can tell you now it's very easy to do, it helped to have Mike there watching my moves and guiding me through it the first time but I am now confident I can do it again by myself, with no problems. Next major task, throttle body sync, will be watching Mike do his motorcycle in about 3k miles.

Link to "Oilhead Valve Adjustment for Dummies". Great work. If the link does not work, post a request and I can email it to you. It shows the "approved BMW way" of using separate feeler gauges. Great pics to show you the way.

Link to BMWMOA Forum posting of a Valve Adjustment done on a hexhead motorcycle, same principles and hardware is pretty much the same. (Thanks to Mike for the link)

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