Lost a key so had to take our 2008 Mazda 3 hatch to dealership - $175 later the service person told me that one of my engine mounts was broken but I don't remember which one. I have looked at YouTube videos showing how to replace them and it looks like I can do either one myself. How can I tell which one is broken?

Thanks!

 

The main engine mount on the RHS / Passenger side of the engine bay will either split the rubber section underneath the mount ( you need a inspection mirror) or "Break" & ooze goo all over the chassis rail. That's the tell tail sign.

The rear mount attached to the bell housing will simple tear the rubber section.

The main gearbox mount can sagg & go floppy, causing issues, haven't seen 1 split yet

 

Thanks. The main mount doesn't have any fresh goo on the bodywork underneath but it does have some stains - I also felt around the mount yesterday and couldn't feel anything. I clean the engine compartment regularly so maybe I washed off the fresh stuff.

I'll take another look with an inspection mirror later today - hopefully it's this one because it's by far the easiest one to replace, but if it's the bottom one will I be able to see the tear with the bottom plastic engine cover still in place?

My car now has 85K miles and I understand these mounts last about 50K - could be that it was broken when I bought the car last year with 73K miles on it - it has always vibrated a little when idling in gear.

 

You can also identify broken mounts by observing the engine. Mount a camera to record your engine and then rev the engine while in gear but with the brake applied. You should see it twist more then usual, and may even hear a metal klang as the mount is now metal on metal.

 

Thanks - don't have a camera but I can get the wife to rev the engine!