<<2) In 90 degree weather, oil pressure tends to idle around the mid-point
between 25 lbs and 0 lbs on the gauge, and at driving rpms, oil pressure
tends to hover around 25 lbs. I use 20W-50.
3) I have not opened the engine yet. I've been hoping I could get another
25K miles on it before a rebuild.
4) I have not yet done a compression check. I'm thinking this might be a
good idea, but am afraid to drive the car for the 10 minutes prior to
compression testing to warm the car up.>>
here's my guess...oil pressure too low for sure (all bearings in engine
probably ready for changing including cam ones)...lower rod bearings not
getting enough oil at speed..hence the worn-out bearings are 'clacking' since
not getting enough oil to fill the gaps...
things to consider
1)why is oil pressure so low? can pressure be increased by tightening up
pressure relief valve at oil filter bracket? (like on a TR4) maybe you could
get away with using 20-60 wt oil (seems abundant at the British car vendors
in England I noticed)
2) maybe you could get away with a quick fix to get 25k more miles by
dropping the pan and swapping out rod and crank bearings and using the
thicker oil.
Definitely time to investigate before something expensive gets ruined..
I had a similar clacking and my lower rod bearings were down to the copper
but not into the steel backing yet on the tri-metal bearings.
Carl
'64 TR4 since '74
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