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YOUR RESEARCHoverheating - pulling my hair out
Reported or suspected cause
ballast
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No successful repair reported for this finding.
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Reported cause
I recently had my drivers side fan cease to work and it was the ballast on that side.
Leading evidence: 'ballast' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'ballast' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check air 'again' in the system (very important step)' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Reported cause
The low speed fan problem is more than likely faulty capacitors.
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Just joined this forum. I'm looking for some help on my 1999 C2 coupe 6mt with 112K.
Problem: overheating
Attempted fixes:
1. new water pump
2. new low temp thermostat
3. new hoses
4. removed and cleaned both radiators
5. drained and refilled coolant system using airlift II
6. installed 3rd center radiator
7. installed two new electric cooling fans
8. filled system with brand new coolant
9. New coolant reservoir cap
Current symptoms:
1. overheating
2. no coolant leaks
Not sure what to do next. Looking for some solid advice.
Regards,
Cj
Describe what you mean by overheating? 996 temp gauges are pretty active and fluctuate, unlike newer gauges that seem to give an average and hold steady in one spot. Are you spewing coolant out of the radiator, or just the gauge getting to the "0" on the 180 mark which is normal.
Has it always been like that or is it something just manifested itself recently? Have you verified both fans are working at low speed and high speed settings?
Is it overheating while driving down the highway at 70? Or sitting in traffic? Do you keep the AC button depressed all the time, even if it�s not warm outside?
What temp does your gauge read? Have you checked with ODBII or Durametric the temp values? My 99�s gauge reads 15F higher than the DME values.
1. the airlift ii helps to remove air from the system. also I made sure the bleeder was opened
2. overheating that I experience shows a temp indicator at around 200C and rising. I don't let the temp go above the zero, but it would if I let it. Engine and coolant are visibly HOT.
3. overheating takes place while at idle ( I understand that the center radiator will not provide much of any cooling while sitting at idle)
4. fans seem to be working only at low speed setting despite replacement
5. this is a new problem
6. climate control system is set to HI at max fan speed
7. have not checked durametric
8. not sure about sending unit ( do you mean relay?)
If you idle long enough, it would run at 190F so that is visibly hot but not overheating. Hook up an OBD2 scanner and read live data. What does the computer think it is seeing?
I agree with yelcab here. Get another source to rule out a fault in the temp sensor. If the OBD2 live data is still showing overheating, then I would imagine you have some sort of blockage. When you removed the old water pump, what did the plastic impellers look like? Upload a pic?
You threw enough random parts at it without a proper diagnosis. Now get an infrared gun and make sure the engine is actually overheating. If it does, use the gun to check for circulation and then go from there.
I would characterize my efforts as a cooling system refresh rather than 'part throwing'. This is a 20 year old vehicle with 100k plus miles with an overheating problem.
The old water pump was in perfect condition. Impellers all intact. I replaced it to refresh the system given the vehicle age.
Please explain why an infrared is needed given the gauge temp, coolant, and engine itself all clearly indicate overheating.
Thermostat was changed to low temp version.
Since you have a MK1 '99' 996.......Have you tried this little function? May tell you if your temp gauge is accurate.
Only works on the Mk1 cars. I use this all the time to get a slightly more accurate reading of operating temps, but there's a long list of other things it tells you. Here's how to do it:
Press and hold in the recirculate and the top (arrow up) buttons on the right side of the panel for a few seconds. The left screen will change. Using the + key below that screen, advance so the display reads 6c. Then press the center vent button once. The display will show you your coolant temp.
To revert to the original HVAC settings, just press 'auto'. For the rest of that drive cycle, you can get the temp info again by pressing the recirc and arrow up buttons again, and the temp will appear immediately. You have to repeat the whole process for the next drive cycle
My 99 high speed fans only come on when the indicated temp is like 225F+. This is because my DME temps are often way below 225F+. I was always worried about my temps showing the very last white line before high speed fans would come on. Yet Durametric and ODBII showed temps were still below 212F, which is still less than 5psi coolant pressure.
If it�s really hot outside, however, the high speed fans will come on, but it�s probably the AC pressure that kicks them on. The high speed fans will come on if AC pressure is above a certain number.
^^^^ this !! I expect you are actually NOT overheating. Do this procedure to get the ACCURATE engine temp. You are probably not getting hot enough to even turn on the high speed fans. You indication of 200C is not plausible, 200C =392F, assuming you posted a typo and meant 200F, 200F is NOT overheating, and is not enough to even turn on high speed fans. Please be more specific in presenting accurate indication of temp so help can be presented.
Quote from the service manual :
There are two radiator modules installed in the front of the vehicle (on the left- and right-hand side). These radiators are each fitted with an electric fan. They can be operated at two speeds and are activated by the DME control unit whenever the following conditions apply: Electric fan, speed 1 (Ground to DME control unit, terminal 35) Coolant temperature higher than 96.75�C or air conditioning switched on. Electric fan, speed 2 (Ground to DME control unit, terminal 36) Coolant temperature > 102�C or air-conditioning fluid pressure switch closed (coolant pressure > 16 bar). Note: The electric fans for the radiators are only triggered when the engine is running
!
Meaning.....low speed kicks on at 206F degrees and high kicks on at 216F degrees. I can attest that this is correct as i just changed to a low flow LN t-stat ans factory water pump with a complete flush of 6 gallons of coolant. Watching on the scanner (NOT THE DASH!) these are the exact temps my fans kicked in. This was all done with the A/C off.
If you car is running around 200F and the fan is not on.......nothing is wrong with it.
Also to note, none of this has anything to do with the under hood fan. That is controled by under hood temps only and not coolant temps.
If you are expecting you temps to be lower due to the Low Temp T-stat........please read my recent post on the issues https://rennlist.com/forums/996-forum/1130727-what-temp-to-expect-with-a-ln-low-temp-t-stat.html
You ARE throwing parts at it and hoping something will work and in that process you've replaces almost everything with no results. You wouldn't have replaces all this if you didn't think you had an overheating issue, right?
You need an independent source to see if you actually have an overheating issue and this is where the infrared comes into play. The temp gauge isn't that accurate and if the issue only happens at idle than you need to look for why the coolant isn't cooling at idle. You need to do a systematic diagnosis or else you will keep chasing your tail. If the gauge hasn't gone into the red then your engine wasn't overheating. Let it idle and see if it goes that high and trips the warning light. Nothing will happen to the engine if it goes into the red during idle. Just don't let it keep going up.
The low speed fans on my car will also not come on until it "appears" as though it's too hot. However, if yours aren't coming on at all (even when you press the AC button on the dash), then something is broken. Please try the AC button and report if those low speed fans are still not coming on.
Check: Radiator hose in left upper wheel well fairly cool.
Check: Verify engine overheating(use IR gun, contact thermometer, burn your hand, etc).
If both true, then you are not getting circulation. Two things generate circulation. Water pump impeller not turning(has happened before), or thermostat not opening. Easiest, is to remove t-stat and drop in a pan of water on the stove. Heat it up and watch what happens. Next, is to remove the water pump and verify impeller integrity to pulley. The last thing would be an obstruction in the circuit. Could happen but unlikely.
Perhaps I�ve missed something here but you can check functionality of the fans pretty easily: start the car and turn on the ac. Fans should be running regardless of engine temp. If they are not, your fans don�t work, the ballasts are bad (one mounted to each fan housing) or the wiring in between is bad. I recently had my drivers side fan cease to work and it was the ballast on that side. Hope that helps.
Several people (including myself) have already pointed out that this car may not even be overheating. The OP has said his car gets up to 200f and the fans dont operate. 200f is not overheating! Yes turning the ac on to verifiy fan operation will tell us some of the info like fan and wiring integrity. But regardless the car needs to be started cold with coolant at the correct level with the ac off. Watch the coolant temp with a scanner. Do not do anything other than watch. The car should get up to north of 210 degress which is normal. As previously posted the l
ow speed fan does not operate untill 206f and the high speed until 216
. The car is expected at an idle to get more than hot enough for the fans to turn on. You should expect to see the temp climb to over 210 and then drop due to the fan coming on. After a few minutes the temps will climb again until the fan turns on. This is completely normal and is exactly how the car was designed. Low temp tstats will allow the tstat to open earlier.....not run at a lower temp. At cruising speeds you can expect a consistant 180 to 190 temp due to constant air rushing thru the rads. At idle this will not happen. This is the entire purpose of ths fan. Before throwing more parts at it or assuming there is a problem - confirm there actually is a problem. When i got done with my water pump and tstat the temp climbed over 225 degrees the initial time. This was also using an airlift.
if your temps start climbing over 230 and the fans have not turnes on then we can start diag. But confirm it first.
200F is not that bad. The low speed fan problem is more than likely faulty capacitors. If it's not the capacitors, then it is the relays. However, the capacitors are known to fail.
I agree with this. Only comment is that the gauge on the dash and the AC hack that shows temps might show 225-235F temps, but as many have said, these numbers are not accurate, so don�t go by them.
You may or may not have an overheating problem but the maintenance you've done was not a complete waste. Except for the replacing the fans, those are all good things to do on a 20 year old 996 if you don't know when they were done last.
Exactly! That's what I meant. Thanks for the correction. I had just changed out my capacitor on my home's HVAC compressor fan and it was still fresh in my mind. But I did have problems with the "resistors" on the 996. Seems like a common failure with these cars.
OP, another thing I would like to mention... Last year I had my coolant flushed from the system and when I first drove the car I noticed abnormal temp readings. The tech told me the car's ECU needed to "relearn" and in the meantime I would experience some temp faults. He was right, after several long drives, the car normalized and was reading the proper 180F mark.
It was completely unnecessary. With that mindset you should replace everything in a 20 year old car. All the owner needs to do is inspect the coolant hose once a year or whenever the car is off the ground and if they show sign of aging THEN you replace those ones.
I think the mechanic was telling you BS. The system had air pockets that worded their way out over time. The ECU gets the input from the temperature sensor. The sensor is set based on temperature. There is nothing for he ECU "to learn".
What coolant brand/type are you using? Not that you should need it, but since you have done everything else, have you considered additives like Driven's Coolant System Protector or Redline's Water Wetter? Both do improve cooling performance by reducing surface tension and improving the contact area between the coolant and the radiator.
I agree with everyone else, it would be really helpful for you to access the more accurate temp reading within the system or to use an IR reading. When you say there are "visible signs" that it is overheating, what exactly are you seeing? Is it boiling over?
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