<VV> Replacing Oil Pressure Regulator Spring

[Tom Hughes]

Here's the full story of this engine. I had a '66 with a 95 HP engine with
a couple cylinders with low compression numbers (down in the 50s, if I
remember correctly). I don't know the history nor the mileage on the
engine. I tore down this engine saving the bearings and marking for
location; found some low-mileage jugs; had them cleaned up and honed;
cleaned and checked a set of LM pistons that measured within spec., scraped
out the ring grooves and matched the pistons to the jugs for best
clearance; cleaned and checked the rods. When disassembling the 95 HP
engine, I could not get all the upper head nuts to come off due to heavy
rust. On a couple I had to cut the stud to free the head. This block half
ended up getting scrapped when all my efforts (including soaking in
ATF/acetone and heat) would not free one of the cut-off studs from the
block. I had another LM block from a dead 110 (bought used out of the car
so now known provenance), so I used it for the new engine. I cleaned and
blew out everything, found the best used crank and rod bearings,
plastic-gauged all the bores/shafts and they were within spec. I put the
engine back together per the manual with torques to spec. Cleaned up and
reinstalled the rear engine cover with the same gears and the thinnest
gasket. I did not plastic-gauge the gears. I tried turning the pump shaft
and it would not move. I replaced the thin gasket with the other gasket in
the kit and completed the rebuild with new rings, re-guided and lapped
heads, filled the crankcase with straight 30 wgt. Rotella and a dose of
ZDDP additiive. I'd been doing neighborhood runs at twenty minutes or so at
a time with top speeds of 45 without the idiot light flickering. Then, on
my first drive on the highway (60+ for fifteen minutes), I came to a stop
with the engine in Drive and rpms around 500 and the idiot light came on.
As soon as I shifted into Neutral, the light went off. I went home the same
way and the light again came on when I stopped in front of the house. I
installed a pressure gage in place of the switch and measured 30 psi cold
at idle and 20 psi at idle after about ten minutes sitting in front of the
house. After the next highway drive to work, the gage read about 5 psi when
idling in Drive. Drove home and the same in front of the house. I figure I
have about 100 miles on the rebuilt engine and the level hasn't dropped
noticeably on the dipstick. The oil on the dipstick does not smell like gas
at all and still seems to have the right viscosity.

That's the engine's history as best as I can remember. Today I will pull
and inspect the regulator and spring and compare against all the other ones
I have lying around. I reinstall the longest, stiffest spring and with
nicest looking regulator and see what the initial pressure is cold. I'll be
pleasantly surprised if this is the problem. I'm leaning towards the oil
pump, and I have at least one known good rear cover/pump assembly that I'll
probably end up having to install. I'll keep you all informed.

On Fri, Mar 23, 2012 at 8:45 PM, shortle <shortle556 at earthlink.net> wrote:

> I am kind of curious on this subject. The engine was "recently rebuilt".
> Were all the bearings and journals (camshaft, rod, and main) plastigaged?
> What was the history of this engine before it was rebuilt? Are all holes in
> block and crankshaft with good flow? Are all the bearings installed
> properly (all 4 mains in proper order, all rod caps installed properly)?
> How long has this engine run before this became an issue? Finally,
> (actually first), what kind of oil are you running and what brand of
> filter? How many miles since last oil change? Is any gas mixing with the
> oil?
> Timothy Shortle in (nice, warm, perfect) Durango Colorado 81301
> I love/hate cars!
>
-- 
Tom in Baltimore
corvairfleet.blogspot.com