Re: [FWDLK] Desoto 361 Update and Resolution
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Re: [FWDLK] Desoto 361 Update and Resolution



Congratulations on a well fought battle Dave! Its been fascinating and
educational to have a glimpse into your persistent revival efforts on this
old engine. As always, in the end, there was no 'black magic spell on the
beast' but rather a 'physics based' cause. The sound I hear from the horizon
must be the euphoria of a successful 361 doctor!

Cheers!

Al

-----Original Message-----
From: Forward Look Mopar Discussion List
[mailto:L-FORWARDLOOK@xxxxxxxxxxxxx]On Behalf Of Dave Stragand
Sent: Sunday, January 13, 2002 8:38 AM
To: L-FORWARDLOOK@xxxxxxxxxxxxx
Subject: [FWDLK] Desoto 361 Update and Resolution

Hi All,

Okay, so you know I was going to attempt to "wash" the cylinders.  That
went just fine. I could see immediately the effect, as what often began
as Motor Flush pouring straight through the cylinders would eventually
slow down to a trickle as the rings got cleaned and began to seal
better.  Compression on my gauge went up from 90-110 PSI to between 135
and 150 PSI on all cylinders -- that's a straight 40 PSI boost!

I had the valve covers off to spot the bottom of the compression stroke,
which would be just after the intake valve closed.  Something struck me
as a bit odd there, in that the rockers would all "settle" back flat
after I stopped cranking.  Hmmm... back to that later.

Anyway, I replaced the valve covers and flushed the cleaner through
there and the distributor valley as well.  So much gunk came out, that
it was constantly clogging the fuel filters on my solvent pump.  I
washed it as long as I could, and when I finally poured out the solvent
from the bucket, there was close to a half-gallon of sludge down at the
bottom.  WOW.

I added about a tablespoon of STP with an oil can and clear plastic hose
all around the bore of the cylinders, and spun the engine over a few
times to ensure that they had lubrication for startup.

I installed the spark plugs, connected the wires, added a gallon of oil
+ two cans of STP and cranked her over.  The oil light was bothering me
a bit, as heavy cranking still wasn't building up the pressure enough to
turn the light out.  I figured it would build up after the STP-thickened
oil had time to circulate a bit.

I added a bit of starting fluid and cranked.  This time, I could hear
each cylinder firing, but there still wasn't quite enough "oomph" to
keep the engine going.  It was finally turning well enough to spin-out
the starter, but just couldn't keep going.  I kept this up for about
three hours... figuring eventually it would catch enough to run, but no
luck.

The oil pressure light still wasn't going out, so I pulled the sender
and cleaned it too.  When cranking, -no- oil came out through the
sender's hole.  Ah ha.  Problem.

I drained the fresh oil back out into a clean container, and was
surprised to see it was barely even dirty.  I then hooked up my solvent
pump again, this time to the oil pressure sender hole.  I removed the
oil filter, and tons of goop started pouring out.  Turning over the
filter, I noticed it too was full of goop.  (Backflushing like this
should also loosen and flush out all of the crud on the pickup screen
and oil pump -- an added bonus).

Quickly I put two + two together.  The rockers... the rockers were
"settling".  They weren't getting enough oil.  If they don't get the
oil, they don't pump up.  If they don't pump up, they don't have enough
lift.  If they don't have enough lift, they can pull a good vacuum (but
not enough volume!), and also choke the mixture with unexhausted burned
fuel, which would tend to blow by the partially opened exhaust valve
into the crankcase.

Okay, so now things were making sense.  If the oil pressure comes up,
things should be good.

I replaced the oil filter with a new one, and cranked the engine until
the pressure came up (about three cranks).  The pressure would stay up
for about 30 seconds -- also a good sign.  I repeated this cycle for
about 5 minutes to make sure oil was getting flushed into the entire
system, and then added a shot of starter fluid.

The car fired, ran briefly, backfired through the carb, then quit.
That's the first time that car's made noise since Nixon was President.

By now, I started getting excited.  I pumped the gas a bit, and cranked
it again.  It caught, but stumbled, so I kept gooseing the throttle and
it stayed running.  Smoke started pouring off the oily exhaust
manifolds, and finally the engine smoothed out, so I let off the gas.

PERFECT idle.  No vibrations, no misfires, nothing -- she absolutely
purred.  And she stayed purring.  I adjusted the timing a bit, and found
a small but very distinct "sweet spot", and locked it down.  It sounds
like a brand new car.

The car now starts and runs like it was hot, even in a 30 degree garage.
I ran it through the gears, and the transmission seems decent for now at
least.  In short, it looks like I'm now ready to go for a little test
cruise as soon as I put the gas tank back on.

A BIG THANKS to everyone who helped to solve the problem!  I'll keep
y'all posted on the results of the test cruise if I do it today.

-Dave



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