Mk3 golf petrol to old diesel lump

[Bugsy_malone 666]

I should know what I am doing by now having spent so much time mucking about with engine conversions in old cars, but I was trying to ascertain the level of work required to do a petrol to diesel conversion.

basically I have a 1.6diesel and I plan to drop it into a 1.8 petrol mk3 golf. I will be bolting on a 1.9tdi turbo and different injector pump.

So basically, I understand I need to change the fuel gauge sender from the tank as its different petrol to diesel as the petrol one has an integrated pump. The engine will bolt to the gearbox thats in there and all the engine mounts and bits will bolt straight on the diesel engine, with the only mod needing to be done is the front pulley is different.

With a 1.9tdi turbo I should be able to use the 1.9tdi downpipe which should pretty much fit straight to the current exhaust (may need a little modification).

So then its electrics, which is the bit I am trying to work out. How integrated is the FI system? Its a single point injection unit but I didnt know how much it connected into. With the diesel I just need a live to power the injection pump fuel cut off and also a glow plug relay. I was looking to strip the injection system/ECU out so the petrol engine can come out and go in something else maybe.

Anything else I should really know?
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[trev]

I did this conversion into a '95 B4 Passat, was 1.8 single point injection, now 1.9D. Electrics are easy, just get the live for the diesel solenoid from the plug where the coil was. water temp, oil pressure are all the same and swap over. Make up a new glow plug relay/fuse/switch circuit. I have a manual push button on the dash, never bothered with a timer.

you'll need a diesel gearbox or you'll get no speed out of it at all.

exhaust, find the proper downpipe for a diesel mk3 and pop it on. I found the rest of the system (petrol engine exhaust) rotted out pretty soon afterwards so I got a used B4 diesel exhaust system to put on.

I think you need the petrol ECU to run the clocks, diesel clocks WILL NOT just plug in, white smoke time petrol rev counter won't work with diesel engine. I left the petrol lift pump in the tank and it's running fine pumping diesel.

very easy conversion, mine's in daily use for 3 years now.

best of luck with it

[Bugsy_malone 666]

See I was thinking that the clocks were actually seperate as I have seen dash conversions in other cars without the ECU, so the speedo just has a speed sensor, milage is built in, lights are just lights. I have a mk1 speedo and the only real difference I can see is the fact on early cars its cable driven speedo.

Timer relay for the glowplugs is a piece of cake, got one on my bus and it takes about 4 wires, just need a light which I think which is an extra wire.

Gearbox wise I didnt think it would be too much of a problem, current petrol engine does 70mph at 3200rpm diesel turbo doesnt produce full pressure till 4000rpm and with a few mods it will be fine to do that

Exhaust I was gonna go with the tdi downpipe as its straight bolt on but the thing I wasnt sure about is catalytic convertors? I have an old cat thats nackered that I can knock the core out of to make it straight through, but the golf currently has a newish cat on it, but I dont know if the diesel works with a stock cat.

what did you find out about diesel clocks? I know the rev counter runs from the W terminal on the alternator, my alternator has it so I can probably put in the red counter from a diesel and wire it as required.

I'm hoping its a nice bolt in conversion. I am using a 1.6D as the base engine, so I am bolting on a different injector pump/turbo to turn it into the TD, need to do something to the pulleys as I am using all the 1.8P mounts/alt on the 1.6D so its literally like a block swap. I have a 1.9tdi fuel tank sender just in case theres to much difference. I am planning at a later date to run this on veg oil as I have done my van and the system works, but my vans not as fast as my golf!
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Second Gear All The Way Baby!

Doing Thing Differently.

[trev]

thinking about it again, maybe the ECU isn't needed for the clocks in the B4 Passat. I don't know how similar they are to the mk3 but I'd imagine fairly close. I got a set of clocks from a B4 diesel and just plugged them into the loom. No go. So I put the rev counter from the diesel cluster into the petrol cluster but no-go either. So what's in there now is the petrol cluster with the diesel rev counter in situ but effectively dead.

engine mounts are all the same, nothing different there. pulleys, the petrol ones probably won't work due to the location of the alt versus injection pump. Or maybe they will and you'll have to get creative with the belt lengths. I just used the the pulleys etc on the 1Y engine. The newer multi-vee pulley/belt system is way better than the vee-belt system.

[Bugsy_malone 666]

Well the reason the rev counter isnt plug and play is because of the way it works and where it connects to, the petrol one takes a signal from the coil, the diesel one takes a wave frequency from the alternator, on my petrol alt there is a connection for a diesel rev counter (which is handy!).

With the pulleys and stuff, basically my golf is one without aircon so the alternator fits in a position which effectively clears the injection pump as it sits right over the water pump. I have once before looked into fitting a later alternator on the same bracket as my mk3 for my van, trouble was I didnt have an alternator of the right fitment! but I know the bracket fits and should clear. I think everything should just swap over, but I know that diesel cambelts are 1/4" wider than petrol ones, which would cause alignment issues. My mk3 pulleys are pressed steel so I'd be unable to alter these to take into account the thickness, GTi engines however have an aluminium centre to the pulley which I think has sufficient thickness to machine off the extra 1/4" (I say I think because I was looking at mods done on vwdiesel net and vw vortex etc) failing that if I use a modern skoda pulley and a spacer like my bus it might work!

I'm sure I have it mostly covered, but really need to bulletproof the project so that I can rebuild my engine have everything I need and convert the car in just a weekend so not to have it out of commission for to long or sat knocking about for my dad to complain about!
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Second Gear All The Way Baby!

Doing Thing Differently.