Oil Pressure dropping after load....oil too hot?

[Conn]

I've noticed that since I installed my Isspro oil pressure gauge, my oil pressure is a little funky. Under normal driving, 65-75 MPH for a little distance, the oil pressure stays at about 40-50 PSI, when I pull off the interstate, it normally drops down to 20 or maybe a little less.

NOW....under load, anywhere from 4500-10000 lbs. towing, the oil pressure on the upper end stays about the same, 40-50 PSI, but when I pull off the interstate, sometimes it will drop below 10. the factory idiot gauge still reads, and my isspro drops out at 10, so i assume after pulling a heavy load, the oil pressure is somewhere between 7-10 psi. I'm usually on the gas pretty hard when pulling (it IS an old IDI )

could the oil cooler be crapping out? the oil heating up so much that it's breaking down and lowering the viscosity?

i thought about trying some synthetic oil. i'm runnign just regular old rotella 15w40 right now.

any thoughts? i haul with this thing constantly and would rather spend some $ now to fix a potential problem rather than be broke down with a trailer and jeep behind me.

any help would be appreciated.

thanks.

conn

 

[towcat]

firstly, what kind of oil are you using? the values you are telling are OK. since the oil cooler is cooled by water, what is your water temps on these runs? more info please.

 

[argve]

ummm when did you buy this ISSPRO gauge?

Is this the Enhanced Vision set? if so read the following - if not the EV line then skip the following as it only applies to the EV line (ones with the little box/amp to drive the gauge head/face)

___________________________________________________

Reason I ask is back when these gauges were the brand new kid on the block the senders for the oil pressure were a single wiper sender and they had all kinds of problems with them dropping to zero when you idled down when the engine was hot. It would also intermittenly drop to zero while I was running down the road. Well needless to say I pitched a royal fit over it with them, I got dang near to the point of being on a first name basis with their tech, I want to say his name was Don Windlick or something to the effect - it's been a couple years at this point. Well anyways they developed a dual wiper sender that was suppose to fix this problem but at the time they still were not shipping that because it was not fully out of engineering at the time. I suspect/hope/assume that it's being shipped at this point.

I worked with Don (I think that was his name) quite a bit and I figured out through trial and error that what was causing the biggest problem with the single wiper design was heat and vibration. I ended up wrapping the sender in alum foil and isolating it from the engine (moved to inner fender) to make it work faily decent - only everynow and again would it fail when the air temps were really up there. I think Don ended up sending me something like 2 complete gauge set ups and 3-4 extra senders trying to get it to work, he even offered to buy them back from me because of the problems that I was having. I naturally declined because I just wanted it to work because they are extremely accurate to fluctuations (by design - it's a 4-20ma system) and aesthetically they blow the doors off anything else (my opinion only).

So if you have the EV line try moving it away from the heat and isolate it from the vibration that a diesel creates. I would still place a call to ol Don and give him my regards. I ended up selling mine on ebay to some dude that put them in a gasser and he did not have a problem (I contacted him a few months after the fact to see if they were working up to par - would have refunded his money if they weren't).

I truly think that because these are 4-20ma driven that they are extremely sensitive to vibration because a small change on the sender end will only be amplified to the max after it goes through the amp to the gauge head. So by saying that if the wiper bumps off just the least little bit you will see a big swing of the needle. Maybe they are just too sensative.... dunno...

But Don did tell me on my last conversation with him that the new senders were supposed to right around the corner.

 

[Conn]

yes. i do have the EV series with the goofy, big as a brick amplifiers....or whatever they are. findind a place to stick those things is a pain.

the gauge has recently started freaking out in the mornings, sometimes *******, sometimes dropping to zero...but you can obviously tell it's a problem with the gauge as the needle swings much too fast for any type of pressure drop....

the gauge does work most of the time. i have no idea as to what my water temperature is. my "warning" sending unit is faulty and usually kicks on within 20 minutes of highway cruising. it has done that since i bought the thing. i did order an Isspro EV MECHANICAL water temp gauge, as i didn't want to screw around with another black brick to mount. but i haven't got around to installing it yet.

i seem to have developed some sort of "leak" around the oil cooler. it's engine oil for sure, and it seems to be dripping ever so slightly off the drver side framerail, and blows back onto my purty new white shocks.

it's only a slight leak, so i'm not worried arbout it. the truck has sooo many slight leaks, i could spend a month trying to fix them all.

if i weren't so leary of getting oil all over the inside of the truck, i'd jsut install a mechanical oil pressure as well.

i'll install the water temp this weekend and see what happens. you're right...if the water is hotter...the oil will be too....


thanks.

conn

 

[The Warden]

i did order an Isspro EV MECHANICAL water temp gauge, as i didn't want to screw around with another black brick to mount.

I thought I heard somewhere that one black brick could handle multiple gauges? Or am I remembering it wrong?

 

[argve]

Nope each "Brick" (4-20ma amp) only runs one gauge and is calibrated to each sender/gauge head - that is the nice thing about these - accuracy.

Now the other thing (your statement of it slams high everynow and again) that tells me your problem might be in your wiring. These amps need a solid wiring job - meaning no fluctuations in the incoming power or they will/can slam high. Make sure that your wiring is clean/tight on all connections especially the incoming power and ground. If you have a funky voltage regulator these gauges will find it/show it. They are extremely sensitive to power fluctuations of any kind. I intially found that out the hard way

That sounds more like your problem because of the statement of it slams high. These gauges have a very quick movement - much quicker than any stock type gauge even quicker than the EV line of voltage gauges - I found my voltage fluctuation by having a very ultra nice voltmeter from work hooked up and watching my "power grid" if you will. Mine ended up being both voltage reg and my ground I was using under the dash.

 

[geonc]

if i weren't so leary of getting oil all over the inside of the truck, i'd just install a mechanical oil pressure as well.

Sounds like the lift pump rumor about the diaphram failing and filling the crankcase full of diesel

Having run mechanical oil pressure guages in the last 4 diesels I have owned.....each passing 300k BTW I have not seen a failure.

Of course I run quality guages AND use AN fittings along with high pressure braided stainless lines.

You can get reliable, high burst braided lines from any hyd hose shop or speed shop.
Most speed shops carry #3 AN style NOS line pre-made in lengths from 12" up to 8'.

Don't really see an failure issue running 60 PSI/190 temp oil thru line rated at 5K {read thousand }PSI

You spend good $ on a quality guage....don't skrimp on the connection to the eng using 1/8" compression copper or that plastic white crap

Just my couple pennies............

 

[argve]

Sounds like the lift pump rumor about the diaphram failing and filling the crankcase full of diesel

I mopped up oil one night from off my dash - lost a cd player to the oil slide coming from on top of the dash. Gauge let go - not good - every try to clean diesel oil from the dash before - not fun...