constant ticking inside #1 valve - why?

blcperiod · Newbie Joined: Jul 03, 2004 Posts: 2 Location: California

My 2000 GS-R with 50500 miles suddenly developed a ticking noise in the engine.

It gets regular oil changes at 3000 miles and 3-4 months. Just had one two weeks ago when the thermostat was replaced (started running cool, and fluctuating downward when coasting) - lots of oil, and temp now constant.

I tend to drive fast and run the revs up to gain speed. In the past, I've hit the 8k rpm and the limiter kicked in (it's easy to do, but the limiter always cut it back, with no unwanted effects). Fast means about 95.

The driving situation just before the noise was: long incline freeway on-ramp, long wind up to about 7k rpm, then 80-95 mph, with a brief downhill pass to about 105 (in California, tickets get more serious when you hit 100). Outside air temp about 70-75 degrees Fahrenheit. Drove 12 freeway miles, ending with a slower uphill grade that always requires manuevering past trucks and sluggards. Immediately heard the ticking at off-ramp.

Noise is noticeable, but not loud. It occurs all the time (idle, underload, etc.) with a constant rhythm.

I took it to an independent Honda-Acura garage (I'm a new customer from previously going to the dealer, but they have a very good, long-term reputation, and they recently stole a factory trained mechanic from a dealer). They removed the manifold cover, and inspected lifters etc., looking for signs of sticking. Everything is at or within specified tolerances. They isolated the noise to the #1 cylinder (driver's side of engine). Short of tearing the engine down, they believe that the best policy is to drive it unless there is some obvious change or the "check engine" light comes on (if something starts going amiss inside the cylinder, one the sensors will spot it before it becomes critical).

Any ideas?