Engine lid fan question

I did a search and came up with some answers but got a little more confused along the way which is why i am posting. I have a 99 C2. There is a single fan in the engine compartment cover / lid. This is what i know for sure!!! I would like to know when does this fan come on and why? Is it due to a sensor which activates it at a certain engine temp? What is the correct term for this fan (during my search, some referred to it as the fan that comes on for emissions purposes and i dont know if that is correct.) I am asking because of the following: Had the car for 7 months - no issue with temp gauge (does what everyone else posts that there gauge does). so far paranoia in check. Had the starter replaced due to nasty sound at start up. Since then noticed smell of antifreeze. i always smelled it a little, but after the starter change it became more. too much actually. kept an eye on the coolant level. no drop, no leaks, everything looked ok. just figured a little came out the vent on drivers side and burned off causing smell. so far ok, paranoia still in check. Today, Drove the car with a/c on, as i always do cuz its hot here in LA CA. drive spiritedly, again as always (hell its a porsche, no other way to drive). Then all of a sudden notice temp gauge start to kiss the bar to the right of the 180 degree mark. Paranoia, oh yeah!!! turn off a/c, no difference, turn up a/c no difference. Oh the indignity of being stranded on the side of the road beside my p-car. shame!!! sorry, back to the topic. got home, noticed fan beneath spoiler which is part of the engine compartment cover on, never shutting off (until i turn off engine). start car, fan on! Is that normal? At this time i noticed that the coolant level was actually quite low, well below the minimum mark, so i waited for car to cool, added antifreeze, (sorry guys emergency situation had to add non dealership brand OK!!!) started car and fan does not come on. Now is that normal? should it come on when i start the car, or was it kicking in because the engine / compartment was too hot? Incidentally, the entire rear of the car was way too hot to the touch. I mean the rear bumper, spoiler (especially the area above the fan to the exterior) super hot, had never as far as i know been that hot before. The only thing i think have discovered is that the black gasket like material on the inside of the radiator cap had some whitish crud (probably the dried deposits of the ethylene or whatever chemical it is) on it. I am thinking the cap has seen better days and is letting some fluid out? So i will replace with new just to play safe. Anything else? I know long post, but i want to describe and ask my questions as clear and straightforward as possible so someone else with same issue can be just as certain of the correct answers. thanx for helping me out and anyone else who has this same issue. Peter

Eeeek...right, first thing I'd do (not *that* experienced on Porsche's...sure there'll be a couple of experts along when you guys come online in a few hrs...) A 99 C2 will *prob* still have the original header tank fitted, unless you know for sure it's been changed. There was a prob with early tanks, hairline fractures, generally unnoticeable, as it cracks around the back of the tank (a water return, IIRC)....not only will this dribble fluid out (poss antifreeze smell) but it will allow air to be ingested into the coolant system, hence massive overheating. Design of header tank has subsequently been changed, afraid I don't know old or new part numbers, but if it's overheating THAT much (ie untouchable bodywork) don't drive it until inspected, you're risking damage to block/head...all other car's I've worked on, this will cause warping, followed by either water getting into oil, or vice-versa. Again, apart from the warning light on the water temp gauge coming on if the engine fan fails, I don't know when and how this should operate under normal conditions. Hope this helps Spen

Okay, here is the scoop. First of all, the gunk in the coolant reservoir may be a result of old coolant or incompatable types of coolants being mixed. You can use oany type of coolant you want in the Porsche, but you cannot mix different types of coolant. I use PEAK. The coolant system should be drained and refilled with fresh coolant mix. The fan on the engine lid, when running, should be drawing air INTO the engine compartment. Test that it does by placing a peice of paper on the lid opening when the fan is running and see if the paper gets sucked to the lid. There were some fan cables that were installed with the polarity reversed causing the fan to blow OUT of the engine compartment. This is an easy fix. The fan comes on when the coolant temo gets excessive (I forgot the exact temp) OR when the engine compartment gets above 180F. If either of these conditions exist, the fan will run whether the car is tunred on or off. There is a sensor between the intake tubes on the right side of the engine (top side) that monitors the engine compartment temp. There is a 2 wire connector on this sensor. With the engine on, unplug this connector and the fan should immediately come on and not turn off until you reconnect it. When the cable is disconnected, your temperature gauge on the dash will also flash. The design of the cooling system for the cars with a 3.4 engine is bad as far as keeping the engine at normal temperatures druing city driving in hot temps. It is common for the temperature gauge to ride just to the right side of the 0 in 180. This translates into a coolant temp of about 220F. Getting the car on the open road will reduce this temperature. Your gauge is a little too high. This may be caused by partial blockage in the cooling system becuase of gelling. I would flush the system and replace with a 50/50 mixture. You can buy premixed coolant/water which is what I use to make sure that I get distilled water. Also check for debris that may be in front of the radiators on each side of the car. Finally, contrary to what Porsche suggests, replace you engine oil with a 15W50 weight oil to properly protect your engine in hot climates. 0w40 will destroy a hot running engine in the long run. Check the coolant cap's part number and call the dealer to confirm it is the newest cap design. If not, get the new one.

Personally, and some one correct me if my thinking is wrong but don�t add coolant solely based on the marks in expansion tank in the rear. I would be hesitate to add coolant/water to the system if the red light on the right side of the temperature gauge is not flashing. The coolant level sensor is very sensitive and when it detects low coolant levels it will flash the read light on the right side of the temperature gauge (no matter what the operating temperature of the engine). You will find that completely bleeding the system of air is rather difficult and will likely take a couple of times of adding water/coolant. Take a look at the DIY write up on Renntech.org regarding the installation of a third radiator. It gives a good tutorial on bleeding the coolant system. In hotter climates the running of the engine compartment fan is very normal.

My engine lid fan isnt coming on at all! It was staying on before adding coolant. I dont know if tank has been changed. I guess i could take it to a dealer and have them tell me if its new or old. (I dont know where the part number is on it so as to just call them and ask). I will order a new tank cap just because its not that big of a deal. I would like to test to see if my fan is operating correctly. Just so that i understand correctly - If i disconnect the 2 wire sensor located on the right side of the engine on the top (standing at rear of car looking at engine right?) when disconnected the fan should come on, correct? (obviously when engine is running) and when plug back in, fan turns off. If this is what happens, then it indicates a correct setup. no sensor problems or issues with the fan. Then the problem is someplace else. if the fan is blowing air OUT instead of IN then do I just rotate the plug that i just disconnected when testing the fan the other way around and plug back in? Is that the correct way to correct the polarity? Thanx

Just have the key to the ON position and disconnect the wire from the sensor. Should come on and then go off when reconnected. Your fan will SELDOM (if ever) come on during normal operation. If the fan is blowing in the wrong directions, jsut reverse the 2 wires on the connector at the fan.

What do you consider normal operation? During the summer during hot ambient temperautres, while driving in in-town traffic conditions and running the AC (or not running the AC), the engine compartment fan frequently operates. Additionally, after shutting off the car after such driving conditions the fan will kick on also. This would seem like normal conditions.

Switch-on conditions for engine compartment fan (this fan pulls air into the engine compartment). The engine compartment fan is switched on when the engine compartment temperature is > 176 degrees F or the coolant temperature is > 216 degrees F. If the ignition is switched off and the engine compartment temperature is more than 140 degrees F, the DME control module remains in readiness for another 20 minutes. During this time, the engine compartment temperature is retrieved every 10 seconds. If the engine compartment temperature is > 185 degrees F, the engine compartment fan is switched on for 20 seconds. If the engine compartment temperature is still > 185 degrees F after this time, the fan remains on for a further 30 seconds.

Sounds like you just may need to replace your coolant tank...I had the same problem with my '99 996.

I hope i am disconnecting the right wire! i am standing at the rear of the car looking into the engine compartment. On the right side there are black plastic tubes at the top of the engine ( i assume those are the intake headers or something i dont know) in between the two most closest to me (the ones closer to the rear bumper instead of towards the passenger compartment) there is a wire with a connector located there. Is that the one that is being referred to to test the engine lid fan? If so, then I have a problem, because with the engine running, i disconnected it, and the fan did not come on! Did i test the correct wire? Thanx

Sounds like the one to me. By opening the connection, the fan should power itself on. You can also jumper the relay behind the drivers seat to turn the fan on. Slot #8, bottom row, 2nd in from left.

Well, i did disconnect the right one, and unfortunately, fan did not come on! CRAP! I went to dealer and bought replacement extension tank cap and installed. There was an actual difference between my old one and the new one i put in. So therefore i was hopeful. The good feeling lasted for about 15 minutes the needle stayed between the 8 and 0 with a/c on and good driving, in town, stop and go. Then of course, the inevitable. gauge moved to right line of the 0, but thats it, no higher, not like before almost on the bar between 180 and 250. Pulled over just to check one more time if fan in spoiler, (correct term - blower fan - per service advisor) would come on. Of course not. Started to walk away to turn off car and heard whirring sound. the blower fan kicked in. seriously, talk about temperamental!!! so now.... i know it works correctly, the fan that is, but is it because the engine is running too hot and triggering it, or is this all just normal, because the weather is real hot today, plus stop and go, plus a/c...: I'll keep you all posted but if anyone else has anymore thoughts, much appreciated. Oh, by the way, after new cap install, so far no sweet (pun intended) smell of antifreeze on driverside rear tire/fenderwell area. Hey, at least its a start. I am also thinking time for thermostat change!? worth it or not? Peter

One more thing, If i disconnected the correct wire to test the fan and it did not come on, but the fan did come on when triggered by the computer, then someone please explain why the wire test did not work. I did play with the fan a little, you know give it a good couple of spins (yes i was being careful about my fingers) in between my testing it and it coming on itself. Maybe it was stuck???

Your coolant expansion tank could be leaking. Monitor the floor under the car for any fluids. If you see some coolant (smell sweet) on floor, get the tank changed. When you are driving, you smell coolant? Do you get wet carpet w coolant on it? If so, your heater core may be leaking. Check your radiator cap. It may fail and need to be replaced. A cap not sealing well will reduce pressure which will lose coolant boiling off. Get the coolant tested to see if it's still good. Autoparts store sell a test kit that tells you if the coolant needs to be changed or if your water/coolant mixture is optimal. If it's bad, repace the coolant w Porsche's. Porsche manual states only to use theirs. Sure it's 3-4x most costly but it's supposed to last a life time. If cooling system wasn't serviced by dealer before, you could have aftermarket coolant added which is bad. Engine fan turns on when engine temp is overly hot. If yours is failing, you'd get a warning light.

Sounds like everything is working fine. Your car will run with the needle just to the right of the 0 in 180 on hot days in city driving. Fan is normal.

Took the car out for a nice 115 mile drive up and down hills on the freeway with a/c on the whole time with whole family (+wife and 2 kids and shopping stuff), needle played a little, went up to the inside edge of the right line of the 0 of the 180 mark, and it only did that when i was going uphill. on the decent on flat parts, it was almost right smack in between the 8 and the 0, the way it used to be. I did change the cap, so i was pretty sure that was probably the cause of the coolant leak/smell observed initially. After 115 mile trip, noticed puddle of coolant forming next to driver side rear tire. inspected the cap and surrounding plastic drip hose and it was all dry ( i had previously dried and cleaned the area for future observation sake) so there was no change at the cap area, it is working as it should. So I guess i really do need to change the tank, unless i have a leak from some hose or something. Any thoughts? Peter

Unless you are losing coolant, the tank is fine. Do not mistake a drop in coolant level in the tank as a leak. Air could have been in the system and it just burped.

uddle at driver side rear tire, large drop in level of coolant, below minimum now. loss so bad that it looks like it splashed on the tire while driving and the tire shot the coolant all over the inside of the fenderwell. I think it is time to face the truth. I need a new tank. I will have it checked out first just to make sure that it is not a loose hose or cracked hose. Thanx everyone. Peter

I had the same issue about 3 years ago with my 99... you need a new coolant tank - it's pretty common. If you take it into a pcar dealer they will want to pressure test it for you just to make sure it's not leaking into your engine (if it was you wouldn't have a puddle... so be glad you see the puddle!) it's no biggy... just get a new one.

thanx everyone