btu44

Some time ago I installed a SR5 gauge cluster in my 89 pickup. It's nice to have the tachometer but the other gauges were somewhat vague. So I took these pictures and thought someone else might find them interesting.

Here are the oil pressure gage pics. These pictures were taken with a fresh Mobile 1 10/30w oil change with 0 miles.


Cool engine oil at idle


Hot oil at idle.


Cool oil at revs.


Hot oil at revs.


Oil pressure tap

Here pics of the volt meter.


Battery voltage with the engine off.


Battery voltage during engine starting.


Engine running

And finally the temperature gauge. There was a lot of lag between the temp gauge cluster and the place were I placed the temperature probe. This is the measurement I got after the meter stabilized,

grumpin

Very cool! That's a lot of work, but neat to see.

btu44

I mainly did this because the oil gauge barely moves at idle. Just making sure there was good pressure.
Does anyone else's oil gauge move this little as mine. I wonder if it is because I'm using aftermarket oil pressure sender?

millball

I think low factory oil pressure gauge readings are common on these trucks.
My '95 with low miles shows similar indications, but is in excellent condition with original Toyota sender.
Your tests should give you confidence that your engine is solid.

kcaudill

My oil pressure at idle and hot is above your current reading. ihave heard that the gauge/sending unit is not accurate but i must have the one built on tuesday or something. I have over 170k and all original.

RSR

Owners manual says oil pressure should be between those two lines when not at idle.

Cold oil idle, I'm near that first line, but not over it.
Hot oil idle, I'm about little left of halfway between no pressure and the first line.

Cold oil 3k rev -- I'm about 3/4 way between those two center lines.
Hot oil 3k rev -- I'm about 1/5 or so to the left of the first of those center lines.
*3k is about where I am at 60-65 or so on the highway, so I see these often.

I run 5w30 synthetic. And synthetics will read lower pressures on these gauges than dino.

Bottom line, looks normal to me, but wouldn't hurt to replace w/ OE sending unit(s) if you're worried. SR5 sender connects to standard sender if I recall correctly, so you'll need both (again, if I recall correctly).

btu44

Thanks for the replies. I'm not surprised that other gauges read differently even with the same oil pressure. The accuracy of the sending unit is a factor and also the meter itself. It's nothing more than a bimetal strip with heating element wire wrapped around it. The sending unit is a variable resistor that controls the current flow through the heating element.

I played around with a power supply and a variable resistor to find a resistance that would give a meter reading more towards the middle. Then I was going to put a resistor in parallel with the sending unit to get that same resistance as the bench test. I decided against this because sending unit is an open circuit at 0 oil pressure. This way the meter is not drawing power with the ignition key is on but the motor is off. A resistor in parallel would defeat this feature. Also while testing on the bench, the meter movement was pretty linear to resistance changes. But at a certain point the meter would thermal runaway and would race to maximum deflection.