The reason I ask, is I have been hearing a mild whine from the front of my vehicle for about as long as my gas milage has been bad. The milage has been getting worse and I need to fix that. The reason I bring up CV joints is because my front inner boots are both torn open and have been for a while. I was going to drive it that way until my next off road excursion or until they fail. My questions:

1. What does a bad CV joint sound/feel like?

2. If it is a bad CV joint could it be causing undo stress on the motor and cause my poor gas milage?

 

To check out your CV joints, turn your wheels ALL the way to the left first. Drive real slow with your window down,if you hear a snapping,popping sound then the joints bad on the drivers side. To check the passengers side, turn all the way to right and check for the snapping sound.
The drivers side usually goes first. If both your boots are tore, then its a pretty good chance there going or gone. I never heard of it affecting gas milage though.

Whining noise...hummm, have you checked you differencial fluid level lately?

 

I have not.... I guess that would be a good thing to do, huh?

 

Yeah, If you gettin a whine, it's usually gears or a bearing.

 

It doesn't sound like a CV joint to me. You will get a loud clicking when turning if it was a joint. I agree about it being a bad bearing.

 

The test of turning the wheels will tell you if an OUTER CV joint is going bad. The inners won't change sound or pop/click. I would change them now, and not wait for a failure. If they are open, they get dirt in them. Dirt makes it difficult for them to change angle, which could put stress on the bearings in the front diff (as that is what the inners are connected to)

They could be the cause of your mileage drop. I would check the wheel bearings too. Good time to service them before winter.

 

I will do that this weekend.

 

Similar question...when I am engaged in 4wd and turn hard either direction, it feels like someone is standing on my breaks. Would this be cv joint, wheel bearing or a combination of both? My boots look good but have never replace the joints. (92' 4runner 175k on odometer

 

Actually, that would be 4wd. Let me guess... this is your first? Your front drive axles don't have the differential that your rear axle does. That is why you don't use 4wd on dry pavement or anything where you are getting good traction as it will only hurt your drive axles and wear down your tires. If you don't off-road much, it is good to at least engage it from time to time in hard rains or quick dirt runs where the tires can slip without causing harm. One thing many 4Runner owners did was add in the locking hub even though it has shift on the fly. This is because with the shift on the fly, the hubs are always locked which is spinning your CV joints all the time. When 4Runners are even marginaly lifted, this tends to cause stress. you just have to remeber to lock your hubs before shifting into 4wd, but it save a headache down the road with replacing the axle, which really isn't too hard either.

Hope that helps and enjoy your 4Runner! I know I did!!!

 

That's the thing, i swapped my hubs out years ago. No, i am not new to 4wd but understand the impression i might have given. I have never felt this aggressive stopping power when engaged. But as you mentioned i have not used my 4wd in sometime. Moved back from Colorado and became an unfortunate pavement pounder. Thanks for the response.

 

OK... so you shouldn't have any axle spin when getting this tension, correct? I mean, you have seen it free wheeling?

Sorry about the misunderstanding. I can't tell you how many of those I have answered with that alone. A lot of people are just missing the basics...