I suffered from low oil pressure in my TR6 - with a newly rebuilt engine - for
8+ years. Like the Kelly Green TR6 in Dave Massey's post, the pressure in my
TR would drop to 20 PSI at 3000 RPM and near zero at idle when hot. I tried
everything to get the pressure up. I calibrated my pressure gauge, I rebuilt
the oil pump and I inspected my new main bearings - only to find nothing
wrong. I grew to believe that it was the nature of my engine and like Dave, I
convinced myself that good, healthy oil pressure is over-rated if your engine
is also running well....and then I came across Fred Thomas' post to this List
in April, 2004 on low oil pressure - which I've copied below.
It seems that Castrol oil leaves a film on the pressure relief valve - which
prevents the valve from seating properly, which in turn prevents the engine
from reaching a healthy oil pressure. The solution Fred put forward was
unbelievably simple - if you also happen to be using Castrol 20/50 oil (which
I think most of us do): take the pressure relief valve out, clean it with
lacquer thinner, put it back in and presto, the oil pressure should be right.
This ran against years of commercial indoctrination that Castrol GTX could
never do anything wrong. Nevertheless, I cleaned the valve, put in a
different brand of oil, and I've had wonderful oil pressure ever since.
This little bit of TR tribal knowledge is invaluable and it needs to be
repeated on the List on a regular basis. It does work (if everything else is
OK with your engine) and it can save hours and hours of frustration and extra
work for those searching for a solution to their inexplicably low oil
pressure.
Cheers,
Brian Lanoway
1973 TR6
Winnipeg
Here's Fred Thomas' original post:
Date: Sat, 24 Apr 2004 20:33:35 -0400
From: "Fred Thomas" <vafred@erols.com>
Subject: oil pressure
When I'm on a long trip I do not amble along, I drive on the
fast side,
returning from VTR S/E (868 miles less than 13)normal oil
pressure is 65lbs
at
cruise and 40 at idle, well suddenly the pressure dropped to
50, then 40,
then
35 cruising, and ==5==at idle, I did make it home with no
engine noises,
oil
was full and clean, normal oil leaks, filter tight, still 40 &
about 5, I
called Ken Gilanders @ British Frame & Engine his first comment
was you are
using Castrol 20/50 aren't you, the pressure relief valve in
the filter
head
gets some sort of coating on it and this effects the pressure,
take the
valve
assembly apart and clean it in "Lacquer Thinner" and reinstall
it then all
will be well again, and thats what I did and it is well again,
might be a
good tip for T/R owner to remember should this happen to you
"FT"
On May 5, Dave Massey wrote:
"Here's an anecdote:
A friend of mine bought a used TR6. Kelly Green. At cold startup it
would
show 70 PSI. When hot it showed 20 PSI at speed and at idle it read
about
zero. Tom, being the engineering type decided to see how long it would
run
like
this so he continued to drive it. After a couple of years like this he
decided
to sell it. A year after selling it the new owner called. Tom thought
that
he was in trouble for selling a lemon but, no, the guy just called to
say how
much he enjoyed the car.
Good, healthy oil pressure is overrated, I think.
Dave"
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