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Pelican Technical Article:
Replacing Motor Mounts
 

 
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: 

Need to buy parts for this project? Click here to order!
   
     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!
The first step is to jack up the car and support the weight of the engine with your floor jack.
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.
Large Image | Extra-Large Image
The engine carrier is attached to the chassis using four studs and nuts shown here (blue arrows).
Figure 2
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.
Large Image | Extra-Large Image
The engine mount is attached to the front of the engine case using four bolts (two shown with the purpose arrows).
Figure 3
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.

Note: Although the coolant hoses are not shown on the car, the mount will still come out without removing them. However, you may find it easier if you loosen the hose/pipe mounts, allowing more room to maneuver the mount.
Large Image | Extra-Large Image
Some models have an 
                          extra torx headed bolt in the center of the aluminum 
                          casting (yellow arrow) that attaches to the engine 
                          block. To remove the torx bolt one must remove the 
                          bolts through the motor mount, drop the chassis 
                          fixture, and remove the torx headed bolt.
Figure 4
Some models have an extra torx headed bolt in the center of the aluminum casting (yellow arrow) that attaches to the engine block. To remove the torx bolt one must remove the bolts through the motor mount, drop the chassis fixture, and remove the torx headed bolt.
Large Image | Extra-Large Image
With the engine mount assembly on your bench, disassemble the mount from the engine carrier.
Figure 5
With the engine mount assembly on your bench, disassemble the mount from the engine carrier. Two large bolts affix the two together (yellow arrows).
Large Image | Extra-Large Image
Shown here is a brand new later-style engine mount, ready for installation.
Figure 6
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.
Large Image | Extra-Large Image
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Bonus Photos
Looking for more photos? Click to see bonus pictures for this project.
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Comments and Suggestions:
Rick Comments: The lower mount bolt that attaches the mount to the engine is too long; it hits the frame and won’t come out. I put the other bolt next to it so I could see how much I needed to get it out, It is about ½” to long I have gotten all the bolt’s out but that one what can I do to get it out?
September 29, 2014
  Followup from the Pelican Staff: Once the mount is unbolted from the body, lower the engine slightly, the bolt should clear the body. - Nick at Pelican Parts  
Dick George Comments: It took exactly 2 hours and everything went smoothly. All the studs came out and that made the job easier. If they did not come out, I would have double nutted them and removed them. I removed the access panel from behind the seats and was able to loosen the upper bolts easily from there. Those 2 really only need to be loosened as the holes are slotted so you you pull down one side to disengage on and slide sideways to disengage the other. Of course, I discovered this after removing the bolts completed, but if I had to do it again ............
June 24, 2014
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
dan Comments: I was able to torque every bolt to 34 ft/lb except the passenger upper side bolt that attaches the mount to the engine because the 2 bolts that connect the mount to the yoke are directly in the way. Has anyone experience this..Should I be ok?
June 21, 2014
  Followup from the Pelican Staff: Have you tried removing the bolts that are in the way, then reinstalling then once the other are torqued? - Nick at Pelican Parts  
Jonasd Comments: Hi, I have a 987S, when going around 100 km/h I get vibrations that comes and goes in cycles around ones every second. I also have a klonking noise when liften the gas. I assume that this could be the engine mount. Have anyone else had vibration that comes and goes in cycles?
February 23, 2014
  Followup from the Pelican Staff: I have not experienced this. See if the sound matches the frequency of the drivetrain, engine, etc. This will help you narrow down the possible causes. - Nick at Pelican Parts  
Thommo Comments: Hey, old article I know, but.....

I'm finding my '01 2.7 boxster is wandering around when going over uneven road surfaces. A search has said this could potentially be the fault.

What do you guys think?

Cheers
November 28, 2013
  Followup from the Pelican Staff: Could be a bad mount. I would also check to see if you suspension components are tight. Jack the vehicle, then wiggle the wheel while monitoring each ball joint and connection. If something is loose, you could have the same symptom. - Nick at Pelican Parts  
Sumflow Comments: I Imagine a triangular trailer with hitch in the front two wheels touching the ground in back carrying an engine. The hitch is centrally mounted suspended in a rubber sleeve. The cadence probably only beats when turning right because the RR wheel under power tends to rotate the car left against the cracked insert.

The thumping was most persistent in hairpins on the ÔHill of EscapeÕ a heiau luakini used for human sacrifice, so I always suspected a supernatural origin for the drumming might have been possible. For whatever reason, the noise stopped after the installation of the redesigned mount. With the new mount the Boxster feels tighter, more stable, more responsive, more like a formula car than a sports car.
June 30, 2013
  Followup from the Pelican Staff: Thanks for the additional information. We appreciate it. - Nick at Pelican Parts  
jnbgriffin Comments: I just finished my 2000 Boxster S w 53K miles in about 3 hours. I removed the 2 clamps along the coolant lines going towards the front of the car to give me more room to pull out the mount. The new mount has solved my vibration issues as well as the clunking sound I was getting when I would fully turn my wheel to either side. Thanks for the pics & instructions.
June 23, 2013
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help. - Nick at Pelican Parts  
Sumflow Comments: About a year an a half ago I started to get this strange drumming whenever I took a hard right with the pedal down. The harder I accelerated the more pounding I would get. It was as if some entity was playing a Tom Tom up under the car. The sound seem to be moving around, not always in the same place. I had my suspension guy put it up on the rack, a few times, as well as my own mechanic. They assured me nothing was falling off, so I kept on doing laps. They could not make the car do it on the rack no matter what they tried. But when I hit the hairpin on the way home, I still had to back off.

So of course when I went to replace it, I looked for something better. If original equipment failed once it is bound to fail again. But as you can see here, that would involve another trade off. Use the performance mounts and you get increasing engine vibrations and a harsh ride. Just my opinion but a softer ride keeps the tyre patch on the ground, a stiffer go-cart ride leaves them in the air. So with Porsche as is so often the case, factory designed comes out optimal for street road racing, racing.

Poesche ~ Anything you add to it, diminishes it.
June 12, 2013
  Followup from the Pelican Staff: I guessing it wasn't the axles but a motor mount. A softer ride prevents inexperience drivers from getting into trouble. As with any Porsche if you change something you should upgrade the whole system. Ask yourself how many miles did the original part last. - Nick at Pelican Parts  
Pete Comments: Ive already done this once on my car and changing it make a big difference.

Please note new part number is 987-375-023-05. Its the 5th version and hopefully much better!!
June 7, 2013
  Followup from the Pelican Staff: Thanks for the additional information. We appreciate it. - Nick at Pelican Parts  
Nick Comments: 2000 2.7 l boxster....engine bay fan not working. I figure either the sensor, relay or fan is bad. Is there a picture or way to jump the wires on the fan? I would like to try to isolate the problem. My thoughts are its the relay. Does Pelican parts have any experience with the Boxster engine fan issues? Let me know...thanks!

Nick
May 28, 2013
  Followup from the Pelican Staff: The cooling fans usually fail, the sensors are pretty reliable.

I would remove the fan and connect fused 12 volt and ground to it. The fan should run, if it doesn't, replace it. - Nick at Pelican Parts
 
WILPWR Comments: Went the cheap route and paid for the $30 part, had it pressed. Old mount was shot. Finished mine this morning. Runs like new. No vibration around 3k, no vibration or anti lock feel from the outside wheel going around corners aggressively. Best $60 and time I've ever spent. Love every second of it.
April 5, 2013
  Followup from the Pelican Staff: Cool, thanks for the feedback and the photo. - Nick at Pelican Parts  
ELoomis Comments: Did this last weekend. What an improvement. 3000 RPM vibration gone and no movement in the shifter on acceleration. Gear changes more precise as well. Old mount was trashed. 2001 base 85,000 mi.
March 23, 2013
  Followup from the Pelican Staff: Thanks for sharing. - Nick at Pelican Parts  
WILPWR Comments: I believe that this is the vibration issue that I am having with my 04 Boxster - vibration happens 1 when I decelerate around 3K RPMs, 2 and is a lot more harsh when I go around a corner aggressively. Is this the fix for my 2nd issue as well? Thanks
March 17, 2013
  Followup from the Pelican Staff: Does your shifter move as described in the article? It could cause both of your symptoms, so it;s worth a shot. I would inspect the mount and see if it is worn or sagging. - Nick at Pelican Parts  
Z. Clark Comments: Very strait-forward instructions, thanks again. Jacking up the car looks confusing but luckily I had a lift I was able to use.

Something worth noting, I was able to save quite a bit of money by buying only the bushing and not the complete aluminum mount assembly. The part number is 987-375-023-05-M69.

You'll need to carefully use a hydraulic press to push the old bushing out and the new one in. Be carefull with the hydraulic press and aluminum, I didn't have to apply much pressure before the bushing started moving. Never having been underneath a Porsche before, everything took me about 3 hours.
November 23, 2012
  Followup from the Pelican Staff: Part number for your AOS is 996 107 023 04. I would also recommend replacing the hoses and clamps. The parts numbers are listed on our site or you can call our order desk at 888 280-7799

Denny at Pelican Parts
 
JeremyL Comments: I am going to attempt this next week. Thanks for the advice. Did anybody have issues jacking up their car? Did you just jack up the front as mentioned here?
September 3, 2012
  Followup from the Pelican Staff: Please read the linnked article on jacking your Boxster it will give you the detail you need.

Denny at Pelican Parts
 
wheelieboy1 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
  Followup from the Pelican Staff: As stated in the article the maount was updated. Your mounting bolt solution was the right one. Happy to hear your Boxster repair gave you such great results.

Denny at Pelican Parts
 
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
  Followup from the Pelican Staff: Happy to hear that worked for you. Thank You for the response, it will help others during mount replacement.

Denny at Pelican Parts

 
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
  Followup from the Pelican Staff: It is acceptable to lower the engine a bit to facilitate replacement but a warning is needed. That procedure can put stress on or damage the many hoses, cables and wiring that go from the engine to the body. Extreme caution is needed to prevent damage.

Denny at Pelican Parts
 
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: 

 

Got more questions?  Join us in our Boxster / Cayman Technical Forum Message Board or our Carrera 996 / 997 Technical Forum Message Board and ask a question to one of our many automotive experts.

Or, see what other questions readers have asked about this article...
  Applies to: 1997 Boxster, 1998 Boxster, 1999 Boxster, 2000 Boxster, 2001 Boxster, 2002 Boxster, 2003 Boxster, 2004 Boxster, 2005 Boxster, 2006 Boxster, 2007 Boxster, 2008 Boxster, 1999 Carrera, 1999 996, 2000 Carrera, 2000 996, 2001 Carrera, 2001 996, 2002 Carrera, 2002 996, 2003 Carrera, 2003 996, 2004 Carrera, 2004 996, 2005 Carrera, 2005 997, 2006 Carrera, 2006 997, 2007 Carrera, 2007 996, 2008 Carrera, 2008 997
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