UPDATE: Motor Mount Stud Bolts - Size Listed | Ford Explorer Forums - Serious Explorations

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UPDATE: Motor Mount Stud Bolts - Size Listed


Active Member
March 18, 2010
Reaction score
City, State
Amory, MS
Year, Model & Trim Level
1998 Mountaineer AWD
I have a 1998 Mercury Mountaineer with the 5.0L V8, formerly an AWD.

I have broken the two motor mount studs on the passenger side of the motor. Can anyone tell me what size and thread they are? I would appreciate it very much.

UPDATED 12/28/2020: After successfully replacing these broken studs, I will share their size for the benefit of anyone else who might need this info. The studs on my Mountaineer were 7/16-14 reduced to 3/8-16. The 7/16-14 threads into the engine block and is 1-1/4" in length. The other end is also 1-1/4" in length and is used for bolting line supports or brackets to the motor. The overall length of these studs is 2-1/2".

Replacing them wasn't very difficult, not nearly as bad as I thought it would be. I loosened the right motor mount and then placed a jack under the motor to support it. After completely removing the right motor mount, I had a little more access to the broken studs, which were broken flush in the engine block. I was able to get the forward bolt out with a sharp punch, gently tapping it in a counter-clockwise motion until I had enough protruding enough to remove it with my fingers. The rear bolt was not accessible with a punch, but with an extension, I used a 1/4-20 LH drill bit in a 12" extension and turned it out with a cordless drill. I replaced both with grade 8 bolts.

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Got it myself:

7/16-14 x 1-1/4" stud downsized to 3/8-16 x 1-1/4" for mounting brackets, 2-1/2" overall length.

Do you have a part number of what you picked up?

Mine broke on the drivers side, they don’t look like they hood anything so I’m curious what the bolt length needed you be

7/16 - 14 x 1.5” ?

I replaced badly worn engine mounts and 3 (out of 4) broken studs on my 1999 Ford Explorer XLT 5.0 v8 AWD today.

I went to a Ford dealership to confirm that the OEM bolts(studs) are discontinued by Ford and no dealer in the country has them in stock.

So, I got grade 8 bolts (7/16 - 14 x 1") with grade 8 washers from the hardware store for $7 and was ready to use them until I found that ARP makes a kit of premium bolts for that exact purpose:

ARP Motor Mount Bolt Kit
Ford 289-302-351W, hex
Kit #: 150-3102

Link on Amazon:

ARP seems to be the best quality bolts you can buy for this application.
I paid around $20 for the set of 4. I think it's worth the extra bucks.