Morris Minor Forum

Heavy duty equipment like class 8 trucks have oil temp gauges for engine, gearbox and both differentials. They need them for the extreme pressures from 1500 pounds of torque pulling steep grades. I drove a couple million miles in these trucks, rarely did I see oil temps above 225ºF. I don't see the need in our daily driver, light duty cars. Maybe if you are racing them turning 5-6000 rpm for extended periods.

Mike, I think you are missing the point of gauges in a passenger vehicle. They are to monitor a change in normal operation. Of course if you are doing an intensive design study on engine lubrication you would need both temp and pressure, but when you are driving down the road, you just want to be warned that something drastic is happening and you should stop and investigate. A sudden change in the properties of the oil is not something that happens. Do you plan your oil changes, for example, when the pressure reads A when temp is X or B when temp is Y? If so when and how did you establish the critical pressure and each and every temperature. This is TMI for the driver who is too busy texting or looking out the window, or just trying to remember why they are on the errand.

I am making the point Jim

oil pressure information without
oil temperature ain't any use.

I don't see much point
in an oil pressure gauge
on a cooking car Jim.

There's an oil pressure
gauge on my car that I
watch when I am a bit
with things.
It amuses me the way
it tracks revs pretty
closely once the oil is
up to temp.

Then the traffic lights
change, and I forget it.

When Phil posted a pic
of revs against oil pressure
I needed to know the oil
temp to learn from the pic.

You know the rest

What is more likely to happen?
A broken fan belt (or bad electric fan switch) or a change in oil viscosity?
A change in the massive bearing pressures or a loose of coolant because a hose split?
But that really isn't your argument. What could change the viscosity in between oil changes? Suddenly enough to be noticed by the driver. It would tell you if a blanket got tangled around the sump. I'm still trying to understand what more likely occurrences will change oil temperature but not oil pressure.

For those people who use the oil pressure gauge or light to tell them the oil is low, an oil temp gauge would give them some warning.

A fully instrumented vehicle should have an oil temp gauge, but for many there is limited space to easily integrate into the dash, so a choice is made. For the typical owner, oil temp is lower on the priority list. Even the importance of a pressure gauge is low to many drivers but it has its value to show wear over time or a loss of pressure because the oil didn't return to the sump fast enough on a cold engine.

Phillip is reporting a change in pressure from 80 to 85psi with the new type of oil. Do you suspect there was also a change in temperature? That's right you don't know because he doesn't have a oil temp gauge. Where do you recommend to put the sensor? The external oil line to the filter? The A Series don't have a obvious place so some changes and plumbing is required.

Jeez you do make life complicated Jim,
what's the matter with you?

If you want to measure the temp of your
oil, the simplest method I know is to braze
a female barrel nipple into which you can
screw a water temp sender to the back of
the banjo bolt on the oil line.

Probably a bit slow responding, but within
the accuracy of the usual guessing gauge.

You and I live in different worlds Jim.

I use instruments to make informed
decisions that effect the way I drive.

They may not be wise decisions.
They may not be good decisions
They may not be clever decisions
They may not be intelligent decisions

They are my decisions,
and I am fond of them



Edited 1 time(s). Last edit at 2017-04-27 03:37 AM by 0123.

I absolutely use the gauges to affect my driving.

When the fuel gauge is low, I stop and get fuel.
When the coolant temp starts rising, I turn on the heat. If it goes too high, I pull over and let it cool if going up a hill, otherwise pull over and investigate.
When the ammeter or ignition light change, I investigate and maybe hurry and limp home without lights or take the belt off if the dynamo is smoking. If the ammeter is flicking while cranking, I know the ignition is probably working.
When the oil pressure gauge drops or the light comes on:
In one car when it's cold, I shut it off and coast until the oil has a chance to fill the pump intake.
In another car it tells me the oil pump has been successfully reprimed and it's okay to proceed.
My ex could have used it to tell her to stop driving when all the oil drained out after hitting the pan rather than waiting for the noises to start. Personally the oil puddle when getting back in the car would have done it for me.

I suppose you would look at the oil temp gauge and ponder as to what the oil pressure gauge was telling you.

Supposition, 0/10

Your gauge use reads like
disaster management
not pleasure enhancement

As I said, we live in
different worlds Jim

I can also use the fuel gauge (the ones without the voltage regulator) to tell me when to get the revs back up when driving with a battery with a bad cell. It's a great impromptu volt meter.
Tachs are useful when a gear change is needed and the truck next to you is making too much noise to hear the engine and just fun to watch until the novelty wears off.

Yeah, I don't see much pleasure enhancement looking a drop in oil pressure and then checking the oil temp and then crunching relationships in my head to understand what's happening. Let's see pressure drop but temp's the same - problem to investigate. Pressure drop, temp up - problem to investigate. Pressure up, temperature down - not working the oil hard enough or cold engine. Pressure up, temperature same or down - problem, possible blockage. Pressure steady, temp down, I must be stuck in an iceberg, but the PRV is working. Pressure steady, temp up - problem to investigate. Pressure steady, temp steady - pleasure.

I almost forgot. The oil viscosity must be changing randomly when the pressure changes are noted but the temp stays the same. No worries, just some uncharacteristic behavior of the oil. Sure glad I added that oil temp gauge otherwise I wouldn't know whether to stop or not when the oil pressure suddenly drops or spikes or know when there is some unlikely changes in the heat dissipation of the oil that caused no change in the oil pressure.

Now I know oil pressure gauges are useless without an oil temp gauge, which is all I need. The next time I change the oil/filter and fire it up for the first time, I'll watch the oil temp gauge to make sure the filter is full and the pump is still primed. I don't know what all that noise is coming from the engine. I'm still waiting for the temp to change so I know the oil is circulating. Disaster management or avoidance has a ring to it.

I have always run 20/50 in my 1275 cc motor till this year.
I was told by Bill at Min Comp racing to use 10/40.
He told me they run 20/50 in the mini because the transmission is part of the oiling system.
It did not make a difference in the reading on the oil gauge.
It runs at 20 at idle and 60 at running temp with both oils.
I think you need to verify your reading is correct with a different oil gauge.
If the reading is truly that high you need to change the pressure regulating valve and spring.
Or at least check it to see if it has a flaw.in the spring.

VIGIL

---

The Morris registry club USA.

It is $20 to join - http://www.morrisminor.us/

Post #7 has a gauge screwed directly in block. Same reading as inside. You are correct, it reads the some with 10/40 as with 20/50 and I will be going back to the 10/40. I do feel that it probably should not be that high so I need to replace the spring I guess.