# MK4 VR6 swap into a MK3



## SoCal Driver (Nov 14, 2002)

Hi all!

I have a 98 GTI VR6 with almost 240k miles. About 40k miles ago I had the timing chains and stock transmission replaced; I went with with a Corrado CDM transmission with a quaife LSD. The car is now burning/leaking about 1Q/1k miles and I'm tired of always topping it off. Over the last month I've been pricing out the parts I'd need to rebuild the motor in my garage, with the help of some talented friends of course . Earlier this week I came across an entire motor for sale but it's out of a MK4. The engine has 56k miles and recently had the timing chains replaced when they had a BVH and new cams installed (DSR 256). 

A few questions I had...

- Are the motor mount points the same on the MK4 block as the MK3? or will I have to make new motor mounts?
- Can I use the MK3 engine sensors so I don't have to swap out the harness?
- what would need to be done to keep the MK4 intake manifold functional?

I'm sure this swap has been done before, so does anyone have any links to build threads I can check out? I tried searching but didn't come across any relevant posts.

Thanks! :beer:


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## V-dubbulyuh (Nov 13, 2005)

SoCal Driver said:


> A few questions I had...
> 
> - Are the motor mount points the same on the MK4 block as the MK3? or will I have to make new motor mounts?
> - Can I use the MK3 engine sensors so I don't have to swap out the harness?
> ...


Motor mount points are compatible... ignore the holes tapped in the side of the block intended for Mk4 mounting and transfer your Mk3 engine mounts to the front and pax side of the engine to be swapped.

While some sensors might be salvagable you will run into problems with many of them, eg TPS and the Mk4 throttle body being drive-by-wire. If you are planning on retaining the Mk4 TB you will run into problems here. Some people revert to a cable throttle body to avoid this. The connectors on several other sensors are considerably different too, MAF.

Not sure how the Mk4 intake manifold is going to like your Mk3 ECU (different cam profile altogether). Unless you are planning either standalone or running a Mk4 ECU I am doubtful about having a "properly" running Mk4 variable intake. You've probably noticed that since the Mk4 intake places the throttle body on the driver's side you will need to do some harness rerouting anyway to get your MAF connector to the driver's side.

Path of least resistance is to use your Mk3 lower & upper intake manifolds mating to your Mk4 engine.


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## vwmaniac16vr6 (Nov 17, 2004)

strip all accessories & sensors from the mk4 long block and replace them with the mk3 accessories & sensors, also you may have to change the upper timing cover and cam sensor as well as the cam sensor trigger wheel if you have the earlier set up. then your done:thumbup:


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