2000 Volvo XC70--feels like I'm dragging an elephant


#1

The car has drastically dropped gas mileage from 17mpg to 11-12 mpg. It’s laboring, and I even have to accelerate going down hills where I am usually breaking to keep from going too fast. I have had the whole car looked over twice – timing belt was a little old, so we replaced it. The gas filter was full of gunk, and it was replaced. Still has the same problem. Mechanic can’t find anything else wrong. I’m getting ready for a long road trip and don’t want to pay for all that gas or break down along the way. Any ideas?


#2

It is possible that your catalytic converter is clogged up.
Have your mechanic check the exhaust flow.

If that does not help, have him check the output pressure of the fuel pump.
If your gas filter was really overdue for replacement, the fuel pump could have been weakened by having to try to force gas through that gunked-up fuel filter.


#3

Thanks. I will try those.


#4

I had a similar problem on an older car…It turns out the brakes were dragging…Not the usual stuck calipers either but one of my brake flex-lines had swollen up internally enough to pinch-off return fluid flow, causing that brake to drag badly…I replace all the rubber flex lines on the car and order was restored.

Check your brakes and see if any of them are dragging…


#5

Having to use the accelerator when going down hills to maintain your speed suggests very strongly that you have a brake dragging. This might be easy to confirm by simply jacking up each corner of the car and trying to spin the wheel by hand. Don’t forget to consider the parking brakes too. Many cars, this one may be included, use a small drum cast into the center of the rear disc with little brake shoes. It’s entirely seperate from the main brake system.

Post back with the results. We do care.


#6

wouldn’t the old hand test be quicker and easier to tell? Go for a little drive, then feel the wheels to see if one is hotter than any of the others; do NOT touch the brakes directly unless you have some form of protection against heat.

Is there any odd smells coming from the wheel areas after you’ve stopped?


#7

I had a '98 V70XC wagon. The parking brakes on these cars can rust, stick, and even fall apart. There are little brake shoes in the rear wheel brakes which are disks but also have a same brake drum incorporated into the rear disks just for the parking brake. The little brake shoes inside my XC’s rear wheels had completely rusted out and come apart and were causing a drag and lots of strange sounds. Eventually I had to replace the entire parking brake system including all the cables. The cables rust out and then stick, so if someone puts on the parking brake it might not release properly. Have the parking brake system checked out, including pulling off the wheels and disks to see what the condition is of the internal parts inside those little brake drums.

You might also have a sticking caliper on one or more wheels. I’d say a brake sticking somewhere is very likely or dragging parking brake are most likely causes.

Other possibles, but not likely, are very bad wheel bearing(s), and bad joint in a drive shaft (the one driving the rear wheels most likely), or your viscous coupling transfer case for the AWD could be failing. Any and all of which can be expensive repairs.


#8

Bscar, the old hotwheel test works but the jack-it-up test doesn’t boil any fluid.

Seriously, I never recommend driving a car that may have a serious brake problem.


#9

true, but if they don’t have a place to jack the car up, it’s about the only other way to check.


#10

If there’s a slight grade handy the OP could park on that, place the trans in neutral and see if the car will roll on its own. That could weed out a dragging brake problem.

If brakes aren’t the cause of this problem then I might suspect a clogged converter as VDCdriver mentioned.
I woud strongly suggest connecting a vacuum gauge to the car to check for a converter problem if this has not been done already.
If it hasn’t been done then I’d wonder why not.


#11

Thanks so much for all the ideas. I will definitely check them out. I believe the mechanic checked the brake pads/calipers, but I don’t know about the parking break. I appreciate the help.