dbiller1

Dear Forum Members,

I recently had my 2006 C4S with 82,000 miles serviced. Before the service, my car would consistently run with an oil temperature of 200 degrees and a water temperature of 175. If I drove hard, I could get the oil temperature up to 225 if the external temperature was in the 90s or hotter.

After the service, my oil temperature runs at about 210 and goes up to 225 very easily even if the temperature is in the 60s. If I drive harder, it will continue up to 250.

Something changed following the service. None of the things that I had done should have affected the oil temperature. This is an Indy mechanic who I have used for 5 years on this car.

The service included:

Upgraded alternator cable.
Replace slightly cracked coolant overflow tank.
Replace torn right CV boot.
Oil and filter change.

Any ideas what might have gotten messed up to cause the increase in my oil temperature? I have used the car as a daily drive for five years, so I am very tuned-in to what is "normal" for the car.

Thank you very much for your help!

Cheers,
David

Macster

What is the coolant temperature? Is it elevated too? Do the radiator fans both run, come on at the same time when coolant gets hot enough? (You have to leave the A/C off.) Do they both appear to run the same? Blow the same amount of air out and does it feel the same temperature?

Are the radiator ducts getting full of trash?

What oil did the indy use? Did he switch oils? Is the oil level too low? Too high?

Which reminds me: Have you asked the indy about the change in oil temperature?

What is the coolant level? Check this cold!

Spiffyjiff

i vote for oil brand switch.

user 72902

Oil is cooled by exchanging its heat with the radiator fluid so if the coolant is running hotter or if its ability to transfer heat has decreased you would see an increase in your oil temps. How much coolant was replaced when the coolant tank was replaced and did your mechanic refill the system with water or coolant? Too little water will result in the inability of the coolant to effectively transfer heat and produce elevated oil temps as you described.

BED997

Mine does the same thing after an oil and coolant change. I never thought about it, but I bet that jkw is correct. The ratio of coolant / water could affect the temps. My oil temp runs a little hotter (+10 degrees) with newer Porsche coolant.

Petza914

Coolant temp on the gauge is not actually coolant temp, it's an idiot light that looks like a gauge. I vote that when he changed the coolant tank, he trapped air in the cooling system and it's not cooling properly. The cooling system needs to be burped using the valve on the coolant reservoir.

KNS

I wouldn't be surprised if you were running those oil temps all along. Your old alternator cable might have built up a bit of resistance after so many years not giving an accurate reading to various gauges.

As mentioned above, they're idiot gauges these days - just use them to monitor trends.

Petza914

Oil temp is a real gauge, it's the coolant or water temp that isn't.

Robocop305

I pay attention to the oil temp and not so much the water temp.

Philster

Coolant service done improperly. Engine is running hotter because of reduced coolant flow/cooling and causing oil temps to be higher.

As noted, the engine temp gauge is bogus. You could have been running at 190 before service and now run 200+... and you'd never know with that gauge.

dasams

The coolant temp is reported via the OBD system and can be read on your smart phone using a cheap OBD reader (I use GoPoint w bluetooth but there are many others). Sadly, since OBD was developed for emissions monitoring, oil temp is not reported for 911's (unless you have a 993 since the oil is the coolant lol).

BED997

Do you just raise the burp valve, crank up and drive around until the system is hot, and then lower the valve? Not sure exactly how this practice works.

Once you do this and the system is cools off after you drive, do you then add distilled water to bring to the max line?

mikeborden

Pretty much, but don't rev it much past 5 while engine is cold. Also, the burp valve automatically opens when the engine is up to operating temp.

Don't do Max line, cause it will expand when it gets hot. Fill to min or halve way between min and max. Then keep an eye on it for a few days to make sure you aren't getting low from working the air out.


Mike

drh

Bingo. A simple transfer of heat from where we don't want it (engine/oil) to where we don't care (water/radiator/atmosphere) The water is simply the medium to transfer internal engine heat to the atmosphere. Like another has said, air in the system is a possibility. Air will not allow the complete transfer because it gets trapped and will compress unlike fluid, and flow will be ruduced or even stop if enough air makes it to the pump.

Correct me if I am wrong, but when refilling the system it should be pulled to a negative pressure and the coolant drawn thru the system, not pushed or assumed gravity to do its work.

Petza914

Yes, the best way to do it is with an Airlift kit that creates a vacuum and then sucks the coolant into the system, but you can do it successfully just by filling the resevoir, but then you have to watch it and keep topping it up after it cools down after every drive. You'll end up adding almost a 1/2 gallon of fluid over a period of a few days before it's full and stabilized, doing it without the vacuum fill approach.