[ChadG]

Originally Posted by 911medic

Well, I'm not a service tech or engineer, so I guess I can't say for sure, but I believe that's the idea behind the walnut shell blasting. Abrasive enough under pressure to clean, but the natural fibers/bits burn up/flow through if they get in the cylinders.

BMW's direct injection engines suffer from the same issues ours do, and their dealerships do walnut shell blasting with a special tool.

Here are a couple of links to BMW user forums where the blasting is discussed:

• First, a thread regarding manual cleaning of the valves (similar to the procedure outlined in this thread). There is some discussion of walnut shell blasting in posts #49, 62, and 137. One user mentions issues of the shells just sticking to the gooey build up, but there are some pics of some VERY clean valves after shell blasting in there, so it is effective.
• Second, a thread where a user bought the BMW blasting equipment. The end results are impressive--pristine valves.

I know Harbor Freight has some walnut shell blasting media equipment for pretty cheap, IIRC, but I don't know how good it is.

As far as checking for valve closure, I don't know of a better way than seeing if an engine-friendly liquid will pool on top of the valve. That's what I did when i cleaned my valves (see post #73).

That makes sense, but now I'm worried that if you check that the valve is closed with something like Seafoam then the walnut shells will get all wet and stick to things?

Originally Posted by terry_b

I may be making a trip up to harbor freight tomorrow. Wow! Those are some clean valves!

So I guess it would be easiest to remove the spark plugs to rotate the motor and shut each set of valves, and then just hook up the blaster and a vacuum and go to town right?

Is there anything special about removing spark plugs?

I think the spark plugs are pretty straight forward, what you said should work fine.