Jay Snavely writes:
>I am thinking maybe I should put in an oil cooler and
>put off the rebuild a few years/thousand miles. Any comments.
I have a TR4A which had low oil pressure when I bought it many years ago
with 55k miles on the clock. Kept the pressure to a reasonable level by
adding STP for a while . Then rebuilt engine completely which resulted
in book pressure of 70psi and 35-40 at 800 rpm idle. Only ever used
Castrol GTX 15-50
Last summer, 55,000 miles later I noticed that after typically a 60-100
mile dash down a French Autoroute at say 85 mph with temp in high 80's
although there was 70psi at 3500 rpm, when leaving on the slip road
there was only 30 psi at 2000 rpm and 5-7 psi at idle. As you drove
normally and the oil cooled, pressure would recover to 50-60. Thought
long and hard about installing an oil cooler but decided to go for the
obvious first.
This spring, dropped the sump and found main bearings virtually unworn,
big ends showed moderate wear, and wear plus a few scratches was evident
on the lobes of the oil pump rotor. Replaced the oil pump rotor and big
end shells, and the result is book oil pressure (70 psi) at all revs
above 1500 and 35psi at idle regardless of OAT and whether car has been
just been belted or not. Perhaps you only need an oil cooler for racing
use.
It seems that when you get some significant wear on your engine the oil
pressure becomes temperature sensitive
IMHO it is important to maintain close to book oil pressure so that the
valve gear and the rest does not suffer excessive wear from oil
starvation.
Regards
David Brister.
67 TR4A, 63 P4 Rover 110.
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