Engine swap - 2.5tdi for 1.9tdi AVF

[p-rossi]

Hi, I’ve just written off my A4 B6 Avant Quattro due to hitting a deer on the Isle of Skye & looking to replace it. She was in showroom condition.

Just seen one with a 2.5tdi & was wondering if I can fit the 1.9tdi AVF engine from my A4 B6 saloon into it?

The saloon chassis is rusting now &, although I’ve put 343k miles on it, my indy says the engine runs sweet & looks like new inside (he inspected it when replacing the sump & he has one, too). I get about 55mpg from it.

If so, does anyone know what needs to be swapped? I was intending to bring the gearbox over as well.

Also, considering it’d be a modification (a downgrade from ~180bhp to 130bhp), would a change like that affect my insurance a lot?

Thanks,
Paul

 

[DieselJake]

Technically possible but (and I hate to be the guy saying this) for the effort of swapping an engine and availability/cost now of 1.9tdi's it might just be best finding another 1.9tdi, especially if you are planning to declare engine swaps because like you say insurance companies can be funny with stuff like that.

 

[p-rossi]

Thanks for your advice, DieselJake. I was reading up on the reliability of the 2.5tdi compared with the 1.9. Injector issues for the 2.5 (££££) came up a couple of times going by online reviews but I’m happy to be corrected. I’ve been spoiled by a faultless AVF.

I looked on AT &, based on searching by year for a B6, 1.9 engine, Avant & 4WD, there are 2x for sale in the Uk. I’m trying to avoid a B7 (no offence, folks) due to the 2.0tdi oil balancer issue. There are many 2WD AVF Avants to choose from but I was surprised how much better the handling is with 4WD, so much prefer a Quattro - esp during a Scottish winter! My 2WD B6 is on its 9th winter up here using Nokians & handles fine.

Yeah, certainly wouldn’t modify & not declare it to insurance & DVLA.

 

[QuattroCalum]

I'd run the 2.5 till the pump gave up then replace with the 1.9. Both quattro?

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[p-rossi]

Thanks, QuattroCalum. The 2.5 I’ve been looking at is a Quattro. The 1.9 will be from my 2WD B6 saloon. Not sure if it’s a straight engine swap or if I’ll need parts to fit the 1.9 to the Quattro’s gearbox, exhaust system, etc.

Lots of things to find out - does a 1.9 use a different radiator, intercooler, air intake, engine mounts, etc ..... ? The good news is that everything works on the saloon so I’m hoping that some parts can be transferred.

What pump do you mean?

 

[DieselJake]

Off the top of my head engine mounts should be the same, radiator should be fine, intercooler might need some adaption or could be a good time to upgrade to a universal front mount kit, air intake might need some 1.9tdi bits but they're cheap, exhaust in my head should be fine but I'm not sure worst comes to worst it can be adapted, gearbox could be the biggest pain but I'm not sure as I could be confusing this with people swapping fwd car's to fit quattro bits (as I'm sometimes tempted).

Could be understating and overstating some of that though as I'm just going off the multitude of parts from other cars that are on or will go on mine haha.

 

[QuattroCalum]

Thanks, QuattroCalum. The 2.5 I’ve been looking at is a Quattro. The 1.9 will be from my 2WD B6 saloon. Not sure if it’s a straight engine swap or if I’ll need parts to fit the 1.9 to the Quattro’s gearbox, exhaust system, etc.

Lots of things to find out - does a 1.9 use a different radiator, intercooler, air intake, engine mounts, etc ..... ? The good news is that everything works on the saloon so I’m hoping that some parts can be transferred.

What pump do you mean?

The fuel pump, that's the achilles heel of the 2.5tdi engine. You have both cars with all the parts so it will work.

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[DAN@ADRIAN FLUX]

Hi.
With regards to insurance as you are down grading the engine hopefully this should't cause you too many issues unless you have an modification unfriendly insurer. If you do have any issues though then please feel free to drop me a line.
Regards,
Dan.

 

[QuattroCalum]

Thanks, QuattroCalum. The 2.5 I’ve been looking at is a Quattro. The 1.9 will be from my 2WD B6 saloon. Not sure if it’s a straight engine swap or if I’ll need parts to fit the 1.9 to the Quattro’s gearbox, exhaust system, etc.

Lots of things to find out - does a 1.9 use a different radiator, intercooler, air intake, engine mounts, etc ..... ? The good news is that everything works on the saloon so I’m hoping that some parts can be transferred.

What pump do you mean?

The gearbox bell housing will be the same, they only used one with bolt holes in different places to fit all engines. Personally I'd use the quattro gearbox, you've driven a quattro so you know why. You will find the gearbox codes on the build sticker in the boot or the owners manual if you have them, you can then find the gearbox ratios, i think the 1.9 might struggle a bit with the quattro system compared to FWD but a remap would fix that.
The exhaust I think you'll need to use the 1.9 down pipe and may need to fabricate something to join with the centre section. I do know that the gearbox mount bracket on the downpipe are in different positions between FWD and quattro.
There's probably a lot more that you'll need to work out but you have both cars so the answer should be right in front of you.

 

[p-rossi]

QuattroCalum - many thanks for your knowledgeable replies - very much appreciated. I now have much to debate over doing the swap. You say about the 1.9 struggling with the Quattro gearbox - well actually, ‘her indoors’ thought that the 1.9 Quattro Avant (RIP) had a good bit less poke than my 1.9 2WD saloon - it could have been mapped badly. I thought it would be only marginally noticeable with the Quattro’s extra mechanicals.

TBH, I think my Avant was a ‘cut-n-shut’ due to an accident or harsh driving as there are chalk marks around the engine parts & various bits , which I thought were on different models. Also, the airbags didn’t go off at about 50mph & it was a big stag that I hit. I saw the smoke from the steering wheel but no bag! I was going to switch out 1.9 engines in Jan due to rubbish mpg - glad I didn't now. If i get the 2.5 I’ve been looking at, I’ll take your advice & switch it with the 1.9 but only when the fuel pump goes.

Interesting note about the gearbox bolt holes on the bell housing. Yeah, as you say, the answers should be obvious but don’t think my indy mechanic has done this before. As usual, Audi won’t give out the info to do it since they're not getting the work. Unfortunately, the Bentley book doesn’t show diesel engines.

It’s all a big if just now. If the saloon passes its MOT in a couple of weeks , then I’ll have some time to look for a good B6 Avant Quattro.

Dan, thanks for the insurance info. I’ll see how it goes & may contact you if things are not going well

 

[DieselJake]

Might sound like a daft question but how written off is the car in question? Just thinking it might be easier/cheaper to fix that than swapping engine's, I know a deer is a hell of a beast but I'd be interested to see how broke the car is as I've had allot of car's/motorbike's brought back from very painful deaths, suppose either way you might need another car to be the donor or donate bits to as your saying (actually could even buy any old A4 and swap the full quattro, gearbox and engine into it... guess it's allot of effort but if the engine is being swapped anyway it's not that much more of a headache, could even start with a b7 s-line car if you like the look of those as they share the same chassis, my b6 has a b7 front end just 'cause I liked the look of it).

 

[QuattroCalum]

Might sound like a daft question but how written off is the car in question? Just thinking it might be easier/cheaper to fix that than swapping engine's, I know a deer is a hell of a beast but I'd be interested to see how broke the car is as I've had allot of car's/motorbike's brought back from very painful deaths, suppose either way you might need another car to be the donor or donate bits to as your saying (actually could even buy any old A4 and swap the full quattro, gearbox and engine into it... guess it's allot of effort but if the engine is being swapped anyway it's not that much more of a headache, could even start with a b7 s-line car if you like the look of those as they share the same chassis, my b6 has a b7 front end just 'cause I liked the look of it).

Around 15 hours of work for FWD to quattro conversion, you even have to change the fuel tank.



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[DieselJake]

Around 15 hours of work for FWD to quattro conversion, you even have to change the fuel tank.



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Save 15 hours of customising parts to make them fit plus no weird gear ratio's or any other potential differences and the car's can be side by side so it'll be easier to see what goes where; one bit off one bit on.

Failing that a shell with quattro and a duff engine can be had for next to nothing but again still might need to swap a few things. As with my original answer the easiest is just getting what's wanted from the start or as with the last thing I said; how broke is the car that it is unrepairable.

 

[QuattroCalum]

As I said the only thing you will need to fabricate is the 1.9 tdi cat/downpipe to the 2.5 tdi centre section, everything else, bolt on.

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[DieselJake]

Wish I could agree but we can only speculate and the exhaust is the least of someone's worries when doing an engine conversion, haven't even took into account 1.9tdi's are over 100kg lighter than a 2.5tdi and we don't know what parts can be salvaged from the original car to compensate for this (and any more "bolt-on"s mean more effort which is a bit hypocritical considering your last post...).

 

[p-rossi]

Jeez, this is tough! Quite naively, I thought I could simply unbolt the 2.5 & throw in the 1.9 - bleedin’ amateur!

Although I think that it could be repaired, there are 2 reasons why the car won’t be repaired. 1 - Even though they haven’t seen the car since the incident, the insurance company won’t entertain a repair as it’d be the second rebuild (I travelled from the Isle of Skye to High Wycombe, bought it in May 2017 & was driving it home. I got to Fort William &..... yep, a deer jumped out & I destroyed the front left - he was unscathed & ran off!). They tried to repair with after market parts but fitted so badly that I refused the work & they eventually sent it to Audi. I got it back 5 months later & they’d spent much more than the car’s value getting it repaired properly. 2 - for this deer hit (this one couldn’t run off), the ignitor for the steering wheel went off (smoke seen) but the bag didn’t deploy. I truly believe that this car has been rebuilt & I don’t trust the airbag system or much else - several codes on VCDS. I did say in OP that the car was in ‘showroom condition’ but I was meaning the paintwork & interior. The <30mpg avg engine is a rebuild (I’d bet the DVLA don’t even know) & there was about 4 litres of water under the carpet due to damaged ECU seal (posted elsewhere on A-S.N). The bonnet, headlight, lock carrier, radiators, wing, bumper, framework in front of ABS module & windscreen all need replaced, as well as seatbelt + whatever airbag system components are on it.

Once again, thanks for your input, guys. I’m amazed that there’s 100kg difference between the 2 engines!

The Avant is being collected in a day or 2 so no time for stripping down. If I do get the 2.5 that I’ve been looking at (near Norwich) & install my saloon’s 1.9, I will need to get the downpipe fabricated - I guess this means I can’t buy a part from Audi. I’ll just do what you said, QC, & run the 2.5 until it pops its clogs. Gear ratios is another thing I didn’t think of so switching might not be possible . I think you’re right, DJ; if I can, I’ll get the right car in the first place, & as I’ve written above in this post, I think the car is repairable. Costly doing it myself but it’s a rare machine to come by. It’s killing me to think that it'll be sold at an auction place for half a k or crushed.

Will let everyone know how this turns out.

Cheers,
Paul

 

[QuattroCalum]

Jeez, this is tough! Quite naively, I thought I could simply unbolt the 2.5 & throw in the 1.9 - bleedin’ amateur!

Although I think that it could be repaired, there are 2 reasons why the car won’t be repaired. 1 - Even though they haven’t seen the car since the incident, the insurance company won’t entertain a repair as it’d be the second rebuild (I travelled from the Isle of Skye to High Wycombe, bought it in May 2017 & was driving it home. I got to Fort William &..... yep, a deer jumped out & I destroyed the front left - he was unscathed & ran off!). They tried to repair with after market parts but fitted so badly that I refused the work & they eventually sent it to Audi. I got it back 5 months later & they’d spent much more than the car’s value getting it repaired properly. 2 - for this deer hit (this one couldn’t run off), the ignitor for the steering wheel went off (smoke seen) but the bag didn’t deploy. I truly believe that this car has been rebuilt & I don’t trust the airbag system or much else - several codes on VCDS. I did say in OP that the car was in ‘showroom condition’ but I was meaning the paintwork & interior. The <30mpg avg engine is a rebuild (I’d bet the DVLA don’t even know) & there was about 4 litres of water under the carpet due to damaged ECU seal (posted elsewhere on A-S.N). The bonnet, headlight, lock carrier, radiators, wing, bumper, framework in front of ABS module & windscreen all need replaced, as well as seatbelt + whatever airbag system components are on it.

Once again, thanks for your input, guys. I’m amazed that there’s 100kg difference between the 2 engines!

The Avant is being collected in a day or 2 so no time for stripping down. If I do get the 2.5 that I’ve been looking at (near Norwich) & install my saloon’s 1.9, I will need to get the downpipe fabricated - I guess this means I can’t buy a part from Audi. I’ll just do what you said, QC, & run the 2.5 until it pops its clogs. Gear ratios is another thing I didn’t think of so switching might not be possible . I think you’re right, DJ; if I can, I’ll get the right car in the first place, & as I’ve written above in this post, I think the car is repairable. Costly doing it myself but it’s a rare machine to come by. It’s killing me to think that it'll be sold at an auction place for half a k or crushed.

Will let everyone know how this turns out.

Cheers,
Paul

I found this thread, please pay particular attention to post number 14, Adamss24 really knows his stuff, he's not around the forum any more though.

https://www.audi-sport.net/xf/threads/does-a-2-5-quattro-box-fit-a-1-9-engine.235090/