2.4E - engine too cold?

[Peter77]

Hello! I have a 2.4E Targa with a strange problem — I can’t seem to get the oil up (or rather above) operating temperature no matter what I do.

The car was bought from the 3rd owner two years ago. It has 87k documented miles with the original engine, but the engine had a (minor?) rebuild done two years ago. exhaust valve guides, piston rings, reseal and some other things.
It seems to run very strong with no visible smoke even under hard acceleration, but I just can’t get oil temperature gauge to reach a temperature above 80°C/175°F.

My local Porsche mechanic told me not to worry but today I did an oil change and found some sludge on the inside of the oil drain plug, which suggests that the oil never reached a hot enough temperature to boil off the water (from condensation) in the oil.

I always drive at least 20km/12 miles to warm the engine up before putting the foot down.
Engine temperature never goes above the mentioned 80°C/175°F, even when driving up a mountain like a bat out of hell (for my own standards) in 37°C/100°F weather. Multiple times.
Same with relatively hard driving on a small racetrack during a classic car track day. Oil temperature never passed 85°C/185°F which is the current record.

Front oil cooler stays cool to the touch so I don’t think that the thermostat is stuck open.
We checked and replaced the internal engine thermostat but that did not change anything. My Oil is Castrol Classic 20W50 (mineral).

I'm really confused, most search results return posts from people complaining about their engines running too hot.

Peter

[chrisbruck]

You checked the oil temp sender and gauge for accuracy?

[boyt911sc]

Peter,

Check the engine thermostat in a water bath and observe its operation. It might be stuck OPEN. Test and confirm. Below are four (4) engine thermostats at different degree of opening during a thermal test. The one on the left was fully opened, second to the left was half opened, second to the right was partially opened, and the one at the right was fully closed. Except for the engine thermostat on the left most, the other three (3) engine thermostats were considered bad or defective.




In your case it could be the opposite condition where your engine thermostat is not closing which rarely happens. Only a test could confirm and verify the condition of your thermostat. Before you proceed to do the above test, check your temperature gauge and sending unit. They could be the culprit/s. Keep us posted.

Tony

[LakeCleElum]

You may have more cooler than you need. If i recall, the 2.4 only came with the engine cooler....I added the trombone system when I replaced my 2.4 with a 3.2 and very happy. I can't seem to get it over 195 and no sludge issues......

[Peter77]

Originally Posted by chrisbruck

You checked the oil temp sender and gauge for accuracy?

I checked the area around both the oil temp sender and filter with an infrared thermometer and it roughly showed the same result. (70°C)
Also I figure that if the engine runs warmer than indicated by the gauge, I shouldn’t have problems with the sludge buildup.

Originally Posted by boyt911sc

Peter,

Check the engine thermostat in a water bath and observe its operation. It might be stuck OPEN. Test and confirm.

Tony

Tony, thank you for the instructions. I only mentioned it briefly in the posting above but engine thermostat was already replaced with a new Behr OEM example from Porsche. I later tested the old one with the water boiling method and it turned out to be fine. I left the new one in for now.

Originally Posted by LakeCleElum

You may have more cooler than you need. If i recall, the 2.4 only came with the engine cooler....I added the trombone system when I replaced my 2.4 with a 3.2 and very happy. I can't seem to get it over 195 and no sludge issues......

Yes you are right, the 2.4E does not have a front cooler stock but the very first owner put a 2.4S cooling system in it because it ran in southern italy. But since the front oil cooling lines and the cooler are always at ambient temperature, even the one time I ran it on the track, I assume that the second thermostat is closed and not causing those low temperatures. Hmm.

[RSTarga]

Is your sending unit correct for your gauge?

[HarryD]

Not to be a wag, but maybe it's the oil? Try VR-1 for the next change and see if you still have the sludge problem.

[Peter77]

Originally Posted by RSTarga

Is your sending unit correct for your gauge?

Yes, it was checked (we put it in 100°C hot oil and it showed exactly 100°C).

Here is the absolute maximum temperature I was able to achieve today:



flogging it up a mountain in 32°C summer. Front oil cooler was warm this time. I suspect it is over-dimensioned for the engine and/or the thermostat opens too soon. As mentioned the car ran in southern italy with very hot weather, maybe it was warranted there.

The car has the oil-tank/thermostat and cooler of a 2.4S. Is this thermostat adjustable? If I could get it to stay closed until 100°C, maybe the car would run warmer.

I will also consider switching to VR1 as that seems to be mineral based as well...