Oil Pressure

[B1B Keven]

18 hours ago, Kels said:

UPDATE:  Installed a modern oil pressure gauge at the engine..Pressure is around 55-60 PSI.. So, I think I am in spec on the pressure.. The old Gauge must just read high.

 

Havn't been driving it much to see it anything else changed..

 

Thx for all the advice on my car!

 

The old gauge is adjustable.

[Kels]

46 minutes ago, B1B Keven said:

 

The old gauge is adjustable.

OH.. how is it adjusted?

[B1B Keven]

10 hours ago, Kels said:

OH.. how is it adjusted?

 

There's an arm between the bourbon tube and needle that can be bent.

Set your air compressor at 60lbs, use a rubber tipped blow off tool

and adjust the gauge until it reads accordingly.

[Todds53B4]

Working on my new to me 53 B-4-B truck.  I removed the pressure valve and found that someone had added a bolt behind the cap, to increase spring pressure.  What would be the reasoning behind this?  I haven't run it yet to see what difference it makes in indicated oil pressure.  I've only been able to drive the truck a couple of times so far.  The oil pressure was great, then suddenly dropped across the board.  Still not sure if it has actually dropped or the gauge is acting up.  I had soaked the cylinders with Marvel Mystery Oil to see if I could lessen some smoking.  Not sure if I stirred up some sludge and plugged something up or not.

[rustyzman]

Confirm your pressure with an external gauge.  If it is indeed zero at that point, shut it down and run no further.

 

Putting anything behind the spring of the relief valve would just increase the total pressure required to unseat the valve just like you said.  Normally, you increase this by using the optional higher compression spring, but a "shim" will have sort of a similar effect.  If the bolt was long enough, it could stop the valve from unseating at all, jamming it in place.  Overall sounds like someone was trying to find a cheap way to fix a bigger problem.

 

Sudden catastrophic loss of oil pressure can come from a number of sources.  One common issue is a spun bearing.  That will cause lots of bigger issues if it continues.

A clogged inlet screen or a broken crossover pipe similarly will cause the same thing to happen.  A totally failed pump is possible, but usually I see those lock up and break the drive gear.  That kills the engine because the distributor stops rotating too.  Happened to me on a new pump.

 

Drop the pan and take a look.  You can pull bearing caps too and see what the bearings and journals all look like too.  Mine was very damaged on two of the mains.  Good oil pressure dead cold, dropping to almost zero warm at idle.  Also found out that I had a clogged chain oiler and that the timing chain had absolutely never seen a drop of oil in the 15 years I had owned it and drove it.  That was a surprise.  Checked it out and found the cam was retarded 9° because of all that chain wear.  It explained a LOT of odd issues I was trying to work out.  No audible indication at all.

 

Now with my rebuild complete and all issues corrected I am 40psi at idle hot and about 50psi cruising, and that is with the chain oiler open again.

Edited November 18 by rustyzman

[Todds53B4]

Thanks!  I started off by cleaning out the back of the gauge, then tested it with air.  It was right on the money.  Reassembled it and ran the motor and the pressure looks good now.  It's actually showing slightly higher pressure than before across the board.

 

I think the relief valve was stuck in place, it took a bit of wiggling and turning it inside the get it out.  Cleaned up that assembly and replaced it was as well (without the nut).  Always pleased when the simple solution in the correct one.  I'll sure be watching the pressure closely as I continue to wake the truck up.