Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must login to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)
tt2001

Engine and Transmission mount replacement

33 posts in this topic

My service shop tell me my '99 C2 enging is vibrating too much and the engine mount needs to be changes . After they changed two engine mounts, they found out

the problem is comes from the transmission mount. They tried to order the parts form dealer and the dealer said parts are not available. Can some one give me an idea what are engine and transmission mounts? and where can get the right parts?

Share this post


Link to post
Share on other sites
    You can remove these ads by becoming a Contributing Member.

this reminds me my experiences with my dealer (or dealers). they kept fixing the wrong parts and broke my AC until I fed up and went to a local shop. Bob just fixed it with a $100 part. I think it's a way that dealer plays with you when they try to get you back to pay more or they simply are not capable of find the problem.

find a local porsche specialist and have them take a look at it. dont guess what's going on unless you really know about it. In Silicon Valley, you can try Bob @ RMG. but looks like you are in LA. maybe someone can recommend you one.

Share this post


Link to post
Share on other sites

My shop shown me the damaged part: which is the mounting between the transmission with the chassis. inside the mount has rubber brushing to absolve the vibration/movement. The rubber brushing inside was broken so caused the engine+transmission vibrated. They also shown me a taken down Boxster engine, which use the same mounting part between the engine and transmission, also the same thing, the rubber broken inside. Dose any one has the some type of problem? how to obtain the replacement parts? Any feedback will be highly appreciate.

Share this post


Link to post
Share on other sites

So, your service shop called a local dealer for the transmission mounts and the dealer said that "the parts are not available"? Does that mean that the dealer does not have them in stock, or that you can't even order the parts from Porsche? The latter seems strange for something as simple as a mount so it's probably the former.

I'd clarify with your shop what "the parts are not available" means and get the part numbers. You can call around to other dealers and see if anyone has them in stock or can order them (try board sponsor Sunset Imports). In the rare case that the parts cannot be ordered, you could try a dismantler and get used parts off a low mileage 996 or Boxster (if the parts are the same) -- someone like LA Porsche (www.laporsche.com 818-767-7243).

Share this post


Link to post
Share on other sites
So, your service shop called a local dealer for the transmission mounts and the dealer said that "the parts are not available"?  Does that mean that the dealer does not have them in stock, or that you can't even order the parts from Porsche?  The latter seems strange for something as simple as a mount so it's probably the former.

I'd clarify with your shop what "the parts are not available" means and get the part numbers.  You can call around to other dealers and see if anyone has them in stock or can order them (try board sponsor Sunset Imports).  In the rare case that the parts cannot be ordered, you could try a dismantler and get used parts off a low mileage 996 or Boxster (if the parts are the same) -- someone like LA Porsche (www.laporsche.com  818-767-7243).

Thank you Coaster, according they told me the mount brushing is part of transmission, if the car under warranty, Porsche will replace the whole transmission. There is no parts number for it alone. I just don't know how true it is.

Thank you for your input , I will try what you say. I might taking a picture for the broken piece and post it again.

Share this post


Link to post
Share on other sites

I think you are talking about the only mount at the rear of the transmission. There is no single part listing in my parts list either. It looks to to be pressed in at the least.

post-2-1115773652_thumb.jpg

Share this post


Link to post
Share on other sites

How much does the engine vibrate? Can't imagine not being able to confirm if it is the mount (unlikely) or not. The area of the suspected bad mount can be easily secured mechanically to see if the vibration goes away. Is the vibration at speed or at idle or both?

Edited by 1999Porsche911

Share this post


Link to post
Share on other sites

Loren, thank you for your nice picture.

Please see these pictures for the detail.

1. The end transmission mount

2. Broken robber inside the bushing.

3. A Boxster parts, you have to buy the whole set (bracket + the mount) and

press out the mount unit to use it in my 996.

The robber in bushing is very easily broken which will cause the Engine and transmission vibrate and more damage can be happen if ignore this problem.

Porsche should do something improvement. And they should make this parts available.

post-1034-1115832370_thumb.jpg

post-1034-1115832463_thumb.jpg

post-1034-1115832500_thumb.jpg

Share this post


Link to post
Share on other sites

I wonder if that was damaged in a previous repair? Like a an RMS repair where they take the transmission out to get to the RMS. Hmm... :unsure:

Share this post


Link to post
Share on other sites

This is interesting. Us Box owners do not have this issue. We get the housing with the rubber bushing - except on our cars it is an engine mount - not transmission.

So after the tech session at an independent shop today I went by the local dealer on the way home. 2 of the mechanics I know where there doing their personal stuff in the shop. Both said they have replaced this mount on a 996, but it was not pounded out of a Box engine mount and put in a 996 transmission.

Then one of the mechanics went on the parts computer and could not find a 996 transmission mount, just like Loren said.

The other mechanic thought this part was sold as an aftermarket part.

It might be hard to understand but there is a 'back' parts department at my local dealer that you never see as a customer. A mechanic needs a part and the back parts person gives it to him. The mechanic does not pay attention to where the part comes from or the number since that is not his job.

post-4-1116120707_thumb.jpg

Share this post


Link to post
Share on other sites

The #s on mine are;

On one side

986=996

133 135

98637505700

On the other side

99637505505

Jeff at Sunset was unable to find the part # in the catalog and didn't have one in stock to look at.

He ordered 99637505505 and offered to send me the specs and pics before he ships it to me just in case.

Here's my real problem. I didn't anticipate needing to replace this when I dropped the transmission.

So I didn't jack the car up high enough to get the gbox out from under the car. So I'm going to have to lift it

off the jack while under the car, slide it out, cart it to a shop, have them press in the mount, then lift it back on the

jack while under the car, and try to realign everything.

Did I mention I have noone around I feel comfortable asking to help me with this? I've disassembled myself into a corner.

My other option is to roam arount Home Depot and try to build some kind of tool to pull the mount in while under the car.

Or use my big metric hammer, and hope I don't destroy it.

Anyone ever replace one of these without using a press? :help:

post-34457-1230848008_thumb.jpg

Share this post


Link to post
Share on other sites

Is this mount easily visible without disassembling anything?

I just want to make sure it's in good order.

Edited by MagnusB

Share this post


Link to post
Share on other sites

Yes and no.

If you jack the car up and get your face right up to it and fold back the

soft rubber gasket things you can see most of it. If it's completely broken

you'd be able to see it.

Notice the picture of the broken one with the screw driver. In order to say for

certain that it's not split you'd probably need to do that on both sides.

The drivers side of mine looks fine, but if you pry on the passenger side you can

see the front side is split nearly all the way through.

Share this post


Link to post
Share on other sites
My service shop tell me my '99 C2 enging is vibrating too much and the engine mount needs to be changes . After they changed two engine mounts, they found out

the problem is comes from the transmission mount. They tried to order the parts form dealer and the dealer said parts are not available. Can some one give me an idea what are engine and transmission mounts? and where can get the right parts?

Does anyone know if the tranmission mount mentioned in this thread (part #996 375 055 05) is applicable for both Manual and Tiptronic transmissions?

My car is an early Tiptronic and the mounting isn't in good shape. I couldn't find the part number for the mounting until I came across this thread. However, correct me if I am wrong, the original poster is driving a Manual. If the part number is the same for both versions, that would be great news, I could then buy one quickly and resolve my transmission mount problem.

Thanks in advance!

Share this post


Link to post
Share on other sites

I replaced my 99' C2 motor mounts last night. About a 30 minute job. Very easy. And yes, I used the motor as a jacking point while replacing each mount.

This drastically helped damper the vibrations, nearly entirely present at warm idle. Manual shifting smoothness is also much improved!!!

However there is still a little bit of residual vibration. I'm not sure if it's enough to worry about at this point.

I looked at the tranny mount and poked around with it but couldn't determine if it was bad.

Visibly with the car started I could see a very slight vibration and the mount appeared to be doing it's job of "soaking it up".

Any way to test the tranny mount without removing the transmission (and mount)?

Share this post


Link to post
Share on other sites

Interesting, I have noticed a slight drop in one of my exhaust tips. I will be checking exhaust and engine mounts. Is there a DIY on the replacement of the motor mounts. I have tried searching with no luck.

99 C2 Tip

Share this post


Link to post
Share on other sites
Interesting, I have noticed a slight drop in one of my exhaust tips. I will be checking exhaust and engine mounts. Is there a DIY on the replacement of the motor mounts. I have tried searching with no luck.

99 C2 Tip

Are you sure the tailpipe is not just mis-adjusted or came loose. Fairly common.

Share this post


Link to post
Share on other sites

when my engine mounts started failing i too had one side of my exhaust hang lower. Replaced and they evened up.

Share this post


Link to post
Share on other sites

Could be out of adjustment. I have not looked under the car to check. I am thinking I will be able to compare both sides and have an idea if there is a problem.

Edited by carsareart

Share this post


Link to post
Share on other sites

Ok, I have had some time under the car and engine mounts seem to be extended on one side. So I have replaced them both and adjusted one side for left to right of the tip. I would like to adjust the drivers side down just a bit...

How do you adjust for height on the tips/mufflers? I did a search and was unsuccessful finding a post that helped me.

Share this post


Link to post
Share on other sites

This is interesting. Us Box owners do not have this issue. We get the housing with the rubber bushing - except on our cars it is an engine mount - not transmission.

So after the tech session at an independent shop today I went by the local dealer on the way home. 2 of the mechanics I know where there doing their personal stuff in the shop. Both said they have replaced this mount on a 996, but it was not pounded out of a Box engine mount and put in a 996 transmission.

Then one of the mechanics went on the parts computer and could not find a 996 transmission mount, just like Loren said.

The other mechanic thought this part was sold as an aftermarket part.

It might be hard to understand but there is a 'back' parts department at my local dealer that you never see as a customer. A mechanic needs a part and the back parts person gives it to him. The mechanic does not pay attention to where the part comes from or the number since that is not his job.

Does anyone know if this transmission mount (part #996 375 055 05) is applicable for both Manual and Tiptronic transmissions?

Mine's a Tip, but the car in the discussion is a Manual.

Share this post


Link to post
Share on other sites

On my '99 manual 996:

This might not be a "legit" way to determine if your transmission mount is bad... but... here's what I did (high risk factor so make sure your jack is SECURE), you wouldn't want your transmission dropping onto the support brace below.

Placed a floor jack with small block of wood under the mount (so it only contacts the transmission, not the tranny brace/bracket) and raised the jack ever so slightly, just a half inch at most. Removed the two bolts from the mount.

At this point with the weight of the powertrain off the mount and on the floor jack, you can easily poke around at the mount with a screwdriver and see the condition of it. To my surprise the center part of the mount where the bolts go through moved around more freely than I expected, and I was expecting to get some resistance or feel some rigidity there. Basically nothing to keep the weight of the engine/transmission from compressing it all the way to the top at this point. Of course, 11 year old rubber is bound to break down at some point.

Started the car up and noticably less vibration from the engine - of course - with only the rear motor mounts and the floor jack at this point holding things to the body.

I don't have a new one (yet) to compare it with, but my guess is that a new unit is going to have stiffer rubber and no tears/breaks in the rubber around the outside edges of the mount.

Can anyone who's done this comment on the condition of a new mount, is the rubber very pliable, or more rigid as one would expect a rubber mount to be (not a solid mount of course)?

I've also read how some people fill their mounts with windshield adhesive to make it more like a solid mount, although I suspect that will do more to increase rigidity and shifting performance, it might make the vibration transfer to the body more apparent.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now