Parts - Modifications - Injection pumps

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Mechanical Tdi pumps( mTdi)

Foggy: I have a 1Z tdi and am looking to convert to a mtdi. Local scrap yard have loads of Bosch pumps but i need number to find correct one Cheers

Simon Baxter: There is no correct one as a AAZ pump is not right or strong enough for TDI without serious modification. Bosch didn't fit TDI pumps with 20mm drive shaft (as oposed to 17mm) for a laugh.

Foggy: OK! But are there any 20mm shaft pumps that can be made to fit?

Simon Baxter: Quite a few, all needing modification to work. Fiat pumps, landrover pumps, there is a VW pump, a Cummins pump....

All good bases for mTDI, non will work out of the box. IDI pumps do not create enough pressure to work the dual stage injectors properly.

Hot 1200: Hi, you can make the AAZ work but you need to keep the internals stock, as Simon has stated, if you modify the AAZ pump, stick in the TDI cam plate etc. you risk breaking the weaker 17mm input shaft. However, if you keep the AZZ pump stock as I have done on our AHU MTDI (Now done 30,000 trouble free miles in two years!!!) You can make it will need to do the following.

Shut down any residual fuel supply adjusting screws (cold start & Air con) Wind out the throttle arm residual screw until the arm wont adjust back any further Screw in the Main Volume control screw at the back of the pump, work in 1/8 increments. This will now be your idle control screw, as you have shut everything else down. Set the idle...TDI's need a faster idle,(1000 rpm) when running on mechanical stock AAZ pumps. Change the AAZ boost pin, you cant haul a heavy T25 using this pin, it wont allow enough fuel on boost. Fit a 1.6TD boost pin, say from a MK 2Golf GTD or similer. Adjust the pin to give best acceration with least amount of smoke, (Do a google search, Im not going in to pin adjustmet here, it will take all day to write in words what acutally only takes 5 minutes!) Give the pump 1.2mm of advance, this works well, so well, Ive not even got the glow plugs wired up, the Mtdi fires up first time everytime and weve had some pretty cold weather to test it!

You should also fit a intercooler, simple to fit and they seem to work ok.......My intercooler is from a VW Sharron...... Ive had over 90mph from our 87 Caravelle, but that really is its max speed and not sustainable. A relaxed ruising speed is anyware between 65-75, above 80 and its really starting to sound 'harsh' Im using a pertrol box, started with a Diesel box, disaster, top speed was sround 65 with ear defenders. Acceleration is excellent, you will need to ditch the AAZ boost pin for good alround performance. I get an average of 38-42mpg, depending on load.......

I would stick with the smaller injectors as fitted to the AHU and 1Z engines, they have lower spring pressures in them a bonus for the AAZ pump. Avoid big nozzles and spring pressures, the AAZ pump in stock form wont like that!!!

Hope that helps......

HarryMann: Some of the Bosch pumps on Peugeots have the larger shafts and woodruff key (don't forget that bit!) Thus a stronger pump throughout.