Amsoil Power Foam

[Geevs]

Thanks. I'm pretty sure I have a valve stem/guide problem and know that replacing these via removing the head is the way to go. Actually just done it recently with my other 850R. My mech friend that did the head job suggested I try Liqui-Moly Motor Oil Saver first before pulling the head. He had success with it in his oil-burning 850s. If that helps with my oil consumption, I was thinking ahead and wondering how to get the valves and pistons clean as I saw how sooty they were when the head was off my other 850R - hence, this topic.

Either way, good to know that oil doesn't cause carbon build-up - I'm learning something new here.

[kcodyjr]

Not to say burnt oil won't cause buildup, but: It's different stuff.

Excess fuel, or insufficient spark temperature, leaves a fine powdery black residue that sticks prodigiously to hot metal surfaces and to itself. It readily builds up to the point that it restricts port flow, or even interferes with proper valve closure. It's basically powdercoating. When mechanically removed, or attacked with heat, it tends to come off in chunks. It also tends to be resistant to chemical attack.

Burnt motor oil, even burnt under compression, still has an oily texture to it. It'll become a gummy coating that'll almost take a fingerprint. Consequently, it doesn't build up as readily or as thickly, and cooks off more easily, and should be vulnerable to degreasers - though I've never taken an oily head apart and tried to clean it.

The two taken together become an unbelievable bitch of a mess, and hard to clean up, so if you're both running rich and burning oil, deal with it quickly.

[kcodyjr]

The valve seats will get ground, I'm not sure if they soak the head or what to clean out the ports. That leaves the valves themselves and the pistons to worry about.

Usually the valves go into an oil bath while the head is being worked on, to prevent surface oxidation or other contamination. I'd suggest soaking them in straight seafoam instead, and then taking a really stiff nylon brush to them. Same with the pistons, just pour it into the exposed cylinder, let it sit, and then take the brush to it.

[JDS60R]

I've been using Amsoil products for almost 20 years now. I don't like the power foam. Seems like diesel fuel in foam suspension. Doesn't clean much.

Try the Amsoil PI fuel additive. It works incredibly well. If you are going to pull the head then just let the machine shop handle it. Some chemically clean valves, others high speed wire wheel it, others glass bead it.

Always let the machine shop do everything they can. Saving $100 by not doing something needed ie valve guides, seats etc, is always a false economy. You will wish you had spent the money a few months down the line. Local shops fully service my 5 cylinder turbo heads for about $300. The head comes back clean , skimmed with every valve and guide perfect. They run for years and really give the car new life.

While the head is out I do fit new "total seal" rings. That combo (fully serviced head and total seal rings ) really pleases 850 owners. The car is more crisp and responsive. I always throw in oxygen sensors as well as usually the worn head/rings has thrown a bunch of oil at them.