thermostat replacement ALH

bowelder

Veteran Member
Joined
Oct 2, 2011
Location
south carolina
TDI
2013 VW golf TDI with tech package
after looking through the TDI 101 how to's, I need to ask a question. What are some of your tips about changing the thermostat and housing on a 2000 Golf TDI?


thanks
 

oldpoopie

Vendor
Joined
May 14, 2001
Location
Portland Oregon
TDI
2001 golf gl, 2006 jetta, 1981 ALH swapped rabbit pickup, 1998 beetle
Biggest tip is to only use an OEM thermostat. Most of the aftermarket ones won't clip into the thermostat housing. Boraparts carries the oem thermostat. Makes the job so much easier.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Yeah, only use OEM from Volkswagen (or whomever can get you one) and a new housing. Clip the new stat on to the housing after installing the o-ring. Super easy job, just 2 screws.

Also, only use the spring-type hose clamp (you can reuse them), as these not only provide constant uniform tension on the hose, but cannot crush the plastic nipple. The hoses themselves generally last forever unless they get contaminated with fuel or oil from a leak or something.
 

chromeBuddha

Veteran Member
Joined
Jun 30, 2006
Location
Arlington, TX - DFW metroplex
TDI
2002 Golf TDI manual
For the relative cost of the new housing, I agree with others on getting a new one. If you want to preserve the integrity of the original, use or make a hook about 8 inches long to hook the loop on the thermostat and pull that as you rock the housing free. Then you will have a good spare with the pins intact for next time...
 

Wksg

Veteran Member
Joined
Aug 2, 2008
Location
Ann Arbor MI
TDI
2003 GLS TDI Wagon
Twice I dropped the lower bolt that holds the housing in place and it fell down into a hard-to-get-to place. The second time I had to go buy one of those magnetic fish things to get it out. So, hang on to that one!
 

boertje

Veteran Member
Joined
May 24, 2002
Location
Coeur d'Alene, ID
TDI
'01, '01, '03, ‘06 NB - TDIs all.
Twice I dropped the lower bolt that holds the housing in place and it fell down into a hard-to-get-to place. The second time I had to go buy one of those magnetic fish things to get it out. So, hang on to that one!
Boy do I know that one! I had to use a camera tube to see the bolt to fish it out. I had to remove the A/C and one alternator bolt to nudge the alternator forward to get to it. I did not want to take the chance that the bolt would possibly touch the alternator windings and cause problems down the road. Took 3 hours for a 20 minute job. This was on my bug. My golf was easier.
 

Victor Huge

Veteran Member
Joined
Apr 18, 2009
Location
Alberta
TDI
Mk7 Golf TDI
Yeah, i think i dropped that bolt as well, very frustrating. Plan for that and the mess.

If you plan, to change to coolant, keep in mind you'll have a hard time draining it if the thermostat is cold so you might as well remove it and then drain
 

rackaracka

Veteran Member
Joined
Nov 15, 2001
Location
Monroe, NJ
I take a small scrap of paper and wrap it around the bolt head and then shove the bolt into the 10MM socket. Then I use a small extension and get the bolt started. When you pull out the socket the paper falls or sometimes stays in the socket. You can blow it away with compressed air.

A small magnet in your socket also works really well.
 

ymz

Top Post Dawg
Joined
May 12, 2003
Location
Between Toronto & Montreal
TDI
2003 Jetta TDI Wagon, 2003 Jetta TDI Wagon
I had to go buy one of those magnetic fish things to get it out.
A magnet on an extendable stick should be one of the first tools one ever gets... (also good for finding plastered-over drywall screws when hunting for studs in the wall...)
A small magnet in your socket also works really well.
Good idea... I've used that magnet-on-a-stick mentioned above to get the bolts started... it holds the bolt through enough turns to get the threads meshing...

bowelder: make sure to clean the sealing surface on the block really well with a plastic Brillo-type pad... if there are too many surface irregularities, the new thermostat and "O" ring will leak...

Yuri
 

JC_1992

Veteran Member
Joined
Mar 6, 2010
Location
Grand Rapids, MI
TDI
2002 Jetta GLS, 2001 Jetta GLS
I replaced my thermostat on my 02 jetta this spring and was able to save the old thermostat housing clips. None of them broke when removing the old thermostat, but since I had already purchased the new housing I put that in for good measure.

If you're careful and dont just yank the thermostat out I dont see why the clips would break.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Because the o-ring sticks to the iron block, holding the thermostat behind it, that's why. I never even bother to try and save the plastic housing anyways, as once they have been tightened, heat cycled many times, and loosened, the likelihood of a leak is just too great.

I have assembled thermostat "assemblies" all ready to go for all the more popular VAG engines sitting in baggies on the shelf here. :)
 

GeorgeZ

Well-known member
Joined
Jan 6, 2009
Location
Montreal
TDI
2000 Jetta
Thermostat change observations

Just changed the stat last night, here are my observations:
1. Difficult to get a wire to hook onto the thermostat since you can't see it
2. My bolts also had 5mm allen heads so with the proper allen key it's a tight fit & may help preventing losing the bolts
3. Despite the inaccuracy of the temp gauge, before the change it only went up 1/4-1/3 of the way, & after it goes to 1/2 & stays there.
 

flee

Veteran Member
Joined
Sep 19, 2011
Location
Chatsworth, CA
TDI
2002 Jetta GLS wagon
Yup, get a long ball-head allen key/socket & new bolts to go with your new housing. Overall, it's not a bad job.
Even with non ball-head long allen on a swivel wrench it took only seconds.
Which was lucky because I got bad replacements from NAPA and O'Reilly both!
Sheesh, it cost me as much in lost antifreeze as the OEM I ended up with!:eek:
 

loco_unoTDI

Veteran Member
Joined
May 1, 2012
Location
Jacksonville, FL
TDI
'03 Jetta 5spd TDI Wagon
Place a large drain pan under the engine past the back of the oil pan. No lost antifreeze. No reason to lose any anitfreeze with this job. Drain the coolant from the oil cooler rubber hose next to the thermstat after the lower radiator hose is drained. Super easy job.
 

flee

Veteran Member
Joined
Sep 19, 2011
Location
Chatsworth, CA
TDI
2002 Jetta GLS wagon
Place a large drain pan under the engine past the back of the oil pan. No lost antifreeze. No reason to lose any anitfreeze with this job. Drain the coolant from the oil cooler rubber hose next to the thermstat after the lower radiator hose is drained. Super easy job.
I did catch the coolant in a drain pan but it had picked up some dirt and debris on the way there.
I ended up using some anyway to top off after pouring all I had bought into the tank for the third time!
 

boertje

Veteran Member
Joined
May 24, 2002
Location
Coeur d'Alene, ID
TDI
'01, '01, '03, ‘06 NB - TDIs all.
Correct. All I can say is that the housing should be genuine VW OEM. I’ve used many after market housings and all have started to leak after about a year due to warping.
 

NarfBLAST

Top Post Dawg
Joined
Mar 3, 2002
Location
Waterdown, Ontario, Canada
TDI
2001 Golf 5MT
Bumping an old thread. I see all the recommendations to get the OEM thermostat. Is it really a player when replacing the housing also? I was looking at picking this up to do it
https://www.idparts.com/alh-thermostat-kit-038121121-044121113-p-5578.html
Highly recommended! Like everyone says:

1. use genuine parts,
2. clip new thermostat into new housing with new o-ring
3. have no regrets.

I like the idea of trying to pull the old thermostat out by the loop and bring the housing with it without breaking clips and save for a spare if possible, but, best to have new housing on hand.
 

olemiss36

Member
Joined
May 26, 2018
Location
GA
TDI
03 Jetta
Highly recommended! Like everyone says:
1. use genuine parts,
2. clip new thermostat into new housing with new o-ring
3. have no regrets.
I like the idea of trying to pull the old thermostat out by the loop and bring the housing with it without breaking clips and save for a spare if possible, but, best to have new housing on hand.
best place to get OEM parts for this?
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
Any on the on line vendors here
Idparts
Metal man
Diesel geek
Kerma
 

unorganizedplan

Veteran Member
Joined
Apr 17, 2013
Location
Okotoks, AB
TDI
2012 JSW Highline w/DSG ; 2003 Jetta ALH w/5spd
I have a recently acquired car with unknown service history. Should I replace my thermostat as PM before winter hits.... Or just leave it and see how winter treats me...

Are there any high temp stats available with the important OEM locking tabs?
(I'm in cold climate and have no EGR cooler)
 

flee

Veteran Member
Joined
Sep 19, 2011
Location
Chatsworth, CA
TDI
2002 Jetta GLS wagon
I have a recently acquired car with unknown service history. Should I replace my thermostat as PM before winter hits.... Or just leave it and see how winter treats me...
Are there any high temp stats available with the important OEM locking tabs?
(I'm in cold climate and have no EGR cooler)
OEM replacements seem to work best. If the 'stat is working correctly I'd leave it be.
 

oldpoopie

Vendor
Joined
May 14, 2001
Location
Portland Oregon
TDI
2001 golf gl, 2006 jetta, 1981 ALH swapped rabbit pickup, 1998 beetle
I have a recently acquired car with unknown service history. Should I replace my thermostat as PM before winter hits.... Or just leave it and see how winter treats me...

Are there any high temp stats available with the important OEM locking tabs?
(I'm in cold climate and have no EGR cooler)
High temp stat won’t make it warm up faster, just run at a higher temp.
 

STDOUBT

Veteran Member
Joined
Jul 30, 2007
Location
Portland, effing Oregon
TDI
dos jettas
I have a recently acquired car with unknown service history. Should I replace my thermostat as PM before winter hits.... Or just leave it and see how winter treats me...

Are there any high temp stats available with the important OEM locking tabs?
(I'm in cold climate and have no EGR cooler)
Stant 45379
Gates 33209
The above two I have used with no problems.
 

unorganizedplan

Veteran Member
Joined
Apr 17, 2013
Location
Okotoks, AB
TDI
2012 JSW Highline w/DSG ; 2003 Jetta ALH w/5spd
High temp stat won’t make it warm up faster, just run at a higher temp.
Yes I understand that. I am not after quicker warmups with a higher temp stat. I plan to have a frostheater for the morning warmups anyway. I have had good experience with diesels that run slightly warmer operating temps, since they tend to lose heat so fast if not driving under much load or when parked. Plus, it might make it easier for engine to keep a higher operating temp when I call for full heat inside the cab.
 
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