mk4 12v swap into mk3 (need info)

[hooddub]

Some of you already know this but the mk3 I recently picked up blew up on me and I ended up with a seized motor.

Highway speeds and oil not moving through the motor combined with shitty luck seem to be a bad combo!

My question to everyone is,

Can a mk4 12v be swapped in to a mk3 vr? I know the mounts are different but I'm told if you bolt up the mk3 mounts to the mk4 vr it will fit.
Can anyone shed any light on this?

Will the transmission bolt up properly?
Just wondering what is involved in the swap as I know of two 12v mk4 motors for sale for good prices but, being my first swap I want to keep it as simple as possible for myself.

Any info would be awesome!

Also, if anyone knows of any relatively low km mk3 vr6s for sale let me know!

[Danaldson]

Re: mk4 12v swap into mk3 (need info)

You should swap a b6 into it.

But for reals, you could buy kuji's motor once he's done with it. I think his is a 24v?

[hooddub]

Re: mk4 12v swap into mk3 (need info)

You should swap a b6 into it.

But for reals, you could buy kuji's motor once he's done with it. I think his is a 24v?

24v swap is quite a bit of work I've read. Would be awesome but not something I'd want to tackle for my first swap. Probably also would be a while before I could get the motor.

[kujiwara]

Re: mk4 12v swap into mk3 (need info)

Yeah mines a 24v but I won't swap it out until summer... It would definitely be cool to see it in a mk3. I think the mk4 12v in a mk3 is a direct swap if you use the mk3 intake manifold.

[GINCH]

Re: mk4 12v swap into mk3 (need info)

Yeah mines a 24v but I won't swap it out until summer...

What motor are you swapping into your GLI?

[Mantis]

Re: mk4 12v swap into mk3 (need info)

You should swap a b6 into it.

+1000000

[onceover]

Re: mk4 12v swap into mk3 (need info)

What motor are you swapping into your GLI?

3.2 VR6

I imagine the mk4 and mk3 blocks are identical

[BolideVW]

Re: mk4 12v swap into mk3 (need info)

You should swap a b6 into it.

^like x10000

[GingerBeef]

Re: mk4 12v swap into mk3 (need info)

The mk4 AFP long block is identical to the mk3 AAA long block. Although pretty much all the accessories have to be swapped over. Obviously the intake manifold is completely different, you can run the MK4 manifold if you want, but im not sure how you could get it to be functional. I would just use the Mk3 manifold. All the holes for the mk3 mounts are on the mk4 block and the tranny bolts right on. Once you have the motors side by side it will be very obvious what you need to swap over.

As far as the differences between the mk3 OBD2 12v VR6 and the mk4 12v VR6, as far as i know the mk4 has a thinner, metal head gasket, instead of a paper composite. I have a mk4 HG in my mk3 for better reliability and a little bit more power (the mk4 HG is thinner, thisll raise your compression from 10:1 to 10.5:1)

Next up is the head, the head itself on the mk4 and mk3 are identical, but internally the mk4 head has a different set of cams to run optimally with the variable intake runners of the mk4's intake manifold. You can either swap the cams over, or just put your mk3 head on the mk4 block.

Lastly, as before mentioned are the accessories, i know the coil pack is the same, but the electrical connector is different, which sucks. I believe this is the same case for the alternator. Besides that, i dont know the similarities or differences between the mk4 and mk3 powersteering pumps, water pumps, AC compressors etc. But it doesnt really matter as all the mk3 bits will bolt right up to the mk4 block.

Overall, if you decide to swap over a mk4 12v engine into your mk3 youre only realistically creating an extra afternoons worth of work, as i found when i was puling my motor that with the mk3s packed bay it was easier to get the engine out with the alt and AC compressor removed anyways.

[Veedub_Jetta]

Re: mk4 12v swap into mk3 (need info)

MK3 Engine mounts bolt right up to the MK4 VR6 12v, If you keep the O2J transmission the MK3 transmission mounts will bolt right up aswell but then you will need different driveshaft flanges. Since the MK4 is drive by wire, you will need to convert and there is alot of wiring involved. Depending on how much work you want to set up for yourself it might just be easier and cheaper just to by another MK3 or an already swapped VR MK3.

[BolideVW]

Re: mk4 12v swap into mk3 (need info)

You can either swap the cams over, or just put your mk3 head on the mk4 block.

This doesn't sound like a good idea, considering your old block had low oil pressure, the head may have been starved of oil.

[GingerBeef]

Re: mk4 12v swap into mk3 (need info)

This doesn't sound like a good idea, considering your old block had low oil pressure, the head may have been starved of oil.

Yeah, thats true. I was just talking about the actual swapping process itself. Evan, well have to make sure your cams werent damaged at all. Before swapping the head.. either that or its time for aftermarket cams

[hooddub]

Re: mk4 12v swap into mk3 (need info)

Head doesn't need to be swapped, I just need to run the mk3 intake manifold. Should be fine as far as I've read and what I gathered from George and some of the guys at tunedub. As far as throttle bodies are concerned, I will be using the mk3 TB along with the manifold.
In the process of removing the old Trans from the mk4 motor and swapping sensors.
Thanks for the input everyone!

[hooddub]

Re: mk4 12v swap into mk3 (need info)

Update: To anyone following this or curious how difficult a swap it is to run a 12v mk4 motor in a mk3 car here are some updates!
I have swapped over the valve cover, alternator, oil filter, oil pressure sensor and fit up the old cooling components (crack pipe and coolant flange/thermostat housing)
These parts are all direct fitment and the only thing I had to do was put a thicker o-ring on the oil sensor to get it properly seated.

I am currently waiting on my new headers, intake manifold gaskets, valve cover gasket, new o-rings for my crackpipe (which I lucked out with finding the previous owner had put in an aluminum one!) and my new thermostat, thermostat housing, coolant flange and all the seals and hardware.

Once I get those I just have to throw them on, bolt up the transmission (which I may do this weekend while I am waiting for parts) and it will be ready to go back in the car!

The only thing I have actually had to modify is the cam position sensor, as the mk3 sensor is a little longer than the mk4 sensor so it doesn't fit. I just trimmed the plug on the sensor so the mk3 harness's connector fits over. Both sensors have a 3-tab connector so it wasn't a difficult modification to make.

Overview of everything I've noted needed to do this swap :

-mk3 vr6 valve cover (direct bolt using mk4 hardware)
-mk3 vr6 wiring harness (bracket bolts onto mk4 head)
-mk3 plumbing (crackpipe/thermostat/coolant flange [direct fit])
-mk3 alternator (mk3/mk4 connections are different)
-mk3 oil filter (direct bolt on to mk4 block
-mk3 vr6 intake manifolds (upper and lower, along with fuel injector rail [haven't bolted up but should be direct fit])
-mk3 vr6 throttle body
-modify mk4 cam position sensor connector to fit mk3 harness connector

That's all I can think of for now, when I finish everything I will update and complete this list. I can't speak for a/c and p/s pump fitment because I delete them (racekor) but they should be identical, same deal as alternator, just need to be swapped for different connectors. i also deleted my SAI which I would recommend. probably will be deleting my EGR and PCV as well. Exhaust manifolds are exactly the same too.

Essentially what this swap ends up being is a MK4 VR6 head and block/internals mated with MK3 12v VR6 sensors, accessories, wiring harness, fueling, intake manifolds, valve cover, and mounting brackets.

There is very limited info about this swap on the internet so hopefully this will shed some light on the subject.

Ran into a snag with my passenger motor mount bracket, on the mk4 block the holes for the mk3 bracket are there but they are not threaded, does anyone have a tap I could borrow to make new threads for the bracket?

Still have to swap the transmission as well and I am pretty clueless on this as I've never done a clutch or anything of that sort and don't want to frig it up. For now it will just be a straight swap with the mk3 tranny/clutch and once I have the car back in one piece I will stockpile some parts to get all done at once as well as the chains (upgraded clutch, cams, valves, valve springs etc..)

Here is my thread on vortex: http://forums.vwvortex.com/showthrea...First-VR-Build

If anyone wants to lend a hand or has some suggestions that would make my life easier let me know!

[Ben]

Re: mk4 12v swap into mk3 (need info)

I wasnt going to comment, until i read your post on the Vortex.

""Previous owner didn't have the car long and still managed to **** it up but the guy before him did tons of maintenance (timing chains, clutch etc..) which really upset me. It was such an awesome car until idiot who I bought it from abused it.""

I bought the car in April of 2014, and put over 10k on the car. Not once abusing it. The last oil change i did was at 160k, sold you the car with 163k. Had i known the car had any sort of issue with oil pressure i sure would not have driven it Red Deer to meet you to trade cars as it could have left me on the highway as it did to you at any point.

As for what happened to cause the low oil pressure I am still curious, before you go out calling me an "idiot" id like to see you pull the timing covers and oil pan to see where it failed. If the oil pickup clogged, or a timing component failed I cannot see how that made me an "idiot"

To quote your text "Yeah well the oil light just started beeping at me and i pulled over, checked to make sure the oil was okay which it was, started it back up and kept driving but then it started losing power and finally it just quit on me"

Had you not continued to drive the car with NO OIL PRESSURE the engine in that car may have been ok and not seized if you had sought out to find the issue.

Now as for the main reason to this post - To save the engine you are putting into that car i have a full set of Chains and guides with less than 5000km on them(from a GTI i bought, paid to get chains done, and then it spun main bearings on me) I will gladly mail those down to you at my cost so you can do them before you put the engine with 140k with old chains and guides back into the car.