Serpentine Belt coming off??

[Ryan Coffman]

Around 8 months ago I bought a 2006 Lincoln LS with 142000 miles on it. When I bought the car I replaced the serp belt because the old one was starting to crack. About 3 weeks ago it stated to leak coolant out of the thermostat housing and onto the belt. When I would go to start the car in the morning it would throw the belt as soon as it started. If I put the belt right back on it would be fine and not come off. The belt also appeared to ride perfectly straight once I put it back on. I thought this was because antifreeze was getting on the belt so I didn’t really think anything of it. I replaced the thermostat housing last weekend and it now no longer leaks coolant however it still keeps throwing the belt. I checked the idler pulley and belt tensioner pulley and they both seem to spin freely. The harmonic balancer spins smooth and doesn’t appear to be failing and all other pulleys appear to be in alignment. I can’t really understand why it would all the sudden start doing this. I have put around 10,000 miles on it since I put the new belt on and it only now has been doing it. Could it possibly be a bad tensioner? I have a new one as well as a new idler pulley that I will be able to install this weekend but I’m afraid it won’t fix it. If anyone has any ideas I’d love to hear them! Thanks!

 

[milehighmikey]

I'd start with them two pulleys, and while the belt is off, check the water pump shaft for play. It does seem like it could be happening due to a component locking up. Does your air conditioning work? Also, your existing pulleys should not spin very long, like maybe a half turn or so, when unloaded and spinning by hand. Do they sound dry and spin a few turns? They should not. What a sucky problem!

 

[joegr]

In addition to the above, the service manual warns you to replace the belt if it is exposed to coolant.
Make sure the outer part of the damper pulley is even with the inner part, and that the rubber between the two is at least mostly even with the front and the back. Many of us with 2006 models have had to replace the dampers.

 

[Ryan Coffman]

I'd start with them two pulleys, and while the belt is off, check the water pump shaft for play. It does seem like it could be happening due to a component locking up. Does your air conditioning work? Also, your existing pulleys should not spin very long, like maybe a half turn or so, when unloaded and spinning by hand. Do they sound dry and spin a few turns? They should not. What a sucky problem!

The two pulleys actually felt pretty good when I rotated them, didn’t seem like they were dry. My thought is that maybe they have some uneven wear that I can’t notice because of how tight it is in there. I did check the water pump and it had very minor play in it but to me it didn’t seem like it was nearly enough to be throwing the belt. The a/c does work and I know it has a new alternator(less than 15000 miles on that. It was replaced right before I bought it.) I’m gonna change the tensioner/idler pulley this weekend and I might just throw a new belt on it as well. Thanks!

 

[Ryan Coffman]

In addition to the above, the service manual warns you to replace the belt if it is exposed to coolant.
Make sure the outer part of the damper pulley is even with the inner part, and that the rubber between the two is at least mostly even with the front and the back. Many of us with 2006 models have had to replace the dampers.

I have heard the damper is a pretty common problem on these cars but mine looks really good. Inner rubber is basically symmetrical and the inner part is even with the outer part. I will go ahead and replace the belt when I do the tensioner/idler pulley. Hopefully that will be all the problem is. Thanks!

 

[jerryg2112]

My money is on the tensioner. I had to replace mine on my Continental because the plastic bushing was worn where it mounted to the motor and it was pulling sideways so the pulley was angled instead of parallel to the other pulleys. I didn't have the problem you have with the belt coming off. On mine the belt was rubbing a groove in the side of the tensioner instead. I noticed the side of the belt was all frayed and found it after inspecting everything.

 

[jerryg2112]

Did you ever fix the problem? If so please post the resolution.