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Motor Mount Destruction!!

AdamJ214

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Orlando
#1
Hello!
It is great to be a member here and make my first post.

I am a 2015 Fiesta ST owner and I love my car. I have had two major issues since I got it. At 2,000 miles my transmission, clutch, slave cylinder and master cylinder had to be replaced due to a very loud screeching sound at idle. Now at just under 11,000 miles my motor mount on the front of the engine where the belts are has shattered the bolt in three places. I was not racing or doing anything out of the ordinary. I was making a left turn then BANG! SMACK SMACK on the firewall. Has anyone else had this issue with the main mount? I know our cars have issues with the bottom torque strut mount and it causing the motor to hit the fire wall. I will be posting a video soon of the mount. My service writer at my dealership looked at it and immediately blamed it on the cold air intake I installed. I really do not think the added 5HP from the cold air intake would affect the mount in that way. Cobb has a fiesta putting out over 300 hp and no issues with the mounts that I know of. SO what are your guys thoughts on this and has anyone else had this mount break?
 


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AdamJ214

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Thread Starter #2
[video]https://youtu.be/P4OJ6OF5Rec[/video]

Sorry it is a bit shaky I was rocking the car back and forth. You can see the bolt head missing and the mount moving a lot.
 


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Stafford, CT, USA
#3
Boombots had this issue I believe. Not sure how to link to the thread but if you go into the transmission and drivetrain section and look for the "broke something...it's not pretty" thread you may find some helpful information.
 


BoostBumps

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#4

Sourskittle

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#6
Rodmoe's car made 375whp on that mount.
I've broken that mount. Secret squirrel has broken that mount. And likely others that just don't post on the forum ( but do read, there are a lot of people that choose not to post ).

That mount breaks because.... #1 the bolt they use stock is a POS. its like a powdered metal. #2 the mount is not equal to the task its being assigned to. Its the same mount in my mom's 1.6L SFE gas saver fiesta. Its actually quiet surprising that someone has not created a support to replacement part for it. The trans mount is pretty sad too. Has a huge gap in it for flex/movement.

Mostly likely in your case.....? When they pulled the motor or dropped the trans, they let too much tension build on that mount, weakening it. They fixed the issue with the trans etc, but didn't notice the bolt was at the very least loosened up, if not damaged or weakened when they did the work.

An air intake doing anything remotely like that show's you that your dealership employee is also not equal to the task he/she is assigned to. Only a real moron would look to blame a cold air intake for an engine mount bolt or engine mount failure on an almost brand new car.
 


Sourskittle

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#8




This was mine broken. And the thread/pitch of the bolt to replace it, but I don't remember the length.
Secret squirrel had to replace the entire mount....
 


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Marcellus
#9
I'm wondering if you should just replace it with a stronger bolt immediately. After seeing this when mine comes in I'm wondering if that is something I should do before it breaks.
 


Chris G

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San Diego
#10
Just replace the one bolt there? Is that what most people are doing? Seems like cheap insurance. How tough is it to access?
 


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Campbell
#11
M12*45 is the size to get.

Get a washer too because it seems like the bolt hole in the mount (with aluminum bracket) is about 48mm deep, I don't know how deep the threads extend.

The stock piece has some grey colored thread locking compound so it is a pain in the butt to remove the broken bolt even if you have enough sticking out to grab with vise grips.
 


westcoaST

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#12
If the bolt is a partial thread 12 x 1.75 x 45 fastener, here is a good bolt to use:

https://www.boltdepot.com/Product-Details.aspx?product=17524

I'm using Sourskittles' bolt photos for reference, as I have not pulled this bolt myself. Most likely, the dealer caused the damage by not torquing down the bolts for the passenger side motor mount properly. Take a photo of the fracture face and post it, and I'll tell you why the bolt failed. The photo needs to be a high magnification photo that fills the field of view.
 


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Campbell
#13
The factory bolt is threaded all the way to the head but a bolt with a short shank might work.

Buying a replacement mount, the bolt that breaks is already installed and torqued. There is no reason for a dealer to touch it.
 


westcoaST

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#14
The factory bolt is threaded all the way to the head but a bolt with a short shank might work.

Buying a replacement mount, the bolt that breaks is already installed and torqued. There is no reason for a dealer to touch it.
Depending on what the fracture face looks like, and where it's located, using a partially threaded bolt may be an improvement.

As for there is no reason for the dealer to touch the bolt when removing the transmission, Tell that to the Ford tech who removed the transmission. Instructions on the mechanics manual are typically vague. I work in the failure analysis field. I constantly hear "there's no reason for that to have happened", but it still does. Insert failed part here.
 


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Campbell
#15
One thing you can see on the mount is that the surface that the bolt threads in to has a rectangular top which I am sure they use as wrench flats when torquing that bolt.

If you remove the engine by taking out that bolt (which has thread locker as stated earlier) without a wrench on those flats, you are going to put a big torque on that hydraulic mount, probably tear the rubber and make a big mess.

If that is the way it was done and you have a failure later, you should be able to hold the mechanic liable.

The silly part is that the mechanic was only three bolts without thread locker away from removing the whole thing the right way.

I'm not going to bother with measuring how much shank can fit in the motor mount because any replacement is still a M12 bolt and in my opinion, that's a bandaid not a solution.

At some point I'll drill and tap my old mount for 9/16-18 threads and have a substantially stronger fastener.
 


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