From: jws@billy.mlb.semi.harris.com (James W. Swonger)
Subject: Re: Low Oil Pressure!  Help!
Date: Tue, 26 Jan 1993 23:07:12 GMT
Organization: Harris Semiconductor, Melbourne FL

 20-25PSI is much lower than I'd want to be running. The big block Buick
has pretty large main journals and 25PSI of pressure at the pump is probably
not enough to keep them happy.

 I have a disassembled 430 motor. When I took it down, I found that the 
pickup screen was completely clogged with goo, leaving only the bypass
flap in the pickup for oil to be drawn through. If yours is as badly 
crudded up, it's probably damn near starving. 

 The chugging could be something as simple as an exhaust leak, or some form
of imbalance between cylinders which becomes more noticeable under load. A
lone plug fouled with oil, a weak plug wire or damaged distributor cap, 
and so on.

 My recommendation is that you first check out what you can from the topside
to determine whether the general condition warrants a complete rebuild. At
225K I suspect it does. Feel the air at an open oil fill cap with the engine
revving to see if there's significant blow-by. Run a compression check. Look
at the spark plugs.

 If the compression is good (enough) then I would try (assuming I were not
inclined to just rebuild it for practice) pulling the engine and transmission
and dropping the oil pan. This may be doable without removing it entirely from 
the car, if you can get enough height to work. I don't like doing it that 
way, though. You need to inspect the pickup screen to see if it's plugged up.
Then, after installing a cleaned pickup tube, I'd recommend a high -volume-
oil pump over high pressure (which in the case of Buicks is often just a
stiffer relief spring anyway) since I think your problem is a combination
of oil intake obstruction and increased demand in those worn, big journals.
There are kits and whole pumps available from Poston, Kenne-Bell, et al
for high pressure and/or high volume. The pump is an easy install.

 If you're in the mood to try an experiment, aimed at cleaning the screen 
alone, you could drain the oil pan and refill the sump with a good solvent
(lacquer thinner, etc). Do Not Start The Engine!!! Remove the oil filter and
the distributor (use something to keep the rotor from moving too much and mark
the body orientation) so that you can get to the oil pump drive shaft. Let the
solvent sit in the pan overnight. It's a good idea not to overfill the pan;
you don't want the thinner to attach the pan gasket or anything.

 Spin the oil pump with an electric drill (you'll have to cobble up your own
extension to fit the slot on the pump shaft) until thinner comes out the oil
filter feed (oops, better put a hose on there and run it to a catch pan). 
After the lower intestine is fully primed with thinner, stop and let it sit
again. 

 If you have a reversing drill and run the hose into a can, you can establish
an air-less siphon arrangement and force solvent back and forth. The pickup
screen flap is a one-way check arrangement and reverse flushing will all
flow through the screen. A session of back and forth flushing, drain the pan,
purge the oiling system of solvent. The solvent ought to look pretty nasty.
Now refill the pan with some cheap, disposable 30-wt oil and draw it up
through the pickup and out the oil filter feed. Are you getting decent flow?
Does the drill seem to be working very hard, or is it easy to draw oil?
If you wanted a direct comparison, you could empty the pan via the oil 
filter port (suing the drain plug for the final bit) the first time, noting
the relative ease of draw. 

 After the oiling system is re-primed with (mostly) oil, drain and discard the
remainder via the drain plug. Look for extra chunks and dirtiness in the clean
oil. The pickup tube I have was clogged with sludge and had lots of piston
chunks in it, but that's another story. Suffice to say that high compression
engines with steel head gaskets require a good antifreeze/corrosion inhibitor.

 Another option to consider is picking up a rebuildable or running 430. They
don't seem to get snapped up like the 455s. You might be able to pick up a
running 430/ST400 set for under $300, maybe a whole Wildcat or Electra parts
car. They just don't seem to be that popular, but good, cheap, 360HP parts 
cars make my day. A bore/hone job, valve job, wear parts and gaskets ought
to come in at about $500-$700 plus blood, sweat and hoist rental. 
-- 
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