TDI 90 service help/ tips wanted please!

Audied

Member
Hi all about to service my son's car and wanted to know any tips, tools needed etc for the job . Doing oil, oil filter and air filter.
Can't find a haynes manual, is there something similar? Sorry if it's been asked thousands of times, did have a search on here.
Any advice welcome
Thanks
 

froggy

Member
Going off the 75 tdi (which should be the same in this respect?) you will need a 36mm impact socket for the oil filter, the air filter is under the bumper, front right. OEM, Bosch or Mann are what I use. I think you will need a Torx bit to remove the old air filter. I would use a new sump nut and washer (19mm socket required I think) and recommend 5/30 good quality oil. Lots of how to guides on this amazing site - quickest way is to google something like “a2oc tdi 90 oil service” which will bring up more information 👍
 
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A2Steve

Member
Air filter housing is a cross head screwdriver, but the screws are normally rusted so use the outer 8mm bolt head to remove. Make sure the tab on the removable filter housing goes back into it's slot so you don't suck water.

To get to the oil filter you will need to remove the top fibrous engine cover (3 x 10mm nuts) and then a 36mm socket to remove the oil filter housing cover.

The whole job is very simple, removing the underguard/undertray is the hardest part and that's just time consuming.
 

Audied

Member
Thank you both! I've ordered the big socket, would never have thought of that before I started! so air filter is removed from under car? I presume the undertray will be a pain to remove too
 

froggy

Member
Thank you both! I've ordered the big socket, would never have thought of that before I started! so air filter is removed from under car? I presume the undertray will be a pain to remove too
It depends on how carefully the car was serviced in the past - some cars are even running without, very bad idea! If its been ripped off and cable tied then it could be simple to remove. In this case however, you want it to be difficult as its a crucial part of good running. Lots of torx screws to remove are a pain, but if they are there, it’s a good sign for the car. I did say front right for the air filter location, this is if you are facing the car. For clarity, driver’s side for RHD cars.

Post in thread 'Where is the air filter on the Tdi?'
https://www.a2oc.net/community/inde...s-the-air-filter-on-the-tdi.18745/post-143698
 

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dj_efk

A2OC Donor
My additions:

Look up carefully where you can / cannot jack the car without doing damage to the aluminium shell. Better still would be to use a pair of drive on ramps.

While you’re under it, give the suspension lower arms a good poke with something like a stout screwdriver - they rust out eventually!

Any 507 spec oil will do, search my thread on this but the headline is Mannol 7715 is VAG approved and very cheap. You may choose to buy something more expensive but there’s really no need, especially if you change it regularly

Remove the oil filter before the sump plug, but first check the sump nut will actually loosen off OK (so you aren’t forced to install a new filter and then have the old dirty oil run through it because the sump plug won’t budge and you need the car working and don’t have the time / tools to sort it). You want to remove the filter first because there is a good few hundred ml of oil in the filter housing that will partly drain into the sump once you remove the filter, so you want to give it the time for this to happen.

You can buy a magnetic sump plug replacement from gold plugs (Opie oils sell them, they are the same for all 1.4 and 1.9 TDi PD engines) - first time I dropped the oil on Audrey with this fitted a hedgehog of metal swarf was stuck to it so well worth it.

You may find some of the engine tray torx bolts missing, you can buy them from eBay in packs of 10

Another important point to check while the engine tray is off - carefully inspect the alloy metal boost pipe that runs along the side of the sump and it’s clip! See my warning thread on this, this part is unique to the 90 model and unavailable new - so if yours is wearing you need to take action before it gets punctured / worn through.

It may be worth buy a new OE dipstick from @CreweAudi wjile they’re still available new for £13 plus postage, for when (not if) yours will break!

Good luck
 
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Audied

Member
It depends on how carefully the car was serviced in the past - some cars are even running without, very bad idea! If its been ripped off and cable tied then it could be simple to remove. In this case however, you want it to be difficult as its a crucial part of good running. Lots of torx screws to remove are a pain, but if they are there, it’s a good sign for the car. I did say front right for the air filter location, this is if you are facing the car. For clarity, driver’s side for RHD cars.

Post in thread 'Where is the air filter on the Tdi?'
https://www.a2oc.net/community/inde...s-the-air-filter-on-the-tdi.18745/post-143698
Thanks mate, why is it bad to not have an undertray though?
 

Audied

Member
My additions:

Look up carefully where you can / cannot jack the car without doing damage to the aluminium shell.

While you’re under it, give the suspension lower arms a good poke with something like a stout screwdriver - they rust out eventually!

Any 507 spec oil will do, search my thread on this but the headline is Mannol 7715 is VAG approved and very cheap. You may choose to buy something more expensive but there’s really no need, especially if you change it regularly

Remove the oil filter first after having first checked the sump nut will loosen off OK (just in case / so you don’t have to install a new filter without changing the oil if not and you don’t have the time / tools to sort it). This is because there is a good few hundred ml of oil in the filter housing that will partly drain into the sump once you remove the filter. You can buy a magnetic sump plug replacement from gold plugs (Opie oils sell them, they are the same for all 1.4 and 1.9 TDi PD engines) - first time I dropped the oil on Audrey with this fitted a hedgehog of metal swarf was stuck to it so well worth it.

You may find some of the engine tray torx bolts missing, you can buy them from eBay in packs of 10

Another important point to check while the engine tray is off - carefully inspect the alloy metal boost pipe that runs along the side of the sump and it’s clip! See my warning thread on this, this part is unique to the 90 model and unavailable new.

It may be worth buy a new OE dipstick from @CreweAudi wjile they’re still available new for £13 plus postage, for when (not if) yours will break!

Good luck
Thank you!
 

audifan

A2OC Donor
The undertray serves several purposes. It is structural in that it ties the bumper to the chassis and to the wheel arch liners. It deadens sound. It aids regulating the engine temperature. It keeps road dirt, water and salt off the lower engine area. It protects the engine from damage caused by ground contact. It smooths the air under the car. It makes it harder for animals to get into the engine bay!!!

Audi would not have spent time and money developing it otherwise.
 

dj_efk

A2OC Donor
The undertray serves several purposes. It is structural in that it ties the bumper to the chassis and to the wheel arch liners. It deadens sound. It aids regulating the engine temperature. It keeps road dirt, water and salt off the lower engine area. It protects the engine from damage caused by ground contact. It smooths the air under the car. It makes it harder for animals to get into the engine bay!!!

Audi would not have spent time and money developing it otherwise.
It also lowers the drag coefficient of the car and is therefore key to achieving the best possible fuel economy too.
 

Audied

Member
Hi
Is this the bracket mentioned above? It's broken off, even though it looks ok.
Also it's very oily around this pipe, in other picture. What is it please?
Thank you again for all your help 👍⭐
 

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