Early Cars - Max Oel Temp?

daepp · 06-27-2006, 06:24 AM

Driving the freeway at 70 yesterday in Southern California (ambient temp was 100 deg), my 2.4 heated up to about 225-230 deg f. What is the acceptable range or max temp these cars should see? At max temp, do you shut it down, or let it idle - which is better for the engine?

cnavarro · 06-27-2006, 06:28 AM

Running dino or synthetic? Viscosity?

daepp · 06-27-2006, 06:34 AM

Dino - 15/50

cnavarro · 06-27-2006, 06:41 AM

You have sufficient viscosity then, so your oil pressure should be fine. I didn't realize anyone made a dino 15w50. Have you checked your timing, maybe it's too advanced? Any pinging? I know of people who on their fours hit 250 at times, but they run synthetic. I would think even with the ambeint at 100F you are a little on the hot side at 70 mph for dino oil, at least if those are sustained temperatures.

Jim Richards · 06-27-2006, 07:02 AM

250 is too hot. 225-230 is kinda hot. Run lower rpm's if you can. Higher viscosity oil is better during the summer. Running at idle for long periods of time on a hot day is not a good idea. Do you have an aux. oil cooler in your right front fender? If so, check the oil lines to see if they are hot (indicative of a properly functioning thermostat) and make sure the aux cooler is clean.

kenikh · 06-27-2006, 08:54 AM

I worry if I get over 220. I have seen 230 in HARD driving on 95+ degree says. That's when I pull over, shut off and let the car cool down, unless I have an extended stratch of road to lug the car and let the air do its work. I think I may have a minor cooling problem as I don't know anyone else with an early car and remote cooler that has the same problem.

cnavarro · 06-27-2006, 09:13 AM

Don't lug the car - if the oil is that hot, heaven only knows hot hot the heads are. There has to be a happy medium between rpms, oil temp, and head temp. I know mine is 4000 rpm, but that's the point where my cam comes on and efficiency is highest. As long as you have pressure you're not going to hurt anything- and a good oil won't instantly go to crap, you'll just reduce it's service interval. If it really gets too hot, just pull over let it cool off. I have only had to do that once and that was crossing Blood Mountain in GA on a 100 degree day.

kenikh · 06-27-2006, 09:17 AM

Good advice; thanks! The situation where I had to pull over was very similar to yours.

chris_seven · 06-27-2006, 09:21 AM

I would always like to see oil temperature at around 190 to 200 degrees.

Bearing temperatures are likley to be 90 degree hotter than oil inlet temperature and even if the oil is synthetic I don't think it woul be good to run hotter for long periods.

If the engine heats up to 240 + then it may be better to run gently at light throttle and keep some cooling airflow until temperature falls. If it doen't fall there must be something wrong.

If it always runs hot then it seems as if there is a problem or just not enough cooling.

Emission · Emission's Garage

Pull over and shut down. Idling won't cool the car.

The other day I was stuck in stopped traffic on the freeway in 95 F. ambient temps. There was an accident, and I was crawling along (clutch in... clutch out...) for about 20 minutes watching my temps slowly rise as there was no airflow through the cooler... the oil hit 250 F. and I pulled over on the side of the road.

After about 15 minutes with the decklid open and the engine shut down, the temp had dropped to about 220 F. and the traffic had opened up. I got back on the road and the temps quickly dropped to my "normal" of about 190 F. on the highway.

Always error on the side of caution.

kenikh · 06-27-2006, 09:25 AM

I keep telling myself that I am going to buy a thermostatically controlled fan for the oil radiator.

Emission · Emission's Garage

Quote:

Originally posted by kenikh
I keep telling myself that I am going to buy a thermostatically controlled fan for the oil radiator.

My freeway "incident" (above) convinced me that one will be my next upgrade.

daepp · 06-27-2006, 11:16 AM

My 2.4 T was recently rebuilt to 9.5:1 compression, ported, cams etc. I just wonder if it has sufficient cooling. On the Big Bear Run it got to about 240 deg.

GrantG · GrantG's Garage

Quote:

Originally posted by daepp
My 2.4 T was recently rebuilt to 9.5:1 compression, ported, cams etc. I just wonder if it has sufficient cooling. On the Big Bear Run it got to about 240 deg.

Air-Cooling is less efficient at high altitudes...

klaucke · 06-27-2006, 11:23 AM

240 is definately too hot, especially for a Mg cased motor like your 2.4. I would install a higher ratio fan drive and larger fan(Grady Clay has some excellent threads on this), and optimally also a front mount cooler. I don't let my 2.7 get over about 210.

High engine temps directly degrade engine life.

kenikh · 06-27-2006, 11:27 AM

Quote:

Originally posted by daepp
My 2.4 T was recently rebuilt to 9.5:1 compression, ported, cams etc. I just wonder if it has sufficient cooling. On the Big Bear Run it got to about 240 deg.

Invest in Elephant racing oil cooler lines and a Carrera front fender mounted cooler, for sure. It will cost you about $1000, but the peace of mind you'll get knowing you won't have to spend over double that repairing pulled head studs is worth it. Or don't drive on hot days...

cmcfaul · cmcfaul's Garage

My 2.4 911 E get up to 250 on the track. I find that if I keep the RPM's up on the cool down lap temps come down a lot faster then by short shifting. The higher the RPM's the more air cooling.

Like wise I found if I use 5 th gear on the streight temps will come up faster then when redlining in 4th. Same reasoning as above.

250 is hot but still not at the redline by Porsche's standards as indicated by the later OEL gauges.

Chris
73 911 E 2.4 mfi

kenikh · 06-27-2006, 11:46 AM

I think the later oil gauges are more forgiving due to the aluminum cases. Aluminum cases don't pull studs as easily as magnesium. You have to treat mag cases nicely, especially if you aren't running case savers.

Jim Richards · 06-27-2006, 12:31 PM

Quote:

Originally posted by cmcfaul
My 2.4 911 E get up to 250 on the track. I find that if I keep the RPM's up on the cool down lap temps come down a lot faster then by short shifting. The higher the RPM's the more air cooling.

Like wise I found if I use 5 th gear on the streight temps will come up faster then when redlining in 4th. Same reasoning as above.

250 is hot but still not at the redline by Porsche's standards as indicated by the later OEL gauges.

Chris
73 911 E 2.4 mfi

Chris, do you have an aux cooler on your 73E?

Jim Richards · 06-27-2006, 12:33 PM

Quote:

Originally posted by daepp
My 2.4 T was recently rebuilt to 9.5:1 compression, ported, cams etc. I just wonder if it has sufficient cooling. On the Big Bear Run it got to about 240 deg.

daepp, I'm surprised you didn't go ahead and add a front (fender) oil cooler to complement the HP bump your engine has. If you're making 911S lelvels of HP, you must seriously consider the aux cooler.