# 2.5 to TDi conversion.



## bcplayer07 (Oct 6, 2011)

i have a 07, 2.5 Jetta with 190,000 miles on it now. I drive a little over 1000 miles a week, and am trying to prepare for when the motor craps out on me. So far the car has been very reliable and needed nothing more than regular maintenance, and the cooling fan motor got dirty and stopped working. cleaned it out and it was good to go. Transmission is getting sloppy, although still very drivable. 

I still owe money on the car, and obviously owe more than its worth, so I plan on replacing the motor and transmission. I am a Mechanical Engineer, and have done alot of car work. but am toying with either replacing the 2.5 with a newer 2.5, 2.0T or my real ambition is for the TDi. My drive is 98% highway, so the TDI would do wonders as far as overall fuel costs. Anyone have any knowledge or advice? From my research it should be fairly simple, though no easy.


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## A1an (Mar 22, 2007)

There have been a few MKV engine swaps done but not sure about anyone going to a TDI. 

For what it is worth another 2.5 may be your best value. Low mile motors go pretty cheap and you already know how reliable and relatively maintenance free they are. Certainly there is a mpg disadvantage but the "set it and forget it" nature of the 2.5 almost makes up for that. You could also source a 6 speed to help with the highway cruising. 

Out of curiosity...is your car an auto or manual? What sort of sloppiness are you getting?


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## nothing-leaves-stock (Mar 1, 2005)

TDI and trans swap would cost more then the car is worth.
drive it, save for a tdi oem car. safer bet.


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## bcplayer07 (Oct 6, 2011)

A1an said:


> There have been a few MKV engine swaps done but not sure about anyone going to a TDI.
> 
> For what it is worth another 2.5 may be your best value. Low mile motors go pretty cheap and you already know how reliable and relatively maintenance free they are. Certainly there is a mpg disadvantage but the "set it and forget it" nature of the 2.5 almost makes up for that. You could also source a 6 speed to help with the highway cruising.
> 
> Out of curiosity...is your car an auto or manual? What sort of sloppiness are you getting?


Its a Auto, around 40-50mph, I get a flutter in the transmission wanting to drop down to 6th but it stays in 5th. luckily I drive 80 for most of my drive. I believe its related to the valve body, but with that many miles on my car and climbing quickly, it would be better to go ahead and replace both at the same time. Thanks for the advice, I was thinking staying with the 2.5 would be the better option. ill probably end up just replacing it.

I was thinking about getting a 08+ motor, I am guessing I would need the ecu as well ?


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## nothing-leaves-stock (Mar 1, 2005)

need complete motor, trans, mounts, harness, ecu, cluster, axles, shifter, fuel tank, lines, filter setup, hoses, exhaust(at least downpipe) re-register it for a diesel,

all in all....its not a old mk1 rabbit swap, its a hard swap and big money parts.


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## bcplayer07 (Oct 6, 2011)

nothing-leaves-stock said:


> need complete motor, trans, mounts, harness, ecu, cluster, axles, shifter, fuel tank, lines, filter setup, hoses, exhaust(at least downpipe) re-register it for a diesel,
> 
> all in all....its not a old mk1 rabbit swap, its a hard swap and big money parts.


When I said 08+ motor, I was referring to getting another 2.5. 4K is my threshold, and converting to a TDi is going to be well over that.


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## A1an (Mar 22, 2007)

Newer 2.5 prob your best bet. There is a guy here with a great thread on swapping a newer 08+ 2.5 into an 06 or so Jetta that had timing chain failure. The stuff that didn't share the same part numbers were swapped from his old motor onto the new (intake manifold, accessories, etc if I remember correctly). So you can retain your existing ECU and whatnot. Not sure what all is involved if you wanted to think about putting a 6-speed manual. May be cheaper just to get your existing auto rebuilt.


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## bcplayer07 (Oct 6, 2011)

Humm that could be a idea to toy around with. I am guessing it wouldnt be to bad. Know of anyone who has done it? When did the manual become a 6 speed? I thought it was always a 5 speed.


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## nothing-leaves-stock (Mar 1, 2005)

2.5=5speed
gti=6speed.
but they are swappable with everything


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## bcplayer07 (Oct 6, 2011)

nothing-leaves-stock said:


> 2.5=5speed
> gti=6speed.
> but they are swappable with everything


i didnt know that. Do you know what all would be intelled with going from an auto to 6speed manual? I am an mechanical engineer, and have done alot of car work, but never went from a auto to manual.


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## A1an (Mar 22, 2007)

thygreyt did a 6-speed swap on his 2.5 Jetta. He would be a good resource for specifics on putting a 6-speed manual trans on a 2.5, but I think he started out with a 5-speed manual. You will have a bit more parts to source to get it done. He reports some pretty stellar mpg results but his tune is part of the reason he does so well.


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## PhAyzoN (Nov 29, 2010)

A1an said:


> thygreyt did a 6-speed swap on his 2.5 Jetta. He would be a good resource for specifics on putting a 6-speed manual trans on a 2.5, but I think he started out with a 5-speed manual. You will have a bit more parts to source to get it done. He reports some pretty stellar mpg results but his tune is part of the reason he does so well.


Actually, Fred started with an Auto.


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