Club 80-90 Forums

Just thinking outside of the box.

I have a recon diesel pump off a spare AAZ engine and was musing as to whether it would bolt straight on to an early TDI engine.

The AAZs seem to be getting rarer and I guess that my worn out spare engine (low compression)may be too costly to refurbish.

Any thoughts? I’m in no rush as my current engine seems fine but you never do know!!!!

I have it in my head that the early TDIs were just a slightly upgraded TD. Or am I way off the mark?

Thanks

TDi has very different injectors, and pumps and injectors are very specifically matched (and matched to the turbo and vehicle even); the outlet ports that you fit the injector pipes to on the pump are in fact very special valves so whilst yes it's a pump squirting fuel into an injector it won't be squirting the right amount at the right pressure or even at the right time (direct injection v indirect injection) so basically no, if you want a TDi then you need to do it right with everything that belongs on the engine matching (or modified specifically to suit) and you might as well do it electronically then you get all the benefits of the later engine, though there are those who do like the challenge of modifying a mechanical pump and like the simplicity of that but it is a compromise on a compromise and if it goes wrong then you can't just plug in the diagnostics and figure out the issue as you can on a good full TDi installation

Thanks Aidan.

That makes sense. I do like the simplicity of a non ECU set up but clearly mixing the two isn’t the way forward.

What is mTDI? Is that essentially what I am thinking of but with the correct bits??!

There are those who manage to utilise a Landrover TD or Fiat Croma TD pump to run a TDi engine 
 

Yes we are running a Landrover 300 TDI pump on our 1.9 AHU TDI engine. I sent the van into a fuel injection specialist last year to recondition the pump and injectors as the van didn't seem to have much pulling power and didn't run well. The chap who done the work explained that the engine and injectors aren't designed to run a mechanical pump as the fuel curves don't match (he went into much more detail) and the tune up would always be a compromise. Even so, after getting the van back it was like a different vehicle, really smooth running and loads of pulling power. The bill was over £2.5k but it has made the van so much more useable. Probably the best investment I've made in the van.  

I would also add the the original M-TDI conversion was carried out by a company that specialises in these vans but the pump wasn't tuned for the engine which is why it was running so badly. I'd advise anyone who's going down the M-TDI route to get the pump reconditioned and set up by a specialist with the correct tools and equipment. 

The original VW ecu setup if installed correctly and the loom well made is extreemly reliable and as Aidan has said can be if needed repaired by most places worldwide. A mechanical pump not so and they do sometimes fail.

4x4 Bus wrote: ↑10 Jul 2021, 20:13 The original VW ecu setup if installed correctly and the loom well made is extreemly reliable and as Aidan has said can be if needed repaired by most places worldwide. A mechanical pump not so and they do sometimes fail.

This is interesting reading.  Mine has a Landy fuel pump and was chosen (prev owner) on the reasoning which is the exact opposite to this and being easy to fix in the middle of nowhere.
As I'm not expecting to be overlanding in the middle of nowhere, maybe electronic setup would be better for mine

 

Good diesel mechanics are becoming thin on the ground here in the UK now (20 years ago there was at least one in every town, keeping all the taxis and old plant going if nothing else, but often doing marine and HGV too, and lots in the country too working on Landies and tractors) it won't be long before the same applies in the rest of the world as the working fleet modernises
In fact, good mechanics are becoming hard to find, along with HGV drivers and many other trades