80 Cabriolet Tdi conversion

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

92 2.3 cab bought on ebay with engine problems. No problem, I have a 93 80tdi (1Z engine) and enthusiasm (for the time being!!)

The 80 Tdi was my friends parents car, who used it for many years before getting another car. They kept the 80 as a farm runabout to go between two farms on a private road (no mot, red diesel). They stopped using the car when it developed starting problems, then sat gathering cobwebs for a few years.

I got the car last year then had a look at the starting problems!! The car would turn over and fire, though would only run for a second before stopping!
No problems, a new fuel filter then tickety boo!! Err,,no! Oh well... Gallon can of diesel and hose into filter head then surely....

No....

Top of inj pump to have a look. Nothing amiss though NO!!

Eventually traced it to the cat being full of soot!! The car was only driven for 1/2 a mile 4 times a day so wouldn't heat up enough to get the cat warm, or fast enough to blast the soot out the exhaust!!

The cab seems to have a very sound body with only a bit of rust on the front drivers wing. It seems to have been waxoyled lots of times and the chassis is solid.

I dont know too much about the cabs and i will have a few things to sort out (hopefully with the help of the forum)

Cheers Jim

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

So where have I got to?

Tdi! Engine out, dashboard out. Engine and radiator wiring looms removed (with a few choice words!!). Photos taken of the wiring to help. Didnt take photos of the engine removal cause I thought I'd remember.

Starting to take the 2.3 out of the cab.

Took out the petrol tank to see about the hose layout. There seems to be 2 delivery hoses at the bottom of the tank. Does anyone know which one would be the best to use for a diesel. (I will prob use the large hose unless advised otherwise)

Another difference seem to be the driveshafts! I was hoping the driveshafts would just bolt onto the diesel gearbox.

Back to the grindstone,,, or was it the angle grinder.

Cheers
Jim

Posted: Sun Dec 11, 2011 10:27 am

You need to use both lines for the diesel. One is a return and one is the feed. The transfer pump built into the main injector fuel pump, pumps at a constant rate. From memory once the body of the pump is full and pressurised the excess fuel spills back to the tank.

Post your pictures up ...this is one I hope to copy at some point in my life
Smile

Pic below is the diesel plumbing on the diesel cab.(identical to the audi 80 far as I can see.)

Posted: Sun Dec 11, 2011 10:33 am

Remember that you need to change the fuel tank from a narrow neck petrol one to a wide neck diesel one.Although it might be an insert that makes the diameter change. The part numbers for the diesel and petrol tank are different.

Unfortunately the Audi 80 saloon is a completely different tank shape . The filler neck is the only reason I can think of a difference.

PS I notice that the fuel level sender is different revision between diesel and petrol. Dont think its show stopping. The only other difference is the breather pipe which goes to the activated carbon canister on the petrol. Can probably just delete that bit and leave a drip tube.

The petrol fuel pump and accumulator can be deleted.

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

Hi, don't think the fuel tank is going to be the problem with this change! I think a screwdriver will sort the filler neck! There's a wee bit of plastic that reduces the diameter so.......

About the fuel lines, there are 2 coming out of the bottom of the tank (that's why petrols use more fuel Wink

) and a return going in the top! The two delivery hoses on the bottom are different diameter(large going to electric pump and filter, smaller onto a metal pipe to the front) There are also a couple of hoses on the top of the tank which I think will act as vents when you fill as the tank is shallow in the middle because of the ski hole thingy!!

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

A couple of photos of most of the interior before it came out!!

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

Next onto the interior of the cab! the interior of the tdi got kinda savaged to get to the wiring harnesses, though I took care to get the soundproofing that was around the trans tunnel/ bulkhead area out intact. If it fits I will try to put it in when rebuilding. I took care removing the interior of the cab because I'd like to keep it half decent when it goes back together!!

I did however have a problem taking out the footrest on the tunnel as I savaged it Sad

ho hum...

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

Engine out!!

Posted: Sun Dec 11, 2011 9:33 pm

Way cool. Keep the photos coming!! Cool

The wiring harness is going to be interesting.I had hoped it could be done without taking the dash out.

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

Possibly could have left the dash in though think i've problems with the wiring!! I put the diesel engine/ heater looms in and there are loom plug problems! Sad

the tdi has 3 electrical connections on the pedals! the cab only has 1 for the brake light switch, the tdi has 2 switches on the brake pedal and one on the clutch!! I've already taken out the pedal box to put in the diesel one because of the fly by wire on the tdi. the fly by wire is no prob because it just plugs into the diesel loom! The problem is the additional wiring for the other pedal switches!!

The options are to:
remove the cab switchgear wiring and replace with the tdi switchgear wiring
see if it is possible to remove the tdi wiring required and piggy back it onto the cab loom

Anyone got any wiring diagrams to help?

HHEEELLLLPPPP Shocked

Posted: Wed Dec 14, 2011 8:34 pm

Unfortunately the wiring diagrams that are on-line are all for the petrol cabriolet and petrol 80.

http://www.isham-research.co.uk/quattro/wiring/TypB4/

http://www.autolib.diakom.ru/CAR/Audi/1997/Cabriolet/SYSTEM%20WIRING%20DIAGRAMS/

I have a set of the Audi 80 wiring diagrams which covers the TDI but will need to check if it covers past 1993 and need to find a scanner.

There is a good VAG overview of the TDI system showing all the input signals for the TDI somewhere on line (cannot find it at the moment) it includes the clutch and brake switches - You will need these.

Posted: Wed Dec 14, 2011 9:05 pm

There is an english version of this document somewhere on the net but I cannot find it. The german version is better than nothing.

http://www.volkspage.net/technik/ssp/ssp/SSP_153.PDF

I have pulled the OEM wiring diagrams and will get them scanned tomorrow. They are Audi 80 Edition 06.93 for the 1Z . The aux panel under the dash looks a bit different from your picture but I will scan and let you decode.

PS - found it in English!

http://www.haywood-sullivan.com/vanagon/TDI/tdi-technik-eng.pdf

Site Moderator Joined: Jan 31, 2003 Posts: 9144

I've got loads of TDi wiring diagrams.

Which ones are you after ? Engine, instruments ? What else

Posted: Thu Dec 15, 2011 1:13 pm

Here is a starter for ten.

http://homepage.ntlworld.com/c.caldow/cabriolet/dieselconv/TDIcurrent.pdf

Mike are there actual Cabriolet wiring diagrams or are they always Audi 80? would love to get the cabriolet ones!!

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

Sorry bout the silence at the moment! There's a chunky guy in a red suit coming our way in a couple of days and he seems to take up a lot of time!!

I am having a go at the wiring when I get a chance. I had to take out the petrol dash loom and am adding in the extra wires from the petrol cab loom( front fogs,cigarette light er extension etc. I've also got a hold of an air-con set up from a v6 coupe so......... if anyone has any pics of an 80 tdi with air con I could do with any info, or even any 80 with air con. I could do with measurements of where i need to cut out the bulkhead for the cooling pipes

cheers,

(hammer and chisel in hand)

Jim

Site Moderator Joined: Jan 31, 2003 Posts: 9144

Hi,

Yes, there are some specific cabriolet wiring diagrams. There are also saloon and Coupe ones also and they're always slightly different

I've been adding a few extra diagrams to the s2 site lately.

I'll add a seperate page shortly. Won't be long

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

Where am I at now?

Given up on electrics for a bit, thought I'd have a look at the engine!

Read on the forum to have a look at the inlet manifold and Shock

Don't know how many horses have been throttled trying to get into the cylinders!!

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

No rest for the wicked!

Out with the valves, out with the gunge, out with the drill and grinding paste!

Might as well do it before the engine is in situ.

Anyway the bores look like new, so for a few bob its peace of mind!

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

More pics of the head
new stem seals used

Can't put the camshaft on because I forgot to get a new end seal!!

Back to the wiring then!!

Posted: Sun Jan 01, 2012 11:27 pm

Unbelievable! I have had two tdi both up to 200k. The one I have at the moment runs on veg oil and the power is excellent, but the EGR must be depositing the same gunk in the inlet. The turbo must squeeze the air past the gunk... but clearly your going to get way more power out the engine once its cleaned.

keep the photos coming Very Happy

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

Nothing spectacular today!
Finally converted the petrol tank into a diesel one.......with a screwdriver. Petrol tank has a green bit of plastic in it that stops the larger diameter diesel delivery pipe go in. If anyone has the parts diagram for the diesel cab fuel tank could they post it up to I see how it should be compared with how this one will Wink

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

I've looked at this for a while now...... and to be honest I don't know what it is!! Think I'm going to get a Homer Simpson Doh!!!

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

Help needed!!
On the Cab the roof open warning lamp is in the same position as the heater plug warning lamp of the tdi!!. As I am going to use the tdi clocks and warning lamp cluster, does anyone know if it would be possible to re position the roof open warning lamp to a spare position on the tdi cluster (ie cut out the roof open symbol from the cab warning symbol board then stick it onto the tdi's. I'd then need to find the roof open wire on the cab loom then get it to the new place on the tdis (I think I understand what I'm trying to do)) . If anyone has the cab wiring it would be appreciated.

Site Moderator Joined: Jan 31, 2003 Posts: 9144

Good timing as I've just uploaded some wiring diagrams for the cab online.

http://s2-audi.co.uk/workshop/schematics/cabriolet/cabby.htm

Currently only the automatic roof is indexed. Just need to create the files for the rest

Posted: Tue Jan 03, 2012 10:14 pm

The roof pump normally goes there. If its a manual roof then they install a dummy part which acts as a crash absorber. (I think)

Posted: Tue Jan 03, 2012 11:10 pm

This is a difficult one. Think the lamps get there power off the circuit board so difficult to rewire. The main printed circuit board for clocks seems to be the same between the petrol cab 4 cylinder and the diesel cab 4 cylinder. But you need to check you model years and if they are VDO. The Rev counter is different diesel to petrol as is the card with the light symbols on it. Is your original cab a six cylinder as it has a CAT warning light? - this has a different circuit board

My initial reaction was to use the cab clocks and dump the glow plug light. You hardly ever need to watch the glow plug light as its such a good starter. The only issue is that some audi 80 TDI were fitted with a water detector in the fuel filter which flashes the glow plug light. Its important as the older pumps are very sensitive to water and very expensive to replace. You can see the wires on this diagram at the bottom of the fuel filter. If this was not fitted to the original 80 TDI then I would not worry about it.

Think all these lights are an added complication that do not stop the car running.

Posted: Tue Jan 03, 2012 11:14 pm

The tanks the same drawing diesel to petrol but the part number 1 for the tank changes revision.

Site Moderator Joined: Jan 31, 2003 Posts: 9144

I've uploaded a load more wiring diagrams for the cab.

http://s2-audi.co.uk/workshop/schematics/cabriolet/cabby.htm

Click each image for the full size version

Audi Nut Joined: Dec 01, 2011 Posts: 96 Location: Lanark

Thanks v much for putting up the cab wiring diags, if only I could understand them Wink

Thanks also for the tank drawing. I wondered if the diesel had parts 5 and 6. They look like a vent system to balance the fuel level in the tank. Any chance of the fuel line drawing for the diesel cab?

Posted: Wed Jan 04, 2012 10:25 pm

Yes the design is the same on both the petrol and diesel cabriolet. Part 5 is the breather overflow pipe and 6 is the expansion tank (on the diagram above).

The diagram below is the diesel feed and return pipework. The breather part 5 (above) feeds in to part 10 below and spills to the ground. Part 3 below is the feed line and part 4 in the return both seem to go to the bottom of the tank.