# 1.8T Thermostat replacement... tips?



## idahowind (May 14, 2007)

My thermostat is going out. The car runs at around 140 to 160 degrees, my estimate based on where the temp gauge is reading. I already tried replacing the coolant temp sensor, and that wasn't it. Also, my mileage is down to around 330 per tankful.
My question is, do any of you have any tips for getting the thermostat out? Specifically for a 1.8T, I fooled around with it for over an hour last night and I can't get a socket on the lower bolt. If I can't even get a socket on it, I obviously can't take it out. Now, it might be possible if I take out the throttle body and the alternator, but that would be a last resort.
I've seen DIY threads on this, but they're based on other engines. I think there is more stuff in the way on a 1.8T.
If you had this done by a shop, what did it cost?
Thanks.


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## [email protected] (Apr 25, 2007)

*Re: 1.8T Thermostat replacement... tips? (idahowind)*

Alternator for sure. That means tensioner, acc. belt, as well. Don't even disconnect anything, just remove the alt. from the acc. bracket, and lay it to the side. Then the thermo housing is easily accessible. http://****************.com/smile/emthup.gif


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## idahowind (May 14, 2007)

*Re: 1.8T Thermostat replacement... tips? ([email protected])*

Thanks. That was quick! Did you mess with the throttle body or no? I guess I need to find out which bolts to remove on the alternator....


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## SnowGTI2003 (Jan 8, 2004)

*Re: 1.8T Thermostat replacement... tips? ([email protected])*

-Remove both plastic engine covers.
-Remove the SAI plastic hose that goes down to the SAI pump
-Remove the small tray on the front of the intake manifold that the SAI hoses connect to. Just 2 hex bolts. Move that vacuum hose mess out of your way.
-Release tension on the belt tensioner using a 16 or 17mm open end wrench. Remove the belt from the alternator pully with the tension slack.
-Remove the serpentine belt tensioner. ( 3 bolts )
-Remove the top and bottom alternator bolts. These can be a pain. Use lube and wiggle lots.....
That will give you access to the thermostat housing. Takes about 1.5 hours if you're moving at a beer sipping pace.
I probably forgot something in there... My memory isn't exactly sharp.
/No do not remove the throttle body. No need.


_Modified by SnowGTI2003 at 10:57 AM 1-22-2008_


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## [email protected] (Apr 25, 2007)

*Re: 1.8T Thermostat replacement... tips? (SnowGTI2003)*


_Quote, originally posted by *SnowGTI2003* »_-Remove both plastic engine covers.
*No need for either*
-Remove the SAI plastic hose that goes down to the SAI pump *No need.*
-Remove the small tray on the front of the intake manifold that the SAI hoses connect to. Just 2 hex bolts. Move that vacuum hose mess out of your way.*No need*
-Release tension on the belt tensioner using a 16 or 17mm open end wrench. Remove the belt from the alternator pully with the tension slack.
-Remove the serpentine belt tensioner. ( 3 bolts )
-Remove the top and bottom alternator bolts. These can be a pain. Use lube and wiggle lots..... 
No do not remove the throttle body. No need. Yes, remove the the throttle, it's four bolts, and one elec. harness, leave the vac line connected, and lay to the side. 
I just did all this on Sunday.


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## SnowGTI2003 (Jan 8, 2004)

*Re: 1.8T Thermostat replacement... tips? ([email protected])*

Depends on which way you want to go in there to get it I guess. I did it about 3 months ago. 
I went in from the right side under the intake manifold which is why I moved that big rats nest of vac lines instead of removing the TB. That lower SAI hose needs to be removed in order to get enough slack to move the above rats nest out of the way.
By far the most time consuming thermostat change I've ever done on any car I've owned. Ah well cabin heat is certainly nice when it's -30C outside.


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## idahowind (May 14, 2007)

*Re: 1.8T Thermostat replacement... tips? (SnowGTI2003)*

Yep, why do I put this off until the coldest day of the year..........


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## 01gtiaww (Jan 31, 2006)

*Re: 1.8T Thermostat replacement... tips? (idahowind)*

I changed my thermostat from my GTI 1.8t and i did not have to remove alternator or anything else but the coolant hose to get to the thermostat housing. All you need to get is a flex joint and no need to remove alternator. http://****************.com/smile/emthup.gif 


_Modified by 01gtiaww at 2:38 PM 1-22-2008_


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## my own style tt (Sep 2, 2007)

*Re: 1.8T Thermostat replacement... tips? (idahowind)*

This might help http://forums.audiworld.com/tt/msgs/1304805.phtml


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## 01gtiaww (Jan 31, 2006)

*Re: 1.8T Thermostat replacement... tips? (my own style tt)*


_Quote, originally posted by *my own style tt* »_This might help http://forums.audiworld.com/tt/msgs/1304805.phtml 

That is exactly the way i did mine without touching the thermostat for nothing. The key part is the flex joint. http://****************.com/smile/emthup.gif


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## idahowind (May 14, 2007)

*Re: 1.8T Thermostat replacement... tips? (01gtiaww)*

A few quick notes...
The dealer quoted $340 to do this. Looks like I'm doing it myself.
That last link, Audi, is good but I wonder if there are a few extra inches (or just an inch) in the Audi? I still can't get a good look at it with that tray moved out of the way.
In fact, I did loosen that tray that is hooked on to the oil dipstick chase... AND I BROKE IT! As a temporary measure, I JB-Weld'ed it back in, but does anyone know where I can find one of these on the web?
Thanks for your help everyone.


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## 01gtiaww (Jan 31, 2006)

*Re: 1.8T Thermostat replacement... tips? (idahowind)*


_Quote, originally posted by *idahowind* »_A few quick notes...
The dealer quoted $340 to do this. Looks like I'm doing it myself.
That last link, Audi, is good but I wonder if there are a few extra inches (or just an inch) in the Audi? I still can't get a good look at it with that tray moved out of the way.
In fact, I did loosen that tray that is hooked on to the oil dipstick chase... AND I BROKE IT! As a temporary measure, I JB-Weld'ed it back in, but does anyone know where I can find one of these on the web?
Thanks for your help everyone.

I followed the link above and i have a GTI 1.8t. Worked perfectly.


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## my own style tt (Sep 2, 2007)

*Re: 1.8T Thermostat replacement... tips? (idahowind)*

I am sorry that i didnt tell you but you didnt need to take off the dipstick. This jod is a big PITA and takes time but saves you money. The lower screw to the houseing is the worst to get in. Make sure you have a long magnet cause you might drop it. Just take your time it will all work out. http://****************.com/smile/emthup.gif


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## 01gtiaww (Jan 31, 2006)

*Re: 1.8T Thermostat replacement... tips? (my own style tt)*

It is easier to remove the tray that holds the n valves as well as the dipstick. Gives you better clearance to get at the thermostat housing. The less stuff you have in the way the better. I did this recently. Took me about 30 minutes from start to finish including draining and filling the coolant. http://****************.com/smile/emthup.gif


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## my own style tt (Sep 2, 2007)

*Re: 1.8T Thermostat replacement... tips? (01gtiaww)*

I agree but as you can see alot of people are braking things in the prosess so just giving a alternitive to those that cant get the dipstick off. As for the tray that should be placed out of the way


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## idahowind (May 14, 2007)

*Re: 1.8T Thermostat replacement... tips? (my own style tt)*

Just to close out this thread, and for the people who might search it out later, I did it!
I was able to get the thermostat done. It was so nice to see the needle go up to 190 and then stay there, even on a morning where it was -5 F. And nice hot air through the vents as well.
I did it without moving the alternator. In fact I didn't even take off any connections to it. The key is to get that "tray" out of the way, and also that oil dipstick funnel. That was the only casualty... I broke it, but there was no way to get it out without breaking it. The plastic was pretty much fused to the metal down at the base, and it would have broken no matter what.
Using bungee cords was a great idea, very helpful.
It's essential to have a swivel (u-joint) piece in your ratchet toolbox, and a stubby ratchet was also very helpful in working in those tight spaces.


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## veedubwolfsburg (Jun 4, 2007)

*Re: 1.8T Thermostat replacement... tips? (idahowind)*

Just did this two days ago as well. It was a bit frustrating getting to the bottom bolt, but I did the job without removing the alternator. In fact, most of the difficulty was getting the radiator hose off of the thermostat housing. Car runs at a perfect 190 now, and doesn't deviate at all. I broke my dipstick tube as well, more of a careless mistake really. Should be easy to replace however. http://****************.com/smile/emthup.gif


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## my own style tt (Sep 2, 2007)

*Re: 1.8T Thermostat replacement... tips? (idahowind)*

congrats hope I helped out http://****************.com/smile/emthup.gif


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## INA (Nov 16, 2005)

*Re: 1.8T Thermostat replacement... tips? (01gtiaww)*


_Quote, originally posted by *01gtiaww* »_All you need to get is a flex joint and no need to remove alternator. http://****************.com/smile/emthup.gif 


http://****************.com/smile/emthup.gif 
Its a 10 min job max...


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## cjb (Jul 11, 2001)

Anybody have a part number for the dipstick tube? I'm looking at doing this job soon, and it sounds like a good idea to have one on hand...


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## veedubwolfsburg (Jun 4, 2007)

*Re: (cjb)*

Just ride by the dealer and ask for one. It cost me around 8 bucks. http://****************.com/smile/emthup.gif


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## berry_90 (Nov 14, 2006)

You need these tools: 1/4 inch rachet, 1/4 inch extension kit, 1/4 inch 10mm flex socket. You can get all these tools at sears. they have a three piece extension kit with different lengths. With these tools you can get the bottom bolt out. The alternator wiring harness will be in the way, just try to work around it. Do not take the alternator off unless you have to. The bushings that hold the bolts on rust and you have to hammer them in or you cant get the alternator to fit back on. Also use a telescopic magnet to put the bottom bolt in place.


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## sidemaniac (Sep 4, 2002)

*Re: 1.8T Thermostat replacement... tips? (my own style tt)*


_Quote, originally posted by *my own style tt* »_This might help http://forums.audiworld.com/tt/msgs/1304805.phtml 

this is exactly how to do it!
no need to remove alternator. All told took me about an hour.
don't drop the lower bolt into the engine bay or you will be sorry.


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## Shire (Mar 6, 2011)

I just did this. I found it easier to not remove the rubber hose from the coolant housing. it's flexy enough to move the whole thing out of the way. Seems like i lost quite a bit of coolant. as soon as i removed the thermo from the block, it gushed like mad. THAT should be a quick move--have the new one in your hand, pluck the old one out with that same hand and pop the new one in. 


I also noticed a fair amount of some kind of sediment in the coolant reservoir. any thoughts on that? 


themostat appears to have been replaced in october of '10--as well as the thermo housing, t belt, water pump and etc. recently replaced the CTS a few weeks ago for a CEL. car worked fine until just recently.it was getting nowhere near hot. 

I replaced the VW part #: 050 121 113c with a motorad 4419 (192 deg). seems to be settling on 190. perfect.


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## xXGti2006Xx (Feb 14, 2006)

yea def no need to remove alt, just get a flex joint socket and your good. If you are experienced this can be changed in a half hour or less but you will lose a lot of coolant be aware


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## ruba_dubdub (Dec 26, 2002)

I just replaced a leaking CTS housing and bad thermostat this weekend. I flushed my entire coolant system out and put fresh fluids in there. Car runs noticeably smoother. :thumbup:


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## Shire (Mar 6, 2011)

Shire said:


> I just did this. I found it easier to not remove the rubber hose from the
> 
> I replaced the VW part #: 050 121 113c with a motorad 4419 (192 deg). seems to be settling on 190. perfect.


i forgot to say that the old themo was labeld as 180 deg


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## SB_GLI (Oct 17, 2005)

A passat is really easy to do, there's hardly anything in the way and you don't even need a flex socket. A socket and extension will do. 10 minute job. My jetta looks a lot thougher to get to though and might be easier to just pull out the alternator to avoid cut knuckles and frustration.


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## chris_d (Jan 22, 2008)

I just replaced mine today and the temp sensor...

Kinda frustrating since the old thermostat was basically brand new, OEM and only has 5300km. It's only been used since June last year when I finished building my engine

:screwy:


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## SconnieGTI (Jun 10, 2012)

my own style tt said:


> This might help http://forums.audiworld.com/tt/msgs/1304805.phtml


FWIW this DIY was perfect for my Mark 4 GTI. I have gorilla hands and there was no need to remove the alt or the TB.

Thanks a ton!


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## vatbrew (Jul 27, 2008)

Just a Bump for this thread. I am by no means a mechanic, but I just replaced my T-stat today using this thread. Super easy with the pictures provided above in the link. I lucked out with the dip stick, I just turned it left and right while pulling and it came up very clean.


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## BassNotes (Mar 16, 2005)

SconnieGTI said:


> FWIW this DIY was perfect for my Mark 4 GTI. I have gorilla hands and there was no need to remove the alt or the TB.
> 
> Thanks a ton!


Same here. My thermostat housing blew out a couple weeks ago and the AudiWorld DIY made replacing it and the thermostat and o-ring an easier process than I expected it would be.


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## explicitrock (Jun 11, 2009)

my own style tt said:


> This might help http://forums.audiworld.com/tt/msgs/1304805.phtml


Does anyone have the pictures? these aren't loading for me. and I need this asap!


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## troici'sgti (Aug 24, 2008)

Just get a 1/4 drive extension and squeeze it in with out pulling the alternator and the place the socket on the thermostat bolt. Push the extension in and loose it. That's how I did it with out pulling the alternator off. Also when installing use your fingers to tighten and then tighten with a extension and a socket. A universal might also help.


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## zeusenergy (Feb 25, 2008)

This job only looks threatening. Back a few years ago I did mine on the 1.8T (New Beetle also- FAR less room to play guys) and everyone back then was saying to remove alternator also. I used a 1/4" drive universal joint, 6" extension, and normal 10mm socket for the 1/4" drive stuff. It was easy as sin, although challenging to work your fingers in there and dropping the bolt too. For anyone's T-stat job, on this engine, I suggest buying the housing new, the Oring, plus the dipstick tube. That stuff just breaks anyway and the replacements are cheap as hell. Don't mess around with the old parts hoping to save $20, because you'll be sorry.

WHILE YOU HAVE THE HOUSING OFF FEEL INSIDE THE BLOCK WHERE THE WATER PUMP IMPELLER IS. This is your key to know if the water pump is sh1t and needs to be replaced. :thumbup:


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## rdjarre (Oct 10, 2013)

explicitrock said:


> Does anyone have the pictures? these aren't loading for me. and I need this asap!


This video looks helpful: http://www.youtube.com/watch?v=dxas_zE7HEI

About to tackle mine this weekend!


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## groggory (Apr 21, 2003)

Added to FAQ


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## BassNotes (Mar 16, 2005)

zeusenergy said:


> This job only looks threatening. Back a few years ago I did mine on the 1.8T (New Beetle also- FAR less room to play guys) and everyone back then was saying to remove alternator also. I used a 1/4" drive universal joint, 6" extension, and normal 10mm socket for the 1/4" drive stuff. It was easy as sin, although challenging to work your fingers in there and dropping the bolt too. For anyone's T-stat job, on this engine, I suggest buying the housing new, the Oring, plus the dipstick tube. That stuff just breaks anyway and the replacements are cheap as hell. Don't mess around with the old parts hoping to save $20, because you'll be sorry.
> 
> WHILE YOU HAVE THE HOUSING OFF FEEL INSIDE THE BLOCK WHERE THE WATER PUMP IMPELLER IS. This is your key to know if the water pump is sh1t and needs to be replaced. :thumbup:


:thumbup:

Once you detach the SAI hose rack and remove the dipstick tube, it's pretty easy to get at the thermostat housing with a 10 mm socket, 1/4" extension and a U-joint. You don't need to do anything with the alternator.

I hadn't thought of reaching in to feel the water pump impeller. Good idea!


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## seanr68 (Feb 26, 2010)

I found the easiest way to get to the 2 bolts that hold the thermostat housing in place, was to use a long, "T" handle, 5mm, ball ended allan key. It slots straight in, and when tightening, you can manage to get the bolts to manufacturers torque easily.


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## rockyfan206 (Mar 1, 2007)

*Use a hairdryer to warm up the dipstick tube*

I just did this using the technique mentioned earlier in this thread that does not involve removing the alternator - i.e.:
http://forums.audiworld.com/showthread.php?p=16925102

A couple of tips from my trials:
- I used a hairdryer to warm up the dipstick tube near the bottom where it attaches to the metal portion. After a couple of minutes, I was able to rotate the dipstick tube fairly easily and just eventually kept swivelling while pulling to get it off. Before the hairdryer, it wouldn't budge and I'm sure I would have broke it like the thread mentions. Also I live in Canada and it's currently around -2 deg C.

- Get a telescoping magnetic tool like this: Telescoping pocket magnet - if you're inexperienced like me, you'll drop a bolt or socket into the bottom of the engine compartment :banghead:. This tool saved me. Also, I used it to extract (once loose) and replace the bottom bolt of the thermostat housing, which seemed much easier with this tool, since there's very little room to put your hands in there if you don't take out the alternator.


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## Parsons (May 8, 2007)

explicitrock said:


> Does anyone have the pictures? these aren't loading for me. and I need this asap!


Wont load for me either. I did it once before using the guide, but it was like 6 years ago and I forget how. Would be a bit easier with the pictures!


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## max13b2 (Jul 24, 2007)

Pics don't load and I need to replace the thermo on my 225 TT real soon. Does anyone have the pics? Help! TIA!


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## JustinLoFLow (Feb 21, 2014)

max13b2 said:


> Pics don't load and I need to replace the thermo on my 225 TT real soon. Does anyone have the pics? Help! TIA!


I'm gonna give this a shot tomorrow if I can I'll post as many photos as I can...


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## JustinLoFLow (Feb 21, 2014)

I was kinda rushed and hot so I didn't get to take photos. After taking out the tray under the manifold i couldn't get to the bottom screw. I couldn't get the socket to get a good bite even using a u-joint and an extension. I ended up removing the throttle body and the serp belt tensioner. I was able to get to the thermostat after moving the alternator out of the way. It didn't have to come out completely. I put it back together and refilled the res tank. Make sure you bleed it completely. I let it sit over night and the next morning the tank was empty, I refilled it again and ran the car with the cap off for a few minutes. I actually heard then it bled completely. I engine began to idle a lot smoother.


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## quadracer (Jan 26, 2015)

just wanted to say thanks for the write up. Had to change mine out today, took about an hour, thanks to the good tips here.


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## Jeffrayes9 (Apr 19, 2013)

this one is pretty good http://www.pelicanparts.com/techarticles/Volkswagen_Golf_GTI_Mk_IV/39-WATER-Replacing_Your_Thermostat/39-WATER-Replacing_Your_Thermostat.htm


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## bootymac (Apr 19, 2005)

Bumping an old thread as I recently changed my thermostat and thought I'd share some tips for future readers. It's pretty simple as long as everything goes smoothly.

Initial stuff:
- Do not drain the coolant 
- Do not remove the radiator hose from the thermostat housing
- Do not remove the coolant reservoir cap
- Do not remove the alternator or anything like that
- Remove all of the SAI vacuum hoses and stuff (mine are already deleted)
- Remove the dip stick tube
- Place a catch pan under the car

I used the following to access the thermostat bolts:
- 10mm 1/4" socket
- 4" 1/4" wobble extension
- 6" 1/4" wobble extension
- 1/4" drive ratchet

This is how I accessed the lower thermostat bolt:









Swapping thermostats:
- Some coolant will come out when you remove the housing. Bend it up and out of the way 
- Remove the thermostat o-ring with a hook
- More coolant will come out when you remove the thermostat so do the swap quickly
- Replace the o-ring and reposition the thermostat housing

Reinstalling the housing:
- Thread the upper bolt in half way first
- Use an extendable magnet to position the lower bolt in place and thread it in using your socket and extensions or by hand if possible
- Torque to only 5 Nm (3-4ft lb)

Wrapping up:
- Refill the coolant reservoir with G12
- Leave the reservoir cap off, start your engine and turn the heat on
- Idle for 10-15 minutes to allow air to bleed from the cooling system
- Refill coolant as needed
- Replace the coolant cap, test drive and refill coolant if needed


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