Oil Pressure

[Truenorth]

I have a 97 6.5T. Was -33C out this morning but had plugged the truck in last night for 3hrs.....started fine. After about 10 min of driving(back roads nothing above 50 mph) noticed the oil pressure was 30 psi, it normally is which is about 43 psi. Got onto the highway and was running about 75 mph and the engine temp climed well qbove temp that it would be (205 F) when it normall runs (175 F). Drove 30 miles then pulled into a drive thru to get a coffee and at idle the pressure went to about 13 psi, temp still staying at 205 f. After about 7 min at idle the pressure increased back to 33 psi and the temp dropped back to normal temp. I've never seen my oil idle pressure this low before and was wondering what should it be. My real concern was that the inpressure caused my engine to run hotter than normal and if not for the -33C this morning I may of caused some damage....Engine has 105000KM

[rameye]

Wow -33C is almost 100 degrees below zero!!!

Could it be electical gremlin??

Or

Is frozen/slushy antifreeze jamming the works, overheating the engine and causing the oil to thin thus reducing pressure....
Or...could moisture be present in the oil, restricting oil movement, causing the engine to run hot by way of reduced cooling and friction inrease??

Either way..sounds like a oil change is needed right up front. Cheap insurance. Second I would verify your gages for accuracy when you're getting those odd readings.

[LanduytG]

I have found that you can not trust the gauge in the dash. I put in a gauge and idle was 10 psi when the dash said 18 psi.


Greg

[moondoggie]

Good Day!

[Truenorth]

Frozen coolant with a properly funtioning block heater? Have tested with an OHM meter and I can also hear the heater when plugged in. As far as oolant (Dexcool) have verifed it and it is good to -45C.The funny thing is I took the vehicle out at lunch( -26 celcius ) and it ran fine oil pressure at 2000 rpm was about 45 psi and at idle it was around 35 psi, Truck temperature was 175 F.

[cruzer]

It's what Greg said.
When hot mine at idle GM=approx 30psi Autometer=20psi manual gauge.

[rameye]

shame on me..I found a website to do the Celsius conversion. Didnt input -33

whatta dope I am!

[spra01]

I have also had this happen a number of times when the temps dip below -30C on both my 5.7 surburban and my 6.5 pickup, I am quite sure it is congealing antifreeze even though the tests show the antifreeze is good to -45.
(I have never had my tester checked, but this has happened with a fresh 50/50 mixture)
It only seems to happen when I,m travelly at 90 km/h or more shortly after starting and before the coolant would be circulating through the rad.
I have not had it happen with the winter front installed on the 6.5, and on the surburban I make sure it's thoughly warmed up before leaving or keeping the speeds down until it has, and it has not reoccured.
Can I explain why this works no!
Perhaps burnoui's principle has some effect with the pressure and temperature drop of the ram air over the rad ??
or the same pressure temp drop of the coolant through the rad, perhaps a someone restricted rad? or a combination of all?
It's only a theory, I have scratched my head a bit on this one.
I have replaced the thermostat in the sub every time it happens just in case its a stuck thermostat but they can't all be bad.
I have never had this happen on any vehicle other than the 93 Sub or 94 pickup.

[mhagie]

The one thing that I have found is that the majority of times the OEM gauges are not what I would call accurate,the water temp is closer than the oil pres but neither are believable to me.
At idle oem oil pres gauge says right at 40 psi mech gauge is at 19-20
Mech water at 180, oem crowding 200, that is why I have added mechanical gauges for accuracy.
those readings observed with new senders.
my experience is more in tune with the 73-87, maybe later models better?..........Merle

[dieselbegreat]

I have had the lower radiator freeze and plug up the flow to the water pump causing overheating. Had to remove the radiator and bring it inside to warm up. It pays to buy one of those little testers to make sure you have 50/50 mix!