Bonjo2

When my LS3 crate motor, 231/236 cam, open exhaust/intake, safe tune, 419 to rear wheels, otherwise stock, hit’s 212 degrees water temp, like magic and without fail, I drop 10 psi oil pressure which stays that way accross the board until I completely let the car cool down--2-4hrs--and it sorta resets itself.

So, coasting idle can drop to 12-17 psi, with only 31 psi on highway 2700RPM. Under full load still peaks in the 60s.

When I let cool completely my idle is 37 psi, 41 on highway, will full throttle peaks just above 70.

Not sure if this normal. 10w-40 Oil is clean with no signs of bearing wear or carbon. Motor has about 2600 miles. Replaced pick-up o-ring, no difference.

I replaced the oil pressure sensor (electric) and same result. I do however notice that my volts drop from 14.6 to 13.1 when fans go into full blast mode, which is around 220 deg, digidash shows 210ish. Normal running on highway is 188-195 deg. In traffic, 210-220.

Any advice appreciated.

DietCoke

iTrader: (18)

put a real gauge on it, and stop using the stock one.

Bonjo2

I only have an aftermarket.
No stock oil pressure sender--plugged hole.
Stock water temp sender on left head gives info to GM Controller only. Aftermarket temp sender of pax head provide info to my gauge.
Oil pressure tapped into front main journal.

Bonjo2

Mark200

You need to determine if the drop in voltage (when the fans kick on) correlates to the drop in pressure on your electric oil pressure gauge.

Ideally the oil pressure gauge should be designed so that such a voltage drop does not affect it. Key word here is "ideally".

With a mechanical oil pressure gauge this voltage drop is guaranteed to have no effect.

mr.beachcomber

You may want to add an oil temp gauge in addition to verifying the accuracy of you oil pressure sensor. The problem use describe is reminiscent of a similar problem I had with my Vette. It typically ran ~180F on the street, but when pushed hard during track days the water temp would stay around 220F. The oil pressure would drop like you described as the oil temperature typically jumped 10 degrees higher than the water temp. (I was using 10W-30 Mobil 1 with an oil cooler too.)

Just food for thought, but a heavier viscosity oil like a 10W-40 will retain heat longer and takes longer to cool in the pan than a 10W-30 oil. You may want to switch back to 10W-30 to see if that helps.

Good luck resolving this problem!

Bonjo2

Thanks for the advice. I swapped out a mechanical gauge and found that the oil pressure didn't drop, then at around 230 the nylon line melted at the fitting. A little mess, but worth the revelation. Put the electronic sender at the oil recirc above oil filter and out of the heat and pressure only dropped below 25psi a couple times. No 7psi or 10psi. Seems mounting at the main journal not a good idea when only .5 from header. I also found a couple of sensor wires melted down. So header wrap in order, unless I can find a way to never get stuck in traffic.

Battery--heat is also an issue. Low voltage after long time in traffic--40 minutes idling in line trying to leave fairgrounds. My 5lb battery and Hyundai 60 amp not up to to the GM computer, radar detector, nav. Turn everything off and start on a cool motor and 14.9 volts, down to 11.6 when stuck in traffic. Joy. Not sure I have room for a bigger alternator, but do have room for a more substantial battery.

Had a great time at Carlisle today. 157 mph on a fun run more than made up for the 40 minutes in traffic. I just hope nobody go pro'd it..

Bonjo2

Oh, drove a Z06 in similar situations and it was always at or over 220 on long 3rd gear twisty roads. Dropping to 199 on highway. Similar as my car, so I guess I need to get used to the LS motors liking the high temps.. I'm just thankful I have no electronic aids and my clutch isn't like the Z06. Bleck.

Now sticking to 10-30 Mobile 1 and a GM blue oil filter (LS1 early style) too.