The 75 and ZT Owners Club Forums - View Single Post

Tourist · 18th June 2019, 10:44

Hey there, to test the spark plug unscrew it, reconnect the HT Lead, and use a pair of pliers to hold the metal part at the bottom of the plug against the cylinderhead. Now, if someone pulls the starter cord, you should be able to see the spark jump at the electrode of the plug.

I'd also check the spark plug gap while it was out.

There are some good videos on Youtube about diagnosing your mower issues - I had the same problem as you and it turned out to be corrosion of the armature. I removed it, cleaned it with wire wool and then reset the gap between it and the flywheel using feeler gauges, although you can do it by eye if you saw how close it was before you removed it. If you remove it, make sure that you put it back on the right way up ;-)

If your mower has a kill switch (or handle you have to hold up for the mower to run) then also check that mechanism as I've had issues in the past where oxidation of a copper leaf switch prevented contact and therefore stopped the spark.

If it's sparking then you've got a fuelling problem - can you smell fresh petrol in the cylinder when the plug's out?

18th June 2019, 10:44	#2
Tourist Loves to post 2004 Rover 75 Tourer CDTi Join Date: Apr 2016 Location: Fulbourn, Cambridge Posts: 455 Thanks: 105 Thanked 123 Times in 101 Posts	Hey there, to test the spark plug unscrew it, reconnect the HT Lead, and use a pair of pliers to hold the metal part at the bottom of the plug against the cylinderhead. Now, if someone pulls the starter cord, you should be able to see the spark jump at the electrode of the plug. I'd also check the spark plug gap while it was out. There are some good videos on Youtube about diagnosing your mower issues - I had the same problem as you and it turned out to be corrosion of the armature. I removed it, cleaned it with wire wool and then reset the gap between it and the flywheel using feeler gauges, although you can do it by eye if you saw how close it was before you removed it. If you remove it, make sure that you put it back on the right way up ;-) If your mower has a kill switch (or handle you have to hold up for the mower to run) then also check that mechanism as I've had issues in the past where oxidation of a copper leaf switch prevented contact and therefore stopped the spark. If it's sparking then you've got a fuelling problem - can you smell fresh petrol in the cylinder when the plug's out? Last edited by Tourist; 18th June 2019 at 10:47..