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Pete
Pete, Cadillac Technician
Category: Cadillac
Satisfied Customers: 26258
Experience:  17 years Cadillac experience as a technician.
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I have a 2004 DeVille with 188K. Had rear air shocks replaced

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I have a 2004 DeVille with 188K. Had rear air shocks replaced with Munroe Air but not OEM equipment. Now every little bump has a knock in the rear similar to an exhaust hitting the frame. Not the exhaust though. Never hear the leveler motor kick in. Seems like shocks are in full extension. Mechanic replaced the replacement shocks thinking they were defective. No change. Suggestions?

Pete :

Hi and welcome to Just Answer.I will try and assist you today with your question.Please don't click on accept unless you feel satisfied with my assistance here.

Pete :

If your rear air shocks are fully aired up this can cause this type of noise in some cases as the vehicle can hit harder on bumps with stiff shocks like this here.If this was a problem before these were replaced most likely the shocks werent the components causing this fault.

Pete :

If you didnt have this issue before they were replaced then it may be due to being after market non OEM shocks installed and this can cause noise in some cases.

Customer:

The shocks were not able to inflate. that is why they were replaced. Car was bottoming out. Not bad at the time for 150K.

Pete :

O.k.,it sounds like the old shocks may have been leaking and the new shocks corrected that issue.

Customer:

Mechanic said the replacement shocks were defective. But no change after replacing the replacements.

Pete :

As for the noise though the shock mounting should be re checked to make sure they were installed properly as some have rubber mounts for the top of them and if these are missing then it can cause this noise here.

Customer:

Rubber mounts were replaced at time of new shocks.

Pete :

The mechanic may want to double check the way the non OEM shocks mount compared to the OEM and see if anything is different or missing.

Pete :

Does the vehicle seem like it is riding to high in the rear?

Customer:

Possible that the air pump (it is separate from the shocks?) is not activating or not in this case deflating the shocks?

Customer:

Car is riding higher. But not like a Lincoln. Yesterday I put 300 lbs of fertilizer in the trunk. No sound of air pump. Same knocking sound. After unloading the fertilizer the car did not lower and knock remained.

Pete :

The compressor is a seperate component and does contain the exhaust valve to release the air and also puts the air in the shocks.If this is defective to where it is riding at max then it can cause this with fully aired up shocks.These vehicles also have a level sensor under the vehicle that detect the height to raise and lower the vehicle as needed.

Pete :

If the compressor or level sensor or sensor arm is defective then it can cause this here and needs checked into to locate which is at fault.In some cases it can be just that the level sensor arm is broken or missing.

Customer:

This sensor is not the air pump too. Looking at a picture of OEM Munroe shocks it look as though a pump was attached to the passenger rear shock.

Pete :

With fully raised shocks the ride is usually stiffer which can cause clunk noises over rough roads and bumps in the road

Pete :

Let me double check

Pete :

The compressor is a seperate component under the vehicle.

Pete :

There is a rear level sensor also seperate under the vehicle.

Customer:

I remember seeing the sensor arm when it was on the lift. So if this is also the pump then it is not activating either to inflate or deflate. We are on to something. See from your comment there is a 1. sensor and 2. compressor. Good. I am convinced that this is the problem. I had a problem with my Aurora when ice in the air lines caused the shocks to be fully extended and had a similar problem. But I am not a mechanic.

Customer:

Is the sensor and compressor available other than from a dealer?

Pete :

These are seperate components the sensor and the compressor,it could be either or of these causing this issue,these need checked into to locate which is at fault.

Pete :

You might be able to get these after market I would check with your local parts stores to see if they carry these or can order them in

Customer:

I feel good with our session and confident with your expertise. Many thanks.

Pete :

Your welcome.

Pete :

Let me know if you need anything else,click accept if you feel satisfied with your answer as this is how I get credited for my time,Thanks Pete!

Customer:

Can I print this off to take to the mechanic?

Pete :

You should be able to,you can highlight all of the post here and print from that

Pete and other Cadillac Specialists are ready to help you
Let me know if you need anything else with your question asked or anything else in the future.Thanks Pete!