One of the first things I did when I got my Disco was change the plugs. This, like an oil change, is a routine task but there are a few things to watch out for.
The V8 Disco 4.0s take 8 .032 gap plugs.
For basic plugs, we’re talking under $20 and you’re Rover will see a lot of positive changes. Plugs take an electric charge from the ignition system to ignite a fuel-air mixture in your engine to create combustion. They also contain combustion pressure within the engine.
Old plugs that aren’t completely burning the fuel-air mixture will decrease horsepower, fuel efficiency, and torque. That leftover fuel can also cause deposits and have a bad impact on the oxygen sensors.
To install new plugs simply find your plugs under the hood. There will be 8 of them. Carefully take off the Spark-Plug wires that go to the engine. ( I usually do one at a time so I don’t mix up which wire goes to which plug).
Unscrew the plug with a 13/16 wrench. The wrench will have a rubber insert in it to hold the plug while you pull it out.
(Clean out any excess oil from the top of the spark plug hole. If you have a particularly old Rover, like me, any oil residue build up will smoke when you run the engine. NEVER FEAR! A quick trip around the block should burn off any extra oil and disappear quickly. This happened to me and had me freaking out.)
Add the washer to the bottom of the plug if it isn’t already on and screw in the new plug by hand, first. Take care not to strip the plug hole… that would be bad. Snug the plug with your wrench and don’t over-tighten.
Replace the spark plug wire and you will here it click/snap when it’s properly attached.
Repeat 7 more times and wow yourself with the extra gas mileage and smooth running purr of your Disco.