White 940 2.5TDI wagon

[petiww]

This is my second "dream" project that itched me a long time. Other than building a low and classy cruiser 244, I often played with an idea of building a 7 series wagon aswell.

I did not have any exact plans what engine and trans it should have, but after i started using brownie with B230F/M47, i slowly decided that yeah, i should buy a diesel, with AC. 8v Redblock is cool, has enough power, and has constant 26mpgs. This often turned me off from going on long distance trips.

With a 7/9 diesel comes the problem with the straight six d24 lump. It is just not meant for a passenger car, and many people reported weird failures with them. Of course there are many without problems aswell, but i just did not want to deal with it... A few people had already successfully installed 2.5TDI engines into these bodies, and a few managed to install 1.9TDI aswell. Common wisdom that these are much more bulletproof than the prechamber vw engines.
This narrowed it down to good chassis wagons with blown d24 engine and ac. Blown because I dont need it anyway, good chassis because I do not really want to mess with rust again, or worst case with only a little.
I thought to myself that whenever i have the funds and find a suitable one, i will go and buy it right away.

So here it is, a good chassis 940 wagon with a blown D24TiC, M46 and AC:
20201025_153329 by Péter Gede, on Flickr

It was a very quick purchase. A fellow Volvo owner buddy posted it into a team chat, and after checking the ad i started sweating and got real excited. After a few texts with the owner and receiving a ****load of pictures, i decided i will go there asap and bring it home if the chassis is okay. Only problem it was 300 km away.
I got lucky with renting a car trailer, so next day i could do the 6 hour roundtrip. Got home right about midnight:
20201021_000434 by Péter Gede, on Flickr
20201031_161829 by Péter Gede, on Flickr
I kinda like the interior, but front seats need some attention.

In the 4th cylinder, the exhaust valve said hi and fell onto the piston... PO said he heard weird noises, but the engine kept running. It still brought the family home.
20201021_181449 by Péter Gede, on Flickr
20201020_201001 by Péter Gede, on Flickr

So yeah, suitable car is checked, it even has MOT for more than a year, now i just need to find a suitable TDI donor car...

Plans for this winter:
-source a TDI donor car
-proper installation of the TDI engine
-enjoy the gear shredding torques
-maintenance here and there
-repair the ultra wornout drivers seat

Future plans:
-early 740 front
-full respray in red or blue
-diesel M90
-bit more power, bigger turbo, because why not?
-lowering
-limited slip differential
-Twingo roof if something falls onto the roof, which is still unbeliveably straight

To be continued.

[Arn02]

Nice project Peter ��
Look forward to the progress.

[v8volvo]

Interesting project, should be great when done. The 2.5 TDI engines are legends for power and durability and economy, no doubt an improvement over the old D24TIC in every way except maybe sound. I have looked at doing something similar someday now that these engines are starting to make their way to the US, but my D24T cars keep running fine, so haven't gotten serious looking into it yet, knock wood.

Should be simple to bolt most of it together, I imagine only custom parts will be the shortened oil pan, maybe a custom turbo drain, and motor mounts? M90 trans would be a good choice if you can find one instead of the M46, the TDI will be too much for it.

What TDI engine do you plan to run? As you probably know there are many different factory versions of the 2.5, ranging from 88hp to over 150. From what I understand the most easily found versions with good power are the 140hp Audi AEL or Volvo 850/x70 D5252T.

And, mechanical injection pump conversion or full electronic fly-by-wire install?

I recently finished up a full electronic 1.9 TDI swap into my old Toyota pickup, the custom harness and go-pedal were not as much work as I imagined they'd be. I'd do it that way again, nice to have the clean running and OBD capability, though not quite as simple to drop it in.

Look forward to seeing this come together.

[petiww]

Originally Posted by Arn02

Nice project Peter ��
Look forward to the progress.

Thanks!
I want to do it as fast as i can.

Originally Posted by v8volvo

Interesting project, should be great when done. The 2.5 TDI engines are legends for power and durability and economy, no doubt an improvement over the old D24TIC in every way except maybe sound. I have looked at doing something similar someday now that these engines are starting to make their way to the US, but my D24T cars keep running fine, so haven't gotten serious looking into it yet, knock wood.

Should be simple to bolt most of it together, I imagine only custom parts will be the shortened oil pan, maybe a custom turbo drain, and motor mounts? M90 trans would be a good choice if you can find one instead of the M46, the TDI will be too much for it.

What TDI engine do you plan to run? As you probably know there are many different factory versions of the 2.5, ranging from 88hp to over 150. From what I understand the most easily found versions with good power are the 140hp Audi AEL or Volvo 850/x70 D5252T.

And, mechanical injection pump conversion or full electronic fly-by-wire install?

I recently finished up a full electronic 1.9 TDI swap into my old Toyota pickup, the custom harness and go-pedal were not as much work as I imagined they'd be. I'd do it that way again, nice to have the clean running and OBD capability, though not quite as simple to drop it in.

Look forward to seeing this come together.

Well, yeah, there are a few versions of this engine. I thought I'm better off starting with an already longitudinal engine, so i daily checked local craigslist for Audi C4 100 and A6 with 2.5TDI engines.
Well, i guess i got lucky again, and found one pretty close to me with a busted automagic transmission. Went to check it and towed it home. It did its last few kilometres on its own power.
Only bad thing it is the "not that powerful" AAT engine, but it has healty sounds and no tragic smoke whatsoever. Good thing i can part it out with profit because it was "well" maintaned and cheap.
20201031_160423 by Péter Gede, on Flickr
See you here in a few months
20201031_160227 by Péter Gede, on Flickr

Yeah, Oil pan, mounts, flywheel+clutch, bit of fiddle with auxiliary stuff, wiring and it should be okay.
I'll probably go with dual mass flywheel because for now i will run this current M46. I hope DM fits the bellhousing. Also I'll need a custom clutch disk i think.
I want to keep everything original on the engine, I will be happy with a good running AAT at first. So I'll keep the electric pedal and injection pump. Chipping or anything wont happen before gearbox upgrade.

[petiww]

Over this month I ripped out both engines:
20201122_190659 by Péter Gede, on Flickr
20201128_173749 by Péter Gede, on Flickr

At the D24 i found another worrysome thing, lower coolant hose which was almost totally rubbed through:
20201121_213510 by Péter Gede, on Flickr
So even without valve damage, sooner or later it would have destructed itself. Not to talk about the oil pickup tube, which was once raped very hard. Bent, welded, had some RTV.
20201122_202051 by Péter Gede, on Flickr

[petiww]

So the fabricating began, and i started with shortening the oil pan. Asked my bro to let me use his spare 1.9 carburetted 5 cylinder block as a template and welding fixture.
20201205_214710 by Péter Gede, on Flickr
Drawn some functions on the pan:
20201207_203753 by Péter Gede, on Flickr
Cut out the middle section:
20201207_214035 by Péter Gede, on Flickr
Bit more trimming and root machining:
20201208_013847 by Péter Gede, on Flickr
Brought it to my workplace, and had it properly TIG welded with 4047:
20201208_171756 by Péter Gede, on Flickr
Grinded off the welds to look oem+:
20201209_204759 by Péter Gede, on Flickr

Unfortunately, welding pulled up the end of the pan a little bit, about 1mm at the highest point. I dont really know if i should worry about this or not, i can make it flat with the pan bolts. But at the same time i dont want to risk a possible cracking of the pan or the oil pump casting. Thought about just using some matching shimming washers... I plan to install the pan with rtv only.

Oil pickup tube was shortened aswell, made some temporary brackets to mock it up in the oil pan:
20201210_005114 by Péter Gede, on Flickr
20201211_195422 by Péter Gede, on Flickr
It will get one more support right at the filter head.

I will use the D24TIC flywheel and clutch. It screamed for a rebuild, so i sent the whole set to get it refurbrished and make it a bit stronger, with kevlar friction material. AAT engine has 30-40Nm more peak torque, so this should be enough for my application:
20201211_142129 by Péter Gede, on Flickr
Flywheel will get an external balancing bore to match the 5 cylinder madness, as per this site:
http://www.20v-sauger-tuning.de/vorgabeunwucht.htm

[RvolvoR]

is that C4 an avant by any chance?

[petiww]

Originally Posted by RvolvoR

is that C4 an avant by any chance?

Nope, its a sedan. What would be the case if it was an avant?

[RvolvoR]

Originally Posted by petiww

Nope, its a sedan. What would be the case if it was an avant?

oh, I just need some interior trim parts for my S6 that I can't find anywhere in the US. I know that C4s are a bit more plentiful in your area.

[v8volvo]

Looking great. Nice work on the pan. Hopefully that's the trickiest part of the whole setup.

That is crazy about the patched up oil pickup suction tube on the D24TIC motor. Wonder what did that damage? Maybe it had an internal failure one time before that hammered that tube? Came out of a motor that tossed a rod?

I actually have a question that you might know the answer to. Have you measured the total difference in engine length between the D24 I6 block and the 2.5TDI 5cyl block? I'm guessing it is about 4 inches? Since you have both of them right there, maybe you could take a side by side measurement?

I have an old VW T4 Transporter with the 2.5 gas 5cyl engine that is worn out, and have several good D24T engine here. Thinking of putting a diesel in the van, obviously a 2.5TDI would be the easiest to bolt right in but those are next to impossible to get in the US, have to import them from Europe (illegally). It almost looks like there would be room for a D24T if I could get a passenger side engine mount fabbed and lengthen the oil pan -- basically the reverse of what you have been doing. Trying to figure out what the clearance would be on the timing belt side. It would be close, might have to move the whole engine/trans over a little and lengthen/shorten the drive axles also.

[JW240]

The oil pan looks great, beautifully made.

Like the swap. Brings back memories, my dad had a V70 with that engine circa 2000. Moved nicely and very fuel efficient.

[petiww]

Originally Posted by RvolvoR

oh, I just need some interior trim parts for my S6 that I can't find anywhere in the US. I know that C4s are a bit more plentiful in your area.

Indeed they are, but as i experienced S6s are not that common. Hit me up in pm, maybe i can help with it.

Originally Posted by v8volvo

Looking great. Nice work on the pan. Hopefully that's the trickiest part of the whole setup.

That is crazy about the patched up oil pickup suction tube on the D24TIC motor. Wonder what did that damage? Maybe it had an internal failure one time before that hammered that tube? Came out of a motor that tossed a rod?

I actually have a question that you might know the answer to. Have you measured the total difference in engine length between the D24 I6 block and the 2.5TDI 5cyl block? I'm guessing it is about 4 inches? Since you have both of them right there, maybe you could take a side by side measurement?

I have an old VW T4 Transporter with the 2.5 gas 5cyl engine that is worn out, and have several good D24T engine here. Thinking of putting a diesel in the van, obviously a 2.5TDI would be the easiest to bolt right in but those are next to impossible to get in the US, have to import them from Europe (illegally). It almost looks like there would be room for a D24T if I could get a passenger side engine mount fabbed and lengthen the oil pan -- basically the reverse of what you have been doing. Trying to figure out what the clearance would be on the timing belt side. It would be close, might have to move the whole engine/trans over a little and lengthen/shorten the drive axles also.

Thanks!
I think the pickup tube damaged when somebody in the past tried to remove the oil pan with the engine and crossmember in place, without luck.

I took some measurements when i shortened the pan. The distance between cylinders is 88mm, but the actual lenght difference between the blocks turned out to be 90mm. I did not measure too precisely, just enough to be able to trim out the unneeded section from the pan.
Good luck on swapping in a D24, make sure to install way longer diff or gears or both.

Currently i have 3,54 diff in this car, and in brownie aswell. For the B230F, it feels just about right, but this TDI will hate it. I think i might go with a 3,08. We will see.

Originally Posted by JW240

The oil pan looks great, beautifully made.

Like the swap. Brings back memories, my dad had a V70 with that engine circa 2000. Moved nicely and very fuel efficient.

Thanks!
I never really got a chance to drive a car with an engine like this, but i know it has the potential. Best thing that people in the local TDI groups never really complain about any weird failures with this particular type.

[v8volvo]

Originally Posted by petiww

I took some measurements when i shortened the pan. The distance between cylinders is 88mm, but the actual lenght difference between the blocks turned out to be 90mm. I did not measure too precisely, just enough to be able to trim out the unneeded section from the pan.
Good luck on swapping in a D24, make sure to install way longer diff or gears or both.

Currently i have 3,54 diff in this car, and in brownie aswell. For the B230F, it feels just about right, but this TDI will hate it. I think i might go with a 3,08. We will see.

Interesting, thanks for the measurements. Extra 90mm might just fit in the van, I'll have to look. I may have to move the gearbox over to the left a little bit and shorten/lengthen axles also but probably not by much. Likely would have to drop the engine out for timing belt service, which is not so good, but hey, mid engine Ferraris are that way too so why not the same for an old diesel minivan?

You are right that longer gears will be needed either way. The other option I am looking at putting in is 4cyl 1.9 TDI and that will need taller gears too. I just got a .717 5th gear set but probably will need a taller ring and pinion too. With the current gears (4.61 ring and pinion and .837 5th) the gas engine turns over 3000 rpm at 100 km/h.

Anyway, sorry for the off topic discussion in your thread. On your Volvo TDI setup, perhaps a 3.31 axle (like from an automatic 960-I) *might* be enough to keep the engine reasonably happy? In my experience the TDI engines are just fine revving 3k or more on the highway, though they get a little noisy above that. 3.08 would surely be better, especially if you are keeping the M46 trans with its very short first gear. Taller rear gear would make that first gear a little more useful. I assume you would have to build up the rear end with the 3.08 whereas a 3.31 might be able to be found used?

The 5cyl TDI engines definitely have a reputation for being bulletproof, they are so simple that there is really not much to go wrong with them. I like the 2.5 V6 TDI engine too, but they are known for being far more troublesome and complicated.

[petiww]

Inconvinience of the non accessible timing belt heavily depends on the planned mileage per year, i think. Personally I wouldnt yank out an engine yearly, but after 5 years its kinda ok for this kind of job.

Those ratios sound terrible, but at the same time that van has a heavy aerodinamic drag, so it wont really go past 100kmh with these old engines anyway. Its great for going up a mountain with full load.

I wanted to compare engine torques and diff/gearbox ratios in my excel sheet but did not find time for that yet. I will try it anyway with this configuration. Skandix has new 3,08 ring and pinion in stock, seemingly for older 2/7 axles. I still need to dig a little deeper, but only when this becomes the main irritating problem on the car.

Anyway, progress:
20201216_183139 by Péter Gede, on Flickr
20201217_065029 by Péter Gede, on Flickr
20201222_120737 by Péter Gede, on Flickr
20201222_013253 by Péter Gede, on Flickr

It turned out that one guy in Hungary already did the TDI swap, so i contacted him. He told me about a problem with his EGR valve position, where fresh air and exhaust gases do not mix at all and mostly the fifth cylinder gets the nasty hot stuff. Thats why i flipped EGR flange aswell. I plan to run the engine in stock configuration, with a catalitic converter.

Started to fab the engine mounts. As the bellhousing pattern is exactly the same, i decided to make two simple negatives to the D24 mounts relative to bellhousing bolts:
20201202_215426 by Péter Gede, on Flickr
20201202_222822 by Péter Gede, on Flickr
It has the little orientating pins!

[v8volvo]

Originally Posted by petiww

Inconvinience of the non accessible timing belt heavily depends on the planned mileage per year, i think. Personally I wouldnt yank out an engine yearly, but after 5 years its kinda ok for this kind of job.

Exactly, I only put a few K on the van per year so the tbelt is only every several years. Not such a big deal. Although that also proves that I should probably just keep a gasser engine in it, since it never gets enough miles to make the diesel swap worth the effort.

Originally Posted by petiww

Started to fab the engine mounts. As the bellhousing pattern is exactly the same, i decided to make two simple negatives to the D24 mounts relative to bellhousing bolts

That is a very clever idea, don't think I have ever seen anyone do this before. Should mean you can just bolt the engine right into the car, rather than having to take it in and out several times trying to get the mounts right.

I like your idea of keeping EGR and a catalyst on the engine as well. These engines run so nicely even with all the emissions equipment on board, and it makes the car much more pleasant to use if it doesn't stink or smoke. A lot of (dumb) people think the only way to go with a diesel is to immediately delete all the emissions gear. Not necessary.

Great looking work and fun to watch! Thanks for showing all of it.

[petiww]

Originally Posted by v8volvo

That is a very clever idea, don't think I have ever seen anyone do this before. Should mean you can just bolt the engine right into the car, rather than having to take it in and out several times trying to get the mounts right.

I like your idea of keeping EGR and a catalyst on the engine as well. These engines run so nicely even with all the emissions equipment on board, and it makes the car much more pleasant to use if it doesn't stink or smoke. A lot of (dumb) people think the only way to go with a diesel is to immediately delete all the emissions gear. Not necessary.

Great looking work and fun to watch! Thanks for showing all of it.

Thanks!
Yes, thats the plan, fabricate all the necessary stuff for an easy bolt-in, then fabricate the remaining, accessible bits when its in the bay.

Not that this stock TDI will save the world, but if it is able to pollute and stink less with just minimal effort (just keeping stuff on and keeping it working) then I'm doing it. Even brownie got a cat when i found one (as it became LH2.4 before), and funny that i need to remove it to pass local inspections. Originally it had a carb, but it is not too easy and cheap to get the injected engine written in its papers...

Newer engines however are a pain in the ass exactly because of the overcomplicated emissions stuff. Way too expensive parts which nobody seems to buy, so dpf-s get knocked out, ecus rewritten, etc...

Fabbed the right side engine mount:
Started with a 5mm sheet:
20201214_205617 by Péter Gede, on Flickr

10mm sheet on the block:
20201219_194743 by Péter Gede, on Flickr

Welding:
20201221_211839 by Péter Gede, on Flickr
20201221_215806 by Péter Gede, on Flickr

20201222_205445 by Péter Gede, on Flickr
20201222_211505 by Péter Gede, on Flickr
20201222_211510 by Péter Gede, on Flickr

It will get a bit more grinding and paint today, then its finished. Wanted it to be oem-ish style, its not that far i think. Not too close either.

[petiww]

I did not push it too hard after Christmas, but have made a few decisions to be able to continue fabricating.

As it can be seen on previous photos, the D24 oil filter relocator bracket was installed wrong (on purpose). This way i can use a threaded bore in the block for engine mounting, and i'm able to use the stock C4 turbo drain tube without any modifications. One less tube to worry about! I made a simple sheetmetal bracket to hold the relocator steadily:
20201226_182711 by Péter Gede, on Flickr

Turbo needs an oil feedline, a possible reclock and its ready to spool.
Oil-coolant heat exchanger needs to be positioned, hoses and tubes fabricated, and that should be okay aswell.
Oil filter will be in a nicely accessible position, which im pretty happy about.

Got to the conclusion that i need to decide whether i should keep the car v-belt or convert it to ribbed belt.
There are four things that suggest me to stay v-belt:
-charged AC system which I currently dont want to mess up
-working PS system
-possible engine swap back to D24 for the next inspection
-lack of 850/S70/V70/S80 TDI brackets, AC and PS pump, alternator

I know that ribbed belt is superior to ancient v-belt designs, but im pretty okay with servicing v-belt stuff. So i had to try the D24 stuff on the TDI, and it seems like everything will work.
Ribbed belt pulley has more torsional elasticity than the v-belt pulley, but this is an old fashioned five cylinder engine with a single mass flywheel. We will see how it behaves, if it has problems it will be only near idle rpms i think.
20201230_161634 by Péter Gede, on Flickr

-Crank pulley fits just fine, it needs one counterweight machined out.
-AC bracket needed a tiny grinding from its back side, fits just fine. Did some rough measurements and it will be very very close to crossmember. I'm not too happy about this, but i will either modify the crossmember, or make a new ac bracket. Hopefully AC compressor and its lines will clear the parts there.
-PS and alternator bracket needs a clever solution to the lower bolt, where the block height difference shows:

20201230_161646 by Péter Gede, on Flickr

Did some research about gearbox and diff ratios. Tables showed that a longer ratio axle is needed badly, or a different gearbox, or both. Or double overdrives.

It seems that the available 3,08 ring and pinion is only for 1030 - Dana 30 axles, (which the 7/9 series seemingly never got. I tinkered with the idea of creating a hybrid 1030 axle using an old 2 series one, but the diff case most likely does not have the casting protrusions for mounting the torque rods.) - EDIT - further catalog research revealed that some 3,73 and shorter ratio diffs were 1030!

Also thought about installing a second overdrive unit, which would make it a 6 speed gearbox. The longest ratio would be pretty nice, and there is no need to touch the 3,54 axle that way. Only problem that there is limited space in the driveshaft tunnel, and it probably wouldnt fit.

[OttoB]

Nice work.

Here is a link for Finnish build 945 and tdi.
https://kulmamies.kuvat.fi/kuvat/Volvo+940+D5252T/
F

[petiww]

Originally Posted by OttoB

Nice work.

Here is a link for Finnish build 945 and tdi.
https://kulmamies.kuvat.fi/kuvat/Volvo+940+D5252T/
F

Thanks! I seen his forum thread but not his photo gallery, very cool!

Jumped into gcp.se catalogs, which revealed that some axles were 1030 under the 7 series. If im lucky, my 740 donor wagon with the automatic B230F uses a 1030! Would be great.

[petiww]

Okay, so checked my donor vehicle:

20210103_143640[1] by Péter Gede, on Flickr
Screenshot_20210103-143828_Gallery[1] by Péter Gede, on Flickr

From catalogs it seems like its a 1030.

Found this gem:
https://www.randysworldwide.com/product/yg-d30-308/
I should take apart that axle and measure everything before ordering. It says it fits (at best, some of) 2 series though.

[v8volvo]

Looking great, beautiful work on those mounts.

700 series definitely did come with 1030 I think? Especially gas engine NA cars I am almost sure had them.

[Tfrasca]

Mounts look great!

[petiww]

Thanks guys!
I managed not to touch any part of the car in january. Partly because it was cold outside, but mainly because i wanted to use the d24 oil dipstick and its holder. Massaged out the Audi holder, and found that it has a much smaller bore in the block and its not even o-ringed. Its not a big deal to step bore it, but im kinda afraid i might mess it up and o-ring wont seal. Need to come up with a good solution to machine it properly. This and the left side engine mount, as it will need to go around the dipstick holder.

I thought i should do something else that i find relaxing. So I removed the cluster from the car for a thorough maintenance.
Speedometer did not work, but i found broken wires at diff, hoped only these give trouble.
Fuel gauge readed erratic sometimes i've been told by PO. I think its the fuel level sender itself.
Other gauges are unknown.

Went ahead and ordered every electrolytic capacitor by µF values (choosen voltages higher) i found in the whole cluster.
Completely resoldered the gauge pcb-s, changed capacitors, cleaned boards. Speedo needed a lot of cleaning, because 4 caps at the top leaked their electrolytes.
20210215_191610 by Péter Gede, on Flickr
20210215_212441 by Péter Gede, on Flickr
20210215_215056 by Péter Gede, on Flickr
20210211_221540 by Péter Gede, on Flickr

Hopefully it will work fine from now on.

Scored a bunch of bus headlights for future quad headlight conversion (740 frontend):
20210123_115411 by Péter Gede, on Flickr
These are proper Hella projector type low beams. Not sure about looks, we will see. Car will eventually get a 175 redwood metallic or 404 light blue metallic. I want to add chrome trims, and im not sure how those will get along with these lights.

Finally had the guts to rip out the wiring from the Audi:
20210213_145723 by Péter Gede, on Flickr
Oh damn what a complicated thing it is! Of course the TDI wiring went straight into the main loom right where it entered cabin. Hopefully it will be straightforward to strip it properly to create a separate only-engine loom.

[v8volvo]

Great looking work on the cluster.

How much of the dash harness do you think you will need? Last couple of TDI swaps I messed with, the harness was pretty quick and easy to strip down, didn't use the VW fuse panel or anything. But those were coming out of smaller 4 cylinder TDI Jettas and Beetles and such. Maybe the C4 chassis is more complicated.

Fortunately the old style TDI engines do not need much to run. Should be able to tap the Volvo VSS signal and the computer will be happy with it, and otherwise (AFAIK) there should be no integration with the rest of the car that will cause any trouble on these old model versions. I did a '97 AHU into a Toyota truck last summer and I didn't even need to move away from the stock tune, it was happy enough right out of the box, no codes at all once the VSS and other simple inputs were all up and running properly.

The one thing to watch how you hook it up is the brake and clutch switches, as the TDI computer is picky about seeing what it wants to see on those. IIRC there are three separate wires for this, a couple need to be grounded and the third needs to float? I think I have a document somewhere that gives the instructions, I'll try to find.

[petiww]

Originally Posted by v8volvo

Great looking work on the cluster.

How much of the dash harness do you think you will need? Last couple of TDI swaps I messed with, the harness was pretty quick and easy to strip down, didn't use the VW fuse panel or anything. But those were coming out of smaller 4 cylinder TDI Jettas and Beetles and such. Maybe the C4 chassis is more complicated.

Fortunately the old style TDI engines do not need much to run. Should be able to tap the Volvo VSS signal and the computer will be happy with it, and otherwise (AFAIK) there should be no integration with the rest of the car that will cause any trouble on these old model versions. I did a '97 AHU into a Toyota truck last summer and I didn't even need to move away from the stock tune, it was happy enough right out of the box, no codes at all once the VSS and other simple inputs were all up and running properly.

The one thing to watch how you hook it up is the brake and clutch switches, as the TDI computer is picky about seeing what it wants to see on those. IIRC there are three separate wires for this, a couple need to be grounded and the third needs to float? I think I have a document somewhere that gives the instructions, I'll try to find.

Thanks!

This weekend i spent some more time with wiring and it was not as bad as it seemed when we pulled the whole wiring from the car. Actually its pretty much separated in factory form, just connected to the main loom in weird locations, and have the relays, fuses, control modules in all different places. Its all labelled up and will need another afternoon of work to be ready for installation.

There were a few things which took us time to figure out. Namely:
-Electonic engine mount and its control relay. Somehow it is not controlled directly by the TDI ecu.
-Auxiliary (coolant) heater. I did not find the usual 3 glow plug water heater on the engine and thought it does not have anything similar. Well i was wrong, because there is an electric air heater pad inside the heater box, with two 50amp relays and some weird wiring. Relays are controlled by the ecu.
-Auxiliary heater control module, which seems to be an alternator voltage adjuster/booster when the electric heating is on. It seems it is controlled by the ecu aswell.

Goal is to make an independent plug and play wiring next to the factory D24, if i ever need to put that engine back.