For some time now there have been after market hardened valve adjusters available through local VW shops. The local VW parts shop or a well meaning friend says to try these hardened valve adjusters. You bite on this and install them on your engine. These have caused a problem that has been very hard to diagnose.
A few thousand miles down the road you find your valves seem to be getting louder and louder. You drop the valve covers and do the normal adjust. When you fire up the engine there are still one or two valves that seem to still be too loose. After you have adjusted these valves till you are fed up with it you just drive the SOB with the valves clattering. Here is what happened.
On almost all heads the exhaust valves are too soft for the hardened valve adjusters. The round portion of the adjuster that touches the valve stem has worn a concave dish into the end of the valve stem. This increases the gap and causes the clatter. When you go to adjust the valves, the flat feeler gauge just slides across the end of the valve, thus covering the concave dish in the end of the stem. You set the adjustment and when you start up, the end of the adjuster goes down into the concave end of the valve and it continues to clatter like the hounds of hell. Now what?
Well, if you are lucky you can go back to the stock valve adjusters, but in most cases it has worn down too far into the end of the valve stem. You can do one of two things. First you can pull the engine and then the heads. Then take the heads in to the shop to have the ends of the valves resurfaced.
If you aren’t ready to do this you can drop the valve covers and install hardened lash caps. These go onto the end of the valve stems, and cover up the concave dish in the end of the stem. Then you can adjust the valves as normal. Make sure you replace the adjusters with the stock ones. I have one engine that has 22,000 miles on it running these lash caps. I do plan on dressing the valve stems the next time the engine is out. The intake valves are not as susceptible to the problem, but I recommend putting the lash caps on all of the valves.
– Mike Humeston
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