So jacking up the rear from the engine bottom is OK ?

[ninsei]

Hi. 'looking for the rear jack point. I saw a thread saying it was ok to use the engine (not oil pan though). Keep in mind, i would be putting jackstands under the two, rear factory jack points so I can't use them as jack points.

[dr914jr]

I use the rear of the engine as a jack point on a fairly regular basis. I've also seen a guy use the sump cover and subsequently bust through the cover :o . To jack the car up without doing damage to the car or yourself you only need three things. You'll need a jack, a small section of 2x4, and some common sense.

[deckman]

Some people will scream at you for doing this. Maybe this is the real reason for all the engine failures :) But if they know of a better way to get the car on jack stands I'm all ears. I don't even use the 2x4.

[Chuck Jones]

There are all sorts of pros and cons on this technique. I do it...as does a number of my friends, and my indy, and some of the racing guys...but some folks will decry the dangers of doing it this way. I use a short piece of 2 X 4 that I have a saw kerf down the middle that fits over the place where the casing comes together with an edge. There are a number of threads on this subject on Rennlist and maybe even here that show you pictures of where to put it...some guys put it in the wrong place and end up breaking something, but once you're centered on the right contact point, it's easy and it gets both back wheels up off the ground at the same time and allows you to slip in the jackstands.

[Orient Express]

Here is the way I have been doing it for years without any ill effect. Your results may vary.

[aracerx]

There are all sorts of pros and cons on this technique. I do it...as does a number of my friends, and my indy, and some of the racing guys...but some folks will decry the dangers of doing it this way. I use a short piece of 2 X 4 that I have a saw kerf down the middle that fits over the place where the casing comes together with an edge. There are a number of threads on this subject on Rennlist and maybe even here that show you pictures of where to put it...some guys put it in the wrong place and end up breaking something, but once you're centered on the right contact point, it's easy and it gets both back wheels up off the ground at the same time and allows you to slip in the jackstands.

a big issue is the liquid filled motor mounts....they sometimes give up when jacking up the back of the car via the drivetrain.

[oneyedjack]

a big issue is the liquid filled motor mounts....they sometimes give up when jacking up the back of the car via the drivetrain.

+1. And to add to this......the engine "sits" on the motor mounts. When you jack up the car using the engine, you are asking the motor mount to act in the opposite direction it was designed for...ie to lift the body of the car . Here is a generic picture of a hydraulic motor mount. You can see it is designed to have a load sit down on the mount. The fluid in the mount helps dampen the engine vibrations by isolating the connection to the body and the connection to the engine.

When asked to lift a load these mounts can sometimes seperate. The top bolt (connection to engine) can end up bending the metal can around it and pop out of the rubber housing.

Cars designed mostly for racing generally use solid motor mounts that are more robust and are probably more than capable to lift the load of a race car. Point is that just because they do it at the track does not mean its ok for the driveway. Even if the mounts don't break, they might suffer inernal damage that cause them to leak, etc.

BTW,don;t shoot the messenger. Just trying to give some useful info on the subject so people can decide for themselves. YMMV

[SH-GT3]

Loren had a picture, and I’ll be damned if I can find it now, maybe he will re-post, which also shows using the cross support as a temporary jack point. I used this point a couple weeks ago without issue.

[GranburyChuck]

I had a motor mount fail while jacking from the back engine point. Some have said they would have failed anyway as I had 90K miles on the engine. I know jack one side at a time under each side suspension mount point. Not as handy as in the center of the engine but I don't want to ruin my engine mounts.

[Orient Express]

This issue about motor mounts continues to be a much debated issue, and unfortunately much of the "con" debate is by the lay members of this board.

As someone that has lifted quite literally hundreds of 911s by the engine, I would like to again state that this type of temporary lift to place the car on jack stands is never the root cause of a 993 or 996 motor mount failure. If a mount fails during a lift, then the mount was going to fail anyway due to fatigue. These types of fluid filled mounts used on Porsche. VW, Audi, BMW, are notorious for fatigue failure in as little as 60K miles.

I would much rather have a mount fail during a lift than it fail silently out on the road, and it be many miles, months or even years before it was discovered.

In all the years I have been lifting cars by their engines, I have only seen 2 mount failures. One was already busted, and the other started leaking during the lift. Both cars had 60K+ miles on them. As a routine part of any lift, I also check the mounts for leakage from usage failure.

So in conclusion, I say lift with confidence by the engine, don't leave the car suspended by the jack any more time than it takes to position the rear jack stands, and if you do have a mount fail during a lift, be thankful that it happened then instead of out on the road where you would never know.

Lastly, replacing a busted motor mount is a simple 3 bolt affair that takes 30 minutes or less, and the part is under $150.

[deanslist.us]

I can agree, when I jacked my car up from the engine for the first time (same way I used to jack up my 76 and 84 911's) the motor mount failed. I ordered new ones and it took about 30 minutes to replace both. The old ones were visibly destined to fail anyway, so I wasn't heartbroken. I don't use the engine to jack the car up anymore, just haven't had a reason to in the latest repair dealings.

Edited June 11, 2009 by deanslist.us

[1999Porsche911]

This issue about motor mounts continues to be a much debated issue, and unfortunately much of the "con" debate is by the lay members of this board.

As someone that has lifted quite literally hundreds of 911s by the engine, I would like to again state that this type of temporary lift to place the car on jack stands is never the root cause of a 993 or 996 motor mount failure. If a mount fails during a lift, then the mount was going to fail anyway due to fatigue. These types of fluid filled mounts used on Porsche. VW, Audi, BMW, are notorious for fatigue failure in as little as 60K miles.

I would much rather have a mount fail during a lift than it fail silently out on the road, and it be many miles, months or even years before it was discovered.

In all the years I have been lifting cars by their engines, I have only seen 2 mount failures. One was already busted, and the other started leaking during the lift. Both cars had 60K+ miles on them. As a routine part of any lift, I also check the mounts for leakage from usage failure.

So in conclusion, I say lift with confidence by the engine, don't leave the car suspended by the jack any more time than it takes to position the rear jack stands, and if you do have a mount fail during a lift, be thankful that it happened then instead of out on the road where you would never know.

Lastly, replacing a busted motor mount is a simple 3 bolt affair that takes 30 minutes or less, and the part is under $150.

So, is your reasoning to lift the car using the mounts for support to justify buying new mounts? Why would you want to hasten the failure of what you describe as an already weak mount when there are alternate, safer methods to lifting the back of the car?

Edited June 11, 2009 by 1999Porsche911

[Orient Express]

So, is your reasoning to lift the car using the mounts for support to justify buying new mounts? Why would you want to hasten the failure of what you describe as an already weak mount when there are alternate, safer methods to lifting the back of the car?

I'm not sure I understand your logic. My argument is that there is no difference in lifting the car by the motor or by the suspension crossmember. Both are safe, and it is totally up to the person doing the lifting to decide what works best for them. If your jack is not long enough to reach the crossmember, then use the engine.

The issue about motor mount failures is only casually related to lifting the car, not a root cause. All cars that use fluid filled mounts will have them fail between 60-150K miles. It is a simple truth. If your car has fluid filled mounts, they are going to fail in that mileage window. If you have any car with 100K+ miles and it has the original fluid filled motor mounts still installed, then they should be replaced.

The only question you have to ask yourself is, "Would you rather have your mounts fail without you knowing it and drive around on collapsed ones, or be aware of the condition of your car, and know that the mounts should be replaced?"

[wvicary]

If the mounts have failed would there not be increased vibration? My opinion is that it only takes a few minutes to lift the vehicle using the recommended jacking points so why risk damage to engine/mounts or anything else by lifting from the engine?

[Orient Express]

Increased vibration is a sure sign of a failed mount. Also the engine will not set level and one muffler tip may be lower than the other. In addition a failed motor mount will put stress on the transmission mount by making it twist from the lopsided engine.

so why risk damage to engine/mounts or anything else by lifting from the engine?

Again, this misses the point entirely. Lifting the car by the engine is not a root cause of mount failure. If a mount bursts during a lift, it was because the mount was already beyond its useful life and was going to fail regardless of if the car was lifted by the engine, or not. It was a "dead mount walking" and was going to fail, that is just the facts. If a mount bursts during a lift, be glad it failed when it had your attention, rather than out on the road somewhere, where you would not know that it failed.

[wross996TT]

I think you guys should just agree to disagree FWIW...none of you have data (causal) to support whether jacking the engine promotes failure, creates failure or has nothing to do with failure. So lets be happy that we all have opinions on the matter.

Cheers.

[1999Porsche911]

Increased vibration is a sure sign of a failed mount. Also the engine will not set level and one muffler tip may be lower than the other. In addition a failed motor mount will put stress on the transmission mount by making it twist from the lopsided engine.

so why risk damage to engine/mounts or anything else by lifting from the engine?

Again, this misses the point entirely. Lifting the car by the engine is not a root cause of mount failure. If a mount bursts during a lift, it was because the mount was already beyond its useful life and was going to fail regardless of if the car was lifted by the engine, or not. It was a "dead mount walking" and was going to fail, that is just the facts. If a mount bursts during a lift, be glad it failed when it had your attention, rather than out on the road somewhere, where you would not know that it failed.

It may not be the "root cause" but it puts unnecessary pressure on the mount which stretches the boot. This weakens the mount. Even if it doesn't break, it increases the possibility of the mount not aborbing vibration as well as it is designed to do.

For someone who often stresses that Porsche knows best, note that jacking the car up using the engine as support is specifically not recommended by Porsche and is a ludacris way to test whether the mounts may be leaking or otherwise failing. The mount is designed for hanging and is not designed for compression.

I know I will not change your mind, but hopefully others reading this post will be able to make an informed decision.

[Orient Express]

In regards to lifting the rear of your 911, do what you want as it will not matter one way or the other.

[ninsei]

Thx folks. Does anybody have a pic of this alternate rear jack point(s)? This suspension crossmember?

[Loren]

Thx folks. Does anybody have a pic of this alternate rear jack point(s)? This suspension crossmember?

http://www.renntech.org/forums/index.php?s...ost&p=15860

[SH-GT3]

Thx folks. Does anybody have a pic of this alternate rear jack point(s)? This suspension crossmember?

http://www.renntech.org/forums/index.php?s...ost&p=15860

That's it!