We’re currently on our way to Italy in our Dino and the first day was a 375 mile run through Holland and northern German on motorways. The weather is pretty hot at around 34 degrees C, but the water temperature gauge has started mis-reading high. At times the gauge was showing as high as 120C but when I checked the engine around the sender with an infrared thermometer it was around 85-90C. The oil temperature is fine, showing just below the centre reading and the fans aren’t coming on so I know it isn’t actually that hot. What would cause the gauge to read high? I’ve tried a new sender. Thank, Paul
If the fans aren't turning and the high temperature is Always 120 °C (also at high speed) then very likely the sender has some problem. I would be very careful the same, and would stop at a shop as soon as possible: are you heading for Monza or for Modena? here in Modena there are several Ferrari specialists with the spare in house and can check everything (Always better) ciao
Hi Albert, The fans aren’t coming on because the temperature isn’t high enough for them to come on according to the infrared thermometer. I have tried a new sender but it is the same as the original one. We will be going to Maranello. Thanks, Paul
I’ve just completed a gruelling “ Alpine challenge “ and climbing various passes ( air temp around 30 ) the water gauge would rise to between vertical , 90 to 1/2 way to the right . Say 4 o clock . Oil virtually no change always just L of vertical never moved over to the right quadrant . Just a few things that mat help . Make sure the rad is fully sealed with foam especially at the top - I used adhesive pipe insulation . Bleed the top rad air vent ideally park nose high . In the morning check the expansion tank level - about 1/2 full . My fans work at 90 btw and the AC turns on when you turn the AC on anyhow . That works btw ( apart from wetting the foot wells -on corners +another thread ) I re searched somewhere on here that the OEM plane blade fans need to be as near as possible to the rad core . A blade 2/3 mm away is hugely more efficient than one 1 cm away .They get moved and never put back properly. Adjusting them is easy and worth a look at that .The rad core is super high density fin / sq area and along with gaps at the size air can get pushed round not through . Theses loads of threads about simply changing the fans to better , but I reckoned the OEM set up , set up and regular air vents at the front correctly works . I noticed my water temp would swing from 5 o clock through 6 ( ideal ) to between 7/8 running down a pass , with 30 + degree ambient . Have you put your infa red sensor on the top and bottom of the rad while the gauge is @ 4 or 5 o clock ? .? On the way down to CH on French auto routes it stayed between 6 and 7 ——- guess 80 mph breeze and flat ish ? Image Unavailable, Please Login
Thank you for your comprehensive reply, however, I will re-state that it isn’t overheating, the gauge is simply telling lies and I’d like to know if anyone knows of anything that may cause it. I’ve changed the sender, so the only other item that could be faulty is the gauge, but I don’t think that is the case. I have checked the rad with my infrared thermometer and it matches the water manifold on the engine at around 85C. Paul
If you replaced the sender and it's still high then it's most likely at the other end - the gauge. There's not much else to it.
That would be the logical thought, but I suspect something else is causing the error, maybe a poor earth or connection somewhere?
I have checked the temperature of the water manifold where the sensor screws in. I could only check the actual water temperature once it has cooled enough to remove the cap. I see be reason to believe that the water would be any hotter or cooler than the pipe that it is running through.
If the infrared thermometer shows sound temperatures at the water manifold, where the sender sits, I wouldn't worry much. I opt for the gauge. Next thing I would do, is to remove the gauge and checking it with a test setup (a pot of water on a heat source, a reliable thermometer, a new sender and a 12V-source). That's what I have done, when my gauge went bad. If the result says, that the gauge is o.k., you will have to dig for a fault in the wiring/connectors. But I would test the gauge first. Best from Germany and enjoy the trip Martin
As has been noted, poor connections/bad grounds in the sender/gauge wiring is the first placed I'd look.
Before going into this hassle, I would want to know, whether the gauge is working o.k. Except checking the connector near the sender inside the engine bay, the rest is much more effort, than removal of the gauge and checking it like I described above. This is my test setup when I checked the sender (resistance values) outside the car. Sorry, took no picture of the gauge test, which was even more simple, because just had to compare the gauge readings with the thermometer readings. Test proved, that sender was o.k., but the gauge was faulty. Unfortunately the error was not linear, so recalibrating wouldn't have helped. Purchased a new one. Image Unavailable, Please Login Best from Germany Martin
May I suggest you to try at Toni Auto, in Maranello, just on front of the Historic Ferrari gate? They will help you and very likely they have at home another water temperature gauge to compare. ciao
Thanks for the suggestions guys. The gauge shows what I believe to be the core temperature (just below 90C) for a period and then starts to climb for no obvious reason. I also have an intermittent misfire. I forgot to pack a plug spanner, but I’ve managed to borrow one so I’m going to check and clean the plugs today.
It is possible that the gauge/sender are OK AND that engine temps are also OK! Check the temp at the top of the thermostat housing with an IR gun when the car's temp gauge indicates normal and when the temp gauge indicates too hot. Is there a corresponding difference in the IR gun reading? Now do the same thing but shooting the IR gun at the top of the radiator (as you stated, the fans were not running). Again, is there a corresponding difference in the IR gun temp readings? NOTE - we are not concerned with specific temps, just whether there is a significant difference in temps at the radiator and at the t-stat housing that correspond with the difference in the low-to-high gauge readings. Let us know... I suspect you may see the IR gun and the temp gauge correspond (again, don't worry about the specific temp, just the relative difference) when measuring with the IR gun at the T-stat housing but NOT when measuring the IR gun at the top of the radiator. If this occurs, bleed the cooling system, ensure it is properly filled AND ensure you have the correct type of expansion cap - one that has the small return valve disc spring loaded shut, not hanging open.
Thanks Mike, I’ll check and report back. We’re visiting the factory today, so I could get them to look at it. Paul