Engine Mount: Three Bolt or Four?
 

i've got to replace my motor mount. it's a three bolt type. i have access to a great deal on a four bolt type. i can't remember if a four-bolt will fit on a three bolt car or if a three-bolt mount will fit on a four bolt car.

does anyone know if i can replace my 3-bolt mount with a 4-bolt mount? thanks.

Hello,

I recently had vibrations and took out my motor mount to find the rubber cracked and shifted 5 mm to the right. I went to the dealer and told the parts dealer my model & year. They pulled up the part number and sold me the part with the 4-bolt assembly and my stock one was 3 bolt. The 4 bolt fit up fine, I only used 3 bolts on the new assembly because I do not have the threading for the 4th bolt and driven for about 100 miles now smooth as ever. I also noticed that the assembly metal and build quality on the new mount was considerably stiffer than the old one (not stiffer for driving, it was as smooth as off the factory floor).


Here's a pic I snapped before installing the new mount - old mount (left) and new mount (right).


http://www.ucrpad.org/images/test/motormount01.jpg


It was fine for me, no installation issues or problems with the fourth hole. If you notice the fourth hole is for the upper right of the mount. It clears everything for me in the pulley area.

you are the man. thanks for the input!

Hi


Seems I have the same vibration prob that u had.

What did u pay for the part if I can ask?

Steven.

Hi,

If your car came as a 3-bolt unit, this is what you should replace it with. Using a 4-bolt mount means that one side is not secured and this could cause issures such as the mount failing prematurely...

Happy Motoring!... Jim'99

MNBoxster -

thanks for the concern; i agree this COULD pose a problem. i've seen the mounts side by side, though, and i don't think it will make a difference.

smagerstein -

i purchased the part from German Auto Dismantlers for $85. since it's used, i'm going to modify it with a pass-through bolt to prevent lateral bushing slippage. i'm then going to fill it with Flexane 80 (pourable urethane) to make sure it doesn't go out again. BTW, if you call german auto dismantlers, mention you're a PCA member.

Hi,

Just FYI, the PN#s I have for the engine mounts are: 986.375.023.03 ('97-'98) and 986.375.023.05 for '99 ->. I have no application for the part shown - 986.375.023.07. Perhaps this is for the 987?...

Happy Motoring!... Jim'99

MNBoxster: Maybe so on the part numbers for it being a 987 part. As for the 4th hole and using only the 3 hole....

I didn't take pictures of the back portion but structurally and design, the mounts are the exact same. Especially a pic from the rear of the two, one can see that both mounts were almost identical in design, same metal skeleton lines, same cast and same design as the original only differences between the 3 bolt and 4 bolt was the vented holes on the new one, a sturdier metal compound, and of course the extra hole for the 4th bolt.

I do not see as to why it would not be beneficial, wrong, or harmful to install the 4 bolt mount. The part was made to be obviously interchangeable.

i need a new engine mount and a shop is charging me $430 for new porsche branded one installed... is that a good value..? i'm guessing this is a hard diy...

The part can be had for less then $200 from Sunset Imports,google them and give them a call. A couple of people have made it a D.I.Y. .

http://www.ppbb.com/boards/ppbbphp/showflat.php?Cat=&Board=ARCHIVES&Number=1106222&Fo rum=ARCHIVES&Words=motor%20mount&Match=Entire%20Ph rase&Searchpage=1&Limit=25&Old=1year&Main=1106222& Search=true#Post1106222

Personally if I could find a shop to do it for $200 or so,I would have them do it.

hrmm i'd definitely feel more comfortable getting it installed...

anyone happen to know a place in socal that would do it for 200ish?

F.Y.I. some amatuers did it in 2-4 hours,so pros that charge$100+ and do it for a living should only take 2-3 hours tops.

hrmm alright i appreciate it. btw what is the general rule of thumb about actually bringing parts to a shop. it seems like they tack on a lot of extra to the part for themselves...