Blue smoke is caused by burning oil. That is commonly caused on any engine by worn valve guide seals. Oil will run down past the valve stems into the cylinders when you stop the engine. Later it gets burned and goes out the exhaust. That smoke will disappear within a minute or two.
There also was a problem with those valve guides. They are stainless steel tubes pressed into the aluminum cylinder heads. Over time they could drop down into the combustion chamber causing the valve guide seals to pop off and allow oil to run down same as when they're worn. The difference was that did not clear up in a few minutes and it would get worse when the engine was warmed up and the oil thinned out. Some engines smoked very badly if the owners waited a long time to have them fixed. Other than the smoke there were no other symptoms. The engine ran fine and there was no noise associated with that. The fix involved removing the cylinder heads, then removing the exhaust valve springs and the valves. A special punch was used to push the guides back too far, then that punch was used with a spacer to push the guides back to the proper depth. Another special hand tool was used to cut a groove around each guide, then a wire ring was installed to prevent it from dropping again. You can also buy new guides with the grooves already in them for about three bucks.
Most of those repairs were done under the 7-year / 70,000 mile powertrain warranty. Our engine specialist would also touch up the valves on a valve grinder as long as they were out. You got new valve guide seals too, and of course new cylinder head gaskets. That repair only pertained to the six exhaust valves.
The intake plenum gaskets will solve idle speed problems if they're leaking vacuum but not oil smoke.
The lash adjusters are replaced by removing the rocker arm shaft and lifting up all the rocker arms as an assembly. They slide out of the tip of the rocker arm. If they all want to fall out before you get the assembly set in place, use some Engine Assembly Lube as a glue to hold them in. That's a white grease made especially to keep engine parts lubricated until the first time the oil starts to circulate, and it dissolves into the oil when it gets warm. Do not use any type of wheel bearing grease. You might get away with one little dab but too much of that will collect and harden in the oil filter. You don't want the engine oil having to bypass the filter.
Your parts will be cold by the time you start putting them back together, but for a mechanic when time is money, the engine parts could still be warm. To avoid fighting with adjusters falling out due to that assembly lube melting they would typically stop and work on a different car for a while if one was waiting. Another trick, if you have them, is to use small rubber bands to hold the adjusters in place while you install the assembly.
One of my students did this job about ten years ago and as I recall, at that time new lash adjusters cost about eight dollars each. The valve cover gaskets do not have to be replaced. They are reusable rubber gaskets that sit in a channel around the cover. The biggest mistake people make is over-tightening the two bolts. That will crush the area around the hole and the metal will lose its strength. Snug the bolts down, then another 1/4 to 1/2 turn is plenty. If you see the paint is cracked around those holes you may need to pound them back from the inside.
Tuesday, April 2nd, 2013 AT 11:57 PM
