new mk5 owner

[mjmallia]

in-line stat PN is 4E0 121 113

[ZoliWorks]

I'll get under my car again and check. What exactly does the inline thermostat do? I've changed the other one since my car was cooling down to 50 degrees when driving at highway speeds but when it comes to heating up, if I idle for 7 minutes or drive for 3, it's already at 90 degrees.

[mjmallia]

My understanding of it, is that it allows the turbo to warm up quicker and or the DSG box if you have one, but when they are stuck open it cools the car quicker as everything is free flowing............or if stuck closed overheats.

They are more prone to failing than the main one and often overlooked.

[ZoliWorks]

Alright, checked today as I was changing my coolant. I only have the main thermostat, no inline thermostat behind the AC unit or on-top of the gearbox. Car is a 2006 BWA. Looked on the forums a bit and saw that 2006 was when they stopped putting 2 thermostats on manuals and 3 on automatics. 2006+ manuals have only the main thermostat while automatics get an inline thermostat on-top of the gearbox.

[mjmallia]

On my ETKA the GTI up to 2007 had the inline.  Below is a Golf BWA 2006.  The Octavia BWA 2006 has the later Golf 2008 layout weirdly




Near the end of the Mk5 GTI era 2008 it changed the plumbing

[mjmallia]

Comparing the years  (ignore the additional cooler that was available hot hotter climates ) they simplified the system near the end, so you have given me a new project to replumb the car to the newer layout 

It will get rid of the inline and stop me replacing it every couple of years 

[ZoliWorks]

Lol sounds like a worthwhile project tbh, good luck my guy!

I guess it would make sense for them to use the later designs for the Octavia, Jetta and others, considering that these entered production after the GTI.

[lazy]

Update number 2.
The timing belt is mostly done just need to put the second part of the engine mount back and header tank. I really struggled removing and refitting the engine mount to the block. The bottom cover was in the way, so I had to undo the mount, leave it floating and then remove the cover, which wouldn't be too bad if It wasn't for the top back torx bolt on the cover, getting that bolt back in was not fun at all (lots of swearing  ).
So while I had room with the engine not secured to the chassis I thought it would be a good time to do the thermostat. I've only got the big one at the minute so thought I might as well do it. I would have liked to have done the inline ones first to see if that would have sorted it and save some work as well. I spotted the one on top of the gearbox easily, but couldn't see the other inline one at all. I will have a proper look later once I get the turbo pipe out of the way.

With regards to my oil leak, there's pools of oil on top of the gearbox and quite a lot blown back under the car, but around the PCV looks dry and around the vac pump looks fairly dry. So I'm wondering if the leak has been fixed and they just didn't clean leaked oil away.
I think my first course of action is to clean it all off and then see if I can spot where it's coming from properly.

Again many thanks to everyone for all the input.

[lazy]

Update number 3
Timing belt and waterpump finished and big thermostat fitted yesterday. I haven't been for a test drive yet but I don't think there was anything wrong with the thermostat it didn't look like it was stuck open, unless it's opening too early. I'm 99% positive that I haven't got the inline one behind the alternator. My car is 2006 with engine code BWA. When I phoned TPS back she could only find one other thermostat but she didn't know where it went and I can definitely see one above the gearbox. Ordered it £47 thought the price was a bit steep for what it is, so I looked on eBay and bought a Febi Bilstein one for £12 all the rest were about £25 so had a bit of luck there. So going back to the date and engine code it seems like it could be random as to how many thermostats it's got or could be location specific.
I probably won't get to drive it now until Monday which is quite disappointing after putting all that work in.

[lazy]

Update number 4
The big thermostat fixed the running cold issue. I've been using the car since Monday and so far I'm happy. The only thing I might not be happy with is fuel consumption, it's just so tempting to put your foot down all the time 

[ZoliWorks]

These things eat a lot, that's for sure. On my 1.4 75hp golf 4 I could go to university and back for a week on 20 euros worth of fuel. In the jetta? just 2 days..

[lazy]

We'll have to learn to press the pedal a bit gentler.