symptoms of bad engine and/or tranny mounts
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Category: Technical & Model Specific Forums
Forum Name: BMW 7 Series
Forum Discription: This forum will deal with any issues on the BMW 7 Series (E23, E32, E38, E65, E66, E67 & E68)
URL: http://www.bavarian-board.co.uk/forum_posts.asp?TID=44727
Printed Date: 15-June-2024 at 22:53
Topic: symptoms of bad engine and/or tranny mounts
Posted By: shogun
Subject: symptoms of bad engine and/or tranny mounts
Date Posted: 04-May-2009 at 06:31
Often, bad motor mounts allow the engine to rock and move around, causing noise and interference problems with the throttle, transmission and clutch linkages. For example, a thumping noise when the transmission is put into gear or when the vehicle is accelerating is a classic symptom of a bad mount.
Cracked or broken motor mounts can be an annoying source of vibration and noise, typically a clunk or shudder when accelerating hard.
Tranny mounts have similar symptoms.It is generally a good idea to get these items replaced after 100k miles or so (or 8-10 yearrs) at the most.
Your engine won't fall out as a result of bad mounts, but the vibration can cause other problems as I alluded to.
If your mounts are even 50-60% worn you will find a noticeable difference in replacing them.
Yes, an engine shaking more than usual on startup is a classic sign of worn motor mounts.
If you change, change ALL at the same time, that means engine mounts, transmission mounts and the center bearing, because all are in the same line of the drive shaft.
Then you have a really smooth, straight and quiet driveline.
Moving engine also can cause - in my opinion - the typical crack of the connectors at the radiator. Because the radiator is fixed onto the chassis and does not move, but the engine moves quite a lot when the mounts are not good, sometimes they are completely separated. Recently we changed the mounts on an E32 Alpina B12, the old mounts were only 2/3 of the original size.
Such mounts should in my opinion be replaced anyway after a certain period.
We changed the engine mounts on some other E32 750 and E31 850, so several cars cars with same engine, about 4 years difference in production years and about almost 100 k miles difference in miles. All looked about the same (bad). That tells us that not only driving miles makes the wear but just the weight of the engine over 8-10 years and the aging of rubber. We assume so.
I am still not sure how much effect a bad final drive mount has. I never changed it on my car
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E32 750iL,E36 M3
http://twrite.org/shogunnew/topmenu.html" rel="nofollow - 7 Series Tech Tips
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