Marine Blue

So I took the shark for a spin tonight and after a good 40 minutes of driving the needle was still barely touching the first white block on the gauge. Outside temp was 32.

Is it running too cold or is this normal?

BIMMERMIKE

Do you have a lower temp thermostat? I had the same situation in the colder months and decided to change to an 83 degree thermostat all year round .

jpitman2

Too cool. should be at least midway, to my mind. Did it get there slowly as well? Mine gets off the bottom to first mark within 5 mins driving, on an 83C thermostat.
jp 83 Euro S AT 51k.

Marine Blue

Thank you for the replies.

I'm not sure which thermostat I'm running, is there a quick way to check this? Failed to mention the car has a Ron Racing/Devek radiator although I'm not certain if this makes any difference.

Rob Edwards

Do you have access to an IR thermometer? My gauge reads cool. Shoot a temp on the lower radiator hose to get a sense of the coolant temp in the block, and the upper hose to see the temp drop across the radiator. When warm, my lower hose (driver side) is routinely at 190oF, although my gauge reads ever so slightly above 170F. I get about a 15-20o drop across the radiator.

IcemanG17

Hmm
If you have the cooling vents pinned open, it is possible....when I was at the 1st Sharks at Tahoe..it was quite cold...& during some downhill sections at about 40' my temp would drop just below the 1st white line & my cooling vents are pinned open

SteveG

I have the 83° in the '85. Put some 600 miles on it this weekend. OAT was in the 40s; at speed it stayed just above the first line. There were some serious bumper to bumper spots, maybe an hour total out of the trip, the rest was 75 to 80 mph. got 20.5 mpg. It ran like a top.

mark kibort

32f is pretty cool. if you dont have the cooling fins that can close and open based on temp, then its not that uncommon. especially, under light load and over 60mph!

I had an interesting observation going to the track last week, my oil temp was still in the 180f range, but the coolant was on the cool side, like what you saw. Now, is the problem the oil being too cool, or does the water temp matter too. I guess if you have too much disparate temps between head and coolant, that could be an issue, but as long as the oils is to temp, is that a problem??? (180f oil temp?)

mk

Dennis Wilson

It could also be your fan clutch stuck/locked so that it constantly turns. Same thing happened on my 78 5 speed and it turned out that a PO had welded the shaft to the housing. Since Oklahoma weather doesn't get too cold I have left it that way.

Dennis

Doug Hillary

Hi,
Mark - I have taken hundreds of IR readings off normally used (not raced) 928s and I suspect that many will run too cool in low ambient temps. This will be especially so when non OEM (open sooner) thermostat and the fan's actuator is lower than the OEM

The averaged readings were;

Thermostat housing - 86C (187f)
Top hose (near radiator outlet) - 73C (163f) dependent on ambient
Bottom hose (near radiator outlet) - 76C (172f) dependent on ambient
Valve covers - 89C (193f)
Vee (hottest point near Temp2) - 88C (194f)

The normal core temperature should be in a range around 88-93C (190-200f) after about 30mins use regardless of ambient when using a OEM thermostat

From a cold start oil normally trails coolant by as much as 20C (68f) - the equilibrium then should be around the "core" temperature

An engine lubricant's anti wear (AW) additives are heat sensitive/reactive and progressively take over from the boundary type AW additives at around 50C (125f). Engine lubricants operate best in a band from about 85 to 110C

Engine lubricant viscosity is of course heat dependent and so is flow around the 928's engine as a factor of pressure. Some typical viscosities at 82C (180f) are;

Castrol Edge 0w-40 = 22cSt and @ 100C = 13.5cSt)
Mobil 1 5w-40 = 25cSt and @100C = 14.8cSt)
Mobil 1 5w-50 = 30cSt and @100C = 17.5cSt)
Mobil 1 15w-50 = 33cSt and @100C = 18.1cSt)
Amsoil TRO 20w-50 = 31cSt and @100C = 18.3cSt)

It is clear to see why Porsche opt for a 0w or 5w lubricant for >MY84 engines

Where is your oil temperature gauge reading from? - its location can cause misleading readings

I hope this is of interest
Regards

mark kibort

my oil temp is taken right at the sump. its dipstick thermometer!

the question is that even though the water temp reading is low, (bottom white line) if the oil temp, taken at the sump is 180 to 190ish, where is there an issue?

mk

Doug Hillary

Hi,
Mark - I'm sure you have verified the ACTUAL coolant temp and not relied on the "less than clinical" gauge

Ideally the coolant and the oil temps should be with a few degrees C of each other and in the "core temp" range noted above. Typically oil will/could be up to about 10-15C warmer than the coolant

As the oil interccoler's thermostat is fully open at 99C I never registered that high on the innacurate measurement taken at the intercooler's exit pipes

Regards

worf928

My '91 and my '89 will run at ~180 when just tooling around in sub-45 degree temperatures as far as the gauge is concerned (I 'mentally' calibrated the gauge reading with the IR.) However, the temperature that the computer sees is about 10 degrees higher as shown by the Hammer. I reliably see a temperature difference on either side of the water bridge. The NTC-II (computer's sensor) side is always higher than the gauge sender side.

Of course there are measurement errors involved as well as the linearity of the gauge. However, since I consistently see the right side of the bridge hotter than the left side I don't think its all measurement error.

Afshin, next time you get your shark out, come by, and we'll IR your bits and pieces and see where its really running.

Marine Blue

Thank you for the replies. I'm not certain if the front cooling vents are stuck open or not. This car spent the first 19 years of it's life in Nevada and Norcal so it's possible a PO adjusted the vents open to deal with the heat. I know the fans weren't running last night even after sitting idle in the garage for a minute.

After slowing down from highway speeds the car never warmed up and basically stayed a tick above the bottome white bar.

Dave thank you for the offer, hopefully the snow will stay away for another month to figure out what is going on. I need to get up your way anyways to work on the seats, let me know when you're ready.

worf928

Any time. Just give me a heads up.

Yeah. Well. You're gonna wanna wait until the radiant floor is up an running for that. The plumber has me scheduled for the end of December. Seems he thinks that there are some folks that need heat in their houses first. I mean... really... sheesh. Can't they use extra blankets?