running temperature
 

Does anyone know what the average temp a 2.5 n/a should operate at.
I have replaced radiator, water pump, thermo fans, thermo fan switch, temp sender and thermostate, flushed the cooling system checked the head gasket and the temp still fluctuates from middle mark to third mark. I'm now starting to think it may be the gauge. So Iam going to fit a temp gauge that reads actual temprature. :mad:

try bleeding the colling system again, you might still have air in there. Sending you facts by email, might help you out

at highway speeds, it should stay around the 1/4 mark.

check the leectrical connections behind the temp gauge - they corrode and get "bouncy" over time.

Rebleed the cooling system.

AFJuvat

Reviewing the things you listed as accomplished, and ensuring the cooling system is properly bled. It is my opinion that the fan relay may need replacing. I too change the components you listed and lastly I changed the Fan Relay which cured the problem. The defining indication was with engine running sitting at idle, A/C off the temp would rise quickly to the red zone, then the fan would come on at high speed the low speed fan sensing part of the relay was faulty.

Its perfectly normal to fluctuate between half and 2/3 in traffic, as the electric fan thermostat is set at 2/3 full scale. When driving at speed it should cool down to about 1/3 max.

Mark

This has been my experience as well. In traffic though, my guage fluctuates between the first mark and the last mark, not between the second and the last. The fans come on at the third mark and drop the temperature to the first mark, where they shut off.

Aaron

Actually I meant to say the first notch and the third. So ours are the same. I have to drive at least 40mph to get enought cooling, I wonder if its time for a radiator flush?

Mark

Thanx for the feed back
But I seem to be traveling between 2nd and half past 3rd in traffic. It is of great concern as I do not want the obvious damage to occur.

The one time I went to a mechanic (porsche certified and been working on these cars since the beginning ~20years) I asked him this question as well; my car also runs between number two and sometimes slightly over number three.
On that little trip to the mechanic I ended up getting a thermostat - but not because the engine ran too hot, it was just not working to kick in the big fan. He measured and monitored the actual engine temp and said that the 2 and 3 marks are absolutely fine, though the fans should both be on once the car gets to the third mark.
Low temp thermostats can be used - I think there was a nice write up on that on this board a couple of years back, try searching for low temp thermo or something like that.
Good luck

I don't know. I need to be moving at about 40 mph too. I think it's just a function of the small radiator opening. The car hasn't gotten overly hot so I figure that it's OK.

Aaron

i just got done replacing my stat 2 weeks ago.its a pain but if you have to do it.. now it runs at the first mark on the highway and never gets up above the second mark. i also put in a lower temp stat.

scottSmileWavy

My 87 sits just above the first line, moving or not moving its constant.

What coolant and mixture are you using? I have seen this happen on a few 944's before where there was not enough water in the coolant mixture and the temp was reading just as you described.

It's normal for the temperature to fluctuate in stop and go traffic, but how much is a function of your thermostat and radiator switch settings and the inherent "inaccuracies" of the gage itself.

By design, the cooling system will keep the engine temperature at a safe value without running cooling fans at speeds above about 40 mph.

The big issue is, does the system behave EXACTLY the same way every time under similar or identical conditions. In other words, do the fans ALWAYS kick on at the same temperatue gage indication? Do the fans kick off at the same temp every time? Is the temperature stable at highway speeds? If you are crusing at highway speed and then "punch it," does the temperature increase?

i have let my car idle for 5 to 8 minutes to check if it would get hot and that was in the last week with temps near 90f and the gauge does not move.

scott

I took the thermostat out last weekend to see if made a difference and what a difference it made. It now struggles to get to the half mark but after that it reacts as usual. So I can say the thermostat is fine. I also disconnected the gauge and refitted it and the thermostat. Iam thinking of removing the oil pump to flush the oil cooler to see if this makes any differnce. One step at a time I will beat this problem. As for bleeding the system I have made a tool which goes onto the expansion tank and holds 3 litres of coolant (50/50) above the motor. It seems to work very well.
again thanx for all your help