Thread: Normal operating temps for p38s.

The highest I saw in slow traffic on a 40deg day was 102degs. On the highway it quickly dropped to 90ish. I don't believe that's any reason for concern. I've replaced the pump when the engine was done and have a new thermostat waiting to go in. The expansion tank cap was also recently replaced. All in the name of preventative maintenance. Would like to put in an aussie desert cooler, before the ONE rad craps itself. Car is on 163k.

benji, my electric fans come on with a high temperature, I can hear them in slow hot traffic, so much so that if it's around 40deg the fans will stay on when the engine is off for a couple of minutes....I thought this was normal...isn't it?
My wife's peugeot does the same on an extremely hot day..

Originally Posted by daf11e

benji, my electric fans come on with a high temperature, I can hear them in slow hot traffic, so much so that if it's around 40deg the fans will stay on when the engine is off for a couple of minutes....I thought this was normal...isn't it?

Yes it is. I've had the fans switch on when the car is parked (when they used to work). My electric fans used to come on when the engine was hot but I suspect one of the pressure switches in the AC system has failed and the fans no longer come on. I'm think of adding a manual switch for the fans.

I have a Scan Gauge in mine and I monitored the temps a week back on 35+ deg day as I climbed out of a valley on the Wollondilly River and then along Wombeyan Caves Rd.

On the low speed climb, the car's temp gauge rose a needle width above N and the Scan Gauge read 104 deg.

Once I got moving along Wombeyan Caves Rd (at 40km/h - it's a narrow and winding dirt road), the temp dropped back to N and the Scan Gauge read 94 deg.

As speed rose on the straighter and wider sections of the road, the temp dropped to 89 deg and the needle was in its usual position of just below N.

The key issue is whether or not the coolant boils. A 50/50 anti freeze mix together with a properly functioning radiator (expansion tank) cap (14.6 psi) will sustain temperatures up to about 130 deg C. before boiling.

An engine operating in the 92-96 deg C range is normal ...the warmer the engine runs, the more efficient it becomes. The design specs allow for coolant temps to reach above 100 deg C especially when the engine is under heavy load in high ambient temperatures and relatively low air flow. The other major influence on engine operating temperature often overlooked is the heat transfer efficiency of the oil! An improved oil cooler can be more effective than upgrading a radiator which may well be operating quite satisfactorily!

Driving around town in light traffic my temp is 86-87?C, this climbed up to 94?C the other day when the outside temp was sitting just over 44! I have seen up to 102?C after sustained soft sand driving through the dunes. My temperature reading is taken from an additional sensor (third party) near the factory temperature sensor. The Torque Pro app also indicates the same temperature.

Gary

My temps are much like yours Benji, I have seen 109 wheeling in the bush on a very hot day. This is fine. However, you will rarely see below 90 in a warm country, as the thermostat is closed at this point and fully open at 96 deg. Rave says thermostat opens:

->99MY 88 deg C (190F)
99MY-> 85 +/- 5 deg C (185 +/- 9 F)

80 deg C for diesel.

Glen

That sounds like my thermostat is opening too soon. Given I have 2 independent sources providing the same result, I'm confident the temperature reading is correct. I don't think I'll change anything at the moment as I am pleased to be erring on the cooler side of the temperature range.

Gary

I forgot to say, I don't run the usual P38A thermostat sputnik - min has the item pictured. My thermostat is in the inlet manifold like the RRC and is, I think, an 82 or 88 deg unit.

http://www.aulro.com/afvb/p38a-range...ml#post2187351