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Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329079 is a reply to message #329076]

Mon, 12 February 2018 09:43

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma:

Senior Member

Johnny Bridges wrote on Mon, 12 February 2018 08:47

Then 22PSI running is adequate for my coach? I feel much better if that's correct. It starts over 40PSI cold idle but drops drastically when it comes up to temp. This with 15-45 Rotella. It does, however hold 30 or so at a minimum. Tell me that's safe and I'll quit worrying over it.

--johnny

Kingsley Coach wrote on Mon, 12 February 2018 09:02

Johnny You aren't the only one waiting for more info on this. I've been mentally
doing a rebuild for 6 months now..if I could put it off one more year......

Mike in NS

Neither of you should worry.

Lube oil pressure is only required to get the lube oil where it needs to be and still have it do its jobs.
What are its Jobs?? (More or less in order of accepted importance)
Cooling, things like bottoms of piston crowns
Flushing, the debris from wear and combustion so it will not interfere
Damping, keeping metal parts from banging in each other
Working fluid, for things like lash adjusters and chain tensioners
Metal surface isolation, preventing metal parts from working on each other
Lubrication, forming the hydraulic wedge that actually is the bearing in rotating parts

Notice I got to six before hydraulic lubrication?
Does the pressure of lubricating oil as it is delivered to the bearing of a plain bearing system matter?
Not really, all the oil has to do is get there and the rotating journal will pull it into the load areas.

In an engine such as a BB Olds, you really only need enough lubricating oil pressure to deliver it to the lash adjuster (cam followers) for everything to be good. Everything else (we don't have a chain tensioner), can be handled by the lube oil that is thrown around by the crank. So, regardless of what the oil pressure gauge says, if the engine is not making nasty noises at road load, it is probably good and will be for some time to come.

All that said, low lube oil pressure at idle is an indicator of wear. But is it wear of the bearing, the lash adjusters and bores or the lubrication oil pump itself. There is just no way to know. The best one I have personally known was an engine that was shut down on low lube oil pressure and the problem was a seized valve. That seized valve cause the pushrod to couple and that took the load off the cam follower that popped out of the bore and so there went the lube oil pressure. We got a new pushrod, cleaned the valve stem and screwed the cylinder had back down and put it back in service for another few years.

Matt

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

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[Message index]

		[GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: BobDunahugh on Mon, 12 February 2018 01:25
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: jhbridges on Mon, 12 February 2018 07:47
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: Kingsley Coach on Mon, 12 February 2018 08:02
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: Matt Colie on Mon, 12 February 2018 09:43
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: jhbridges on Mon, 12 February 2018 12:28
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: James Hupy on Mon, 12 February 2018 12:32
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: Kingsley Coach on Mon, 12 February 2018 13:39
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: jhbridges on Tue, 13 February 2018 07:54
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: James Hupy on Tue, 13 February 2018 08:52
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: Keith V on Tue, 13 February 2018 09:22
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: Marsh Wilkes on Tue, 13 February 2018 10:08
		[GMCnet] Sure got this way off topic. Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: BobDunahugh on Tue, 13 February 2018 11:21
		Re: [GMCnet] Sure got this way off topic. Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: James Hupy on Tue, 13 February 2018 11:39
		Re: [GMCnet] Sure got this way off topic. Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: Jim Galbavy on Tue, 13 February 2018 15:37
		Re: [GMCnet] Sure got this way off topic. Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: SpookyEng on Wed, 14 February 2018 05:00
		Re: [GMCnet] Sure got this way off topic. Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: USAussie on Wed, 14 February 2018 05:18
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: jhbridges on Wed, 14 February 2018 08:12
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: Bullitthead on Wed, 14 February 2018 08:43
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: emerystora on Wed, 14 February 2018 11:26
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: Bill Van Vlack on Thu, 15 February 2018 10:00
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: k2gkk on Thu, 15 February 2018 11:14
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: jimk on Thu, 15 February 2018 13:33
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: jhbridges on Thu, 15 February 2018 08:39
		Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. By: Matt Colie on Thu, 15 February 2018 17:30

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