Hey guys, So I've consulted some previous threads on the issue of the car running a little warm, but I haven't been able to find a discussion of a situation congruent to mine; nor have I been able to verify that the issue is "not uncommon" to the 355. Here's what's happening. The car runs a little warm for my taste both at idle and in slow driving situations such as traffic or driving through town. On the highway, the car seems to be just fine. When I say a little warm, I mean that the temperature starts at the center (190 Fahrenheit), and can creep its way up all the way to the last white line before the red zone (about 230). (Again, in traffic or around town). The manual says that once 235 has been reached, now we're getting warm and we should be concerned. I haven't yet seen it go into the red, but then again this summer I stopped the car because I was uncomfortable watching the temperature rise. The car is essentially not driveable in very warm weather in traffic conditions. In said driving conditions, the temperature is consistently at the 1 o'clock position and not where it should be -- at or around the 12 o'clock position. Even in the cool fall weather here in NY, the car exhibits this symptom, but the temperature doesn't go quite as high. I made sure there was no air in the system, and my technician verified the coolant level. Each of the two fans does work, but I suspect maybe a problem here, which I will describe in a moment. We changed the thermostat switch and observed no improvement. If the car is left to sit at idle, the damn temperature just creeps up and up. Is this normal for a 355? I just don't think so. I've never observed another car to do this. Now about the fans. Supposedly the left side fan is controlled by the thermostat, which tells the fan to go on at 192 degrees. Supposedly again, the right side fan is controlled by the Motronic, which tells the fan to go on at some higher temperature (Can you tell me which?). It seems absolutely ridiculous to me that even at temperatures as high as 230, at least one of the fans is not on all the time. What seems to be happening is that one fan goes on and stays on for like 5 seconds and then switches off. Then maybe a few seconds later (maybe) the other fan will come on for a few seconds and then kick off. I know the fans alternate, but shouldn't the left fan be on all the time when the car is very warm? It seems to me that at least one fan should be on the entire time until the temperature goes back down to the 190 zone. I've seen very warm temperatures in the car and have observed, at least for some periods of time, no fan activity. Is it possible that my fans are receiving erroneous signals from the relays? However, I have observed fan activity at the 192 level. Although I plan on changing the thermostat just for the sake of it, I don't think the thermostat is showing a false temperature because the fan wouldn't go on at 192 if indeed the gauge were showing a higher temperature than reality. In other words, if the gauge were showing 230 and the car were really cooler than 230, then the indication of 190 would mean a real temperature cooler than 190, thus eliminating any need for the fan to go on at the indication of 190. I plan on changing the thermostat and the two temperature senders. I've read about checking the relays, but if the fans are indeed working, wouldn't that mean that there would be nothing to check in the relay department? I've also read about changing fuses for the fans, but again the fans work so it seems that the fuses would not be our problem area. Any ideas? Sorry for the wordiness! I just want to be as clear as possible as to what I am observing.
Make sure one or both of the small return hoses that lead back to the expansion tank are not obstructed or clogged completely. This will cause the problem you are having...
Heya Dave. Would it pay to make sure the water temp is actually at the temp the gauge is telling you before you replace anything? You could have a faulty temp gauge mate? I would check the water temp using one of those temp guns 1st. That will establish that you DO have a problem and its not a faulty gauge in the car. One of these temp guns work great. http://easysell.com.au/showad.php?id=1114 If the temp is correct, then perhaps its a thermostat problem. Actually, has your car got a thermostat in it?
That is cooking, mine rarely moves past 190 even when moving slow in hot weather. When I stop for a while and restart while hot it's a few ticks above 190 but comes down fairly quickly when the fans kick on. I've heard of temperature switches going sometimes, they screw into the top of the radiator. I replaced mine (along with the radiator which had a small leak) during the engine out. http://www.ricambiamerica.com/parts_catalogs.php?M=FE&P=&V=diag&I=1463
The fan cycling issue you are describing is usually from an air pockets getting trapped in the area of radiator that houses the fan temp switch. The return hoses I mentioned are designed to allow this air to bleed back to the expansion tank. Try this before replacing the thermostat...These hoses are cheap and easy to replace...When finished make sure the system gets bled properly
Hi guys, thanks for the suggestions -- I've been traveling so I haven't been able to return to the thread. Any additional answers or suggestions would be welcome...
Update: my technician says he replaced those little hoses when he did the major service. So we'll see!
