Airbox thermostat failure...

Craigd2599 · Post by **Craigd2599** » 22 Mar 2009, 14:46

wanting to one-up MIJ, I went next door and borrowed a piece of tin foil so my mod actually cost someone else some money. Not really. But I did do the change...wow! I noticed a difference right away in pedal response. Nice little touch.

beewerks · Post by **beewerks** » 27 Mar 2009, 23:04

I've been running my car for the past year with the hot/cold air splitter completely removed. Thanks to this thread I decided to put it back on and do the "aluminum foil" mod. I'll see how it works.

I didn't see anyone mention what to do with the metal hot air hose coming off the back of the engine, should it be reconnected to the splitter? Or just completely removed? Right now it's just sitting there disconnected. Thanks for all of the previous posts!

Craigd2599 · Post by **Craigd2599** » 29 Mar 2009, 10:05

first full tank of gas through the car since the change...mpg was 21.7 around town, up from 20 even. nice

insndrvr · Post by **insndrvr** » 29 Mar 2009, 14:02

This was one of the first little things I fixed on my '94 that I just bought. I took the thermostat out and replaced it with a 1/4" machine screw (1 to 1-1/4" long) with a nut and washer inserted in the plastic piece that holds the thermostat. The screw head is on the air filter side, the washer sits against the inner surface that held the flange of the thermostat. The nut sits against the washer and the end of the threads fit nicely into the recess of the plastic washer that pushes the spring (where the thermostat piston pushed before). I can adjust the screw with a screw driver to push the flap from full hot to full cold. I had the materials on hand from another project, cost about $0.49.

I have not check gas mileage yet (the odometer needs fixing, next weekend) but the off the line is much more responsive and has better highway passing power.

Post by **polskamafia mjl** » 01 Apr 2009, 01:18

Hi, I am new to this forum but I want to do the airbox mod to my 96 850 GLT. I get pretty low gas mileage and extra uumph would be great too. I was wondering if someone could post pics of how to get to the thermostat from start to finish. I have seen the pics of the Y piece itself but I haven't read/seen any good instructions on how to actually get to that piece. Thanks...

Craigd2599 · Post by **Craigd2599** » 01 Apr 2009, 02:23

No pics but it's an easy one to describe. Your airbox just snaps in place with three plastic studs. Pull off the lid and take our the air cleaner. Disconnect the MAF sensor plug. Looking down on the airbox from the drivers side, pull it back toward the windshield to pop the front two plastic studs, and them forward toward the engine to pop loose from the stud near the drivers side fender well. Then lift it straight out. The thermostat and door are visible when you flip the box over.

Post by **wheelsup** » 01 Apr 2009, 06:05

Also keep in mind you probably don't need any sort of tin foil, screws, washers, bolts, etc. to hold it open. There is a little tab where you push on it and it holds the vent closed. Much easier than shoving tin foil in there and it can be done without removing anything except the air filter. Mine has stayed closed for close to 6 months now.

Post by **tjts1** » 01 Apr 2009, 09:52

wheelsup wrote:Also keep in mind you probably don't need any sort of tin foil, screws, washers, bolts, etc. to hold it open. There is a little tab where you push on it and it holds the vent closed. Much easier than shoving tin foil in there and it can be done without removing anything except the air filter. Mine has stayed closed for close to 6 months now.

The reason why I used aluminum foil in mine is because I removed the whole trap door mechanism. The door is still there, flipped upside down. The aluminum is there to act as insulation and help stabilize the door that has been glued into place. Even with the door in the correct position, the plastic bracket that holds the mechanism in place restricts airflow. Breathing cold air is one thing. I wanted to build the most efficient intake possible with minimum expense and effort.

The 3 way junction as it comes out of the car. Looking at it from the airbox end.

Remove the top half. As you can see, mine was stuck on the hot air side.

I removed the spring, thermostat and door from the Y junction.

Then using some pliars and brute force, I cut out the plastic bracket that kept the thermostat in place. The door was then reinstalled backwards and glued into place using epoxy. You can see the bits and pieces of plastic that were removed on the left.

Then I added the balled up aluminum foil to the hot air side. This is the part that everyone seems to focus on. I don't know why. In hindsight, it was probably not necessary but I feel better knowing that its there.

With the top half of the Y intake in place, you can see a clear shot for the air to travel through from one end to the other.

I hope this clears up any confusion about the aluminum foil in the airbox. This was just 1 of 4 changes I made to the intake. The others being the 960 throttle plate which has been thoroughly discussed here.
https://www.matthewsvolvosite.com/forums ... a&start=14

Like I've done on all my cars, I removed the MAF screen with no I'll effects. Before
http://farm4.static.flickr.com/3584/340 ... 8587_b.jpg
After
http://farm4.static.flickr.com/3648/340 ... 878f_b.jpg

I replaced the restrictive airbox snorkel with a 3.25" piece of flexible tubing I found in the McMaster catalog.
http://farm4.static.flickr.com/3417/340 ... e014_b.jpg
http://farm4.static.flickr.com/3582/340 ... 242e_b.jpg
You might notice in the pics I also had the injectors out for a good cleaning. I use these instructions to clean my injectors at home.
http://www.fordfuelinjection.com/?p=82

Thats about it. I suppose I could go into adding smooth underside plastic panels to reduce drag but I'm already getting way off topic. Our 96 base 855 5 speed has 190k miles, gets 32mpg at 75mph on 87 octane and is quicker than any NA 850 has the right to.
cheers
Justin

Post by **polskamafia mjl** » 03 Apr 2009, 14:03

Thanks a lot guys. I was looking at it and there are two hoses hooked up to it. I guess one is the MAF. What is the other and do I need to disconect both? And finally how do I disconnect them and reconnect them? Sorry for all the questions hahaha...

Post by **Ozark Lee** » 03 Apr 2009, 17:02

One goes to the cold air intake that routes to the front of the car and the other is the silver flexible line from the cover over the exhaust manifold. The MAF line comes off of the top of the airbox.

...Lee

Airbox thermostat failure...

Re: Airbox thermostat failure...