Some cooling issues with my car (oil temps and odd pressure readings)

[captdistraction]

(Warning in advance, rambling ahead)

Background: Built a new coyote/roadrunner motor a while back. Went overboard on cooling and sensor package, and now have some weird symptoms that may be bad gauges or setup.

Setup: MMR1000/Roadrunner (yes, get your pitchforks and torches), Fluidyne radiator, MMR head cooling mod, Boss 302 Oil cooler, homebrew Air/Oil cooler (-10AN lines, supposed 20,500 BTU core), 302S Grilles, speedhut gauges in stock location with T, and in Moroso 10QT pan (total 12 QT capacity for system). 302S hood, wrapped headers (stock).

Symptoms:
Oil temps read 140 if not below if the ambient air is 70* or below and car is highway cruising. Can go 50 miles without fully warming the oil (as read by the gauge).
Oil pressure reads 70-90 on start, settles to about 20, and once coolant reaches about 160, oil reads no pressure on the speedhut gauge unless you blip the throttle (obviously I have pressure or the stock pressure switch would flip - I know it works unfortunately). That or my motor seems to run just fine without any oil pressure (jk)...

I did install a 180* oil thermostat last week to try to combat the temperature problem

Testing: I bought an IR thermometer to test with this evening.
After a 15 minute drive and 5 minutes of idling, the gauge showed 160 (climbed from 145 when I first parked). The Pan as shot by the thermo was 161, the oil cooler lines were 178 and 170 respectively at their fittings. The cooler core was 158 as best as I could shoot it. I am thinking something about that pan may be such that the sensor is getting more of a reading of the pan itself, which may be slightly lower temp than the oil itself. Still not sure why that would be the coolest place in the oiling system. This was all sitting idling in the garage without the car's fan operating. When it did operate, all temps dropped about 5-7*.

Some images of the setup:

factory pressure sender T'ed with speedhut pressure sender

Can't see the gauge wiring, but I have good grounds on both gauges, oil temp is in insert in side of pan with an appropriate brass NPT adapter.

~70mph after 30 minutes continuous running, ~68* ambient. Pressure looks good, temp can't be right.

My thoughts:
The system is too large a capacity for street use, however actual oil temps are higher than the gauge is reading. Is it possible both my gauges just read somewhat low? I'd be inclined to believe both read between 10-20% low. I'll email speedhut for further guidance, but anyone else have some thoughts on a car that seemingly runs too cool? Or the issues with pressure reading low?

 

[Sky Render]

My first suggestion? Get some gauges that aren't pieces of junk. There's a reason no race teams use "Speed Hut" or whatever the hell brand you're using. Get some Autometers. Their Z-series is nice if you're on a budget.

You put good money into that motor build. Shouldn't you also spend a little more on good gauges to monitor it properly?

 

[captdistraction]

I was under the impression speedhut made a quality gauge. I can certainly do some testing with autometer products, but wanted to make sure I made no obvious mistakes in design as the end user.

 

[Sky Render]

I've noticed a lot of the lower-end electrical gauges have difficulty reading temperatures and pressures in the lower portions of their range. I had a cheap electric oil pressure gauge in a previous vehicle that read "0" with anything below 20 or so PSI.

Even so, the important thing in gauges is not the exact reading, but the ability to see deviations from what the readings usually are. Consistency is important.

EDIT: As for your setup, is there a way to eliminate that 90* bend before your gauge's pressure sender? if not, can you switch the two locations? And are you using TEFLON TAPE?! That's a no-no on electrical gauges, unless you also run a second ground wire. Those things ground themselves via the threads on the sender, so Teflon adds to the resistance. Try putting a ring terminal around that pressure sender's oil fitting threads and connect it with a wire to another ring terminal on the block.

 

[captdistraction]

I've noticed a lot of the lower-end electrical gauges have difficulty reading temperatures and pressures in the lower portions of their range. I had a cheap electric oil pressure gauge in a previous vehicle that read "0" with anything below 20 or so PSI.

Even so, the important thing in gauges is not the exact reading, but the ability to see deviations from what the readings usually are. Consistency is important.

EDIT: As for your setup, is there a way to eliminate that 90* bend before your gauge's pressure sender? if not, can you switch the two locations? And are you using TEFLON TAPE?! That's a no-no on electrical gauges, unless you also run a second ground wire. Those things ground themselves via the threads on the sender, so Teflon adds to the resistance. Try putting a ring terminal around that pressure sender's oil fitting threads and connect it with a wire to another ring terminal on the block.

Sure, I'll swap the senders (the pressure switch should only care about any pressure being there, so presumably if there's some loss due to the T, it still should operate ok, not that if its tripped it matters anyways)

On the teflon tape, its actually the paste stuff. However, the sender has a seperate ground post on the body, which I've run to a clean sanded body ground. Same with the temperature sender on the oil pan (it goes to the K member x-brace bolts).

No word back from speed hut yet, but bad come to worse I can always investigate using autometer products (I do have some of their gauges here in the garage, including an electric oil pressure gauge).

 

[captdistraction]

Another update: Colder day (44 out) but I did wrap the core.

It didn't seem to make a meaningful difference on a 25 minute drive.

Some more pictures:

The sender in the pan (note the secondary ground wrapped around it):

the cooler core:

 

[zeroescape]

Are you using the 180 degree thermostat for the oil or are you talking about coolant?

The thermostat should be bypassing the oil cooler til the oil reaches 215 F Degrees.

I think your problem is your thermostat is too low, and its going to take a long ass time to heat up 12 quarts of oil especially if its going through a cooler after 180 F.

You can also get a pressure loss due to how the system is designed. Those pricey Seatrab coolers are pricey because they are engineered to minimize pressure loss. Not to mention the style of fittings used.

Maybe a well detailed schematic of your system might help with the particulars.

Edited: I just realized you have a boss 302 cooler in there too. I think your oil is going on one heck of a ride and could be streamed lined a little better for oil pressure.