Another from the archives! Hey, its cold out. Yea yea, the 4g63T is ready to go in but seriously, it’s cold out. Anyway, today I’ll go over changing out the passenger motor mount on my 2004 Mazda 3. Apologies for the horrible picture quality, this was done later in the day and it got a bit dark for natural lighting to suffice.
For the replacement itself you have two options. You can go ahead and grab a replacement insert or a whole unit if you want a more straightforward swap. The entire unit will cost you though, so I went the cheaper route and just did the insert. Amazon to the rescue yet again!
This is a pretty straight forward operation. You’ll need to move the coolant reservoir tank out of the way, there is a clip on the strut tower and on the fender side that you’ll need to carefully release. With the tank out of the way you have full access to the motor mount.
Next, you’ll want to get a jack under the engine somehow to hold it up, I opted for a board across the oil pan to distribute weight. You only need it snug, so it holds the engine in place, you don’t want to put pressure on the mount. With the jack in place you can go ahead and remove the two nuts that hold the mount to the engine and the two bolts into the frame on either side that hold the whole thing in place.
The engine will probably shift a little even with the jack in place, don’t worry about it too much. You should be able to maneuver the mount out of the bay with the nuts off. I took the whole assembly into the garage as you’ll next need to remove the insert and put the new one in place.
As you can see, mine appears to be the factory unit and has failed as they all eventually do. I noticed this part was bad when I pushed my finger into the top of the mount and met no resistance. I should have met some resistance as these are supposed to be fluid filled.
Now, bearing that in mind, who’s idea was it to fill these with hydraulic fluid? The theory is that it helps dampen the vibrations a 4 cylinder engine naturally creates. The reality is you end up replacing the damn thing every 50,000 miles or whenever you notice an unidentified fluid running down the passenger side engine bay.
Removing the old insert is easy, you just bend the two tabs straight and grab the insert. Then just go ahead and finagle the new insert into place. The hardest part of this whole replacement is figuring out how to crimp the tabs back into place. It’s a bit difficult to hold the insert down and whack the tabs at the same time. You can probably use a vice or something, but it worked well enough for me to just whack it with a hammer. You can tell in the pictures below that it isn’t nearly as secure as the factory unit though.
So you’ll have to use a vice grips or just a bench vice to really get those tabs bent in. Once you get the tabs figured out, you’re ready to put the mount back in and button everything up. You may need to move the jack or raise it get the bolts where they need to be and line everything up again. I bolted the mount assembly to the frame first and then lined the bolts up on the engine side. The torque specs are something like 35-40 ft-lbs for the nuts and 55-70 ft-lbs for the bolts.
The ground strap just forward of the motor mount is something many people move out of the way while doing this. Why? Reasons I guess. I couldn’t find a conclusive answer but feel free to move it if you like that kind of thing.
Otherwise, put the coolant reservoir back in place and you’re good to go.
I drove the car to work and back (about 100 miles for me) and double checked the nuts to make sure they were still tight. I did this again a week later and had no issue with them being loose. Done deal!
If my walkthrough isn’t specific enough head over to HowTune and check out their car work tutorials, I’ve used them to get me started on some of my repairs and they have excellent write-ups.