Listers,
I replaced the front main seal to stop a leak and also replaced the timing
chain tensioner about 500 miles ago due to it having a couple grooves worn into
it. I saw a recent post on the TR Register about slack in the timing chain.
One of the responses state to look in the Bentley in section 12.44 for checking
the chain slack with a straight edge from sprocket to sprocket and if the
slack is more than 0.4" (10mm) to replace the chain. My reprint Bentley (blue
cover edition) does not mentioned this section 12.44 or anything about the 0.4"
slack. I trust the info but wanted to know if others have checked this slack as
well in a similar manner.
I noticed recently a clatter/clunking sound coming from the engine but I
cannot pinpoint where it is coming from. I can hear it at idle, but it is more
pronounced on a deceleration in neutral after a short rev to 1800rpm and then
abruptly let off on the gas pedal. History archive search listed a similar
sound
and diagnosis for a stretched timing chain. I realize I will have to pull all
the stuff back off to pull the timing cover again to look and inspect.
Initial inspection, I have noticed that I can turn by hand the crank about
2-3 degrees total movement back and forth based on the timing marks on the
crank
pulley. This motion quickly back and forth kind of sounds like the clunk I
hear at idle. I did not notice this slack in the crank pully before when I put
it all back together, but I also wasn't looking for it either. I assume this
slack I am seeing the crank pulley is due to the timing chain being stretched
badly. I would have checked the timing chain when I had all this off if my
Bentley would have had the procedure listed on checking the slack in the
chain..(bummer). I have no idea the age or mileage on the currently installed
timing
chain and suspect it needs replacement.
On a similar note, once I get the timing chain off again, what should I look
for on the sprockets for too much wear? I have heard the teeth get "sharp" if
badly worn, but I do not have a new sprocket (crank or cam) to compare it to.
Any suggestions?
I pulled the rocker shaft as well thinking maybe the sound was a valve issue.
I did notice that the rocker shaft is pitted under one (I think #5 from the
front) of the rocker arms. I simply pushed the rocker to compress the spring to
see under it. I could not check rocker arm #1 or #12 as there is no spring to
slide for inspection. Also #6 rocker arm has got a circular recess from the
valve stem contact. This rocker arm will need replaced. It is not yet in my
budget to do a complete rocker assembly overhaul and wanted to know some
comments
on just replacing the few worn rocker arms and just reuse the same rocker
shaft and let it run.
I did loosen and re-torque the head to 70ftlbs while I had the rocker
assembly removed. The head gasket also has about 500 miles on it. I did not
suspect a
leak but heard I should re-torque about 300-400 miles. So I did it.
I also checked the crank shaft end float and was about 0.004-0.006" as I
recently replaced the thrust washers and suspected they may also have failed
prematurely. That does not seem the case as acceptable float is 0.006-0.008"
Thanks in advance for the comments.
Michael Rankin
1971 TR6 CC 61212 L
Louisiana, USA
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