Volvo 850 Seat Cushion Foam Replacement Tutorial

Eventually, the foam in your Volvo 850 seat cushion is going to break down. Professional replacement – either at your Volvo dealer, your preferred independent mechanic, or an upholstery shop, is likely to be pricey. With a little luck and skill, you might be able to fix it yourself like our friend here:

The driver’s seat foam in my Volvo 850 seat cushion had broken down to the point where it was very uncomfortable to drive. I investigated having the bottom seat cushion foam replaced at a local upholstery shop and found that the foam cushion itself sells for $250.00 without the heater element and, with labor, their estimate was “at least $600.”

As luck would have it, I found a guy parting out a couple of 850s and bought the passenger side foam from him for – I think – $35.00 shipped. Subsequent to that purchase I found that my driver’s side seat heater had burned out; and I was pleasantly surprised that the cushion came with a heater pad in good working order that I could use to replace it.

I purchased a passenger’s side cushion since the driver’s side foam and the passenger’s side foam are identical. I figured the passenger’s side would have less wear and tear than the driver’s side. This isn’t a huge job but it requires some patience.

Seat Foam Procedure

Ozark Lee » 

My first step was to disconnect the battery. I’ve seen postings that the airbag system runs through the seat and it will trip an airbag alert if you don’t. I could find no evidence whatsoever that that is true but I did it just in case.

Important Note: All cars equipped with SIPS do have SRS wires running to the seats and it is imperative that the battery be disconnected. The seat should further be deactivated with the Orange safety.

I next removed the headrest. The headrest removal requires an assistant as the procedure is to depress the seat back, simultaneously, in two places while lifting the headrest out. Unless the headrest has been removed before there are no indentations that tell you where to push so it takes some trial and error to locate the exact spot.
I next disconnected the wiring to the seat from the seat heater circuit, the main power source, and the power seat controller. I did them in that order as removing each plug gave me a little more room to release the next plug. The power seat controller plug is a bit of a bear as its release tab is conveniently placed on the bottom of the connector. There is no way to see the release nor is there a real good way to feel it. I used straight blade screwdriver to pry up the release tab while simultaneously pulling on the plug.
I next removed the seat control panel by lifting the front edge until it releases and then pushing the entire panel toward the back of the car. The panel has clips molded in which grab around the frame rail pipes. It doesn’t feel intuitive until it releases and you see the scheme.
At this point the seat belt bolt is exposes and I used a 12 mm combination wrench to remove the seat belt bolt. Be sure to note the direction of the seat belt tag so as to not inadvertently twist the belt when reinstalling it.

My next step was to remove all of the trim caps that cover the seat bolts, they just pry out, and then remove the four seat bolts with a 14 mm socket.
At this point the seat can be removed from the car and moved to a well lighted work area. In my case it was the front stoop of the house in the bright sunshine.
I removed the remaining electrical connections to the seat cushion which was both the heater and the thermostat.

From here it is a matter of removing hog rings. There are a series of hog rings across the front bottom of the seat, along bot sides of the seat and then the back “flap” of the seat. Once the back flap is undone a couple more hog rings are revealed that tie down the back ends of the side upholstery. As far as removing the hog rings I found the easiest method to be to grab them with a pair of pliers and twist them to loosen them up. At that point they can be worked out in one piece.
Once the hog rings are removed, all that is holding the seat cushion into the frame is a series of 5 springs that go between the frame rail and the cushion. I used a big hurkin pair of channel lock pliers to remove the springs from the cushion.
From here the cushion with the upholstery can be removed from the frame by pushing it forward an inch or so and then lifting it out.

Next I folded up the upholstery which reveal a series of hog rings along the side seams that hold the upholstery to the cushion. I pried those rings out along both sides and thought I was home free to remove the foam. Not so fast, there is another set of hog rings which hold the center panels in place. These were tough to get at but I found that taking the front set off first and then continuing to the rear set from the front was the easiest method.
At this point the upholstery comes free from the cushion.

My seat heater problem was instantly revealed once the cover came off. If I had cloth seats I’m sure it would have burned a hole through the seat cover.
Re-assembly

Putting it all back together again is, more or less, the reverse of the teardown but I found a few tricks to make it easier. On the advise of others I used tywraps instead of hog rings in most places to put it all back together. When it comes to tywraps, long is good. I used 11” tywraps and for the center panels and the side seams. The center panels are the toughest to get to so I pre-loaded the tywraps and then just barely tightened them until all four were in place. At that point I got to them from each corner and pulled them tight. To cut off the ends I used some long nosed tin snips. This is a place to be careful if you have heated seats as it would be easy to snip into the heater mat. I followed the same procedure down bot of the side seams until they were secure to the seat cushion. Once each tywrap was tight I rolled it so that the “head” was into the foam rather than upward where it could wear on the upholstery.
At this point the cushion goes back into the frame and the springs go back in place. You will notice that there are a series of catches on the front side of the seat that grab a bar in the seat cushion. Make sure they are in place before hooking the springs back up. The springs themselves were tough but, after futzing with it, I found the easiest method was to insert the spring into the cushion, looping the bar in the foam, and then using the channel locks to get the rear end of the spring into the frame rail.

From here it is a matter of using the hog rings or tywraps to secure the edges of the upholstery. Once everything is pinned down the seat is ready to re-install. I hooked up all of the seat heater electrical connections that are under the seat before I put it back in the car.

The only trick to the re-installation of the seat is to get all four bolts started and then tighten down the two front bolts and the bolt toward the center of the car on the rear. The last bolt to be tightened is the door side rear.

I must say it was a success. The seat sits much better and the heater works.

850 seat cushion foam replacement.