Hi, I'm new to the forum. My family has had at least 10 jaguars over the years. We currently have a 89 xj6 which was just hit and a 64 mark X for sale. I found a cheap 90 xj6 sovereign for sale around me that has a compression problem with cylinder 2. I was wondering how involved or complicated it would be to replace the 4.0 in the '90 xj6 with the 3.6 in my '89. Any help would be appreciated

 

This should be a fairly straight forward swap as theyare bothAJ6 engines,the 4 litre is a bored out 3.6 engine. The gearboxes are probably different as I think the later 4 litre has a stronger more advanced computer controlled box, but as the blocks are physically the same you should have no problems fitting the 3.6 into the 4 litre carleaving the 4 litre box in place, you mayneed to swap the 4 litre torqe converter, starter and flywheel onto the 3.6 litre engine. I would also be tempted to try and use the intake and exhaust system off the 4 litre onto the 3.6 if possible as this should enable you to re-use the 4 litre wiring loom which will help keep things simpler if indeed there are any wiring differences. The worse case scenario is having to swap the engine, box and prop etc but as you have a complete donor car this should still be reasonably easy.