Thumping / creaking when accelerating

[eric9274]

I have a 2001 Lincoln LS with V6 and 5 speed manual. I have 187,000 miles on the car and it still runs and drives great. It recently started making a creaking or thumping sound when I accelarate from a stop. The harder I accelerate the louder the noise, and if I accelerate very gently I get nothing at all. I would say I feel the thumping in the floor board more than hear it. It only lasts a second or so and then its gone.

I suspect the noise is driveline related because I get nothing when going over bumps or rocking the car to work the suspension, or stopping with the brakes. I was convinced it was the differential because mine seemed to have excessive backlash. I found a new diff from a salvage yard with ~30,000 miles on it. Once that was installed the noise seemed to be less, but is still there. I inspected the CV joints and both of the rubber flex couplings on the driveshaft and all appear to be fine.

I was going to try to replace the driveshaft carrier bearing next but can not find a new one anywhere. I guess I'll have to search salvage yards for this part also.

Anyone have suggestions what the problem might be? I hate to just keep replacing parts and throwing money at it without knowing what the problem is.

 

[milehighmikey]

Hi Eric, welcome.

Your thumping and creaking seems to be what I was experiencing recently. Broken left motor mount. You can confirm easily. Step on the gas from a start and watch your shifter. Does it go from side to side? Open the hood, set the parking brake hard, try to start off in first gear. Hard. Does the engine lift up on the driver's side?

The thumping is the engine hitting the hood maybe, and the creaking is your exhaust system getting twisted up.

You can rule out the driveshaft support bearing by grabbing the driveshaft and checking for play, lots of it. That manifests itself as a thump-thump-thump noise going through the power band as you accelerate through first. I did that last summer, and changed my motor mount this summer. You may also want to check your rear transmission mount for being soggy and replaced that is it is needed.

Check Rockauto.com for all of the parts. I bought the $50 motor mount from them, as they have a few different selections.

If you are changing it yourself, get ready for some fun. Make sure you open the shop manual and see what is involved it you do it yourself.

Mike

 

[2000sport]

I've run into this same problem.

Left lower mount is shot.

 

[eric9274]

Thanks for the suggestions. I am thinking it is in the drivehshaft. I can feel play when I move it up and down and a slight clunk. I figure either the center bearing is shot or the length adjustment nut has loosened up. I could not find a center bearing anywhere (Ford has it on backorder) but I found a used one from a junkyard. I don't see any movement in the shifter and I also rocked the engine by hand to test the motor mount. Every thing feels fine there.

I'll post what I find when I take out the driveshaft.

 

[milehighmikey]

OK, the bearing does seem bad. It tears away from the rubber surrounding support and the shaft is then able to float around inside of the bearing holder.

 

[eric9274]

I removed my driveshaft and found that it was the drive shaft center support bearing. The rubber had completely torn away from the support bracket. I had bought a complete driveshaft from a salvage yard because I can't get a new bearing anywhere. Its on backorder indefinitely from Ford. I found out that you can't press the bearing assembly off of the shaft from the shaft without destroying it, so I was forced to use the rear half of the salvage yard shaft and my front half, because my car is a manual and the shaft I bought was for an auto and the length was different. So then I had a balance issue. I have the shaft back out of the car and I'm taking it to a shop to get balanced tomorrow.

I'm really disappointed in Ford for not supplying a part like this for a car less than 10 years old. Hopefully once I get the shaft balanced the problem will finally be fixed for good.

 

[eric9274]

My driveshaft is now balanced and re-installed and my problem is finally fixed. I found out later that the bearing assembly is now available from Ford service. Apparently they were only temporarily out of stock. The dealer I called should have known this and been able to tell me when parts were coming in, but maybe they did not know or did not care to take the time to find out.

If anyone reading this ends up in a similar situation where you can't get a critical part, don't give up because one dealer tells you they can't get it. Call around to several different dealers.