V
MKV Thermostat Replacement
- Thread starter jgeeky
- Start date
Scanned for fault codes and there were none. I'm waiting to get a vag com cable to log coolant temperatures, but the problem seems to be getting worse. The temperature dropped to almost 60 degrees this morning and is struggling to get to 90 for any sustained period of time.
IrCsabi
Passed Driver's Ed
- Location
- Cork, Ireland
hi guys
does anyone know of a DIY on this?
thanks
does anyone know of a DIY on this?
thanks
mcpot
Slave to speed
- Location
- Mchenry IL
- Car(s)
- 07 GTI
Prep... Remove battery cables/remove splash guard/ remove engine cover/remove noise pipe/drain coolant/
1. Remove serpentine belt. (get an adjustable wrench place it on tensioner, pull towards front of car to loosen belt.)
2. loosen 2 bolts on alternator. (don't remember size, but you'll need to loosen tensioner again to get the bottom one.)
3. Remove nut on dipstick to remove coolant hard line. (follow hard line and remove second bolt near left side of the valve cover.)
4. Finagle alternator so you can remove wires attached to the back, and remove alternator (really tight but try different angles you'll get it. after removal knock the brass washers out a little bit, NOT ALOT!!
5. Remove throttle intake pipe.(band clamp on throttle body, bolt near the middle of pipe, an electrical connector that's in the way and clip on intercooler.)
6. Remove clamps and hoses on thermostat.(two normal clamps and a clip on the bottom. My bottom hose was so tight i had to remove lower radiator hose and have 2 people pull separate ways.)
7. Remove thermostat ( two bolts, very straight forward)
8. Reassembly ( do everything in reverse)
9. Fill coolant (fill reservoir to max line, let it sit a bit, fill again, let it sit...
10. Bleed cooling system ( start car let idle watch coolant keep up near max. Do this until car is fully at temp and the fans kick on. Turn off the car and let it sit a bit. Let aux pump run awhile.)
11. Watch your coolant level for the next couple days add as needed. Obviously not while it's hot!!! ( unless you like burns)
This is an outline probably missed a couple things but I'm on my phone so yeah...
When i did this it took a little while. Some very tight spaces to deal with, but if you are mechanically inclined and have some experience working on cars i think you'll be alright.
1. Remove serpentine belt. (get an adjustable wrench place it on tensioner, pull towards front of car to loosen belt.)
2. loosen 2 bolts on alternator. (don't remember size, but you'll need to loosen tensioner again to get the bottom one.)
3. Remove nut on dipstick to remove coolant hard line. (follow hard line and remove second bolt near left side of the valve cover.)
4. Finagle alternator so you can remove wires attached to the back, and remove alternator (really tight but try different angles you'll get it. after removal knock the brass washers out a little bit, NOT ALOT!!
5. Remove throttle intake pipe.(band clamp on throttle body, bolt near the middle of pipe, an electrical connector that's in the way and clip on intercooler.)
6. Remove clamps and hoses on thermostat.(two normal clamps and a clip on the bottom. My bottom hose was so tight i had to remove lower radiator hose and have 2 people pull separate ways.)
7. Remove thermostat ( two bolts, very straight forward)
8. Reassembly ( do everything in reverse)
9. Fill coolant (fill reservoir to max line, let it sit a bit, fill again, let it sit...
10. Bleed cooling system ( start car let idle watch coolant keep up near max. Do this until car is fully at temp and the fans kick on. Turn off the car and let it sit a bit. Let aux pump run awhile.)
11. Watch your coolant level for the next couple days add as needed. Obviously not while it's hot!!! ( unless you like burns)
This is an outline probably missed a couple things but I'm on my phone so yeah...
When i did this it took a little while. Some very tight spaces to deal with, but if you are mechanically inclined and have some experience working on cars i think you'll be alright.
mcpot
Slave to speed
- Location
- Mchenry IL
- Car(s)
- 07 GTI
In all honesty you'd probably be better off removing intake manifold and cleaning your valves at the same time. I really wish i had done that instead of fighting everything the way i did.
Natalie
Ready to race!
- Location
- Madison, WI
- Car(s)
- 2007 GTI
Did you have to pry on the alternator at all? I've got the 2 13mm bolts out and the wire clip detached but still sitting there. Pelican guide (http://www.pelicanparts.com/techarticles/Volkswagen_Golf_GTI_Mk_V/13-ELEC-How_to_Replace_Your_Alternator/13-ELEC-How_to_Replace_Your_Alternator.htm) talks about prying on the alternator to free it.
Nothing is moving and I feel like I'm missing something.
Goingnowherefast
Go Kart Champion
- Location
- Walled Lake, MI
Yes, it takes a lot to get the alternator free
Britishav8tor
Ready to race!
- Location
- Frederick MD.
So I have the same problem, engine takes a while to warm up then comes off 190 while going down hill or if the revs drop below 2500 for too long.
I noticed this also - it appears that my AC condenser fan has died even though it spin freely by hand, in turn (bad pun) the radiator fan runs at hurricane speed to make up for the little one not working. I dont know why but the even with the heat on the AC will run meaning the little fan should be running but because the big one is instead its over cooling the radiator and thus the engine. something to think about. When it gets up to a reasonable temp I will pull it apart and take a look and test the thermostat.
I noticed this also - it appears that my AC condenser fan has died even though it spin freely by hand, in turn (bad pun) the radiator fan runs at hurricane speed to make up for the little one not working. I dont know why but the even with the heat on the AC will run meaning the little fan should be running but because the big one is instead its over cooling the radiator and thus the engine. something to think about. When it gets up to a reasonable temp I will pull it apart and take a look and test the thermostat.
Natalie
Ready to race!
- Location
- Madison, WI
- Car(s)
- 2007 GTI
My needle never moved once the car was "warmed up." I had to log with vagcom to see the actual engine temperature. That's when I noticed it never got to 190F.
Sounds like the thermostat is one of your issues.
Athfar
New member
- Location
- Keller, TX
any trick to getting the alternator back on? ive brute forced and malleted for about 30mins and cant get the stupid thing back on. no clue why they made that thing so frickin' snug.
EDIT and CONCLUSION:
If anyone is on the fence on this job I'd say it's doable. I followed the Pelican guide (google MKV thermostat pelican) and went the route of taking the alternator off. It took me 4hrs, mostly spent getting the alternator off or on. Here's a couple notable things:
1. be sure to have pry bar set otherwise you wont get the alternator off
2. when removing the alternator there's two coolant lines, a metal one attached to the dipstick bracket and one attached to it that goes to the coolant reserve tank, i only removed the hose for the one attached to the dipstick and then pulled them over the intake manifold out of the way
3. before removing the alternator remove the two bolts at the top of the accessory belt tensioner then loosen the bottom bolt, the tensioner will then rotate out of the way so you can get the alternator out without as much fuss.
4. i found that a legit hose clamp remover (the tool with a brake cable) works so much easier than struggling with a pair of channel locks to get the clamps off.
5. get a hook and pick set, i'm baffled by all these folks complaining it took forever to take hoses off. i had zero trouble removing any hoses with the right tools (there's maybe 3 you remove in the whole process if you dont count charged air pipes which are very easy), the hardest was the bottom hose that you empty the fluid out of.
6. the bottom quick release hose on the thermostat WILL be stuck so just remove the thermostat sensor connector and undo the clip at the bottom of the car that holds the hose, this is the same hose you emptied the radiator with. the quick release mechanism DOES NOT TWIST so dont try that. you can pull the hose, coolant sensor and hose all out at together. once you get the hose with the thermostat attached out of the car it was still a beatdown the get the housing off the quick connect. i was able to get mine off in the sink, just keep pulling with hot water running down the crevice of the quick connect, its a rubber oring thats stuck.
6b. looking back i'd probably replace the termostat sensor housing and the sensor considering how stuck the oring was and how available the sensor is
7. the hardest part of the job for me was getting the dang alternator back on. i honestly have no idea how i got it back on, it involved alot of banging and wiggling. there really is no good place to pry or pull the thing into position. tools that were marginally helpful were an assortment of prybars, a hammer, some screwdrivers to bang on and a punch tool which i stuck in the alternator holes to wiggle and hammer the holes into alignment.
happy wrenching
EDIT and CONCLUSION:
If anyone is on the fence on this job I'd say it's doable. I followed the Pelican guide (google MKV thermostat pelican) and went the route of taking the alternator off. It took me 4hrs, mostly spent getting the alternator off or on. Here's a couple notable things:
1. be sure to have pry bar set otherwise you wont get the alternator off
2. when removing the alternator there's two coolant lines, a metal one attached to the dipstick bracket and one attached to it that goes to the coolant reserve tank, i only removed the hose for the one attached to the dipstick and then pulled them over the intake manifold out of the way
3. before removing the alternator remove the two bolts at the top of the accessory belt tensioner then loosen the bottom bolt, the tensioner will then rotate out of the way so you can get the alternator out without as much fuss.
4. i found that a legit hose clamp remover (the tool with a brake cable) works so much easier than struggling with a pair of channel locks to get the clamps off.
5. get a hook and pick set, i'm baffled by all these folks complaining it took forever to take hoses off. i had zero trouble removing any hoses with the right tools (there's maybe 3 you remove in the whole process if you dont count charged air pipes which are very easy), the hardest was the bottom hose that you empty the fluid out of.
6. the bottom quick release hose on the thermostat WILL be stuck so just remove the thermostat sensor connector and undo the clip at the bottom of the car that holds the hose, this is the same hose you emptied the radiator with. the quick release mechanism DOES NOT TWIST so dont try that. you can pull the hose, coolant sensor and hose all out at together. once you get the hose with the thermostat attached out of the car it was still a beatdown the get the housing off the quick connect. i was able to get mine off in the sink, just keep pulling with hot water running down the crevice of the quick connect, its a rubber oring thats stuck.
6b. looking back i'd probably replace the termostat sensor housing and the sensor considering how stuck the oring was and how available the sensor is
7. the hardest part of the job for me was getting the dang alternator back on. i honestly have no idea how i got it back on, it involved alot of banging and wiggling. there really is no good place to pry or pull the thing into position. tools that were marginally helpful were an assortment of prybars, a hammer, some screwdrivers to bang on and a punch tool which i stuck in the alternator holes to wiggle and hammer the holes into alignment.
happy wrenching
Last edited:
+1 for the Pelican DIY. The trick to getting the alternator back in is mentioned in Pelican's Alternator DIY! Place the alternator ear on a vice or hard surface to fully support the ear, then whack the steel insert with a hammer, just once was enough to make the outer dimension a wee bit smaller. It then goes in like a charm!