[jb's335]

I was doing an oil pan gasket change the other week and had my intake manifold off to make getting to bolts a little easier. I also sprayed seafoam on my intake valves to make the walnut blast I plan on doing next weekend easier (not sure if this actually helps but I had some seafoam and the manifold was already off so there was no risk in trying).

Anyway, I turned over the motor with a wrench and could hear air escaping from my intake valves while they were "supposed" to be closed. They are EXTREMELY DIRTY, I have 116xxx miles on my engine and the last time they were cleaned was at 45k. I had not heard of improper seating of the valves due to them being dirty but I guess it makes sense. But, I just wanted to see if anyone else here has had compression test issues with dirty valves. If so, how can I clean the valve seats if I do the walnut blast at TDC? If the valves would still be open that little bit even at TDC and walnut particles could possibly be let into the cylinder, is that normal? But then again I could always pull the plugs and vacuum out excess particles from inside the cylinder.

I know there are a lot of walnut blasting "guru's" on here, any advice?

[pwr hungry]

I'm also interested in any outside the box ideas here.

[dfjaws]

I cleaned my valves the hard way, with gun cleaning brushes, lint free rags, and carb cleaner. It actually worked very well, it just took a long time and my hands were tired as hell. That might be an option for you. If you don't want to spend forever on it, you could always brush them a little bit to get them to seat better and then have the walnut blast done.

[jb's335]

Honestly that is how I did my first cleaning, the hard way. The only problem is I have not found a decent brush that can make it all the way down to the bottom of the valve that is worth a damn. And trust me, I have looked EVERYWHERE.

I finally broke down and bought a walnut blaster from China Freight and am going to get the BMW attachment for it. Just waiting for that to come in before I do the blast. But I am fixing this issue whether someone chimes in or not, I will let you guys know how it works once I finish. Hopefully it helps, I could imagine more than a negligible amount of power loss from improperly seating intake valves...

Just a good idle will be worth it though. It misfires like no other when its cold, sounds like it has a cam or a crappy tune.

[blaster3500]

I could be wrong but I am sure they are closing enough not to get walnut shells down in the cylinder. A little air getting by can be a small gap. If it was me I would do the walnut blasting. Then turn it so the valves are open and try to clean the seats with a small brush and carb cleaner. Also pretty sure the walnut shells burn up at start up so if a few pieces got in there it would not be a big deal. Curious to see others thoughts

[MGM]

It's inevitable the "some" walnut shells will get in the cylinder. They burn off once the car is started up. Every car I have cleaned starts rough and then becomes silky smooth.

[tcw]

Are you sure the cylinder is suppose to be completely closed? Have you tried rotating the crank/wheels? I find it hard to believe that cylinder pressures + the valve springs are not sufficient the break the carbon up blocking the valve.

[jb's335]

I am just stating what I saw when I rotated the crank. Air was leaking from the valves when the piston was on its compression stroke.

[SharkBait]

If your valves are open enough to allow walnut media into the cylinder at TDC, you're probably looking at more than just dirty valve seats. Do a leak down test.

[raceyBMW]

The reason walnut shells are used in the first place is that if they accidentally get into the cylinder chamber, they will not cause havoc like sand...they will simply burn up as long as its not a ton of them.

[MGM]

Originally Posted by raceyBMW

The reason walnut shells are used in the first place is that if they accidentally get into the cylinder chamber, they will not cause havoc like sand...they will simply burn up as long as its not a ton of them.

+1