Pelican Technical Article: Replacing Motor Mounts Wayne R. Dempsey
Time: 2 hrs
Tab: $185
Talent:
Tools:
Floor jack
Applicable Models:
986 Boxster (1997-04) 987 Boxster (2005-08)
Parts Required:
Motor mount
Hot Tip:
Remove the entire carrier and take it to your bench
Performance Gain:
Stiffer ride, better handling suspension
Complementary Modification:
Replace transmission mounts
This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your Porsche Boxster. The book contains 312 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 950+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Boxster owner's collection. The book is currently available and in stock now. See The Official Book Website for more details.
Check out some other sample projects from the book:
One of the most common parts to deteriorate on the Boxster cars is the engine mount. After years of use, the rubber that is contained within the mount becomes old and brittle, and doesn't perform a good job of isolating the drivetrain from the rest of the chassis. The inside of the Boxster mount is hollow, to help with reducing vibration. Unfortunately, this creates significant areas of structural stress and weakness, which can encourage cracks to appear in the mount.
Old, worn out motor and transmission mounts can sometimes cause clunking and vibration problems because the drivetrain is no longer firmly held in its position. One sign of this failure mode is the gearshift knob jerking backwards under hard acceleration. A visible sign that the motor mounts need replacing is the appearance of cracks in the rubber of the mounts (impossible to see without actually removing the mount). The rubber will deteriorate over the years and needs to be replaced, even if the car has relatively few miles on it.
There have been many redesigns of the motor mount, and the latest one (PN: 987-375-023-04) is the strongest, and should fit all Boxsters and Caymans. Early mounts (through 1998) were only attached to the engine via three bolts. You can use the later-style mount with four mounting holes to replace an early mount, but if you want to have it mount via four bolts to your early engine, you will need to upgrade/replace the oil pump housing (see Photo 17 of Pelican Technical Article: Boxster Engine Conversion Project).
There are alternative mounts you can use in place of the stock ones for your car. You can purchase a set of solid, or performance mounts. I don't recommend these for street cars as they may give you too harsh a ride. Stick with OEM mounts if you're going to be driving your car on the street most of the time.
Replacement of the mounts couldn't be easier. Simply jack up the front of the car, and support it on jack stands (Pelican Technical Article: Jacking Up and Lifting the Boxster on Jack Stands). Gently place the floor jack under the engine sump, taking care to only apply enough pressure to relieve tension on the front mount. Disconnect the engine carrier, and then disconnect the motor mount from the engine case. Take the assembly to your workbench and swap in the new mount. Bolt it back up, lower the car and you're done!
Figure 1
The first step is to jack up the car and support the weight of the engine with your floor jack. Don't actually lift the car or the engine, simply place the jack under the lower engine cover until it lightly makes contact. In general, you should never lift the engine from the bottom sump. But for the purposes of simply supporting the weight of the engine while replacing the engine mounts, the cover should suffice.
The engine carrier is attached to the chassis using four studs and nuts shown here (blue arrows). Carefully remove all four. There is a good chance that the entire stud will come out of the chassis: this is okay, as you can remove the nut and reinstall the stud later.
The engine mount is attached to the front of the engine case using four bolts (two shown with the purpose arrows). Remove these four and the engine mount should simply drop down.
Shown here is a brand new later-style engine mount, ready for installation. If you're looking for added performance, then I recommend going with a solid polyurethane mount like the one manufactured by WEVO and available through PelicanParts.com. This mount will translate more engine vibration into the chassis, but the ride will feel quite a bit more stable and stiff. Simply press out the old worn out rubber from your old mount and install the polyurethane insert. I definitely recommend the polyurethane mounts if you're designing a track car. However, if you install the poly mount on the engine, I do not recommend installing solid transmission mounts. The resulting engine vibrations can cause lots of problems like knock sensor errors which may actually result in a loss of horsepower.
Comments: Very simple job. Only issue was that the mount I ordered for my 99 did not look the same. It had an extra mounting hole on the engine side which matched up to an existing bolt, but the factory bolt was too short. A quick trip to the hardware store solved the problem and it was the best money I ever spent. All vibrations went away and the car feels smoother and very tight. What a difference!!! If you have a vibration around 2300 RPM in any gear, this is the fix!!
April 4, 2012
Canuck hoopster
Comments: *Did not have to remove the radiator hoses, but the hose brackets had to be removed, to allow the hoses to move.
May 14, 2011
Canuck hoopster
Comments: Definitely easier to drop the engine after the first four studs are out, to access the last four bolts. Seat the studs with a quarter inch 7mm socket when you reinstall. Total start-to-finish was 3.5 hours.
May 14, 2011
Vic
Comments: Started removing undertray parts and it looks very tight around the engine carrier. Do the radiator hoses need to be removed prior to removing and installing the engine carrier? And if I do remove the hoses, will it completly flush all the antifreeze?
May 9, 2011
Followup from the Pelican Staff: You should be able to get the mount in and out without removing the hoses. If you do remove the hoses, you will need to capture the coolant and reuse it, or replace it. Also, you'll have to rebleed the system, which is not difficult, but can be a pain. - Wayne at Pelican Parts
GGR65
Comments: I just finish this project today. I also agree with Klickdavis about the extra support for the engine case. I think it is important. And the radiator hoses are in the way of the carrier and the mount. It is very tricky to the mount out.
But biggest puzzle was installation, I bolted up the motor on the engine firmly first, it is not going to work. Because lining up the carrier and the 4 bolts is impossible if the mount is bolted. I had to loosen everything, align them, jack up the engine. And then it worked out perfectly.
January 9, 2011
Followup from the Pelican Staff: Yes, I did indeed have the luxury of taking these photos with the radiator hoses removed. Tight access and a bit tricky, but doable. Thanks for the feedback! - Wayne at Pelican Parts
Klickdavis
Comments: Hey,
Just finished doing this project.Replace engine mount 02BoxterS
Couple of hints:
Helps to to remove ALL the body mount studs 8mm 1/4 drive works fine, these guys were almost hand tight in my car giving lots of room to manuver.
We dropped the engine 2 to 3 inches to allow removal of the long bolts from engine side of mount.
Your procedure shows rad hoses removed, harder with hoses in place, helps to remove midship undertray to facilitate moving hoses around.
Removal was a bit of a chinese puzzle but if right it just falls out.
Also remove the rubber "cheek" cushion pieces from old mount and place in new assembly.
Dropping down the engine just a smidge is cake with a good jack but best to have a safety jackstand +block o wood to keep the engine from plunging,
Thanks very much for all the great techs you do and fair pricing on parts and pieces.
Rick Davis....
November 7, 2010
Followup from the Pelican Staff: Thanks for the additional feedback and tips! - Wayne at Pelican Parts
Check out some other sample projects from the book:
