I pulled a couple of main caps when I was doing the car and had the engine
out a couple years ago (maybe 5k miles since then). A bit of wear, but
didn't look too significant. I did have to do the timing chain (it was way
out spec for deflection), and I'm not entirely certain of the lineage of
the oil pump. I'm going to try a new sending unit, then I'm also going to
switch to a 40W oil (I'm running 10W-30 right now). If the new sending
unit helps, obviously that's the issue. If the heavier oil works, it has
to be a bad pump or bad bearings. I guess it would be easy enough to
replace the oil pump, provided it's easy enough to drop the pan on a '71
Mach with a Cleveland with it in the car.
I suppose I could change the rod & main bearings with the engine in the
car. I've done it before in a 289 in a '65 Fairlane. But what I intend to
do is to get the motor thru this summer (another 1k miles or so), then go
thru the engine this winter. There's a really excellent machine shop here
that'll charge me only $200 to do both heads, $50 to boil the block, and
$8/hole to bore the cylinders (I'm thinking .030 over), plus $50 for things
like truing the deck if I need it. I don't think I'll need to have the
crank turned, but I suppose it's possible.
At 06:59 PM 5/30/2009,
Flick01@Aol. Com wrote:
>The pump itself may be worn. Back when old Mustangs were a common sight I
>used to replace timing chains which had slipped on a regular basis.
>Whenever I saw a top gear which was almost worn smooth I would tell the
>owner to replace the oil pump because it was a matter of time before the
>pressure would become low. Tiny particles of nylon make their way past the
>pickup screen and cause the gears to wear. As Phils2888 mentioned, it
>could be bad bearings, I ran into that in my own car last year, but if
>you're sure the bearings are good then low pressure is very likely a worn
>pump. Even if you never had a timing gear issue sometimes it just happens.
---
Dan O'Reilly
1971 Bright Red Mach 1
2002 Black Deluxe Convertible
Colorado Springs, CO
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