Broken valve stem stuck in the valve guide

[Unregistered]

I have a case of a broken valve stem stuck in the valve guide. I have a about 1/4 inch sticking out of the block. I am currently soaking it with some penatrating liquid, which hopefully would ease it out. I am looking for some tricks you may have to pull this stuck valve, maybe some special tool.

Once I get this valve stem out, would I need a new valve guide? Can I easily insert a new valve guide without taking it to the machine shop?

[Don Moyer]

I'll assume a worst case scenario, which is that the engine is still in the boat. In this case, I would try to tap the valve down (even an 1/8" if that's all the travel you can get). Then turn the engine over and let the cam move the valve up that small amount. You might do this a few times in the hope of freeing the valve, if only slightly.

After you get a small amount of movement, insert flat tools between the top of the tappet and the bottom of the valve and continue turning the engine over to let the cam push the valve up higher. A screwdriver blade will work as the first step in this process, then an open-end wrench, a thicker wrench, etc. If the valve is still quite hard to move, tap it down again and then move it back up a few times at each of these new heights.

Eventually, the valve will be loose enough (and high enough) that you should be able to grab it with a vise grip and continue twisting and pulling it out of the guide.

Fortunately, it's seldom necessary to replace a guide simply because a valve stem broke.

I wouldn't say it's impossible to replace a valve guide with the engine in the boat, but it would be extremely difficult. Guides are normally driven out from above when the cam shaft and tappets are removed, and new guides driven in (also from the top down). The determining factor in whether or not it is even possible to remove the guide while the engine is in the boat with the cam shaft installed is whether or not the adjustable part of the tappet can be adjusted down far enough so that you can slide the tappet up and out of the block.

If the tappet can be removed, then the guide can be driven downward, but you should borrow a special punch from a local machine shop to do the driving. Be sure to put a thin sheet of metal over the tappet hole so that the guide will not fall down into the crankcase after you've driven it out of the block.

The new guide can be driven in from above to the same depth as the rest of the guides. It is especially important to use a properly sized guide punch to drive in the new guide.

Don