How to put the drive belt back?

My drivebelt slipped out of its way because I drop oil accidentally on it.
I clean the belt and all pulleys with soap, now I'm trying to put the belt back.
The problem is I can't relieve the tension off the tensioner. I use a 3/4 socket, I turn the hex bolt with the tool toward me. With a lot of force, the bolt turns, but not the tensioner. I pull the belt w/ the second hand at same time, but it still doesn't move.

I do something wrong, or what is the problem with this tensioner? It's not rusty.

Forget to mention, it's a Windstar 98 3.8L.

I did this a couple of weeks ago on my 2000. I took the passenger side wheel off. Then got under the van. Used an ordinary open ended wrench to push the tensioner. I pushed it one way the bolt was coming off. Then I pushed it the other way and the tensioner was easy to move relieving the tension. I got some one from above to push the belt over the alternator. Make sure you tell the other person not to get the fingers caught up in case you slip the wrench. Don't forget to tighten the bolt. This may be a time to change your belt also.
The other way is from above. You have a have a long iron rod. Wedge it between the motor pully and the tensioner bolt. Push it up to move the tensioner. Slip the belt over on a non-grooved pully with the other hand.

In the 98, the tensioner is at top of the vehicle. I finally understand that I should pull the tensioner pulley by the bolt of the pulley, not the one of the tensioner. And I shouldn't turn the bolt, but pull it.

But the problem now, is I can't rotate the tensioner. A mechanic come to the place where the incident appear, and after trying himself, he tolds me that my tensioner spring is damaged, cause it doesn't move. I should change it, it cost about 160$ just for the tensioner. Plus labor of course.

What do you think? It has a way to repair the tensioner, or put tension on the belt by another way?
Or do you think that it doesn't move because I tight the tensioner bolt too much?

Because the tensioner seems in good shape, it's not loosen. It just doesn't move. The belt was replaced a month ago.

Damn, I took all day for this small problem, it still not repaired.

I'll try tomorrow to push the tensioner on the belt with an iron bar, then screw the tensioner. I hope it'll work. Replacing the tensioner doesn't make sense.

I had no luck to push the tensioner against the belt, it's too hard.
I'm re-trying the standard method, which consist to fix the tensioner on the engine, then pull the tensioner pulley bolt away from the belt. The problem is that I have not enough space at the back of the tensioner, it's too close from the firewall. Cause I need a 180° angle between the tool and tensioner to have the best torque. I can only have a 100° angle at most, which is not enough.

I don't know if someone have a tricks or tips to rotate the tensioner on the 95-98 3.8L engine?

Also, I'm not sure if I have to replace the tensioner, cause it's too hard, maybe the spring is stuck inside, how can I determine that?

I use a Serpentine Belt Tool I got at Autozone for $25. It's saved me countless hours and knuckles. It makes belt removal and installation almost effortless.

http://www.autozone.com/autozone/catalog/accessories/accessoriesShelf.jsp?categoryDisplayName=Tools&fromType=accessories&fromString=search&parentId=6-10&filterByKeyWord=BELT+REMOVAL+TOOL&currentPage=1&navValue=100330&categoryNValue=100006&fromWhere=&itemId=330-10&displayName=Serpentine+Belt+Tool

Interesting, I'll try that.

I finally understand why I was not able to rotate the tensioner. I realized that the end of the flat spring (inside the tensioner) is out of its alignment. And it has erosion between each layer of the spring. It's why it's locked up. So, I will replace it. I hope I'll able to rotate it.

Ford make it very complicated in this engine. There's almost no room to do this job.

Well....at least you know that you were doing it correctly, just the fact that the tensioner was seized was stopping you.
It would be best to replace the belt.....as the oil may cause the belt to fail.
I know that from personal experience.
I would guess that the tensioner being seized was a contributor to the belt coming off in the first place.....the oil would cause the belt to slip....but not come off.

The belt is in perfect condition. Cause it slip after only 0.3mile. And I saponified all the oil with soap dish and water.

I would guess that the tensioner being seized was a contributor to the belt coming off in the first place.....the oil would cause the belt to slip....but not come off.

It makes sense.