The service bulletin involves removing the heads, removing just the exhaust valves, then modifying the guides. This involves three special tools. The guides slipped down into the exhaust runner. By sliding down, the seal lets oil run under it into the exhaust system.
Once the valve is out, you use the special punch to push the guides back up too far. From the top, you install a spacer, then use the punch to push the guide back down. The spacer sets the proper depth. The third tool clamps over the guide, and as you turn it, it cuts a groove into the outside of the guide. Install the special wire ring onto the groove, and you're done.
It's hard to believe this is just happening to your car. Most of these engines were modified many years ago. It was done to my 1988 Grand Caravan at 64,000 miles. By the way, this only applies to the 3.0L Mitsubishi engine which is what you have.
If your friendly dealer won't borrow you the tools for the job, (they probably can't find them anymore), you might consider just buying new guides. They're only about $5.00 each and will have the grooves already cut. Use a good punch to install them. A mushroom head on the end of the punch will cause the hammer to glance sideways and crack the new guide. Happened twice to one of my students before we figured out the problem.
Before you go through all this work, you might want to consider pulling one front valve spring and seal off and looking for the wire ring. Based on the mileage, there's a good chance this was already done and you just need new valve seals. You can remove a spark plug and stuff the cylinder with rope to prevent the valve from dropping down. An air hose from a cylinder leakage tester works too when hooked to compressed air, but don't use the hose from a compression tester because they have a check valve. Remember, this only applies to the exhaust valves because they get hotter.
Caradiodoc
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Monday, March 30th, 2009 AT 4:53 AM
