SOS - Overheating after T-stat and water pump replacement
07-27-2018, 01:10 AM
#16
Instructor
Thread Starter
Thanks for all the replies guys!
I did verify operation of the new water pump/swapped the old one back in because I was so stumped. I had the same line of thought because it’s happened to me before. I also made sure the car was running hot, turned it off, removed the upper hose and inserted a long length of regular coolant hose, then started it to check for flow - had nada.
I ordered the air view vacuum bleeder and will try that and/or the incline burping method. The replies give me more confidence that the cooling system is fine and it’s just air caught in the system. I’ve replaced just about everything on top of and in front of the engine; fingers crossed it works out!
I did verify operation of the new water pump/swapped the old one back in because I was so stumped. I had the same line of thought because it’s happened to me before. I also made sure the car was running hot, turned it off, removed the upper hose and inserted a long length of regular coolant hose, then started it to check for flow - had nada.
I ordered the air view vacuum bleeder and will try that and/or the incline burping method. The replies give me more confidence that the cooling system is fine and it’s just air caught in the system. I’ve replaced just about everything on top of and in front of the engine; fingers crossed it works out!
07-27-2018, 05:13 PM
#17
Instructor
Is it possible your new thermostat is defective? Or installed incorrectly? I have not done a Cayenne thermostat but I've done a variety of MB and BMW ones, and they frequently have a bleed valve that must be installed in a certain position. Possibly that's wrong or the T-stat is defective?
07-27-2018, 07:08 PM
#18
Is it possible your new thermostat is defective? Or installed incorrectly? I have not done a Cayenne thermostat but I've done a variety of MB and BMW ones, and they frequently have a bleed valve that must be installed in a certain position. Possibly that's wrong or the T-stat is defective?
08-05-2018, 04:33 PM
#20
08-05-2018, 05:32 PM
#21
Instructor
Thread Starter
I purchased the "UView 550000 Airlift Cooling System Leak Checker and Airlock Purge Tool Kit" from Amazon. Not sure which brand the ebay unit was since the tool is a couple years old - generic, has a yellow case, and was cheap.
08-05-2018, 09:37 PM
#22
Burning Brakes
dpatel710: Did the new t-stat rattle? Mine did and the one I pulled out of the P!G did not (seems stuck). When I say rattle, I mean the middle thing inside the spring would move few mm up and down.
Cheers,
-K
Cheers,
-K
08-12-2018, 12:57 PM
#23
Instructor
Thread Starter
New thermostat was working ok. I tested it in the thermostat housing with a boil pan of water - great thing to do the first time before you reinstall the housing. I had to go back and pull the intake again to test mine and rule it out.
New issue - I only have heat at idle. I bled the system and had heat at idle while letting the car sit in the driveway. Once I started driving, heat died down a little and once I got on the highway (>2k rpm) the heat became a/c. On the way back home, at a stoplight the heat came back and blew very hot. Could the electric coolant pump be shot and causing this issue? I am a little deaf but I hear the pump working intermittently, ambient temps here are around 75F.
Car was working great, heat blew fine, before the preventative maintenance. Sometimes, if it ain’t broke don’t fix it applies.
Tips for others bleeding their cayenne:
With the airlift tool, make sure to get a vac of -25 or better otherwise the system will have residual air. Let the car idle BUT once its at operating temperature, make sure to put the coolant cap on the reservoir. On my past (older non-turbo) cars, I would leave the radiator cap off during the entire burping procedure and even after it was up to temp but with the cayenne it boiled over and dumped its coolant.
New issue - I only have heat at idle. I bled the system and had heat at idle while letting the car sit in the driveway. Once I started driving, heat died down a little and once I got on the highway (>2k rpm) the heat became a/c. On the way back home, at a stoplight the heat came back and blew very hot. Could the electric coolant pump be shot and causing this issue? I am a little deaf but I hear the pump working intermittently, ambient temps here are around 75F.
Car was working great, heat blew fine, before the preventative maintenance. Sometimes, if it ain’t broke don’t fix it applies.
Tips for others bleeding their cayenne:
With the airlift tool, make sure to get a vac of -25 or better otherwise the system will have residual air. Let the car idle BUT once its at operating temperature, make sure to put the coolant cap on the reservoir. On my past (older non-turbo) cars, I would leave the radiator cap off during the entire burping procedure and even after it was up to temp but with the cayenne it boiled over and dumped its coolant.
08-13-2018, 11:46 AM
#24
The after run pump in the driver's fenderwell is in line and not required for heater core flow. It is mainly for circulation after shut off, component protection , or when using the cabin "rest" feature. Obviously something changed along the way but what? You have checked everything. Longshot, but you are sure you have all the new parts on the front drive and the serp belt installed correctly?. Also maybe look at temps into and out of the radiator with a temp gun. Personally I do not think that the vacuum bleed is part of the problem. I never owned one before the Cayenne. I never used one for the first 5 years I owned the Cayenne. I always did it the old fashioned way by burping and heat cycles/top offs. I never had an issue. I probably have the same vacuum bleeder as you. My compressor is like a 40 year old Montgomery Ward's 15gal. ............I pulled enough vacuum to crush ALL the hoses flat, it wasn't near 25. When I bleed with the cap off I don't fill the reservoir all the way up to leave room for boiling/burping when the thermo opens. I can usually get a complete purge by filling while running until the thermo opens, topping off, cooling down, topping off.
08-13-2018, 11:54 AM
#25
New thermostat was working ok. I tested it in the thermostat housing with a boil pan of water - great thing to do the first time before you reinstall the housing. I had to go back and pull the intake again to test mine and rule it out.
New issue - I only have heat at idle. I bled the system and had heat at idle while letting the car sit in the driveway. Once I started driving, heat died down a little and once I got on the highway (>2k rpm) the heat became a/c. On the way back home, at a stoplight the heat came back and blew very hot. Could the electric coolant pump be shot and causing this issue? I am a little deaf but I hear the pump working intermittently, ambient temps here are around 75F.
Car was working great, heat blew fine, before the preventative maintenance. Sometimes, if it ain’t broke don’t fix it applies.
Tips for others bleeding their cayenne:
With the airlift tool, make sure to get a vac of -25 or better otherwise the system will have residual air. Let the car idle BUT once its at operating temperature, make sure to put the coolant cap on the reservoir. On my past (older non-turbo) cars, I would leave the radiator cap off during the entire burping procedure and even after it was up to temp but with the cayenne it boiled over and dumped its coolant.
New issue - I only have heat at idle. I bled the system and had heat at idle while letting the car sit in the driveway. Once I started driving, heat died down a little and once I got on the highway (>2k rpm) the heat became a/c. On the way back home, at a stoplight the heat came back and blew very hot. Could the electric coolant pump be shot and causing this issue? I am a little deaf but I hear the pump working intermittently, ambient temps here are around 75F.
Car was working great, heat blew fine, before the preventative maintenance. Sometimes, if it ain’t broke don’t fix it applies.
Tips for others bleeding their cayenne:
With the airlift tool, make sure to get a vac of -25 or better otherwise the system will have residual air. Let the car idle BUT once its at operating temperature, make sure to put the coolant cap on the reservoir. On my past (older non-turbo) cars, I would leave the radiator cap off during the entire burping procedure and even after it was up to temp but with the cayenne it boiled over and dumped its coolant.
08-13-2018, 12:28 PM
#26
Instructor
Thread Starter
J's world - I doubled checked the routing on the serp belt, everything looks good. The alternator water connections were pretty straight forward and the way the hose routing looks (paralell), I don't think it would affect the rest of the system. I'll grab a temp gun and check the radiator temps. What values should I be looking for around the upper and lower hoses?
PartsGuyGT - I had very hot air at idle and could switch from heat to ac, I can also hear the fresh air door actuating. The airflow is pretty noisy once it changes over. I also changed out all my servos last summer for 957 units.
Thanks for the replies, I am legitimately stumped and appreciate the help!
PartsGuyGT - I had very hot air at idle and could switch from heat to ac, I can also hear the fresh air door actuating. The airflow is pretty noisy once it changes over. I also changed out all my servos last summer for 957 units.
Thanks for the replies, I am legitimately stumped and appreciate the help!
08-13-2018, 01:11 PM
#27
J's world - I doubled checked the routing on the serp belt, everything looks good. The alternator water connections were pretty straight forward and the way the hose routing looks (paralell), I don't think it would affect the rest of the system. I'll grab a temp gun and check the radiator temps. What values should I be looking for around the upper and lower hoses?
PartsGuyGT - I had very hot air at idle and could switch from heat to ac, I can also hear the fresh air door actuating. The airflow is pretty noisy once it changes over. I also changed out all my servos last summer for 957 units.
Thanks for the replies, I am legitimately stumped and appreciate the help!
PartsGuyGT - I had very hot air at idle and could switch from heat to ac, I can also hear the fresh air door actuating. The airflow is pretty noisy once it changes over. I also changed out all my servos last summer for 957 units.
Thanks for the replies, I am legitimately stumped and appreciate the help!
08-13-2018, 01:13 PM
#28
Instructor
Thread Starter
Assuming the thermo is open at least partiallyand there is flow; going in the rad should be dash guage temp + whatever the coolant took from the engine. Coming out would the differential would vary based on several factors. Did you say that it is NOT overheating now and you just have the cold heat issue?
