Re: IML: 1961 oil preasure should I be concerned

[randalpark@xxxxxxx]

The oil pressure on the gauge has nothing to do with the pressure that 
is pushing oil out of the filler cap.

The lubricating oil pressure is created by the oil pump and pushes the 
oil through the oiling system to keep the engine lubricated. The gauge 
may read low due to worn engine parts or due to a faulty gauge. The 
gauges on our cars are notoriously inaccurate. You can have the oil 
pressure checked at a shop. They will connect into the system with a 
real gauge and tell you if the oil pressure is okay. Generally, any oil 
pressure is enough. When it is too low, you will hear the lifters 
tapping at stop signs at idle when the car is warmed up.

The pressure pushing oil out the filler cap is crankcase back pressure, 
and can be caused by worn engine parts, namely piston rings, or a 
plugged up crankcase ventilation system. 1961 uses flow through 
ventilation. This means that air is usually sucked in though the 
breather cap and expelled via the draft tube. The draft tube starts on 
the right valve cover and runs down the passenger's side back of the 
engine. It ends under the car by the bell housing. If there is 
smoke/air/oil coming out of the filler cap, there should also be some 
coming out of the draft tube. If not, the problem isn't likely due to 
engine wear as much as to a plugged draft tube, or draft tube filter.

It is possible that at some time in the car's past, that it has been 
fitted with a pcv valve. If so, this likely would have been done in the 
vicinity of where the old draft tube had been, right side valve cover. 
If this has been done to your car, and the vacuum hose has become 
disconnected or split, or the valve has failed, crank case pressure 
will increase and oil will be pushed out the filler cap.

I hope this helps.

Paul W.

-----Original Message-----
From: rcjm60@xxxxxxxxx
To: mailing-list@xxxxxxxxxxxxxxxx
Sent: Tue, 13 Mar 2007 12:56 PM
Subject: Re: IML: 1961 oil preasure should I be concerned

Hi,

My 61 does the exact same thing.  The oil pressure reads pretty low and 
I get some smoke out of the breather cap until it warms up.  I only 
have 81K miles on mine and it runs great.
It may be normal for this engine with some miles on it.
Kevin

"Steve B." <Imperial59@xxxxxxxxxxxxxxx> wrote:
> My 1961 oil preasure gage has always on the low end. It has never 
even
> read dead center. I have had the car for 15 years and rarely drive it 
,
> and it runs good. But now it needs to be my main and only car to get
> around. Im curiose if the preasure is low why then does oil blow out
> threw the breither cap . Wouldnt that appear to prove that there is
> plenty of preasure? What is the normal amount of preasure on the oil 
for
> this 413 wedge moter? Als the car does not ever over heat wouldnt low 
oil
> preasure tend to heat the moter up ?

Oil pressure gauges are kind of like fishing buddies... You can trust 
them
to tell you the basics but when it gets down to the nitty gritty they 
might
not tell you the whole truth. The best way to know for sure what is
happening is to temporarily connect a mechanical calibrated gauge and 
see
what your pressure actually is. I consider 10psi per 1000rpm (hot)to be
safe. Anything below that I start to worry a bit.

The oil blowing out the breather cap has nothing to do with oil 
pressure.
As an engine wears more and more of the combustion gas blows by the 
rings.
These gasses have to get out somehow and the breather is the easiest 
way
out. You have to have a pretty good bit blowing out to carry the oil 
with
it. I dont remember what year PCV came out, but if you have a PCV valve
make sure the valve is good and the hose and passages aren't clogged.

> From your description of the low oil pressure and excessive blowby it 
sounds
like you have an engine that is starting to get old and tired. A 
rebuild
would bring it back to good as new, but you likely have thousands of 
miles
of life left in it. Change the oil often and make sure you keep it full 
and
watch the oil pressure. I would expect it to slowly get worse and worse
until it reaches the point that it will be obvious to you that it is 
time
for a rebuild.

Steve B.



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