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In Reply to: Re: rough idle - valves noise when cold posted by Kevin on April 15, 2002 at 10:00:34:
The two problems may or may not be related. I'd start by pulling the engine codes. Often a rough idle when an M70 is cold is a sign of leaking intakes. The plastic gaskets are notorious for developing leaks after about 50K miles and the check engine light will come on because the O2 sensor goes out of range. The leaks often seal themselves up when the engine warms and things start to expand. On the valve noise, it sounds (sorry) like you may have an oil pressure/delivery problem. The M70, unlike the big 6, has hydraulic lifters (try getting to the valve covers and you'll know why they used hydraulic lifters). Usually it takes a second or 2 for oil pressure to pump up the lifters, but it sounds like it may be taking longer than that in your case. This could be a sign that you have restrictions in the passages or that your oil pump is not working effciently. Before jumping to any drastic conclusions, I'd try running some flush through the motor on your next oil change and then adding a detergent like Rislone in the appropriate amount, to the fresh oil. It's possible that the low or unequal valve lift caused by the lifters not pumping up all the way is responsible for the rough idle, but I'd put my money on the intake gaskets unless your check engine codes indicate otherwise.
Kevin
Morning start up getting rough idle and valves noise for 2-3 minutes. And check engine light also came on. Engine run smooth and no valves noise, no check light when warm, back to normal. How do I attack this problems? Thanks. don750
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