Does anyone know the normal operating temp of a 1995 3.6L 993 engine?



I did a quick search but didn't come up with anything useful ...

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.

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.

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.

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?!

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.

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

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

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.

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

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.

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.

Read this page

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

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

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.

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

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

Rich

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

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?

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

Already running 0W40 ...

Don't ask Amoy what's in his battery.

Take a look at an original volvo PV 544.

They have what looks like a window shade mounted in front of the radiator.
(Think about the temps they see in northern Sweden)

Anyways, its really a simple design.
Roller at the bottom, slides on the side.

Pull up the shade to stop all air, or just partway, all depending upon what you want.

Cable runs from the shade, up over the engine, all the way to the dashboard.
The end of the cable is a chain made up of 1/8 inch "ballchain" the kind with one ball connected to the next ball.

The lock is simple...it is shaped like a keyway.
Round and the top, with a slot at the bottom.

Pick up the chain, get it into the round area...pull to adjust.
Slide into the slot and one of the balls locks in place.

Its elegant and simple...

There is a spring in the roller so when you unlock the chain, it wants to roll down.

I was originally thinking of putting a shutoff valve inline, and within reach of the driver for the oil lines.
I think the window shade would be safer.

rich

What were your oil temps at before you made your hood vent? I may be having a similar issue, but my car is too "new". I am going to check my sender and gauge out. Tape up half your air inlet and see if your temps rise. Cheap and easy test.

My sending unit was broken for a while but before that the temps were more in the 200 range on the freeway.
That was without a shroud and only two small holes in the bottom of the front trunk (The stock holes that have the round plugs in them).


It looks like i'm getting much better air flow now with the shroud and the louvered hood exit.

For an SC, the manual states that 194 degrees is fully warm, up from previous years where the mark was 188. So I'd guess somewhere in the same ballpark.

Did you check to see if your gauge is accurate? Last three oil gauges I hooked up all had different readings...

This is a hotrodders dream- a cool running engine! I could screw this up in no time, pop those heads and shave enough deck to
raise the CR to about 15:1

So yesterday i blocked off 2/3 of my front cooler and only left about 1/3 exposed in the center.

Then i went for a 20 mile drive, mostly freeway. Ambient temp was in the mid '70s.

I was seeing a good 10 to 15 20 to 30 degree rise in temps. When cruising on the freeway in 5th, i got a steady 190F.

Academic tangent: higher temperature lowers viscosity for oil, but I don't remember the effect of viscosity on temperature being as simple as saying "the lower the viscosity the higher the temperature."

I would say the effects of lower viscosity on temperature are that it would increase the rate at which the fluid heats up and cools down, ultimately resulting in less time needed to reach a thermal equilibrium or at least a steady-state thermal transfer. I think it's more to do with the Reynolds number (i.e. the ratio of inertial and viscous forces) than just viscosity alone.

I, too, think Andy should just run higher comp since he's so worried about cooler engine temps.

Did another test run, this time in ~85 ambient temp. Same 20 mile drive.

With 2/3 blocked off i got up to 200F on the freeway and 210F in slow traffic.
With full cooling going back, i never got over 180F even in city traffic and it ran at about 170F on the freeway.

I really think i need some sort of mechanical block-off for the cooler to get it up to temp on those colder days.

home depot window shade.

Seriously, look at the Volvo 544 radiator shade...
You will see a pic on goggle if you search it.

I bet you can get a shade from HD and cut it down and fab a bracket to make it work from the cabin.

Venetian blinds might be even easier...a little electric servo to turn the blinds closed or open....

Rich

What would dampen the reed effect?

Foggy low 50s CA morning, 25 miles, mostly freeway, 2/3 of the cooler blocked off.

The temp never got over 160.


It seems i do need a solution to completely block off the cooler for those colder days.

How about an electronically controlled valve, mounted up near the cooler with a bypass hose.
When it's cold, loop the oil back without going through the cooler....

Too complex. I think a manual shutter type solution would be much less of a hassle ...

Coming from a guy who won't take road kill off his windshield for over 20 miles....eewwww

Just looking for a button you push...simple.

Seems wierd you don't have some sort of inline thermostat for the cooler lines...
My race car had a simple setup like that..

Where did i say that? Of course i have a thermostat It's mounted close to the engine on the rear firewall.

I thought that was the idea,,,,
It still won't heat up?
Or does it heat up, then get cool to fast?

I am lost

Took you a while old man ...


The temp i'm seeing when the car is running too cool is right around the temp where the thermostat opens.
So on a freezing cold CA day (low 50s) my temps hover somewhere between 160-170.

Basically, oil gets over 170, thermostat opens, oil goes to the cooler, comes back way too cold, temp falls below 170, thermostat closes.
Rinse and repeat.

Get a warmer thermostat?

As much as it pains me, I have to agree with SLITS here. Keep it simple.

How about taping or blocking the underside of your hood for most of the time, then for track and warmer days take the tape off?

How about blocking/taping up the original vent holes you were using, then work figuring out how much air to block out your hood? I could see a cable actuated sliding piece of sheet metal you could work from inside while driving. Kinda along the lines we were talking about Sunday...

I'm gonna try metal shutters operated by a cable. That shouldn't be too hard to build.

I need something in front of the cooler that can block off the air flow completely ...

Many ultralights use them-
Ultralight shutter

tourval makes some electric ones

https://www.youtube.com/watch?v=NGDXDKNEtGw


Think this is what you are thinking-

https://www.youtube.com/watch?v=CW_C4ieHVMQ


Old farm tractors all had them. You could use a bi-metal spring mounted on the cooler to open and close one, sort of like a bi-metal fan clutch.

My 993 runs way cooler oil temps than any other -6 that I own. The same goes for the head temps. Its the twin plugs and efficiency :-)

I'm happy to report that i was able to get my oil temps up to ~215 this past Saturday by blocking off the oil cooler completely and doing several back to back AX runs and a few rather high speed figure 8 skid-pad runs.

It just occurred to me that maybe you could block off behind the cooler inside the trunk to reduce the exit path which could be a similar result, but a lot easier to fabricate and less visible...
Inside your custom duct....