Greetings Graham,
You mentioned that your OD leaked like a tea strainer - my overdrive
leak experience was not unlike that of Randall Young. My overdrive
functioned fine - as long as there was enough oil - the leak had gotten
to the point that I didn't drive the car with out first checking and
filling the trans/OD. Unsatisfactory.
The first thing I attacked was the "big brass plug" since this could be
managed with the unit in the car, and the gear oil dripped off from the
plug. I got 2 new gaskets, a custom spanner wrench
http://www.britishtool.com/index.html to mate w/ the notches around the
circumference of the plug, an adjustable hook spanner (Armstrong #
34-310) http://www.armstrongtools.com/catalog/products.jsp?groupID=863
,gasket sealer (Hylomar HPF by Permatex), and satisfied myself that the
"big brass plug" joint was tight. Refilled w/ oil and the leak was still
there. The leak now seemed to be at the bottom center rear joint of the
adapter plate, just above the "big brass" drain plug.
The next point of attack was the adapter plate joints which ofcourse
demands that the trans/OD be removed from the car. I got 2 ea (front &
rear) adapter plate gaskets and removed the trans/OD from the car. Oddly
the 2 rear adapter plate gaskets, from different suppliers, were of
different materials - one was red and of paper thin gasket material, the
other black and about 1/32 inch thick thick (substantially thicker than
the red one). I disassembled the OD from the trans and found one
stripped stud (bottom right). This was good news since I feared the case
threads were stripped and a helicoil would have to be used. Fortunately
the stud threads in the OD case were fine. A red paper thin gasket was
found - no doubt there from the beginning since I've owned this car
since '67 and this is the first time the trans has been out.. The bottom
of the adapter plate was very, very slightly warped when checked w/ a
straight edge. I put everything back together, using the thicker black
gasket and ofcourse a new stud. I refilled w/ oil and the unit sat on an
engine stand for a week and didn't leak!
The next weekend I put the trans/OD back in the car and started the
engine (car on jack stands) - all was fine but the OD would not work -
and it had before. The solenoid could be seen moving the operating
valve shaft. When the operating valve plug was cracked open no oil
seeped out - the pump was not working. After much head scratching I
decided the pump cam had been assembled incorrectly and the cam was not
engaging the roller on the pump plunger. I removed the trans/OD from the
car, disassembled and found the cam in correctly but the pump plunger
was bound in a down position. I was able to straighten and free the oil
pump plunger with careful prying - it must have been bent slightly when
the OD was mated to the trans. Everything was put back together - using
the red (thinner) gasket. I used wire to hold the pump plunger back
from the cam as the OD is drawn to the trans, as suggested by the TR4
Haynes manual this time, not the cumbersome 2 screwdrivers method as
shown in the Triumph Shop Manual & the OD Service Instruction Manual.
The wire method positively prevents the roller end of the pump plunger
being pinched by the cam as the trans and OD come together. When the
engine was started the OD worked fine but the oil leak was back - at the
same place - bottom center rear of the adapter plate joint - 1 drop per
30 min. Less than before but very disappointing.
One more time - trans/OD out of the car, disassemble and reassemble
using a new 1/32 thick gasket - which I cut from a roll of rubberized
fiber gasket material - and trans/OD back into the car. At last the
trans/OD doesn't leak and everything works.
If I ever do this again I'll certainly rig up a way to test the unit on
a bench and have only one in/out. Nelson Riedel's photos of his set up
and that of Ronnie Babbitt along with Kai Radicke's idea of how use a
drill motor are helpful. I think the thicker (1/32") rear adapter plate
gasket is important to take up any slight irregularity of the adapter
plate. Holding the pump plunger back with wire while drawing the OD to
the trans is definitely the best practice.
brgds, Jay
'64 TR4 CT38875/LO
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