gas-diesel conversion checklist - General - VWDiesel.net The IDI, TDI, and mTDI source.

• gas-diesel conversion checklist by fillmore on 09 Sep, 2005 17:56
• ok im in the prosses of doing my a2 conversion so heres what i have ahead of me so far. (if im missing anything or anyone wants to add anything feel free)
  
  1) the motor mounts are the same so my diesel will bolt right up (i think)
  2) fuel filter has to be mounted, im using the stock braket on the shock tower
  3)run the gas engine dry, get all the gas you can out of the tank and than fill with diesel, about a gallon of gas is ok to burn off but anymore and the engine will have serious heat issues
  4)stock gasser pump has to be taken off and chucked, the ip will do all the work from here thanks, so long
  5) if your diesel engine is not equipped with pwr steering, than the racks have to be swaped(or you'll have soar arms)
  6) wireing glow plugs to ignition may be tricky so im just mounting a switch on the dash.
  7)gas filler neck has to be change because gasser filler necks are to damn narrow for a diesel pump!
  8)wiring shoudnt bee to much of a mess but gassers are filled with stupid sensors so beware
  9)you'll want to swap a diesel tranny in also to get maximun power out of your engine
  
  thats all i can think of at the moment, im sure there tonns im forgeting so people add what ever you know plz..
  
  also a couple questions,
  1) are the exsaust mani's the same? or am i gonna have to do some sliceing and dicing?
  2) can i use the gasser rad? are they different?
  3) TACK, i know that gasser tacks run off then coil but i heard something about magnetized on a diesel engine?? anyone know about this, it would be nice to hook up my tack
• #1 by Master ACiD on 09 Sep, 2005 19:31
• you dont have to swap racks per sae. a power steering rack has no more resistance than a manual rack. afterall, the power steering fluid is the equivalent of a 20 weight motor oil, very thin.
  
  if you want to test this out for youreself, just jack up the front end of the car  so the front tyres are off the ground and try turning the steering wheel when the engine is not running. there is no increased resistance compared to a manual rack.
  the only difference there could possibly be is perhaps a difference in rack mechanical advantage ratios between power assist aned manual, for this i do not know but i can tell you that the "power" part of a power steering rack provides no more resistance than a manual rack.
  
  by the way, i am also in the process of doing an auto to manual conversion, if i come up with anything helpfull, ill be sure to share.
• #2 by SMOKEYDUB on 09 Sep, 2005 19:51
• Im doing a gas to diesel swap right now. Some moron hit my diesel and i couldnt seem to find a decent diesel so I am changing absoloutly everything so it will be a true diesel accept the ownership. I am changing all the wiring harnesses and i changed the heater box because the gasser had ac (that didnt work) so i shaved off a bunch of weight there  I know its not adding to your list but i thought i would let you guys know what Im doing.
  
  Jeff
• #3 by zyewdall on 11 Sep, 2005 18:34
• I believe the exhaust manifold will bolt right up to the diesel engine.  And from the looks of it, it should offer a bit less back pressure than the stock diesel exhaust manifold.  Anyone have ideas on whether I should remove the cat or not?  I'm not going to be running petro-diesel in it, so the sulpher shouldn't be an issue.
  
  For the wiring, does anyone know if it'll even start with the ECU removed?  I don't know if the ignition switch goes directly to the starter motor, or through the ECU and all kinds of interlocks.  If not, it might get a big black start pushbutton on the dash like my landrover.  Although that button actually IS the plunger on the back of the solenoid, not just a switch to a relay.
  
  I'm planning on a manual glow plug switch on the dash as well.
• #4 by fatmobile on 12 Sep, 2005 02:45
• On the A1s the radiator is the same.
   On the A2s the upper radiator hose connection is in a different place. Might be to miss the alternator on the cars with an AC setup. You might even be able to get away with the gasser radiator if you don't have AC but I haven't been there.
• #5 by BlackTieTD on 12 Sep, 2005 07:47
• i'll write a bit more later... but i want to mention wiring.
  
  sounds like one of your big hangups is wiring... go to the junkyard, find a diesel mkI or mkII and pull the complete wiring harness and any glow plug stuff, ignition stuff, that you might need. i just pulled a complete harness out of an '84 GTi yesterday... didnt cut a single wire or bust anything and it took me a few hours (i was gutting the rest of the car at the same time). for the amount of time invested (or maybe you can find one for sale cheap that someone else has pulled), its definitely worth it to get a diesel harness to do the job right, and save yourself hassle. if you plan right, it should all be plug in and go.
• #6 by fatmobile on 12 Sep, 2005 21:42
• I converted a gasser Rabbit to diesel this spring.
   I pulled great gobbs of wires out of the engine bay. They run across the firewall over to the computer.
   I put a manual glow plug switch in it.
   After I installed it and went to part out the diesel Rabbit the engine came from, I found that all the engine bay wires come through the same hole in the firewall. Upon further exam found that I could have pulled only these wires and swapped them over to the gas car and ended up with the stock glow plug setup. Minus the glow plug light in the dash, everything that came through that hole in the fiewall was plugged into the fusebox or the glow plug relay block (which can be unsnapped from the fusebox) ... except one wire. The wire that went to the injection pump, went to the coil on the gasser would have to be cut and spliced.
   The rest of the wiring was for lights and other things that were the same diesel or gas.
   This was on the '81 ... both cars were '81s. This might not apply to cars with the switches on the injection pump (which a gasser doesn't have)or different reverse light switches between the cars being swapped.
   I one other guy said (long time ago and I can't find the post over on vwdieselparts.com) it's easy to swap the stock glowplug setup onto an A2.
• #7 by Master ACiD on 30 Sep, 2005 12:23
• somthing i didnt see mentioned but i just found out the hard way is the exhaust of a gasser seems to be different than a diesel.
• #8 by zyewdall on 30 Sep, 2005 13:11
• Quote from: "Master ACiD"

  somthing i didnt see mentioned but i just found out the hard way is the exhaust of a gasser seems to be different than a diesel.

  
  
  What's the difference?  I was planning on using the gasser exhaust on mine too -- it looks like the gas exhaust manifold should bolt right up to the diesel head.   I must be missing something there....
  
  [Edit]Sorry, I should specify details here.  Gas engine was 1.8liter, 8 valve from 1991 GTI, and diesel is 1989 1.6L NA.
• #9 by Master ACiD on 30 Sep, 2005 14:35
• thats what i meant. i *^*think*^* you have to use the gas exhaust manifold to use a has exhaust.
• #10 by zyewdall on 30 Sep, 2005 20:25
• Quote from: "Master ACiD"

  thats what i meant. i *^*think*^* you have to use the gas exhaust manifold to use a has exhaust.

  
  
  I'm okay with that... I think.  Just got the extra subaru out of the driveway and running again this week, so I can start working on the rabbit again....