Andy,
If the noise is from the front rather than the top the valves are probably
fine. The timing chain is a possibility but how about a loose fan? I have
seen the long bolt that holds the original fan spacer come loose. See if you
can rock the fan back and forth.
Good luck,
Rick Patton
http://topshamautoparts.com/tr6/
> From: apackard68@comcast.net(Andrew Packar
> d)
> Hello list:
> It's been a while since I needed serious help figuring out a problem,
> but an unfriendly noise developed recently and I fear the worst.
> Background:
> TR250 with recent engine rebuild. 10:1 compression, GP2 cam, .30
> overbore, rimflow valves, uprated valve springs, 1.65 ratio roller
> rockers, triple webers, 6-3-1 pulse header, Toyota 5-speed, Nissan
> viscous LSD, balanced drive shaft.
> Last weekend I adjusted the valve clearances and changed the oil. I had
> been about 800-1000 miles since the rebuild, so I removed the regular
> oil and replaced it with synthetic, as recommended by the machine shop
> that rebuilt the bottom end and did the head work. The valve adjustment
> made the engine run smoother as the gaps were high in several of them.
> Shortly into my first test drive, I began to hear a sound that sounded
> like rocker activity with the valve cover off, but about 2X as loud. I
> thought that perhaps a securing nut was loose on one of the rocker arms,
> so I readjusted the valves last night, only to hear the same noise while
> running. In the garage, the noise is most prevalent at 2000 rpm and
> sometimes appears at 1000rpm for a short time. While driving, I can hear
> it again at higher rpms on the freeway. With my head under the hood, I
> revved the engine enough to create the noise and tried to trace it.
> Although it sounded like rocker noise, it seemed to come from the front
> of the engine, perhaps at the end of the crankshaft. It's difficult to
> pinpoint with the fan spinning and sounds certainly getting deflected
> around the engine bay, but that's my best guess and worst fear. The
> timing chain was in good shape when I did the engine rebuild, but I did
> consider the timing cover as a source of the noise.
> Any thoughts are invited and appreciated.
> Andy Packard
> CD6746L
> Bay Area, California
|