Random Overheat and leak issue
 

Hey guys, my 2009 Gen5 has the problem that it starts overheating randomly i thought it ran out of water, so i refilled it with water from a gas station, to get back to a workshop. but after a few kilometers it said its hot again, so i pulled over and looked there was water running out of my car, but i couldn't say where, so i called a tow truck and he pulled me back home. While waiting i had a big puddle under my car. This all happened Saturday. On monday afternoon i looked how much is in the water tank and it seems there was eough water in it so i drove to a workshop that had time to look, i arrived after 5min and my engine was normal warm and he couldn't find any leaks, so i drove back home 5min, i looked under my car and there was water dripping, so i drove back. On the way the check engine light went on because of that overheating. On Saturday he called me and said the pipes going from the engine to the heater was leaking a bit but i wouldn't be able to repair it, so i asked an other workshop. He preasurised the cooling system, drove around for an hour but couldn't find leaks and the flor in his workshop stayed dry.


How is that possible, that one day everything is overheating and water is dripping anywhere and an other day nothing happens?

Weather outside was 22°C on Saturday, 18°C on monday and 30°C today. Car had run about 101950km


PS: sorry for my bad english im from germany so everthing is metic in my report

Possible sticking Thermostat, I think I would start there.

This could explain why it sometimes stays normal and sometimes overheats. When it overheats the relief valve dumps all the water.


But if it operates normal, like getting up to teperature as usual, why does it get hot out of nowhere? Maybe due to riding an uneven road?


Is there a way to measure if the Thermostat is open or closed? Or is it a mechanical one without sensors? Or could it be the Temperature sensor which trigers the relief valve?

What about trapped air in the system, so the waterpumps suckes air, the engine gets hotter, and then the next flush of water comes up so it goes back to normal? This mixed with the Thermostat could be the perfect solution. What are your Ideas?

It could be a air pocket but air should not have gotten into the sealed system, You can take the thermostat out and check it in a pot of boiling water, Check you tube and you will see videos about it, But honestly if I was taking it out I would be replacing it anyway.



I would also check to see if your fans are coming on at the correct Temp and if both Hi and low speeds are working. After you change stat and verify everything is good I would make sure to flush system and put correct coolant and ratio back in.


And just for good measure I would put new radiator cap on.


I believe after this you will be good to go. Usually if water pump goes bad you will see coolant weeping from it and it will slowly get noisy.

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I made those pics last night this is the upper front portion of the engine. Both fans are working fine at low and full spead, but i dont know how to check at wich temps they get on, can i check it with the OBD2 tool?

You should be able to see the temp on the dash if you scroll through the menus. Just let the car idle until the fans cut on and read the temp.

So i let it ran now. In Idle it goes up to 100°C (Open hood) and 105°C (Closed hood). In drive it went up to 110°C shortly but then goes down to 92°C looks like both fans are on between 102/103°C and 108/109/110°C


When i came back, the upper hose was warm but squashy, warm is good, but squashy? And it looks like the thermostat gets stuck sometimes but not allways



To replace the thermostat i would need to take off the whole intake system, right? or is there a shorter way? My Workshop meant he would take 3-4h to replace the thermostat. Do you have any clue how long it takes and how much they charge?

The fans didnt came on in Idle only after driver for a few min

Eventually they will come on at idle, at least on a hot day.

temp outside are 22-23°C (71°F-73°F) on a hot day we can get 35-40°C(95°F-104°F) and the Water temps were as said between 102°C and 105°C (215°F- 221°F) in idle, not warmer

I ordered a thermostat incl. housing and an Intake Mainfold Gasket. If i replace the Thermostate i need to remove the mainfold and therefore i need a new gasket, right? They should arrive in the end of next week



so the question of the workload stays, how much is it?

Hi I am sorry if I missed it but what motor do you have, The 8 cyl version you just remove thermo housing, 6 Cyl I am not sure. I do believe this is going to be your issue.

I'm in the V6 LLT Engine forum, so yeah i have the 3.6l v6 with 224kw/305hp