Volkswagen Parts Catalog Volkswagen Accessories Catalog Volkswagen Tech Information Volkswagen Tech Forums
 
Follow Pelican Parts on Facebook Follow Pelican Parts on Twitter Follow Pelican Parts on Instagram Follow Pelican Parts on YouTube Follow Pelican Parts on Pinterest Follow Pelican Parts on Tumblr
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
Bookmark and Share

Pelican Technical Article:

Replacing Your Thermostat

Steve Vernon

Time:

2 hours2 hrs

Tab:

$15

Talent:

**

Tools:

5mm Allen, 10mm socket lots of extensions and

Applicable Models:

VW Golf GTI (2000)
VW Golf GTI 1.8T (2002-05)
VW Golf GTI 20th Anniversary (2003)
VW Golf GTI 337 (2002)
VW Golf GTI GLS (2001)

Parts Required:

Thermostat, gasket

Hot Tip:

Work on a cold engine

Performance Gain:

Engine runs at the proper temperature

Complementary Modification:

Replace older hoses

The thermostat helps control the engines temperature. If your car is running too hot and there is the proper amount of coolant in the car and it is not leaking, or your car is taking a long time to warm up, there is a very good chance your thermostat is bad and needs to be replaced.

The thermostat on the GTI Mark 4 is locating in one of the most inconvenient locations to access and replace of any car I have ever worked on. That being said with this method you should be able to replace it the first time in under 90 minutes and get the time down to under an hour with repetition. While there are many methods on the Internet on how to replace the thermostat (and we have tried them all) this method is the quickest and easiest.

If you are going to be working on the thermostat, make sure the car is cool and not under pressure. Working on a hot engine or one under pressure can cause serious harm and should never be attempted. Coolant is also very toxic and needs to be collected and disposed of in accordance with your local regulations as pouring coolant down a drain or into the street is illegal. Also, be sure to wash your hands thoroughly after working around it.

If the coolant in the car is new there is no reason to replace it as long as you drain it into a clean container. Coolant is expensive and not great for the environment so if the coolant in your car is good, try and save it to reuse.

Begin by safely jacking up and supporting your car. With the car safely off the ground you will need to remove the engine tray. A great many of these car have had the engine trays and front side shields removed over the years and not replaced. If you happen to have a car that still has all the under trays and original hardware here is what you need to do. There are four T25 Torx bolts holding the tray on, remove them and slide the tray back out of the friction clips on the front air dam.

There is access hole in the left side shield that you can access the drain plug from, or if you want to remove the shield it is held in place by friction at the front and a speed clip on the frame rail.

With the tray removed you will see radiator drain plug on the lower left front of the car. Place a catch bucket or tray under the plug and turn the drain knob to open. The fluid drains out a small spigot facing downward. Remove the cap on the fluid reservoir to help drain the coolant. You do not need to drain all the coolant from the car, but just enough to get below the thermostat level. If you are going to flush or replace the coolant, drain completely.

You are going to need to remove the battery and engine covers. Please see our article on removing these covers.

Disconnect the negative cable on the battery and make sure it cannot accidentally make contact with the post while you are working. You are going to be working around the alternator and fluid so you don't want any power flowing in the car while working.

At the front of the engine remove the two 10mm nuts and the two 5mm Allen bolts.

With the bolts removed lift the shelf up and off the dip stick tube and remove the electrical connection. Slide the shelf out of the way.

Disconnect the two vacuum lines that run across the front of the engine and tie them out of the way.

Remove the dipstick tube by pulling it straight up. Use caution as they get brittle with age.

Cover the open dipstick tube with a plastic sandwich bag so fluid and contaminants cannot get into the motor. Remove the hose clamp and hose from the thermostat housing.

You can now see the two 10mm bolts holding the thermostat housing to the motor. Use a series of extensions and universal joints to remove the bolts.

Pull the housing off the motor and you can get access to the thermostat. Remove the old thermostat and install the new one. Make sure that the rubber O-ring goes on the outside of the thermostat between it and the housing.

Check all your hoses while performing this job and replace any that are old, getting hard or brittle or beginning to weep.

Installation is the reverse of removal and do not forget to replace your coolant.

Begin by safely jacking up and supporting your car.
Figure 1

Begin by safely jacking up and supporting your car. With the car safely off the ground you will need to remove the engine tray. A great many of these car have had the engine trays and front side shields removed over the years and not replaced. If you happen to have a car that still has all the under trays and original hardware here is what you need to do. There are four T25 Torx bolts (yellow arrows) holding the tray on, remove them and slide the tray back out of the friction clips (red arrows) on the front air dam.

Figure 2

This photo illustrates where the plate connects to the two side shields (red arrows)

There is access hole in the left side shield (red arrow) that you can access the drain plug from, or if you want to remove the shield it is held in place by friction at the front and a speed clip on the frame rail (yellow arrow).
Figure 3

There is access hole in the left side shield (red arrow) that you can access the drain plug from, or if you want to remove the shield it is held in place by friction at the front and a speed clip on the frame rail (yellow arrow).

With the tray removed you will see radiator drain plug on the lower left front of the car.
Figure 4

With the tray removed you will see radiator drain plug on the lower left front of the car. Place a catch bucket or tray under the plug and turn the drain knob to open. The fluid drains out a small spigot facing downward.

Remove the cap on the fluid reservoir to help drain the coolant.
Figure 5

Remove the cap on the fluid reservoir to help drain the coolant. You do not need to drain all the coolant from the car, but just enough to get below the thermostat level. If you are going to flush or replace the coolant, drain completely.

Disconnect the negative cable on the battery (yellow arrow) and make sure it cannot accidentally make contact with the post while you are working.
Figure 6

Disconnect the negative cable on the battery (yellow arrow) and make sure it cannot accidentally make contact with the post while you are working. You are going to be working around the alternator and fluid so you don't want any power flowing in the car while working.

At the front of the engine remove the two 10mm nuts (red arrow) and the two 5mm Allen bolts (yellow arrows).
Figure 7

At the front of the engine remove the two 10mm nuts (red arrow) and the two 5mm Allen bolts (yellow arrows).

With the bolts removed lift the shelf up and off the dip stick tube (yellow arrows) and remove the electrical connection (red arrow).
Figure 8

With the bolts removed lift the shelf up and off the dip stick tube (yellow arrows) and remove the electrical connection (red arrow). Slide the shelf out of the way.

Disconnect the two vacuum lines (yellow arrows) that run across the front of the engine and tie them out of the way.
Figure 9

Disconnect the two vacuum lines (yellow arrows) that run across the front of the engine and tie them out of the way.

Remove the dipstick tube by pulling it straight up (red arrow).
Figure 10

Remove the dipstick tube by pulling it straight up (red arrow). Use caution as they get brittle with age.

Cover the open dipstick tube with a plastic sandwich bag (yellow arrow) so fluid and contaminants cannot get into the motor.
Figure 11

Cover the open dipstick tube with a plastic sandwich bag (yellow arrow) so fluid and contaminants cannot get into the motor. Remove the hose clamp (red arrow) and hose from the thermostat housing.

You can now see the two 10mm bolts (yellow arrows) holding the thermostat housing to the motor.
Figure 12

You can now see the two 10mm bolts (yellow arrows) holding the thermostat housing to the motor.

Use a series of extensions and universal joints (red arrow) to remove the bolts.
Figure 13

Use a series of extensions and universal joints (red arrow) to remove the bolts.

Pull the housing off the motor and you can get access to the thermostat (red arrow).
Figure 14

Pull the housing off the motor and you can get access to the thermostat (red arrow). Remove the old thermostat and install the new one.

Make sure that the rubber O-ring (red arrow) goes on the outside of the thermostat between it and the housing, and the spring side (yellow arrow) goes in facing the engine.
Figure 15

Make sure that the rubber O-ring (red arrow) goes on the outside of the thermostat between it and the housing, and the spring side (yellow arrow) goes in facing the engine. Installation is reversal of removal. Don't forget to replace your coolant.

Bookmark and Share
Comments and Suggestions:
Domfromguam Comments: Would you be able to give me a part number for that pipe Nick?
July 14, 2016
  Followup from the Pelican Staff: I’m not the best with part numbers. I don't have access to the look up tool.

Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Domfromguam Comments: What is the black pipe called going into the side of the thermostat housing?
July 14, 2016
  Followup from the Pelican Staff: It is a coolant pipe.

Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Project/Wish List]
  [Privacy Statement]  [Contact Us] [About Us] [Shipping] [Careers]

Copyright © Pelican Parts Inc. -    DMCA Registered Agent Contact Page

Page last updated: Wed 12/7/2016 02:35:37 AM