Tricks to Replacing a Valve Guide

Engine parts wear, although, most things that are metal coming in constant contact with other things that are metal will wear.  One part that will leave your engine in a not so well operating state is a worn valve guide.

This is the part of the head (in the case of an over-head valve engine) or block (in the case of a L-head engine) that the valve travels up and down in while opening and closing.

Now, getting the old worn guide out is relatively easy, you can pound it out, heat and press it, grind it out, as long as you do not hurt the engine component that it sits in.  Getting the new one in can be a little bit more tricky.

The one trick that I picked up and use most often, I feel works the best and is the easiest.  First, you are going to put your new valve guide in the freezer until it is frozen solid.  Once that is done, you want to start heating the seat (I typically use a propane torch or a acetylene torch).  Now going off of the presumption that common sense is in fact not so common I will explain why.

The new valve guide must fit inside the seat, so it must be small enough o fit in, but snug enough not to fall out under normal use.  Freezing the guide will cause the metal to shrink, while heating the seat will cause it to expand.  Thus, making the guide slip more easily into position.

Once the guide is frozen and the seat is heated and everything is ready, place the guide into the seat (take extra precaution to ensure that it is completely straight).  With a towel over the guide (protecting it from mushrooming and ruining it), pound it into place (the use of a impact socket provides a nice contact surface and displaces the force evenly across the top of the guide).  Pound the guide until it is perfectly flush with the surface.

The engine is now ready to reassemble.