My vw passat B5.5 vibrates when I start the engine even
There are 3 engine mounts that keep the engine steady and transfer the torque to the transmission. One solid mount on the front, and a hydraulic mount on either side of the engine. Worn mounts will cause sloppiness and difficulty in shifting, and noticeable play when pressing and releasing the accelerator.
The front mount, also known as the snub mount, is a rubber or polyurethane bushing that centers the engine in the engine compartment. This is a common wear point, and causes vibrations at idle when misaligned or worn out. Since your car is several years old, it would be a good idea to replace it and is a fairly easy operation (2/5 on the difficulty scale).
The mount should cost around $8-12 for a stock type mount, and around $35-40 for a high-performance polyurethane bushing. The upside of the high performance is that the engine pay is greatly reduced; the downside is that there is more likely to be slight vibration transferred to the engine compartment at idle, which is what you are trying to avoid. Unless you are a "spirited driver", I would suggest that the stock type mount (looking a bit like a mushroom versus a topless cupcake) should be just fine.
If your car is running rough, then you should really look into a tune-up before starting the installation, as adjustment will be difficult is the engine isn't running smoothly. On these cars, new plugs and air filter, as well as vacuuming out the airbox pre-filter of leaves, dirt and bugs can do wonders for a smoother idle. (The next level of sophistication is cleaning the Mass Airflow Unit, but that's a more extended topic.)
Here is the process for installation:
Raise up the vehicle on wheel ramps or with a jack and sturdy jack stands. DO NOT EVER WORK UNDER A VEHICLE SUPPORTED BY A JACK, USE THE JACK STANDS. You can get the jack stands for under $30, and your life isn't worth taking a chance. While you are being a good mechanic at the deep end of the gene pool, put on goggles or safety glasses. There is greasy dirt that WILL fall in your face, and it will get in your eyes, believe me it is nasty.
After the car is fully supported, take off the splash shield, which is held on with several quarter-turn screws. You might want to take picks with your phone or digital camera during the whole process to be confident on alignment.
You should have a good flashlight or worklight. While you're under the car, inspect for oil leaks, and peek up at the motor mounts on either side of the engine. If you see an oil dirt at the bottom of these mounts, they are likely worn out and should be replaced. That's a bigger job, probably about $500 at the dealer, $120 at home with the right tools and half or a full day of your time. But you can still replace the snub in the front independently, so don't give up.
There are three bolts on the front lower engine mount at the front of the engine. You can now see the mount protruding into the front rail of the car. Remove these 3 bolts. (Don't worry, they center the engine, they don't hold weight.)
You can now remove the old rubber snub mount. Clean the mounting post, and press on the new snub to the aluminum engine mount. This may require some force and may be helped with a little silicon grease or soapy water.
Next loosen the four nuts holding the snub basket to the front clip. (Do not remove, but leave hand-tight as these will facilitate adjustment.) You can now reinstall the lower engine bracket onto the engine and tighten the three allen head screws.
Start the engine and let idle for about a minute, popping the accelerator a few times to help center the snub and the receiver. Let idle for 10 seconds more without touching the gas, and turn off the engine.
Back under the car, tighten the four receiver nuts without moving the receiver. Start the engine back up, and check to make sure there isn't any unreasonable low frequency vibes transferring to the car. (Assuming you did the tuneup.)
Finish up by ensuring that all nuts and bolts are properly tightened, reinstall the splash shield and screws, and lower the car back on the ground.
Take the car for a test drive and see if it solved your problem.
Mar 13, 2010 |
2001 Volkswagen Passat