XK Engine Replacement 3.7 V6
I just purchased a 2006 Commander with a blown engine. The PO said they had had the oil changed by a chain store and then two weeks later the engine locked up. I am not sure on how honest they were with me. The oil was the dirtiest I had ever seen. Definitely hard to believe it was only two weeks old!
Shopping for a replacement engine via car-part.com revealed very few low mileage engines available in my area. 2007-2008 engines were plentiful, however. Searching forums it was hard to determine exactly what the difference was. Previous research on the 4.7 V8 had revealed changes to the intake manifold/throttle body. Turns out similar differences apply to the 3.7 V6. The 2006 uses a throttle cable and has only 3 bolts attaching the TB. The 2007-2008 were drive-by-wire and use 4 bolts. I swapped the older 2006 intake and throttle body onto the 2007 engine. The knock sensors under the intake manifold were also different. Again, it was easy as swapping in the older part to the newer engine. The last difference was the addition of an EGR valve on the 2007 engine. I simply left it in place but left it disconnected. I used the 2006 engine wire harness for guaranteed compatibility.
I have a few helpful hints for others attempting this swap in your home garage. I have a very good selection of tools and a fair bit of experience performing this type of "repair". There were a few problems that left me scratching my head and wondering, "how in the heck did they do that?"
One of the major challenges was removing the intake manifold. There just was not enough room to lift the engine out of its mounts with the intake in place. Also, the intake is too thick to remove from the engine when it was still in place! It turns out that it is necessary to remove the long bolt from the passenger side motor mount and allow the engine to drop down into the mount. This will give you enough room to remove the intake.
While we are on the topic of motor mounts....I found it easiest for both engine removal and installation to simply unbolt both mounts completely from the block. It gives you more room to maneuver the engine through the engine bay.
Removing the intake gives you access to the top transmission bolts. They are easily reached with a wrench when the intake is out of the way. There is another bolt on the passenger side of the bellhousing that is a BEAR to get to! It is the one that attaches the transmission fill tube to the engine. The best way to reach it is to use a loonngg extension, go over the top of the transmission crossmember, through the exhaust and use a universal/swivel into a short 16mm socket.
Another hint is to remove the inner front fender wells. They are held on by several plastic pop rivets. Just push the center pin into the rivet with a sturdy pick. They pull out easily but will not be able to be reused. You will need to purchase new rivets.
The final big challenge was re-filling the cooling system. After nearly an hour of slowly refilling as the air burped from the radiator I still had way too much air. I had had the front and rear heaters cranked full blast but couldn't get the temperature guage to settle. Against my judgement based on prior experience I followed the recommendation in the factory service manual to drive the vehicle for an hour and then refill the reservoir. During this drive I was worried about overheating the engine but it did allow me to add more coolant. Finally I parked it for the evening and in the morning the reservoir was low again. After this final refill, temperature is rock solid. Perfect!
I hope this info helps others. Except for the coolant tip, none of this is covered in the service manual.
