Ok, have bought a 1999 TDi 110 Octavia (130k) which had one honest owner from new, though not sure about the service history as although he took it regularly to his brother at a local garage to have it serviced, he didn't actually keep a record of what was done...

So, symptoms:

1, instrument needles don't work

2, trouble starting when warm

3, 40 mpg with normal driving and possibly a sign of a little black smoke, though hard to see in the wing mirror

4, runs cool even on motorways and hills

Having read and read the forums I just want to check with you guys that the initial, and cheap fixes to the above are:

1, remove fuse 15 and say goodbye to the clock, but have my speedo/rev counter back

2, grease up my starter motor gearing

3/4, replace lambda sensor and fuel temp sensor

Any other ideas? My budget is minimal but I have a haynes manual and a reasonable amount of experience in the garage (lots of old cars and motorbikes)

Not a single response?! Come on, I might be a newbie but I do hope to be able to share my own experiences in return, once I have them :-)

Sounds like it needs a new thermostat aswel to cure the cool running.

I wouldn't bother with the starter motor, you only need to grease the gears in it if it's screeching when you try and start it.

The temp problems definately sound like either the temp sensor or thermostat have given up the ghost, the Haynes manual is pretty good at explaining how to change them, the one piece of advice I would give is use genuine OEM parts, I had similar problems with my 1.8T petrol and fitted pattern parts and it started playing up again within a few days, my local garage had a look at it as I told them I'd changed the sensor and stat and they put on a genuine VAG sensor and that cured it! :(

Edited 21 April, 201016 yr by chicken_eyebrow

I wouldn't bother with the starter motor, you only need to grease the gears in it if it's screeching when you try and start it...

Not so.

Almost every old VAG starter motor will run faster if the planetary gears and motor bushings are cleaned and then greased.

Running slower (than new) and 'the screech' are different problems.

The bendix gear is usually the cause of the screech but does not affect motor speed.

Having said this the most likely culprit is the battery. If may still test as being good, but may not be good enough to reach 260rpm.

take a look at post #7 in the link below

http://briskoda.net/forums/topic/139926-tdi-hot-starting-problem/

1, instrument needles don't work

2, trouble starting when warm

3, 40 mpg with normal driving and possibly a sign of a little black smoke, though hard to see in the wing mirror

4, runs cool even on motorways and hills

2 could be the battery or the starter, when warm the ecu doesn't start injecting fuel until the engines turning over at 250rpm, so elderly battery could also be the problem.

3 do you know if the MAF has been replaced at all? Also what about the coolant temp sensor? - does the diesel even have a lambda sensor?

4 does sound like the thermostat, if it was jammed open then cool running on the motorway isn't a surprise.

would be worth getting any error codes checked

Also the EGR valve and inlet manifold probably look like tar has been poured in and the injectors may be a bit tired after 130k.

Edited 21 April, 201016 yr by trundlenut

Thanks guys, you have given me a few more things to investigate. I will add a MAF to the list as I don't know if it was changed. The guy who owned the car before me looked after it in so much as he drove it carefully and cleaned it regularly, he also ensured it had an oil change every 5000 miles. But regarding everything else, I think he just put up with it and carried on, whereas I want to get it back to the efficient reliable motor it should be :-)

1, instrument needles don't work

2, trouble starting when warm

3, 40 mpg with normal driving and possibly a sign of a little black smoke, though hard to see in the wing mirror

4, runs cool even on motorways and hills

Not sure on 1 and 2 but 3 sounds like MAF, especially if original as mixture is rich, Faulty temp sensor could be a result of symptoms of no 4, resulting in in issues experienced in no.3 as ECU thinks engine is too cold and causing overfuelling resulting in poor fuel consumption!! (should easily be 50+mpg)

I would get scan done on VCDS first as it will be able to identify the faults above before going off to the dealers or TPS. The MAF and temp sensor combined will be under £100 and very easy to fit DIY.

Keep us posted on how you get on!

Good luck!

Dan

I would get scan done on VCDS first as it will be able to identify the faults above before going off to the dealers or TPS. The MAF and temp sensor combined will be under £100 and very easy to fit DIY.

Keep us posted on how you get on!

Good luck!

Dan

Thanks Dan, how much does the scan usually cost? Does it do anything other than scan, does it 'fix' anything?

when warm the ecu doesn't start injecting fuel until the engines turning over at 250rpm, so elderly battery could also be the problem.

this is a very interesting point which I wasn't aware of until recently - my local VAG specialist was replacing a starter on a TDi Golf that I'd looked at and said it would solve warm starting problem (although he couldn't explain why). Disconnecting the coolant sensor made the warm engine start instantly every time, and I couldn't understand how changing the starter would fix the problem, as it "seemed" to be turning over fine. Disconnecting the sensor makes it appear as if it's cold so presumably the minimum 250rpm cranking speed doesn't then apply.

Do you have any links to more information on this? Or is it just "one of those things" that experience discovers?

Cheers

Rich

Ok, MAF is the old one, so will be fitting a new one this week - see if that improves my mpg :-)

Managed to get my genuine 038906461C MAF from a trade parts specialist for £55, dancer! A mate is bringing it out to Spain with him tomorrow (where I live, near Barcelona), to buy the part from Skoda here would have cost €140! Will fit and see if it improves my mpg.

Out of interest, how accurate do you find the fuel economy gauge in the Octy? I calculated around 40mpg on my tank at the pump, but my guage said I got over 45...

MAF fitted, can feel better performance, have filled her up and will let you know on the economy when empty (hopefully not too soon )