Thermostat Replacement - 1.4 TDI 75BHP 2002

jambost

jambost

Member
Hi,

So i've bought myself a new thermostat with the intention of changing it at the weekend, but before i go ahead can anyone tell me if the thermostat housing needs has a gasket that needs replaced before reattaching the housing to the engine ? I'm not sure if there is a gasket and really want to have all the parts handy when i do the job.

Cheers
Stuart
 
When I changed my stat on the TDI a few months ago I had the same thought, however I looked in the box for the new thermostat whilst still in the motor factors, there was a new O ring in the box - happy days
BTW it is bitch to get at, you certainly need to release the tension on the alternator belt, this was the biggest problem as the Hex cast into the bracket had been sheared off by previous attempt to release the belt tension. I ended up making a plate to hook in the bracket with a handle on it - worked a treat. You also need to drain a couple of litre of coolant from the bottom hose. I would say a 2 hour job, a little quicker if nothing goes wrong.
changing the stat sorted out my cool running issue

Cheers,
 
I think you can get away without messing with the belt if you use a wobbly socket. I'm sure that's what I did.
 
I've got a good selection of spanners and sockets, but I'm damned if I could get to the bottom bolt on the thermostat housing without removing the belt and Alternator bracket, I bow to greater knowledge if people have done it :)
 
depronman said:
I've got a good selection of spanners and sockets, but I'm damned if I could get to the bottom bolt on the thermostat housing without removing the belt and Alternator bracket, I bow to greater knowledge if people have done it :)
Click to expand...

On my car (2004 TDI 90) the bolts are dual drive with both an internal (Allen) 5mm hex key socket and an external 10mm hex head. I used a 5mm short Allen bit with a ring spanner on it to crack the bottom bolt then it turned easily. It is still fiddly, and I dropped the Allen bit and had to retrieve it with one of those magnetic pick-up tools. When refitting the bottom bolt, tie some cotton just under the head so you can retrieve it if you drop it. Then after it is a few turns in, break the cotton and discard it.


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On mine the bottom bolt was worn by somebody's previous attempts, so when I reassembled I put in the top hole & used the undamaged one at the bottom , this made reassembly easier & allows me the opportunity to replace with new when I next go to TPS, might be worth changing the temperature sensor as well while drained down .

Keith.


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Well i managed this job without having to remove the alternator or slacken the tension on the belt. Managed it with the smallest 1/4" drive 10mm shallow socket with a 1/4" ratchet wrench from halfrauds...bit fiddly putting the thing back on as i had to first put the bottom bolt in with my finger tips until it was sufficiently in far enough for me to get the socket back onto it.

Absolute pain in the rear to do and isn't helped when you drop a few items onto the engine tray !
 
Yeah, i had to replenish the system with almost a whole bottle of G12 1.5 Litres of coolant mixed in a 50/50 ratio with water.....
 
I tackled this job myself and replaced my sons tdi thermostat over the weekend as wouldnt go above 60 on the temp gauge although it did belt out plenty of heat from the interior fans, i undid the undertray fixings at the bumper and the 2 side ones and dropped the front of the undertray, then used an old 5L screen wash container with a large hole cut in one side , i positioned under the lowest rad pipe under the temp sender which i pulled the plastic clip off and drained the coolant from hear , squishing hoses to get a good 3Liters of coolant out, i then removed the alternator belt and removed the 3 bolts holding the tensioner, you can then get at the top alternator bolt, after removing the bolt i slackened the lower bolt and with a slight lever i pivited the alternator forward, this gave anough room to get a 3/8 ratchet and 10mm socket onto the lower thermostat housing bolt , after replacing the thermostat and rebuilding in the reverse order i then reused the coolant id captured as looked clean to me and had no G12 to hand, and i was not 100% sure it was the thermostat, so could of been draining the coolant again, as theres also 2 temp senders that could also be at fault.. one on the lower rad pipe and one at the back of the engine under the vacume pump, but after a good run around everythings as it should be and goes up to 90 now within 5 miles id say ..
 
Prity much identical symptoms as mine was exhibiting, also the same fix (£4 from Euro including the O ring), I also removed the alternator to gain access to the lower thermostat housing bolt (I accept that some people seem able to remove/refit the lower bolt without removing the alternator, but for the life of me I can't figure out how it is done)
 
tried and failed today using a wobble joint on the 1/4inch socket, even shortened the socket!
tried a hinged racket spanner and still no joy
allen key wasn't working either

went to halfords and got some of the ratchet spanner adapters to try in the morning...
 
Did mine yesterday - my engine ran at 80 degrees at best. I also replaced the short plastic pipe that covers the thermostat.

I shortened a 10mm socket to reach and loosen the lower bolt. After that I used a standard L-shape allen key with rounded end (I also have the "dual drive" bolts).
Half way out, I tied the cotton under the head and the other end to the car. Putting the bolt back in is easily done with small plyers: grab the bolt by the ring on one side so it sits under 45 degrees in the plyers) and push in and turn using the allen key.

Some 2..3 litres of coolant pour out once you remove the old thermostat - I didn't remove the underguard but jacked up the car on one side so the coolant drips on the other side and little is spoiled (I reused most of it after filtering with a tea strainer).

My engine (as reported by the G62 sensor) now runs at a healthy 90 degrees.
 
So i did the job too (that time of year i guess!)

i tried shortening a socket but i just still couldn't get it to work out for me, the bolt was at the wrong angle maybe or the ratchet was slightly too bulky maybe? either way....

i went to halfords and brought the adaptor set that fits ratchet spanners, you ideally really need the flexi head ones.... and the kit costs £10 odd if i recall (forget if that was before or after trade card) and the ratchet spanners aren't that cheap so unless you really want them, maybe borrow off a friend ect or the job will cost you £60 in tools plus parts!

i got a genuine VW thermostat off eBay with an O ring for £20 delivered, stamped VW and Audi ect. which was cheaper then my local dealer with discount.

also notice i have cut this 10mm socket down which was my first attempt using a socket and wobble bit that failed



that lets you get down there (note the bend on the ratchet head is needed i think)



another view



so got that out and lost a little coolant from the plastic pipe, at first it wouldn't only come out 5mm, you need to fish out the O ring which is normally stuck in there holding the thermostat in place and the stat is sort of held in the black elbow.... i just pulled the elbow in the end and it came away, then removed the stat from the block and about 3 litres of coolant came out.

on refinement, ideally new O ring, and carefully note how the stat is located in the engine orientation wise.

it sits in the elbow and is locked in by turning 90 degrees, then the two get put back on the engine as one, and two bolts snugged up.

i then refilled with water and checked for leaks and a bleed drive ect, and it gave my 90 degrees temps finally!



i then drained the coolant and filled with G13 from VW and all has been well since.
 
I've just changed my thermostat and as everyone pointed out the bottom bolt is a tad tricky so i invented a tool see pic
2ddbc9263955ffce802f9eebec5817d3.jpg


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I need to sort mine as well. I thought that I'd be able to do it this afternoon but I failed at the first hurdle. How do you get the car high enough in the air to remove the undertray? The car is new to me so I'm keen to be as thorough as possible once I've got the cover off so that I can check other things out whilst I'm there. It's been so long since I've removed the cover from an A2 that I've forgotten where to start. Please help.

Pete
 
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