Hi all,

I have a knock issue with my B230E (high compression ratio). It wasn't knocking in its early life - only for the past few years. It had its head skimmed so maybe the CR is higher than spec but it didn't knock immediately after the head job. Changing the knock sensor, new plugs (changed ol Bosch to NGK) and retarding the timing to 5*BTDC have not been able to get rid of the knock. I'm using the highest octane rated fuel available which hasn't helped.

My mechanic think it's due to carbon deposit in the combustion chamber and wants to open up the engine and give everything a good clean. I was hoping to give a go at chemical cleaning first though. I did a search on the brickboard and I've tried FP60 (one post said this is the best). Results - better engine idling and better mileage but knock still there. Maybe this product cleans injector better than the combustion chamber?

I also came across a post saying that the red blocks don't accumulate carbon that much, how true is this I'm not sure. Besides removing the head, is there another way one can verify the combustion chamber is truly caked with deposits?

And if so what's the best way to clean it? My options are Techron or BG44K. How good are they I was hoping the brickboard can advise me. One fellow brickster tried BG44K and wasn't so impressed when he had the head removed later on. The FAQ also describes the water cleaning method but a couple of posts in the archive discourages that and I think one fellow actually had engine damage after doing that.

Appreciate any help. Thanks