There are a several possibilities;
There are rubber bushings that are part of the suspension. After time, they become brittle and are hard to service with axle grease unless you can get some grease in them with a grease gun needle. However, they are generally replaced. They are generally at torque points such as; sway bar bushings, spring seats, control arms, and other points.
The motor mounts are rubber as well, the from mount is usually the first one to fail in front wheel drive vehicles with a transverse mounted engine. You can check this by seeing how far the motor moves under load. Open the hood and have someone watch the motor if you cannot. Put the van in drive and with the parking brake on and your foot on the brake pedal, push the throttle just a bit. The motor will move an inch to three inches and do so smoothly. It may move more, the important thing to pay attention to is if it lifts and drops abruptly. Just like worn out shocks, the damping effect is gone and the motor is not suspended properly. Once the front mount fails, the load increases for the other mounts and they fail quickly. There are four mounts, (front rear, both sides and sometimes there are vibration mounts). When the mounts fail, they have to all be replaced at once as a set. The motor can sometimes end up resting on the sub frame and also cause stress on other components because the position of the motor is not correct.
In some cases, especially if the vehicle has been in an accident, the unibody can be compromised and make noise.
It is very hard to diagnose and can get expensive. Depending on how long you intend to keep the van, you have to way the price against the irritation of the noise and the possibility of the dominoe effect, especially with the motor mounts, that can lead to even higher repair costs.
I would make sure the motor mounts are okay since that is very common in front wheel drive vehicles with sideway mounted motors. It will cost around the same as the repairs you have done, I can give you a closer estimate if you find they are in need of replacing, but it will be well worth it.
It is very hard to diagnose noises like that and your mechanic was taking a logical approach and replacing components that are part of general maintenance.
So, if you need anything else, I will keep an eye on this post for your reply and get back to you ASAP.
Take care and I hope this information helps.
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Sunday, February 6th, 2011 AT 5:16 AM
