Re: Bad news from my compression test I think....how can car STILL refuse to start?

Posted by Ross On 2012/9/9 19:42:53

Good question. The substance of choice is probably carburetor cleaner as its about the only thing that will cut the gum from the bad gas. I recommend Berkebile, which most parts stores carry. Lay a mess of rags in the bottom of the valve chambers so you don't wash all the crap down into your crankcase.

I'd spray cleaner up the valve stem as best possible and let it sit a while. Then I would pry the valve down if it will come, and wash its stem with some more cleaner. Pry it back up and do it again til it will fall from its own spring tension. This may take several attempts as the area with the gum is far above where you are working.

If you can't get any joy this way, you will have to take the manifolds off and do your spraying through the ports so the cleaner can get on the upper part of the valve stem. Taking the head off is actually the last resort.

When you do get it running again, I think a couple of cans of two-stroke oil in the new, fresh gas might help get everything well loosened up.