Oil temperature

[Jeeper6]

Thanks for the feedback guys...very much appreciated. I know our US cousins read these threads, be interesting to hear from them what temps they see in their Jeeps.

Drover, both yours and mine are 2015's, maybe they share similar traits? Though both the thermostats I have on the bench here have no opening temperatures etched on them anywhere.

As far as tyres go yes absolutely, additional drag will send temps north. When I first got this Jeep it had pretty standard Highway pattern tyres on it at 30" diameter, and just a bull bar, spotlights and winch.

I have since fitted my MT's to it which are 32" diameter with a wider footprint, much higher drag too due to the luggy tread pattern...the temps stayed pretty much the same as they were with the original treads. It has the roof rack and the snorkel back on now which all add to the drag.

The spotlights and the winch do block air flow so I have taken the front lower skirt off for now to open up the front. I have the old skirt which i had cut holes in to allow air to hit the bottom half of the radiator, I'll fit that later.

The van is tandem axle and still has the AT's that came with it when new. I could increase the tyre pressures on the van for sure to reduce the rolling resistance...I have the van's tyres at 36psi cold which rise to 40 psi when hot...van weighs in at about 2650kg and is a poptop so a tad less drag. I have never been one to subscribe to 60 psi tyre pressures, just can't see any advantage in that....maybe I should?

I found this trip that sticking at around 1850 rpm in 7th gear is the go as far as keeping temps reasonable which gives me around 95 kmh on the road. The ambient coming back hit as high as 35c which made little difference to the temperatures. Once it creeps over 2000 rpm the temps begin to rise. Dropping back to 6th on an incline sees the temps begin to go north at rpm's go up, dropping back to 5th pushing uphill is when I see the bigger oil temp readings.
Gearbox hits no more than 94c at any point...usually 92c - 93c.

I'll will have the W58 recall done after back from Bathurst, and have them fix the roaring fan on DPF burns...maybe they can tweak the temp the fan comes in to assist...

[drover]

Van tyre pressures fit my procedure, 4-6 psi above cold temp that being usually at a 25c ambient .......... your tranny temps get a tick, if the airflow was restricted your tranny temps would certainly show it, when I'm working the engine its all about revs, speed is irrelevant and temps stay in a good zone I have found, well mostly.... they have climbed up at times but recover quickly so Im happy...

The thermostat temp marking is just a small dot matrix print/etch on the side of the housing, well on mine it is, hard to see unless its removed, mine is an Italian one, not a Mopar to be seen...I should have taken a photo but I was not in a happy place doing the coolant on this thing......
I have found my air intake temp is about 10c above ambient most times and I run with no cover on engine, have no idea if that makes any difference really as I pull them off so I can see the engine easily at a glance it also has saved a vehicle when an alternator went up in flames as I could quickly get to it with an extinguisher, an engine cover melts and spreads the fire, I just had to replace the alternator and continue on my journey not replace the whole vehicle..

[Jeeper6]

I'll be replacing the thermostat for sure with one of the others I have here...
hang on...I just looked at them both a little more closely, and the 2 that I have on the bench are both marked "Made in Italy" and both have 98c etched on them?

I don't get it...I have no idea what temp the one in the engine currently is, but it doesn't appear to open until 97c...(possibly 98c) with the engine temp at least 97c but mostly 99c - 100c while cruising... never falls below 97 unless coasting down a hill where it has dropped to low 90's until accelerating again....where as the other 2 saw temps steady at 94c - 95c and would drop to 92c at times and just sit at that.

It may well be as you wrote earlier Drover the opening temps will vary by a degree or two anyway regardless of what they are claimed to open at...

The air intake temp with the snorkel shows usually 2 degrees above ambient on the Lufi, but shows higher on the SRT gauges...as you note up to 10 degrees.

Before I put the snorkel on, the Lufi showed intake air around 6 degrees higher than ambient as I guess the air had to flow over the top of the radiator panel to get in to the air box, heating up a tad on the way...

[drover]

I wouldn't be worrying about the thermostat, sounds like its normal, no sense swapping things out.............. once the valve is open thats it, job done the coolant temp is then subject to air flow thru radiator and right peddle pressure with gear selection and a temp on these engines of 95 to 115 is nothing to worry about, towing or flogging it up hills all temps will climb up you only have dramas if once your over the other side the temps don't recover quickly and since oil and coolant temp along with AC and Tranny are in it together any one of then can be the problem.....

The temp on the thermostat isn't what your coolant temp should be at all..

[Jeeper6]

I guess if the boffins at VM decided that the thermostat should open at 98 degrees then they wanted the engine to run at close to 100c.

The radiator cap is 21psi...so...as water boils at 212 degrees Fahrenheit...100c. The boiling point of water apparently increases three degrees for every 1 psi the pressure goes up. So if the pressure goes up to 15 psi, then we have added 45 degrees to the water’s boiling point...the boiling point is now 257 degrees instead of 212 degrees...theoretically.
So with a 21 psi cap the water should not boil until it hits 275F or 135C...

The other day when i pulled up for fuel and inadvertently shut it down while still showing 106C on the gauge, it began spitting water out the overflow and I could see water gurgling in to the expansion tank...so it was bloody hot!

Thats when I decided to replace the radiator cap...don't know whether it has helped or not...temps are still the same...haven't tried shutting it off when at 106C though...

[drover]

Originally Posted by Jeeper6

I guess if the boffins at VM decided that the thermostat should open at 98 degrees then they wanted the engine to run at close to 100c.

The radiator cap is 21psi...so...as water boils at 212 degrees Fahrenheit...100c. The boiling point of water apparently increases three degrees for every 1 psi the pressure goes up. So if the pressure goes up to 15 psi, then we have added 45 degrees to the water’s boiling point...the boiling point is now 257 degrees instead of 212 degrees...theoretically.
So with a 21 psi cap the water should not boil until it hits 275F or 135C...

The other day when i pulled up for fuel and inadvertently shut it down while still showing 106C on the gauge, it began spitting water out the overflow and I could see water gurgling in to the expansion tank...so it was bloody hot!

Thats when I decided to replace the radiator cap...don't know whether it has helped or not...temps are still the same...haven't tried shutting it off when at 106C though...

Nulon Red coolant at 50/50 mix brings the boiling point to 123c, so with pressure it would move your figures even higher........................ I wonder if I read my thermostat upside down, or did you 86 or 96 ?????? another thing for to ponder...................... lol,lol,lol........ since I recently changed my coolant Ive been waiting for mine to spit out the overfill in tank, to date it hasn't.... I will have to syphon it I suppose.....

Have you tested your thermosats to see if they will actually open ???

[Jeeper6]

Originally Posted by drover

Nulon Red coolant at 50/50 mix brings the boiling point to 123c, so with pressure it would move your figures even higher........................ I wonder if I read my thermostat upside down, or did you 86 or 96 ?????? another thing for to ponder...................... lol,lol,lol........ since I recently changed my coolant Ive been waiting for mine to spit out the overfill in tank, to date it hasn't.... I will have to syphon it I suppose.....

Have you tested your thermosats to see if they will actually open ???

Nulon Red coolant at 50/50 mix brings the boiling point to 123c, so with pressure it would move your figures even higher

So true...Hmmm yeah, 98 upside down would read 86...lol.




Picture is a little blurry but can make out the 98C stamp. I just tested both thermostats I have here, the one from the old Jeep and the one that just came out of this one.

The one out of the new Jeep seemed to begin allowing water through at around 95c...the one from the previous Jeep appeared to be allowing water through at around 88C.
I had the test water up to at 100C...both were allowing water through pretty freely at that.
I did not see either fully open, or maybe their open isn't wide open like the thermostats of old?

That would likely explain why the previous Jeep ran so much cooler...coolant was beginning to flow much earlier. I don't know whether that was by design or just age of the thermostat. Both have 98C stamped on them, and both "Made in Italy".

I will swap them over later and see what happens...