Thermostat sticking?

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K2edg
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Posts: 121
Joined: Sat Mar 26, 2011 12:00 pm
Passat model: B5 TDI

Thermostat sticking?

Post by K2edg »

Hi all,

Sorry for putting yet another Thermostat question up but after spending a day searching i've not found an answer to my problem.

Ok, so i have a 1999 B5 Passat TDI (AFN) and it seems to be going through a Thermostat every couple of months so am thinking there is an underlying issue.

I have tried a few different manufactures (including OEM) but what happens is the car doesn't warm up (the needle just comes out of the first box on the temp gauge), so i fit a new Thermostat and it works fine for a month or so (about 800 miles of driving) and then all of a sudden it stops heating up properly again.

I did think it might be the wrong antifreeze so bought the G12 direct from VW, the Temp sender is about six months old (genuine OEM), i've fitted a brand new OEM Water pump in November, i replaced the plastic elbow too and it still kills Thermostats....... The odd thing is when i remove the old one it looks closed and in decent condition (tried the pan of water trick and it looked like it was working fine) but then the new one works properly from day one so there must be a fault?

It is starting to bug me a bit now, it does make a slight difference to the MPG (40mpg v's 47mpg) but the main problem is if i drive my car for more than a week or so while it's running cool it starts to soot up the Turbo vanes, which in turn starts to trip out into limp mode every time i get into the higher rev range.

Has anyone come across this before? or can anyone give me a pointer as what i should be looking for? i did ask at the VW dealer and of course they said bad Thermostat!! so they have exchanged the oem one i bought from them once already and that one has now started playing up a Month later :(

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