►Thermostats are a simple device that regulates coolant flow through the engine. When cold it will stay closed, stopping coolant flow and helping the engine warm up faster. Once up to temperature, it will open and allow normal coolant flow and maintain proper engine temperature. Ensuring your Mk4 VW GTI thermostat is functioning properly is crucial to its cooling performance.
There are two types of thermostat failures:
Thermostat stuck open (most common): Coolant will flow through the engine constantly from cold, preventing the engine from reaching operating temperature. Usually this means a rich mixture resulting in poor fuel mileage and potential catalytic converter damage.
Thermostat stuck closed: If the thermostat is stuck closed it will restrict flow into the engine resulting in an overheating condition, resulting in potential catastrophic engine damage.
Follow along as Jay Van Gorden, our VW Catalog Manager, walks you through the steps needed to replace the thermostat on your 1.8t equipped VW Mk4.
Shop the parts used in this video:
VW Mk4 Thermostat Kit: https://www.fcpeuro.com/products/vw-thermostat-replacement-kit-mahle-kit-00303#description?utm_source=youtube&utm_medium=description&utm_campaign=mps%20mk%204&utm_content=thermostat%20diy
Index:
00:00 – Intro & Tools Needed
02:42 – VW Mk4 Coolant Drain Procedure
06:05 – VW Mk4 Battery Disconnection
03:45 – VW Mk4 Air Pump Line Removal
05:40 – VW Mk4 Coolant Flange Hose Removal
06:47 – VW Mk4 Coolant Flange Upper Bolt Removal
07:00 – VW Mk4 Alternator Bracket Removal
07:45 – VW Mk4 Coolant Flange Upper Bolt Removal
08:45 – VW Mk4 Thermostat Removal
09:28 – VW Mk4 Thermostat & Coolant Flange Install
10:48 – VW Mk4 Alternator Bracket Reinstall
11:00 – VW Mk4 Coolant Flange Hose Reinstall
11:23 – VW Mk4 Coolant Fill Procedure
12:45 – VW Mk4 Buttoning Up the Job
14:58 – Thanks for Watching!
This video applies to the following vehicles:
Volkswagen Beetle
1999 Volkswagen Beetle GL 1.8L
1999 Volkswagen Beetle GLS 1.8L
1999 Volkswagen Beetle GLX 1.8L
2000 Volkswagen Beetle GL 1.8L
2000 Volkswagen Beetle GLS 1.8L
2000 Volkswagen Beetle GLX 1.8L
2001 Volkswagen Beetle GL 1.8L
2001 Volkswagen Beetle GLS 1.8L
2001 Volkswagen Beetle GLX 1.8L
2001 Volkswagen Beetle Sport 1.8L
2002 Volkswagen Beetle GL 1.8L
2002 Volkswagen Beetle GLS 1.8L
2002 Volkswagen Beetle GLX 1.8L
2002 Volkswagen Beetle Sport 1.8L
2002 Volkswagen Beetle Turbo S 1.8L
2003 Volkswagen Beetle GL 1.8L
2003 Volkswagen Beetle GLS 1.8L
2003 Volkswagen Beetle GLX 1.8L
2003 Volkswagen Beetle Turbo S 1.8L
2004 Volkswagen Beetle GLS 1.8L
2004 Volkswagen Beetle GLX 1.8L
2004 Volkswagen Beetle Turbo S 1.8L
2005 Volkswagen Beetle GLS 1.8L
Volkswagen Golf
2000 Volkswagen Golf GLS 1.8L
2000 Volkswagen Golf GTI GLS 1.8L
2001 Volkswagen Golf GLS 1.8L
2001 Volkswagen Golf GTI GLS 1.8L
2002 Volkswagen Golf GTI 337 1.8L
2002 Volkswagen Golf GTI 1.8T 1.8L
2003 Volkswagen Golf GTI 20th Anniversary 1.8L
2003 Volkswagen Golf GTI 1.8T 1.8L
2004 Volkswagen Golf GTI 1.8T 1.8L
2005 Volkswagen Golf GTI 1.8T 1.8L
Volkswagen Jetta
2000 Volkswagen Jetta GLS 1.8L
2001 Volkswagen Jetta GLS 1.8L
2001 Volkswagen Jetta Wolfsburg Edition 1.8L
2002 Volkswagen Jetta GLS 1.8L
2003 Volkswagen Jetta GL 1.8L
2003 Volkswagen Jetta GLS 1.8L
2003 Volkswagen Jetta Wolfsburg Edition 1.8L
2004 Volkswagen Jetta GL 1.8L
2004 Volkswagen Jetta GLS 1.8L
2004 Volkswagen Jetta GLI 1.8L
2005 Volkswagen Jetta GL 1.8L
2005 Volkswagen Jetta GLS 1.8L
2005 Volkswagen Jetta GLI 1.8L
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I just replaced mine. The easiest way, believe it or not, is to remove the whole front assmbly to get to those two screws.
the radiators and the front assembly are only linked by 2 or 3 hoses and a few connectors. You have to remove the bumper cover and the assembly comes out with five 13mm screws. Replacing the thermostat is 10 minutes after that. Way easier than trying to fish those screws.
My blower water pump stays on after shutting down engine and my thermostat warning ⚠️ lite won't turn off ?
You say to unscrew the expansion tank cap to help the coolant drain faster, however why doesn't the coolant actually drain from the expansion tank as well when you do this? Isn't that little tap just for the radiator itself?
Great video! I have a 2004 Jetta with the 1.8T that overheated last week in -15 deg.F (I live in South Dakota) after driving about 17 miles. I let it sit for a couple hours, then tried to drive it back home, but it overheated again after just a couple miles and I had to get a tow. I had the water pump and timing belt replaced November 2021, so I hope my issue is the thermostat and not the water pump. Can you give me any tips to help me diagnose it? Thank you again for making great videos!
Thank You !!! Very good !!
Thank you for sharing this great video! I just replaced radiator for new one, but ventilator does not start even when temp goes to 90 , no leak from passenger side, any idea you could please suggest that shall be checked? Coolant just boils but vents just does not start! This Is the first time I do all by me self, losing fear so just doing It, but I don't want to give up and call mechanic. 30a fuse looks good by the way. Allí this Is happening in an Audi A3 2003.
Thanks in advance for any ideas or suggestions.
how many quarts of coolant did it take to fill up ? , or how much coolant does a MK4 VR6 golf take ? thanks God bless …
tools needed….. said 5 mm…. not 5mm allen…. hooray broken vaccum lines , and cant get to the bot on the alternator yay… anyone wanna buy a golf non turbo with an after market turbo… 2.0 with turbo
why is the coolant not g12??? i was told you have to use it
How much is the Labour costs?
First of just wanted to say thank you for posting the video as I need to replace my thermostat. I have a question about disconnecting the connector on the 4:29 min mark because I had a difficulty to disconnect it. Would you please tell me how to do it the right way so I don’t make any damage. Thanks
Lol everything gets fucking brittle its god awful
The more Mk4 content the merrier!!!
Great video, getting ready to do my mk1 TT. When you put in thermostat does it have top and bottom, or do you put it in just vertical.
An excellent walkthrough – much thanks.
What does Code P0304 mean on my 1997 GOLF GL 1997 2.0 Hatch back?
Any info helps. Tried looking this up in google and NADA! 🙁
no VR no care
Good on you guys for helping Chris and Will.
Chris sent me!!