Car is an 89 245 DL

Today I changed the air filter with a Volvo filter. (PO had a generic filter.) What a biatch of a job! I don't remember it being that difficult on my 83 245GL. Man oh man, I was so frustrated and stuff...first trying to separate the air box, then trying to remove the old dirty filter, then trying to put the new filter in, and then finally trying to close the air box. The radiator hose really gets in the way, and the short plastic U-shaped pipe would not remove from the air box lid. I did so much jiggling and "gentle jerking" of the air box and the pipe and AMM unit that I was afraid I might have dislocated something from the air box or put too much trauma on the $$$ AMM unit. It was only after having removed the old filter and literally stuffing the new one between the air box and the lid, I realized that I could not close the lid securely. I had tried removing the U-shaped pipe, but it would not budge. By the time I had put in the new filter and after almost an hour of trying to lock the lower hinges of the air box in place, I realized that to completely remove the air box I'd have to unscrew this freaking screw that holds the AMM unit to the body of the car. No wonder I could not loosen the ends of the U-shaped pipes. GRRRRR! Anyway, the job is done. Now my concern is could I have done something wrong to the AMM or dislocated the big pipes connected to the bottom of the air box? I felt I jiggled and wiggled too much while trying to change the air filter. This is one of the most simplest DIY job and I cannot believe it was so difficult!

Best procedure is to disconnect air intake duct clamps all the way to the intake manifold. Next disconnect the air mass meter bracket from the strut tower. Now remove duct from air box cover by pulling entire duct/AMM assembly towards passenger compartment. This allows you plenty of space to remove and refit cover. While the duct assembly is loose, remove the section between the AMM and intake manifold. Hold it up to a light and look carefully for cracks. These guys ARE fragile and can break when you're wrestling with some other part of the car.

no you won't damage the amm that way. Next time, disconnect the air hoses to change the filter.

The airbox thermostat lets exhaust warmed air into the intake when cold and once warmed will close and allow fresh air into the engine. The metal hose hooked to the bottom of the airbox is the preheat hose. The thermostat is in the front part of the airbox. Mine was stuck so I was only getting warm air so I ripped it out and redirected the hose up to the grill so know I have two cold air sources.

Good luck.
Adam.

You mean in front but INSIDE the airbox? If I recall, there was this circular lid type thing when I looked inside the air box. It was partially opened...is that normal when changing the air filter and the car is off and cooled? The weather was not sunny nor hot. So was it opened because the t-stat sensed a coolness?

Yes, thats the flap that closes off either the warm air intake or the cold air intake. When cool (I believe under 60F) the cold air should be blocked but after that it should seal the warm air intake completely. It should not be stuck anywhere inbetween or the thermostat has probably failed. And if you are getting warm air all the time it can damage your AMM.

Regards,
Adam.

Hey Duckling, like others have said here if your (A/Box) T-stat is collapsed it will allow hot air from the exhaust manifold to flow directly through your AMM, and can and will burn it out, if it is Summer time.

If you don't know how to chk. it, disconnect the Pre-heat hose (usually aluminum tubing) from the bottom of the Air Filter box as a temporary fix.

If you are going to change it, be very careful when you remove the plastic mounting bracket that it is mounted to.

I change the T-stat at each 30,000 mi. service for my customers, because I have NEVER yet seen one collapsed at 30,000, BUT I have found them bad at the 45,000 mi. chk. It's kind of like the T-belts and water pumps... when do you chg. them if they are still good ? My advice to customers has always been, "wouldn't you rather change it at your convience?" Tom