Engine temp and excess fuel use????

9

985J

Member
I have a 2002 A2 1.4Tdi Sport, high mileage but regularly serviced. Tyres are 185/60/R16, pressures F 30 rear 28
Recently I have seen more fuel use for same average weekly use, sluggish engine/acceleration, dash temp gauge does not rise above 65oC and sometimes stays at 60 oc.
Trying to get my head around posts re sender/thermostat faults, on the info I give please can someone direct me a to what part(s) I should be looking at?, where can I get non dealer part if possible?, and is it a DIY job?

Always greatful for advice

J.
 
Typical of failed open thermostat
10-20£ depending on source
Prefer genuine parts personally
NOS available

Fairly sure a search on forum will detail changing procedure covered previously
More fiddly than difficult

10mm spanner / socket and 1/4 ratchet ideally

Plastic housing on front of block has two small retaining tabs internally that are delicate but not essential for refitting if they fail
 
90% thermostat fault 10% sender fault. Not expensive just buy OEM equivalent items, as patern parts are known to cause problems and are frequently faulty on installation. Bit of a messy job are you will spill coolant when you disconnect the hoses or sensor. So before you disconnect cover as muck of the engine and alternator with plastic sheeting ( bin bags ). Buy a spare clip for the sensor and tie string or fishing wire around the old one and tug with pliers to remove, sensor normally pops out on its own along with coolant, just make sure the old seal comes out. Refit now sensor is reverse, lubricate the o ring and fit with sensor, again either reuse old clip with the string or tie to new clip and fit. You have been warned you WILL spend ages trying to find where it went when it drops. New thermostat, bottom bolt awkward but look at my thread on fastest way to change, get the correct stat and o ring, twist it into the housing then fit housing to block. Tighten everything up reconnect wiring and refill the coolant with the correct ONLY G12-G13 coolant. Leave the cap off and run the engine until 90 looking for leaks. Switch off let cool and recheck level. Top up as needed, fit cap and take the car for a 20 minute run to get fully up to temperature. Gauge should read 90 when car warmed up. Turn off and again check the level.
 
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Sounds very like thermostat. Eurocarparts are doing their Circoli thermostat for just over £6 quid this week - I used one last year and it was a transformation, and about 10% of the cost of an official VAG one.

As WT2 above has said, you need a 10mm spanner. Ideally - a 10mm ratchet spanner, with an angle on the ratchet end, a shallow depth socket adapter that goes into the 10mm ratchet, and a set of ball-head long reach allen keys - collectively these will allow you to undo the bolts holding the thermostat housing onto the block in the confined space next to the alternator. You need to remove the engine acoustic cover, and then the boost pipe that goes over this area, then if possible, remove the coolant hose from the thermostat housing - however, this is not essential because I found the pipe clamps were angled such that normal tools wouldn't undo them. Instead, I just undid the housing from the block and pulled it off, breaking the thermostat-installation-retaining-tabs mentioned above, then got out the old o-ring and thermostat, then put in the new ones, then put the housing and hose back on. Finally, refilled coolant circuit, bled, and sorted it out.

Edit - I had a lot of helpful advice from @audifan above in the run up to doing the stat and the temp sensor replacement myself this time last year - take everything mentioned above seriously because I am much sketchier on details than he is. It's not rocket science, but as long as you do it carefully and processively you should be o.k.

If you need more advice, please come back. Best, Robin
 
I don't like the circoli ones, they don't seem to maintain temperature properly. The quality doesn't seem that good. I got a febi bilstein one for a tenner that works much better.
 
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I have a very limited sample size of 1 Circoli (and soon to be a second once fitted) - my one has been o.k in the last year and certainly better than a knackered original. I do agree though, for most things I buy Febi because they are good quality, so I'm not going to disagree with you on that point.
 
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Mine was a sender fault, I believe the ecu was getting the correct info but the gauge was not.
I cant remember if I was able to see the ecu water temp before I changed the sender, but certainly saw the figure that correlated with the gauge after.
 
You can verify the coolant temp sensor's ECU feed by looking at the engine ECU's measurement blocks, whereas the gauge feed is in the dashboard ECU's measurement blocks. My one was the dash side (there was also an error code in the dashboard for the temp sensor, intermittent / sporadic open to earth, which corresponded to the on/off nature of the temp readings once I had replaced the dud thermostat). This then went once I replaced the coolant temp sensor.
 
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I have changed mine as well today after reading so many posts about it and getting paranoid.

Any idea what the extra gaskets are for ? I only used the O ring that came with the kit as that was all that was installed originally.

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