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Old 10-02-2016, 02:44 PM   #1
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Loose engine or transmission mounting bolts?

My newly acquired 2004 Boxter S has a sharp rattle when one of the wheels goes over a severe bump. Rocking the car doesn't cause the rattle, but it only happens when the car is driving at constant speed and I hit a bump or pot hole.

If the car is accelerating moderately or hard no rattle, even when going over bumps or pot holes.

A mechanic friend of mine is convinced that the problem is a loose mounting bolt on the engine or transmission mounts.

Make sense?

Thanks/Anker

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Old 10-02-2016, 03:26 PM   #2
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How many miles on the ODO? The engine mount is a likely culprit. Follow the link and see if this fits your situation.

Porsche Boxster Motor Mount Replacement - 986 / 987 (1997-08) - Pelican Parts Technical Article
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Old 10-02-2016, 03:46 PM   #3
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104K miles, so it is very likely the engine mount as you suggest.

Looks like a breeze to swap it out.

Thanks rexcramer/Anker
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Old 10-02-2016, 07:56 PM   #4
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Sorry to hijack this thread, when my car goes over a bump slowly, I heard a sound like a balloon deflating... Except my tyres are normal.. also sounds like some old spring being compressed.

What could it possibly be?

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Old 10-02-2016, 09:14 PM   #5
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Before you assume that it is a bad engine or transmission mount, check your suspension. The rear trailing arms make a loud banging sound when going over sharp bumps (very common), but it could also be sway bar end links, front trailing arms, or the control arms themselves. The rear trailing arms are pretty easy to replace.

How many miles on the car? 60K - 80K is typically when the suspension starts getting noisy.

Is your mechanic friend really familiar with Boxsters? No offense to him, but if he doesn't work on these cars often, it may worth taking the car to an independent shop that specializes in Porsches.
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Old 10-03-2016, 04:51 AM   #6
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Quote:
Originally Posted by Anker View Post
104K miles, so it is very likely the engine mount as you suggest.

Looks like a breeze to swap it out.

Thanks rexcramer/Anker
With that many miles you may want to check your transmission mounts too. That's real easy to check. Where the transmission mounting brackets meet the transmission mount is a large bolt. Look up that bolt and see if any fluid is leaking out. Leaking=BAD. You'll probably have some suspension pieces that are bad too
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Old 10-03-2016, 09:14 AM   #7
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Quote:
Originally Posted by itsnotanova View Post
With that many miles you may want to check your transmission mounts too. That's real easy to check. Where the transmission mounting brackets meet the transmission mount is a large bolt. Look up that bolt and see if any fluid is leaking out. Leaking=BAD. You'll probably have some suspension pieces that are bad too
Here's an illustration to go with what Woody said. Looking up at the left rear mount, tiptronic at 175,000 miles:



Loose mounting bolts? I think that is unlikely unless someone worked on the car and did not torque them correctly. They will not loosen on their own if installed correctly, but worn out mounts are fairly common, especially the engine mount.

+1 on the suspension having worn pieces.
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Old 10-03-2016, 09:18 AM   #8
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When you do make a correct diagnosis, ask here for a "while you are in there" list of things to check or replace,
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Old 10-03-2016, 11:40 AM   #9
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I am beginning to believe that the problem is the rear trailing arms. The clunk on the right hand side is louder than the one on the left hand side, and there are definitely two places that clunk, so its unlikely that its engine or transmission mounts, but I am going to check them anyway.

Going out to get some jack stands for under car work and also for winter storage. This baby is not going out in snow, ice and salt.

Going on vacation, and when I return I'll buy the shop manuals.

I will definitely post here when I know exactly what is going on.

Thanks/Anker
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Old 10-05-2016, 10:50 AM   #10
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check the front bolts at the bottom of shocks. The bolts that clamp the shock to the spindle, one of which also holds the sway bar links. Torque those bolts to spec.

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