How cold is too cold? Options

[SirAndy]

Does anyone know the normal operating temp of a 1995 3.6L 993 engine?
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I did a quick search but didn't come up with anything useful ...
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[SirAndy]

Found some stuff on Google:
Looks like ~180 is normal for a 993 and ~200+ when stuck in traffic on a hot day and ~240+ when you really push it.

It seems my car is running a bit cooler than that. I got it up to ~190 in stop/go traffic with 80 ambient temp and it went down to ~160 once i got airflow on the front cooler.


I don't have anything to compare this too but 160 seems a bit on the cool side.
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[bulitt]

(IMG:style_emoticons/default/confused24.gif) Beats me? Don't know much about air cooled engines. But seeing oil temps in the 210+ range is good for water cooled engines to remove any condensation. My last corvette regularly ran oil around @ 225-240 and this was normal.

[pcar916]

I've never looked that up in my 993 factory manuals (bought in '98 to do the 2.7 - 3.6 conversion) to know if it's there or not but will peruse later, and transmit if I find anything specific. My 3 .6 runs anywhere from 190 to 210 on the road in humid summer weather. If I have to sit in traffic it'll go a bit higher, and on the track on a hot day it'll hang at around 220-260. But that's after adding the second cooler off of the small oil filter console. Before that it would go above 280. (IMG:style_emoticons/default/headbang.gif)

I'll always wonder if installing -16AN oil lines instead of these -12's would have made a difference. My front cooler has -16 fittings, I just didn't want to spend the money and the -12's fit into the factory heater ducting in the passenger rockers. That would have made for a LOT more fluid volume to carry the heat up to the front. In fact, as near twice as much as makes no difference. i.e. -12AN ~ 176 sq/mm vs. -16AN ~ 346 sq/mm in cross-section.

I've been considering moving the second engine cooler into the space in front of the right-rear wheel with the trans cooler. But I'd then have to separate them and put in a fan system and a scoop to cool them both. I have all of the hardware to do it, but more bodywork! Street/track compromise cars are a pain when you have to make them behave while crawling around in traffic.

The 2.7L engine didn't run anywhere near that hot, but it wasn't making as much power either. Ideally, I like keeping the temps below 205 all the time, but synthetic oil saves the day regardless. That and R&P wear are the primary reasons I use synthetic in my transaxle... but that's another kettle-o'-fish isn't it?! (IMG:style_emoticons/default/beerchug.gif)

[SirAndy]

But seeing oil temps in the 210+ range is good for water cooled engines to remove any condensation.

That is my primary concern, not enough heat to get the water out of the system.

I do get quite a lot of the dreaded white "foam" at the top of my filler neck.
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[r_towle]

But seeing oil temps in the 210+ range is good for water cooled engines to remove any condensation.

That is my primary concern, not enough heat to get the water out of the system.

I do get quite a lot of the dreaded white "foam" at the top of my filler neck.
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can you change the thermostat easily?
Might be worth moving up the opening point to ensure the water gets cooked out.

I noticed on my 911 that when I start it and let it idle for a while, it does get up to operating temps.
then as i start driving, it goes down.

rich

[SirAndy]

can you change the thermostat easily?
Might be worth moving up the opening point to ensure the water gets cooked out.

As far as i know, they all come in the same temp range. My thermostat is (relatively) easy to get to.
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[mskala]

it went down to ~160 once i got airflow on the front cooler.

I don't know much about 993 other than they've eliminated the on-engine
cooler, but on earlier cars even the external cooler's thermostat was similar
innards to internal one.

These things are supposed to open about 176F, so there is really no way to be
running below this temp unless it fails open. Or your gauge is wrong or measuring
in a different part of the circuit.

[r_towle]

The engine oil, used for cooling the engine, is circulated through a mechanical thermostat
(behind the RH sharkfin) and once oil temperature reaches a nominated level the thermostat
routes the circulating oil to the oil cooler in the right front wing. Here a temperature sensor
relays information back to the CCU which will, in turn, control the cooling fan to run at either
slow or fast speed or stop completely. The ballast resistor provides the electrical resistance
to reduce the fan speed when slow speed is selected by the CCU.

So, do you have this fan in place?
Unplug it? do a test ride?

We replaced the CPU connection with a manual switch in the 924S because it was getting too hot while idling....just takes a human to remember to switch on the fan.

Not a great solution, but if you do have that fan...there might be a decent way of working out the issue in that system.


Rich

[r_towle]

a bit more along the same line of thought.
Personally, if it was me, I would see if there are optional thermostats available to deal with this issue.
Patrick Motorsports might know.

Regardless...her is a simple how to.

You can override the thermostat which controls the high speed oil cooler fan. The fan operates in two modes, low speed and high speed. By shorting a wire on the climate control unit ( CCU ), you can force the high speed operation.

This has been especially useful when you are stuck in a long line of traffic or when you are coming off the track into the paddock area. It’s really amazing how fast it brings the temps back down. More information about installing an oil cooler fan switch can be found here: Installation of a manual oil cooler fan switch

Before you install the switch, you will want to verify that your oil cooler thermostat is working correctly. You can find directions here: 964/993 Oil Cooler Fan Operation & Troubleshooting

If you are concerned about premature fan failure, the fan costs about $100 to replace. I would not recommend that you run all the time in the high speed mode, but, as mentioned above, during traffic and during cool down periods in the paddock, it is invaluable. Oil is the lifeblood of your engine, be sure to keep it cool!

[r_towle]

At 87c/188F (per Bruce Anderson's hi-performance book) for a 964, 83c/181F for a 993 (per manual), the oil cooler thermostat opens and oil starts to flow to the cooler.

At 212For 230F (993), the thermosender—via the control unit—starts the oil cooler fan in slow speed.
At 239F (964), the oil cooler fan switches to fast speed. The 993’s fast-speed set-point is unknown.

[r_towle]

Read this page

http://p-car.com/diy/fan/

[pcar916]

I do get quite a lot of the dreaded white "foam" at the top of my filler neck.

I had it with the 2.7L and now as well... dangit.

[SirAndy]

At 87c/188F (per Bruce Anderson's hi-performance book) for a 964, 83c/181F for a 993 (per manual), the oil cooler thermostat opens and oil starts to flow to the cooler.
At 212For 230F (993), the thermosender—via the control unit—starts the oil cooler fan in slow speed.
At 239F (964), the oil cooler fan switches to fast speed. The 993’s fast-speed set-point is unknown.

No fan(s) anywhere, just airflow while driving. At this point, any fan would make this even worse.

I have to dig through my notes to see what the temp setting on my (aftermarket) thermostat is.

I know it doesn't open until i get some heat in the oil, i can tell since the lines run inside the car.
This is under normal operating with the oil hot and the thermostat open.


It just seems that my front cooler works too good for normal street driving.
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[Dave_Darling]

180F is OK if you don't take short trips. Water will still out-gas from oil at 180F, it just takes longer than at higher temps. Lower than that is bad; it means that the oil isn't getting into (or staying at) its working temperature.

I would like to see 212F under all circumstances, myself. But 180F seems to be the low end of the "normal" range. Remember Bruce A's famous scale, below 180 is "cold", 180-220 is "normal", 220-240 is "hot", over 250 is "too damn hot".

--DD

[r_towle]

At 87c/188F (per Bruce Anderson's hi-performance book) for a 964, 83c/181F for a 993 (per manual), the oil cooler thermostat opens and oil starts to flow to the cooler.
At 212For 230F (993), the thermosender—via the control unit—starts the oil cooler fan in slow speed.
At 239F (964), the oil cooler fan switches to fast speed. The 993’s fast-speed set-point is unknown.

No fan(s) anywhere, just airflow while driving. At this point, any fan would make this even worse.

I have to dig through my notes to see what the temp setting on my (aftermarket) thermostat is.

I know it doesn't open until i get some heat in the oil, i can tell since the lines run inside the car.
This is under normal operating with the oil hot and the thermostat open.


It just seems that my front cooler works too good for normal street driving.
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Simple.
Have Mcmark put an inline shutoff to the cooler, one you can reach.

Rich

[SirAndy]

Simple.
Have Mcmark put an inline shutoff to the cooler, one you can reach.

I was thinking about something similar. A flap in front of the cooler that is operated by a cable would suffice.
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[SLITS]

Or use Racer's Tape (Duct Tape) and block off part of the airflow to the cooler. Tape can always be pulled off if it's getting to hot.

Some diesel trucks use airflow control vanes on their radiators to make sure they run "hot" enough in cold weather. Some use a canvas flap over the radiator that can be set to allow air flow in thirds of surface area.

Simple --- nicht wahr?

[infraredcalvin]

How about trying a different weight oil, something with a lower viscosity should get hotter...

[SirAndy]

How about trying a different weight oil, something with a lower viscosity should get hotter...

Already running 0W40 ... (IMG:style_emoticons/default/shades.gif)