VAG V6 2.5TDi-M

[famous phil]

Hi, does anyone know if there's a mechanical pump that will work a VW/Audi  ( year 1998 ? ) V6 2.5TDi , I've looked at a few of these 2.5tdi's but these have the old Lucas designed pumps from what I can see , maybe another pump might be able to run one of these engines from a larger 6 cyl ?

any thoughts greatly appreciated  

[lord_verminaard]

Not sure on the firing order of the V6 TDI, but the Cummins VE pump might work.  I think the V6 TDI uses a VE pump, correct?

Brendan

[burn_your_money]

Check to see if the V6 is base or flange mounted. If it's base mounted there would be a fair amount of custom mounts required I think

You may find some answers in this post

http://www.vwdiesel.net/forum/index.php?topic=22516.0

[famous phil]

cheers for the replies ,
Not sure what vehicle I could search for to find a Cummings pump ( mainly big trucks ) bit of a pity as I can see the Darlington Cummings engine factory from my house!! .  pump from Nissan patrol or Toyota land cruiser might be up to the job but not sure if there a 6 cyl Di , Mounting another type of pump will involve a bit of work but don't think too difficult as quite a few  have threaded bolting points underneath

The V6 TDi uses a Bosch pump that is not to good = VP44 , it is possible to get the engine to tick over with just two wires connected to it  A link below shows some good pics of the different types of fuel pump

http://www.ecutesting.com/audi_a4_a6_a8_vp44_diesel__pum.html

[blackdogvan]

I'd be looking very closly at a 6Bt cummins 12mm pump. FYI if you can get a AAZ or TDI VE pump to fit in that spot there's no reason a 6Bt wouldn't with minor massaging. If its bottom mount I'd bet they all came from the same mold & it would be as hard as drilling & tapping a couple of ready to go spots on the pump. Been waiting for someone to get on this for a while.

[MikkiJayne]

Here's a quick iphone pic of the top of the V6 TDI:



The pump mounts on four horizontal bosses that can be seen in the pic.

This is with a VP37 in place:



It would be very straightforward to make U shaped bracket to bolt a VP37 style pump to the four bosses. The nose of the pump lines up with the belt drive from the cam, and there is space at the back for all the injector pipes.

I'd say this was entirely do-able if the 6BT pump is the same size & shape as the VP37, and you could make up pipes to fit the injectors 

[blackdogvan]

The stock 12mm 6bt pump might be a bit much for the 2.5 displacment  - .416cc/cyl Vs a 1.9's 475cc/cyl. You might look for a 6bt pump off a generator, IIRC some had smaller heads & could be available on your side of the pond from marine gen set applications. That said the mechanical 6bt pump is in no short supply in north america.

[the caveman]

Funny that this came up as i thought i could get my hands on one, but with a blown turbo. I would have gone the SDI route, and asked the guys at Superperfomance diesel what would be involved pump wise. Where did you find the block and can you get any more ?

[blackdogvan]

Probably dime a dozen in the UK...

[lord_verminaard]

...while you're at it, I'd like a 2.5 I-5 TDI too.  Would be perfect for my Coupe Quattro.  :/

Brendan

[MikkiJayne]

They're far from a dime a dozen I'm afraid. Because they are so fragile and eat their cam gear good ones sell for stupid prices 

The one in my pics is from my A6 TDI. It threw 5 of its 24 cam followers and was running like crap so I pulled it for a full top end rebuild. The block was spotless at 235K, but the heads needed a lot of work. Anyway, I've got so fed up of pouring money in to it that I've given up and I'm putting an AFN in there instead with the GT2052V turbo from the 2.5, so hopefully I should get about the same power from it but better reliability and mpgs.

Honestly I think the V6 TDI is the worst motor VW ever invented - certainly this incarnation of it anyway. Later ones got roller rockers and are much more reliable, but they are worth even more. You'll pay £1000-£1500 for a working AKE (180hp version)  For a BAU (180hp roller version) if you can find one it will be >£1500.

I'm open to sensible offers on mine if anyone wants it for a conversion though. It needs head gaskets & bolts, and a few cam followers, and could do with new nozzles, but other than that its complete with everything....

[famous phil]

some great information  thanks for the pics ,

   what makes the top end so fragile    I've noticed the odd few that have overheating problems due to a plastic water pump impeller failing and like mentioned ones with the heads in bits ,,,,,,,,

 Think I might just stick with the four potters for now   unless a six turns up at the right money , going to search for other makes of V6 TDi's problem is there'll be common rail ,
 
anyone had out to do with the PSA V6's in the Range Rovers/disco's/Jags/Peugeot's/Citroen's

[MikkiJayne]

Its all down to fitting too much stuff in not enough space. Instead of conventional tappets the V6 TDI heads use rocker arms and lifters. while this seems to work fine for everyone else, the V6 TDI has a habit of spitting the lifters out, leaving the valves shut. The loose rockers flying around the motor then get smashed up and in to other things which also break.

There are a pair of non-return valves in the oil system which can get blocked up with goo, and then the oil pressure in the head goes through the roof and that also spits the rockers out. As soon as there is no rocker on top of them the hydraulic lifters pop apart and are also done for.

To add insult to injury the early versions of this motor had improperly hardened camshafts which wore prematurely, also allowing the damn rockers to fall out, but at the same time filling the motor with ground up steel shards. A lot of them had the cams replaced under warranty, but many others had cheap crap replica cams fitted, which are known to also fail after only 50K.

On top of hideous reliability issues the port layout & design is bizarre at best and to the untrained eye looks incredibly restrictive. Making it a multivalve motor was utterly pointless as it makes no more power per cylinder than the 2-valve 1.9.

The later versions (B__ codes instead of A__ codes) have roller rockers to fix that problem, but the basic port design is still unfathomable.

In short, it was a design that should never have made it in to production, but Audi were pertty much forced to come up with a replacement for the 5-cylinder TDI motor that would fit in to the shorter front ends of the A4 and A6.

I've spent roughly £1000 rebuilding mine so far, and I haven't even bolted the heads back on. I am so fed up of throwing money at it then hearing tales from others of rebuilt motors still having problems I've given up with it, hence the AFN tansplant.

[famous phil]

  "Its all down to fitting too much stuff in not enough space"   sounds the same as the PD TDi engines
friend has one and it started to miss fire slightly at cruising speed  took it into a garage and they said strait away camshaft snapped , then showed new cam going into one saying its the 5'th
PD cam job in 6 weeks 

[mystery3]

I don't know why you'd go through the trouble for a v6. I don't very well know of a good v6 made, ever. I don't include the vr6 or the fiat 6's or any other "v6" that only has one head in my previous blanket statement.