In my experience with any type of vehicle with a mechanical oil
pressure gauge....
usually a bouncing pressure indicates you have air
in the tube leading to the gauge.
The only way to bleed the air is to pull the gauge from
the dash, loosen the line on the back of the gauge (over a bucket)
start the engine, and bleed the line by letting
the oil pump out through the gauge end for a second or two.
The volume of oil in the line should only be a few CC's as it's
usually quite a small diameter tube. After a few seconds, re tighten
the connection on the gauge ... clean up and remount your gauge.
-----Original Message-----
From: Rick Morrison <gofastmg@juno.com>
To: mikesl@tartan.sapc.edu <mikesl@tartan.sapc.edu>
Cc: Mgs@autox.team.net <Mgs@autox.team.net>
Date: Thursday, November 19, 1998 9:22 PM
Subject: Re: Bouncing oil pressure - MGB
>Mike,
> Let me know if you find the cause of the pressure bounce.
> My GT does much the same thing at times. At idle it will sometimes (not
>always) bounce between 45-60, rather rhythmically. It's been doing this
>for the last couple of years, so (fingers crossed) nothing major.
> i've gone through all the lines, coolers, filters,etc. Even changed the
>pressure relief valve and spring. Still does it.
> I have noticed that it seems to be more prevalent when an oil change is
>coming due.
> Could it be the engine is reminding me?
>
>Rick Morrison
>72 MGBGT
>74 Midget
>
>On Thu, 19 Nov 1998 02:10:50 -0500 "Mike Lishego"
><mikesl@tartan.sapc.edu> writes:
>>Howdy all,
>> Tonight while waiting in line at my favorite burger shack, I
>>noticed a
>>semi-disturbing problem on my MGB. When I had the car in neutral with
>>the
>>clutch out, the oil pressure would bounce from about 55 to 70, almost
>>in
>>time with the idle.
>>When I put the clutch in, or the car was in gear and moving, the
>>bounce went
>>away.
>> Here's my guesses...The I had the choke in and the car wasn't
>>entirely
>>warmed up. When I tried later in the night (when the car was warmer)
>>it
>>wouldn't do it. I'm guessing that the engine was running rough,
>>causing the
>>engine to rock back and forth. This might have put strain on the
>>flexible
>>oil hose, causing the pressure to jump up and down by about 15 pounds.
>> Or, there could be something catastrophic about to take place in
>>my
>>engine when I'm in an economically disadvantaged area, leaving me
>>stranded
>>with one blown up MGB. The only sign I see that this won't happen is
>>that
>>the oil pressure is going up from it's standard of 50, not down. Not
>>only
>>that, the temp has stayed constant.
>> I don't know if the car had just started this behavior; I do know
>>that
>>my burger was late, which led me to linger over each gauge a little
>>longer.
>>Bottom line, should I be worried?
>>
>>Michael S. Lishego
>>http://www.geocities.com/MotorCity/Speedway/3706/
>>
>>
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