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Iirc, the outside temp sensor is behind the bumper and all the plastic air shrouds, attached to the same vertical bar that goes to the hood lock
Yes, that is the sensor I can see through the front grill - can't find a part number for it anywhere, other than the 955 618 550 02 number, which show a sensor that looks nothing like the one behind the grill.
I am sorry to see your ordeal, I am afraid P2181 code is going to be in your case faulty thermostat or quite possibly an issue related to the thermostat housing itself, fingers crossed the housing did not get damaged during the installation as it is an anonymous PITA to remove the thermostat.
Must be so frustrating, wishing you all the best to get it all sorted.
Yes, that is the sensor I can see through the front grill - can't find a part number for it anywhere, other than the 955 618 550 02 number, which show a sensor that looks nothing like the one behind the grill.
Yes! Thank you so much - that would be it. Now, I just have to figure out how to get in there and replace it. Looks like a full front bumper removal (good time for me to get at the parking sensors I 'spose). Also, just got car back after they put in another thermostat and the outside temp reading was spot on today. It's -4 out and the temp reading was -4.
Originally Posted by Rossi
I am sorry to see your ordeal, I am afraid P2181 code is going to be in your case faulty thermostat or quite possibly an issue related to the thermostat housing itself, fingers crossed the housing did not get damaged during the installation as it is an anonymous PITA to remove the thermostat.
Must be so frustrating, wishing you all the best to get it all sorted.
Thank so much for the kind words. Just got car back - another 4.25 hrs labor (and $117 for new thermostat - which was the exact same Borg Wagner thermostat I got from Pelican for MUCH less). They said they replaced it and all is better now. Just took it for a test drive and temp sit dead at 80 (half way mark) and doesn't go down when on the highway, so I guess it was the thermostat after all.
Quick question though.....if the thermostat was stuck open, would it necessarily be physically open upon removal? Because the thermostat I got back looks closed to me (looks exactly like the original one that was removed the first time). Does it have to be compressed/closed to remove it?
Which part "moves" as it opens and closes?
Here is the original thermostat after removal......
Here is the second (new one) that was installed that was stuck open.....
And here is a brand new one before installation....
Anyone see any difference? The spring position looks a tad different between the original and the "stuck open" thermostats and both seem to have the rod at the end in a longer position vs the new, uninstalled thermostat???
So the shop likely botched the original job, charged you full price for a do-over and replacement part that you probably didn't need, and then gave you back the original part without any explanation as to what was wrong with it? That's pretty ballsy.
I'm glad that your car is functioning normally now but the shop owes you an explanation.
The supposedly "stuck open" thermostat looks normal in the picture you posted. There are a number of videos on how to test a thermostat on youtube. If you follow the test procedure then it will be clear to you how the thermostat works, which parts move, etc.
The temperature gauge is not moving though. Does that not suggest the sensor is broken?
The temperature gauge would work. The car would warm up to operating temp (took a little longer than normal) and the gauge would be at the half-way point, but it would start to drop once I was on the highway/air hit the rad.
Originally Posted by brett968
So the shop likely botched the original job, charged you full price for a do-over and replacement part that you probably didn't need, and then gave you back the original part without any explanation as to what was wrong with it? That's pretty ballsy
Yes - I think I have figured out that the thermostat I bought is working fine. I will be going back to the shop tomorrow to let them know and see what they say.
Originally Posted by brett968
The supposedly "stuck open" thermostat looks normal in the picture you posted. There are a number of videos on how to test a thermostat on youtube. If you follow the test procedure then it will be clear to you how the thermostat works, which parts move, etc.
Watched about 6,000 youtube vids this weekend and for the life of me, I could not get ANY parts of the original or the replacement thermostat to move.
1. Tried boiling it in a shallow pan - nothing.
2. Tried boiling it in a deeper pot - nothing
3 - Put it in the oven at max temp - nothing
When I was boiling it, I was watching for the top bulbous part or the disk on the opposite end to move (as it seemed to do in the vids I watched). Tried heating with a candle - didn't work either.
I was under the impression the wax inside the center pellet would melt, thus allowing movement somewhere (and as the wax cooled down, it would cause something not to move) - but after doing more research, it turns out the wax actually melts and expands when it boils. As it expands, it pushes a "rod" outward.
I finally had one last option for heating - the new Air Fryer I recently bought - I know that sucker gets VERY hot (cooks food in half the time an oven does). I popped the original thermostat in the Air Fryer at 400 for 4 minutes. As it's "cooking", I hear a metallic "clink" all of a sudden. Open it up and see that the rod that protrudes out of the thermostat is now laying beside the thermostat and there is melted wax by the hole it came out of. The Air Fryer heat pushed the rod completely out. Picked up the rod with pliers and tried sliding it back in the hole - would not go back in. Kept trying and after a minute or so, it pushed back in. I was able to push it all the way in and it stuck out only a tiny amount (as seen in the pic of a new thermostat I posted above). After watching more vids, I saw a thermostat installation vid (from that guy overseas who always works on that white Cayenne) and as he unboxed the new thermostat, I could see the rod was pushed all the way in, so the thermostat is in the fully closed position upon installation.
Turns out, when the Cayenne thermostat is heated - that rod is forced outward - that is the only part that moves. I assume that the end of the rod sits against something solid in the thermostat housing and as the rod slides out, it forces the disk to move, thus it "opening". As the wax cools down, it exerts less force on the rod and the thermostat spring pushes it back to the closed position (probably why I couldn't reinsert the rod back into the hole while the wax was still hot). Also, when "fully open", that rod extends out pretty far - about an inch farther out that seen in the pic below.
As shown earlier in the thread - that was the position of the rod when I got both the original and replacement part back. With the rod in that position, the thermostat is not fully open (as the shop claimed). I also learned that the thermostat never really opens or closes fully, it varies depending on the temp it reads.
Now, as for a thermostat being "stuck open", I cannot see how this happens without some sort of foreign object physically stopping the thermostat from closing. The pressure of that spring is immense and unless that wax is boiling and pushing the rod outward, the spring will always keep it closed. This is why I am confused as to how thermostats can get stuck open - if a seal fails and the wax leaks out, there would be nothing to force the rod outward, so it would be stuck closed if anything. Not sure how some thermostats are designed to fail in the fully open position, but they do apparently. From what I can tell, the only way a thermostat can be stuck open or partially open is if it opens and then the spring fails or if it gets jammed open/gummed up by say Bars Leaks or something added to the coolant OR if it is installed improperly and catches on something or the rod isn't straight and binds.
Back to the replacement I bought that was deemed a "bad part" (and forcing me to pay for the re-do of the job), I popped in into the Air Fryer at 300 this time and only for a minute at a time and kept checking it. Low and behold, as it started to boil, the rod extended all the way out and I was able to push it all the way back in as it cooled down (I had to physically push the rod myself because when it's installed in the car, I think that the rod is pushed back in by the force of the thermostat sprng and as it was not installed in the thermostat housing, it needed to be physically pushed back in - most of the youtube vids I watched showed a thermostat opening and closing inside the thermostat housing - the Cayenne thermostat seems to be designed a tad differently??) - this shows me the seals are good on the new thermostat and it opens and closes fine when it reaches the boiling point/cools down. From what I gather, this is pretty much the only way a thermostat can fail - the seals go bad, the spring binds somehow or something foreign causes it not to move one way or the other.
So, it appears to me that my thermostat was not faulty and the problems I was having were probably due to the thermostat not sitting correctly in the housing. I believe it wasn't FULLY stuck open, because the car still warmed up and I was getting heat. From what I read, a fully stuck open thermostat will constantly be pulling cold coolant from the rad and would not produce much heat. I think the shop installed it slightly off and this allowed it to not fully close.
Let's see if they agree after my explanation lol
P.S. - on a side note - after learning what part actually moves, I tried boiling it again to see if I could get that rod to move, but it still wouldn't. Once it was heated up, I could push/pull the rod a bit, but the boiling water would not force the rod outward. The Air Fryer, on the other hand, shot that rod out like a bullet. I wonder why the boiling water trick didn't work for the Cayenne thermostat? Has anyone else tested their thermostat prior to installation using the boiling water tricks and did it work for you????
Water boils at 212F. The thermostat or rod should be very open by then as the engine normally operates at a water temp of 175-185. By 214 F, the auxiliary cooling fans are kicking on to move more air though the radiator, and prevent overheating. By 225 or higher, you're in trouble, and aren't far from head gasket failure due to warping.
The temperature gauge would work. The car would warm up to operating temp (took a little longer than normal) and the gauge would be at the half-way point, but it would start to drop once I was on the highway/air hit the rad.
Yes - I think I have figured out that the thermostat I bought is working fine. I will be going back to the shop tomorrow to let them know and see what they say.
Watched about 6,000 youtube vids this weekend and for the life of me, I could not get ANY parts of the original or the replacement thermostat to move.
1. Tried boiling it in a shallow pan - nothing.
2. Tried boiling it in a deeper pot - nothing
3 - Put it in the oven at max temp - nothing
When I was boiling it, I was watching for the top bulbous part or the disk on the opposite end to move (as it seemed to do in the vids I watched). Tried heating with a candle - didn't work either.
I was under the impression the wax inside the center pellet would melt, thus allowing movement somewhere (and as the wax cooled down, it would cause something not to move) - but after doing more research, it turns out the wax actually melts and expands when it boils. As it expands, it pushes a "rod" outward.
I finally had one last option for heating - the new Air Fryer I recently bought - I know that sucker gets VERY hot (cooks food in half the time an oven does). I popped the original thermostat in the Air Fryer at 400 for 4 minutes. As it's "cooking", I hear a metallic "clink" all of a sudden. Open it up and see that the rod that protrudes out of the thermostat is now laying beside the thermostat and there is melted wax by the hole it came out of. The Air Fryer heat pushed the rod completely out. Picked up the rod with pliers and tried sliding it back in the hole - would not go back in. Kept trying and after a minute or so, it pushed back in. I was able to push it all the way in and it stuck out only a tiny amount (as seen in the pic of a new thermostat I posted above). After watching more vids, I saw a thermostat installation vid (from that guy overseas who always works on that white Cayenne) and as he unboxed the new thermostat, I could see the rod was pushed all the way in, so the thermostat is in the fully closed position upon installation.
Turns out, when the Cayenne thermostat is heated - that rod is forced outward - that is the only part that moves. I assume that the end of the rod sits against something solid in the thermostat housing and as the rod slides out, it forces the disk to move, thus it "opening". As the wax cools down, it exerts less force on the rod and the thermostat spring pushes it back to the closed position (probably why I couldn't reinsert the rod back into the hole while the wax was still hot). Also, when "fully open", that rod extends out pretty far - about an inch farther out that seen in the pic below.
As shown earlier in the thread - that was the position of the rod when I got both the original and replacement part back. With the rod in that position, the thermostat is not fully open (as the shop claimed). I also learned that the thermostat never really opens or closes fully, it varies depending on the temp it reads. At room temperature (72 degrees) the rod should be about 75% extended (fully opens at 82 degrees). This is why when I got the removed thermostats back, the rod was in the position seen in the pic above. The shop temperature is probably close to room temp, so the thermostat would not be fully closed like it would be on a cold morning/cold engine.....BUT, if it was "stuck open", that rod should have been fully extended.
Now, as for a thermostat being "stuck open", I cannot see how this happens without some sort of foreign object physically stopping the thermostat from closing. The pressure of that spring is immense and unless that wax is boiling and pushing the rod outward, the spring will always keep it closed. This is why I am confused as to how thermostats can get stuck open - if a seal fails and the wax leaks out, there would be nothing to force the rod outward, so it would be stuck closed if anything. Not sure how some thermostats are designed to fail in the fully open position, but they do apparently. From what I can tell, the only way a thermostat can be stuck open or partially open is if it opens and then the spring fails or if it gets jammed open/gummed up by say Bars Leaks or something added to the coolant OR if it is installed improperly and catches on something or the rod isn't straight and binds.
Back to the replacement I bought that was deemed a "bad part" (and forcing me to pay for the re-do of the job), I popped in into the Air Fryer at 300 this time and only for a minute at a time and kept checking it. Low and behold, as it started to boil, the rod extended all the way out and I was able to push it all the way back in as it cooled down (I had to physically push the rod myself because when it's installed in the car, I think that the rod is pushed back in by the force of the thermostat sprng and as it was not installed in the thermostat housing, it needed to be physically pushed back in - most of the youtube vids I watched showed a thermostat opening and closing inside the thermostat housing - the Cayenne thermostat seems to be designed a tad differently??) - this shows me the seals are good on the new thermostat and it opens and closes fine when it reaches the boiling point/cools down. From what I gather, this is pretty much the only way a thermostat can fail - the seals go bad, the spring binds somehow or something foreign causes it not to move one way or the other.
So, it appears to me that my thermostat was not faulty and the problems I was having were probably due to the thermostat not sitting correctly in the housing. I believe it wasn't FULLY stuck open, because the car still warmed up and I was getting heat. From what I read, a fully stuck open thermostat will constantly be pulling cold coolant from the rad and would not produce much heat. I think the shop installed it slightly off and this allowed it to not fully close.
Let's see if they agree after my explanation lol
P.S. - on a side note - after learning what part actually moves, I tried boiling it again to see if I could get that rod to move, but it still wouldn't. Once it was heated up, I could push/pull the rod a bit, but the boiling water would not force the rod outward. The Air Fryer, on the other hand, shot that rod out like a bullet. I wonder why the boiling water trick didn't work for the Cayenne thermostat? Has anyone else tested their thermostat prior to installation using the boiling water tricks and did it work for you????
Yes I tested both my new and old thermostat side by side last week in boiling water and it did work. I did not submerged them until the water was over 185 degrees. The old one took its good old time to close on removal.
Yes I tested both my new and old thermostat side by side last week in boiling water and it did work. I did not submerged them until the water was over 185 degrees. The old one took its good old time to close on removal.
I don't know what is going on then. I boiled both the new one and the old one and that rod stayed put.
Also strange that your thermostat rod tried to go back inside as it cooled down - I figured it would need some sort of force to push it back in (the spring).
I don't know what is going on then. I boiled both the new one and the old one and that rod stayed put.
Also strange that your thermostat rod tried to go back inside as it cooled down - I figured it would need some sort of force to push it back in (the spring).
Our thermostats are different though but the same should apply I think. No force is needed, just the shifts in temperature....
Our thermostats are different though but the same should apply I think. No force is needed, just the shifts in temperature....
That's what I figured also, but if the rod moves out when hot, and retracts, by itself, when cold, what purpose does the spring serve?. If the rod could open and close the thermostat by itself just by shifting with the temperature, there would be no need for any external pressure from the spring, no? I dunno.....lol
From looking at numerous pics of thermostats, they all seem to have the moveable rod hitting a stop or something like a brace that is attached to the actual thermostat. That's why when you heat them up, you can see the psychical movement of the valve that allows coolant to pass - when I heat my thermostat, just the rod moves - no valves move.
Once it's installed in the housing, I think the rod hits a stop, so when it heats and tries to "slide out" of the brass pellet part, the rod actually stays still and the valve is forced to slide up the rod, which is it opening. In my case, the rod sticks out of the end of the thermostat and does not have any force applied to it (until it's installed,I'm assuming).
When not sitting in the housing/having something to stop the rod, it is free to open when heated, but once it cools off, there is no force to push it back into the hole. I figured it was the spring that pushes the valve back to the shut position when the rod has less resistance vs the rod itself just moving back to the closed position on it's own simply due to it cooling??? I'm learning as I go here lol
03-04-2021, 03:30 PM
