Sunday, July 19, 2020

2020 - CV boot leak on drivers side Nissan Rogue 2009

A testament to the engineering of this car , besides the few things Ive mentioned in this blog this Nissan Rogue 2009 has pretty much kept running without any major mechanical / electrical issues for over 11 years. I will also admit that I havent put much into maintaining this car either beyond the occassional oil change and windshield wiper fluid replenish.

Now however I do have a new situation, this time its with the driver side "CV boot" leaking grease when driving. 

What is a CV boot leak? What is a CV boot in fact?

Basically, a cv boot looks like an accordion sleeve. One side is wide and one side is constrained. It sits over a joint of some sort - and the gears in the join help move wheels forwards , backwards or sideways etc depending on which joint it is. The CV boot is supposed to hold in grease over the joint. The grease is dark sludgy, and helps the joint structure from wearing out or slipping.

When the grease starts spilling out, this is called a CV boot leak.

How many cv boots are there?

There are multiple CV boots along the way from the center of the vehicle where the main shaft powering the wheels forward or backward, following alone to end up at the wheel of the car which has a more complicated joint since it can also turn side to side.

What does the CV boot leak look like?

In my case, the CV boot that was leaking was from the center of the car, and here's a picture to help showing the leak. You can see that due to the car's axl rotation , grease is flung out as the wheel rotated and is hitting other parts of the car.

Note, this is under the car from the drivers side, looking up at the driver's seat. On the left hand side is the driver side wheel.




Why did this leak happen?

I was told that likely the reason for the leak is due to a crack in the CV boot, or loosening of the seals somehow. I also think maybe due to some of the rougher roads I took last year driving around and in some cases through some bad potholes, its possible I unintentionally did some damage.

Is it Dangerous?

The very first question the car mechanic asks is  - do you hear any clicking sounds when you turn the steering wheel ?

If you do, then the joint is dried out and bad things can happen. What kind of bad things?
Depends on who you ask. If you ask the car spot next to a BP gas station they will say "your wheel will fall off on the highway". If you ask the seasoned mechanic you've been going to for years who suggests repairs only when you really need them, they'll say it will wear down your joint and then the whole axle will just need to go if not more.

The other factor at play is - which CV boot is leaking. If its a center one like mine, the shaft that is protected is just driving the wheel forward and backward. Its not involved in any other range of motion/plane . This means it will last  a bit longer in the current situation and the outcome of a worn gear/slip isnt significant.

If however (I was told) if the CV boot is near the wheel, where theres also turning involved, now we are talking about some significant added risk, and therefore a shortened timeline to fixing.

In my case, I hear no clicking sound, however the amount of grease leaking is significant so I will likely do something about it.

What can be done to fix?

This is an entirely budget driven discussion.

if budget is low, some people will opt to replace the CV boot sleeve after regreasing.

if can afford, some people will replace the axle which comes with its own cv boot, because the assumption is unless you catch the leak very quickly, its been going on for a while and some amount of grease/dirt has gone into the joint and done some damage already - and its just a matter of time before you'll need a replacement anyways.

What will it cost?

Labor is the largest cost. The cv boot sleeve is roughly $15, the axl with a new cv boot sleeve is about $45. Local garage wanted anywhere from $250 to $800 for labor if axl replacement is involved (and neither offered to simply change the sleeve).

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