Hi All. First post here. I recently bought a 92 240 wagon, 5 speed with 183K. It runs very well and I'm in the process of giving it some attention and bringing it up to date with maintenance and fixing all the little things that may or may not have been neglected.

I noticed that the preheat hose is missing. I understand what it's for, but I'm wondering if I should go through the trouble of first checking the thermostat in the airbox and then getting myself a new preheat hose? Or do most people just get rid of the preheat system? I'm in MA and it typically gets down to 10-20 degrees (F) for extended periods in the winter. Will I miss it much? I read that sometimes the airbox thermos can get stuck which can lead to a cooked air flow sensor, so I'm wondering do people just get rid of them as a precaution? What's up with these things?
Thanks!
John

 

There are no preheat hoses on the 2 Volvo's in our garage...
The first time I learned about them was after a service job on our car. It was a few days later and I was checking things under the hood (oil etc), and I thought to myself..."hey, didn't there used to be a hose there???"
Called the shop (which is a pretty good place) and they gave me a nice explanation...

The aluminum hoses break down over time, and the bits of aluminum would get carried through the air box and to the AMM, and wreck it. since the AMM is a several hundred dollar part, they prefer to take the hoses out. The only trade off is a slight loss in fuel economy at cold start up...once the engine is warm it makes little difference...
Good enough reason for me to leave it out. But checking the themostat (and that the preheat intake is shut) is probable a good idea...which reminds me, I need to do that as well.

Enjoy!
Koos

 

Hi jmarble,

I recommend replacing the preheat hose and have a spare thermostat in case the original fails. Both can be found at FCPgroton or IPD online. The hose is less than $20 and the thermostat is $8. The main advantage to having this setup working is better fuel economy and your defrost will perform better. Check the condition of the foam gasket around the flapper. They tend to deteriorate from oil blow by. You could easily make a replacement for it by cutting to shape a piece of foam picked up at auto supply or home hardware supply stores. I haven't found anyone that sells new flappers or foam gaskets out of the box.

Best of success,

Brandon

 

Neither of my two Volvo wagons, 1990 DL 240, 1997 960, have preheat hoses and both air boxes have the thermostat removed. I live in Georgia, so cold weather is not really a factor. After modifying the air boxes, I noticed no difference in performance or economy.