Replacing a 4.0 V8 Engine with a 4.2 in a naturally aspirated 1999 XK8.
#1
10-08-2017, 05:15 PM
Replaced a 4.0 V8 Engine with a 4.2 in a naturally aspirated 1999 XK8.
My 1999 4.0 (126,000 miles and Nikasil liners) was lacking a little lowdown response, putting an embarrassing blue fog out the exhaust on engine start and acceleration and was using a litre of oil every 600 miles. 
As the independent specialist garage I use, Rotherham Jag Centre, has put a 4.2 in a 4.0 XK8 before I opted for that option.
The strip down of the 4.0 engine found burnt oil in the crankcase indicating serious piston ring/ cylinder wear, we changed it just in time.
A 4.2 engine was obtained from a 2005 S-Type with 75,000 miles on it that had been rear ended.
The first surprise was a 2002 engine number from a 2005 car! But after looking inside this 4.2 engine appears to have done a lot less than 75,000 (original Jaguar gaskets everywhere and its very clean condition inside) so it may be a factory refurbished engine with less miles on it, were still researching that one.
Because the 4.2 engine came from an S Type the timing chain cover, oil filter, sump, engine mounts and all ancillaries (Alternator, power steering pump, AC compressor, etc) needed swapping out with the ones from the old 4.0 engine.
We re-used the 4.0 engines electronics (and check all sensor plus types) to ensure compatibility with the rest of the car and the 4.0’s wiring loom.
We kept the 4.2’s timing chains, VVT, oil pump and the starter motor.
The Basic process was strip down and remove all ancillaries, wiring loom, Timing Chain Cover, Fly Wheel, Manifolds, Rocker Covers, Coil Packs, Thermostat Housing, Throttle Body, Sump/ Sump Plate/ Oil Pick-up, and replace them with the ones off my 4.0 engine.
The Sump Plate and Timing chain cover need “Modifying” to fit and some Manifold fixings need to be drilled and tapped.
Some unexpected items were, collapsed engine mounts, part load breather broke as it was removed and a few other minor hose plastic replacements.
After all that it started first time and pulls like a train.
Hope this is useful to anyone with a failing 4.0 engine as the 4.2 seems to be easier to source.
As the independent specialist garage I use, Rotherham Jag Centre, has put a 4.2 in a 4.0 XK8 before I opted for that option.
The strip down of the 4.0 engine found burnt oil in the crankcase indicating serious piston ring/ cylinder wear, we changed it just in time.
A 4.2 engine was obtained from a 2005 S-Type with 75,000 miles on it that had been rear ended.
The first surprise was a 2002 engine number from a 2005 car! But after looking inside this 4.2 engine appears to have done a lot less than 75,000 (original Jaguar gaskets everywhere and its very clean condition inside) so it may be a factory refurbished engine with less miles on it, were still researching that one.
Because the 4.2 engine came from an S Type the timing chain cover, oil filter, sump, engine mounts and all ancillaries (Alternator, power steering pump, AC compressor, etc) needed swapping out with the ones from the old 4.0 engine.
We re-used the 4.0 engines electronics (and check all sensor plus types) to ensure compatibility with the rest of the car and the 4.0’s wiring loom.
We kept the 4.2’s timing chains, VVT, oil pump and the starter motor.
The Basic process was strip down and remove all ancillaries, wiring loom, Timing Chain Cover, Fly Wheel, Manifolds, Rocker Covers, Coil Packs, Thermostat Housing, Throttle Body, Sump/ Sump Plate/ Oil Pick-up, and replace them with the ones off my 4.0 engine.
The Sump Plate and Timing chain cover need “Modifying” to fit and some Manifold fixings need to be drilled and tapped.
Some unexpected items were, collapsed engine mounts, part load breather broke as it was removed and a few other minor hose plastic replacements.
After all that it started first time and pulls like a train.
Hope this is useful to anyone with a failing 4.0 engine as the 4.2 seems to be easier to source.
Last edited by smoggyx100; 10-08-2017 at 05:18 PM.
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#2
10-08-2017, 08:31 PM
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