Oil Pressure M998

[Flyingvan911]

Why do we keep looking at the auctions when we are out of space to store these things??????

Because covetting MV's is almost as good as owning them. Covetting is cheaper.

 

[Economist]

It is entertaining to look at the auctions, the for sales, the web listings etc. At least in part, I am trying to feel like I got a good deal (not always confirmed). Then I end up sending an email or making a call and WHAMO, another vehicle on a truck transport coming my way. It there a self-help program or do I need to start attending MV ADDICTS ANONYMOUS?

My name is [insert your name here], and I am addicted to purchasing military vehicles that will require vast amounts of time and money to maintain....

 

[dskupi01]

This is an old post, but I wanted to make a comment. Cold oil is thicker only if it's a single weight oil. Multi weight oils are thinner when cold. 15w-40 oils behave as a 15w oil when cold, the get thicker as they warm up, 40w. The way it was explained to me is the vicosotiy modifiers are like octopus arms. When cold, the arms are tight to the body, allowing the oil to flow more freely. As they heat, the visc modifier arms extend and interact with each other, giving the oil a higher viscosity. I work at Detroit Diesel. For older two stroke engines, multi weight oils weren't recommended. The two strokes were hard on oil and would quickly strip the arms of the visc modifiers, leaving the low viscosity performance. Bad for ring life and rod bearings on high hp engines.

 

[McSpeed]

I know this is an old thread - my stock gauge shows just over 30 MAX when it is cold - after it warms up it drops to 10 or so - It has been this way since I got it - thousands of miles later...same. I suspect the gauge is bad - or sender. About to do an oil change. It does use a little between changes. I had to put a quart in it yesterday before going out on an adventure.

 

[Mogman]

I know this is an old thread - my stock gauge shows just over 30 MAX when it is cold - after it warms up it drops to 10 or so - It has been this way since I got it - thousands of miles later...same. I suspect the gauge is bad - or sender. About to do an oil change. It does use a little between changes. I had to put a quart in it yesterday before going out on an adventure.

Could be a bad gauge or the actual pressure, they don't make or require allot of oil pressure, I drove an old int. (1 ton 345) for almost 10 years and the oil pressure at idle hot was basically zero, it had a mechanical gauge and I tried two others with the same result, figured what the heck when it blows up I will do something about it, the body gave out first and it's rotting down in the pasture, Procrastination really paid off there!!

 

[Mogman]

I know this is an old thread - my stock gauge shows just over 30 MAX when it is cold - after it warms up it drops to 10 or so - It has been this way since I got it - thousands of miles later...same. I suspect the gauge is bad - or sender. About to do an oil change. It does use a little between changes. I had to put a quart in it yesterday before going out on an adventure.

You can simply stick a mechanical gauge on it and see, the factory gauges are notoriously incorrect, BUT say 15 or so at idle hot would not bother me at all, I looked up the specs for my 6.6L Duramax and minimum allowable hot at idle was 14 PSI, seems awful low for a high performance 435hp engine, mine is running about 25 PSI hot at idle so I am pretty happy!
IF you drive a FORD vehicle that has an oil pressure gauge it only has an idiot light switch hooked to the oil pressure gauge, it will be the same hot, cold, idle or agin the governor, they do not get low oil pressure complaints!

 

[Milcommoguy]

Could be a bad gauge or the actual pressure, they don't make or require allot of oil pressure, I drove an old int. (1 ton 345) for almost 10 years and the oil pressure at idle hot was basically zero, it had a mechanical gauge and I tried two others with the same result, figured what the heck when it blows up I will do something about it, the body gave out first and it's rotting down in the pasture, Procrastination really paid off there!!

Here's a Camoteksystems test for the oil gauge. The range of the sender is 0 ohms for 0 pressure. Open circuit to sender... off the chart.

Sender resistance chart tracks really close to a good gauge. HMMVW 0-120 PSI gauge & matching sender components.
30 psi = 10 Ohms
60 psi = 20 Ohms
90 psi = 30 Ohms
120 psi = 40 Ohms
Pegged full scale 50 plus Ohms

SO... having a fixed resistor in place of the sender...say 20 ohms, (not to concerned about wattage 1/4 W ok) reading would be VERY close to 60 psi plus or minus a needle width +/-. It is military truck grade thing, LOL

10 Ohms would be a quick check for 30 psi to check gauge. Or with engine running, a multi meter reading 10 Ohms at the sender, would read 30 PSI on the gauge. Simple. No more guessing or finger pointing.

Don't worry about the voltage, just be in the ball park 23 to 29 volts. The gauge design compensates for voltage fluctuation.

The things one can do with 10 Ohms and a HumV is shocking, CAMO

 

[Mogman]

I think folks obsess way too much about oil pressure, other than using the correct oil and filter there is nothing you can do about it anyway.

 

[Mullaney]

I think folks obsess way too much about oil pressure, other than using the correct oil and filter there is nothing you can do about it anyway.

.
Agreed and when you loose it all at once, it is just seconds until "it's over". I use my gauges to observe consistency. If it is the same today as it was yesterday then the gauges are doing their job.

Long ago in the days of "go fast", the gauges were aligned (indexed?) so that "normal" was pointing straight up.
Rather than looking at a number and confirming what it said before launch - a fast glance showed "all systems go".

 

[Milcommoguy]

I think folks obsess way too much about oil pressure, other than using the correct oil and filter there is nothing you can do about it anyway.

That may be true, a couple pound one way or another no big deal.

My post is for DIYer's and hobbyist a quick & simple check of the electrical components to determine...

Is the gauge working correctly ??? By using a fixed known value resistor. (calibration/reference 20 Ohms = 60 PSI for the 0 to 120 PSI guage only) clears up a wonky gauge issue. One has to start some where... Or fumble around with "what if's" swapping parts, guessing to get good enough reading of what one would like it to be or thinks it is.

Real world... still need an accurate mechanical or electrical transducer to verify the real engine pressure or OEM sender verification would require bench calibration PSI to resistance. (shop air same as above) BUT who does that?

Military vehicle gauges for the most part are satisfactory in this application unless water intrusion, busted or rusted junk.

TM Notes: Engine oil pressure drops below approximately 15 psi (103 kPa) with engine under a load
Engine oil pressure drops below approximately 6 psi (41 kPa) with engine at idle.
TM = Time 4 Maintenance

Surely, some oil pressure is better than none. Now the fuel gauge...that could be a problem, CAMO

 

[Mogman]

.
Agreed and when you loose it all at once, it is just seconds until "it's over". I use my gauges to observe consistency. If it is the same today as it was yesterday then the gauges are doing their job.

Long ago in the days of "go fast", the gauges were aligned (indexed?) so that "normal" was pointing straight up.
Rather than looking at a number and confirming what it said before launch - a fast glance showed "all systems go".

I was just looking at pictures of a Chenowth 2 seat Baja racer, the passenger had all the gauges and they were all skidywampus to make the needles point up.

 

[Mullaney]

I was just looking at pictures of a Chenowth 2 seat Baja racer, the passenger had all the gauges and they were all skidywampus to make the needles point up.

.
It looks incredibly GOOFY, but configured that way you definitely receive instant feedback at a glance.