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Discussion Starter · #1 · (Edited)
MY 2013 Premium

The Problem

- A soft bump, bump, bump can be felt coming from the passenger side front on take-off (gentle or hard acceleration doesn't make a difference).
- At about the 30 mph mark, the bump can be felt a little less.
- There is a slight noise on a medium hard left turn, but I've been reluctant to attempt a test of that. I have not tried a hard right turn, as I've been babying the car.
- The bump can be felt mostly at rush-hour-traffic speeds no matter the road surface (newly paved to medium wear).
- I can feel the bump in the steering wheel and in the seats.

The History

The passenger side front rim broke when I hit a large, triangular-shaped, ~ 8-9 inch rock that rolled onto the road. (I found the rock on the opposite side of the road when I was walking in an attempt to find a cell signal.) Front end was sitting on the ground on that side. After waiting for 8.5 hours for a AAA tow truck to find me in a no cell signal area (looong story) and getting it towed home, the following steps were done:

- Passenger front wheel was removed, and the passenger rear wheel was rotated to the passenger front. The Cadillac spare was mounted on the passenger rear.
- On visual inspection, the brake rotor looked undamaged.
- Refinished rim was purchased off Ebay.
- Car was driven to the tire shop where it was discovered that the tire had a 3 inch, clear-through slash in the sidewall, necessitating the purchase of a new tire.
- Passenger rear wheel was moved to the front and a new tire was installed on new rim and mounted on the passenger rear.
- Upon leaving the tire shop, I immediately felt that the alignment was way out and a very distinct bump, bump, bump was undeniable at any speed. I gingerly drove it home.

- Took the car into a suspension shop who let me look under the car with them. Nothing was completely crushed, but there were harsh smash marks going directly towards the back of the car. I saw that the lower corner of the engine cover was broken off, leaving a large (~ 10 inch diameter) hole that exposed what I now know is the auxiliary heater water pump.
- The owner of the shop took it out and brought it right back. The CV axle was bent. This made perfect sense to me because that's what the distinct bump, bump, bump felt like.
- A new CV axle was ordered, and I brought the car back two days later to have it installed.
- An alignment was done after the new axle was installed. The owner said it was badly out of alignment, which again, made sense to me, as the rock hit was hard enough to break the rim on impact.
- After another test drive, the owner said it was much better. I got in the car to go home, and agreed that the car felt almost like it did before the rock hit.
- Since I was still a bit shook up after the killer rock episode, I did not notice that there was still a very slight bump, bump, bump coming from the same passenger side front area.

- Fast forward to two nights later when the weather took a nose-dive. Very cold temps with rain. I found out that I could not see out the windshield because the defroster wouldn't clear it. Tried moving the temperature setting on High (one past 88 degrees), but no heat could be felt. Put the car in Hold mode in an attempt to have the ICE make some heat, but again, no heat could be felt at all.
- We did some research online and in all the Volt groups and felt we had narrowed it down to a bad heater water pump.
- Took the car into a Hybrid shop. They found that the auxiliary heater water pump was leaking and indeed dead. The pump was visibly damaged.
- The pump was replaced and Dex-Cool filled. Heater was back in working order, and we were happy.

- The next day, the slight, soft bump, bump, bump was felt in the steering wheel and throughout the car, coming from the passenger side front wheel area.

Finally, here is my question section:
- Would a bad wheel bearing cause a soft bump, bump, bump?
- Are there other parts that I could have checked?
- Would there be any use in swapping the passenger side front wheel with the driver side rear?


I have photos, but cannot post them on this forum.
If you've stuck with me this far, I thank you.

Kathleen
 

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MY 2013 Premium

The Problem

- A soft bump, bump, bump can be felt coming from the passenger side front on take-off (gentle or hard acceleration doesn't make a difference).
- At about the 30 mph mark, the bump can be felt a little less.
- There is a slight noise on a medium hard left turn, but I've been reluctant to attempt a test of that. I have not tried a hard right turn, as I've been babying the car.
- The bump can be felt mostly at rush-hour-traffic speeds no matter the road surface (newly paved to medium wear).
- I can feel the bump in the steering wheel and in the seats.

The History

The passenger side front rim broke when I hit a large, triangular-shaped, ~ 8-9 inch rock that rolled onto the road. (I found the rock on the opposite side of the road when I was walking in an attempt to find a cell signal.) Front end was sitting on the ground on that side. After waiting for 8.5 hours for a AAA tow truck to find me in a no cell signal area (looong story) and getting it towed home, the following steps were done:

- Passenger front wheel was removed, and the passenger rear wheel was rotated to the passenger front. The Cadillac spare was mounted on the passenger rear.
- On visual inspection, the brake rotor looked undamaged.
- Refinished rim was purchased off Ebay.
- Car was driven to the tire shop where it was discovered that the tire had a 3 inch, clear-through slash in the sidewall, necessitating the purchase of a new tire.
- Passenger rear wheel was moved to the front and a new tire was installed on new rim and mounted on the passenger rear.
- Upon leaving the tire shop, I immediately felt that the alignment was way out and a very distinct bump, bump, bump was undeniable at any speed. I gingerly drove it home.

- Took the car into a suspension shop who let me look under the car with them. Nothing was completely crushed, but there were harsh smash marks going directly towards the back of the car. I saw that the lower corner of the engine cover was broken off, leaving a large (~ 10 inch diameter) hole that exposed what I now know is the auxiliary heater water pump.
- The owner of the shop took it out and brought it right back. The CV axle was bent. This made perfect sense to me because that's what the distinct bump, bump, bump felt like.
- A new CV axle was ordered, and I brought the car back two days later to have it installed.
- An alignment was done after the new axle was installed. The owner said it was badly out of alignment, which again, made sense to me, as the rock hit was hard enough to break the rim on impact.
- After another test drive, the owner said it was much better. I got in the car to go home, and agreed that the car felt almost like it did before the rock hit.
- Since I was still a bit shook up after the killer rock episode, I did not notice that there was still a very slight bump, bump, bump coming from the same passenger side front area.

- Fast forward to two nights later when the weather took a nose-dive. Very cold temps with rain. I found out that I could not see out the windshield because the defroster wouldn't clear it. Tried moving the temperature setting on High (one past 88 degrees), but no heat could be felt. Put the car in Hold mode in an attempt to have the ICE make some heat, but again, no heat could be felt at all.
- We did some research online and in all the Volt groups and felt we had narrowed it down to a bad heater water pump.
- Took the car into a Hybrid shop. They found that the auxiliary heater water pump was leaking and indeed dead. The pump was visibly damaged.
- The pump was replaced and Dex-Cool filled. Heater was back in working order, and we were happy.

- The next day, the slight, soft bump, bump, bump was felt in the steering wheel and throughout the car, coming from the passenger side front wheel area.

Finally, here is my question section:
- Would a bad wheel bearing cause a soft bump, bump, bump?
- Are there other parts that I could have checked?
- Would there be any use in swapping the passenger side front wheel with the driver side rear?


I have photos, but cannot post them on this forum.
If you've stuck with me this far, I thank you.

Kathleen
Excellent troubleshooting thus far. Sounds like we’re almost there!

I experienced the exact same CV joint bump bump bump after driving through some leaves one year and not noticing a curb! Oh, it was a bad landing...

Work your way from the outside in. You already:

- Replaced wheels
- Replaced CV axle

There’s still a chance the hub/bearing was damaged, or the (I don’t know the term for it) output shaft carrier for the transaxle was bent when the CV axle was damaged.


Sent from my iPhone using Tapatalk
 

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Has anyone inspected the rear tire for damage? Could it have hit the same rock after the front did?
 

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Discussion Starter · #4 ·
Current Update:

Just got back from the tire shop.
I had all four rims checked for round and bend. All were perfect.
Purchased another tire to match the one I bought last month (mounted on the new rim).
Had the guys do the tire grab test (9 & 3 and 12 & 6) and they reported that there was zero wiggle/looseness.
Wheels were balanced and rotated front to back. The new tires are now on the front.

So, the rims are not bent and are round, and tires are matched in pairs.

It feels very good (alignment is perfect), but I still feel a slight vibration on hard acceleration and above 60 mph. This could be the ICE kicking in though.
I did some hard and fast switchbacks on a piece of smooth asphalt to see if there was any lateral motion noise, like clicking. No noise detected from the driver's seat with windows down.
I want to drive it a little more, maybe a day or two, to get a better evaluation.

My next move will be to take it in to the suspension shop and have them look at the hub/bearing assembly to see if the hub is bent. Is there even a way to detect a bent hub? I would think it would simply have to be replaced to see if that was the issue.

I wish I knew how to crank down on the axle nuts. I had the dealer do it last time, so I don't know what all is involved. I have a ft/lb torque wrench, and I'd probably have to purchase a socket.

Lastly, does anyone have an opinion on whether the lower engine cover (passenger side) needs to be intact or not?
The large hole leaves the auxiliary heater water pump exposed.
The CEL has been on for two days now, so I'm going to go plug into the OBD port to see what the code is.

ddm2k: Where is the output shaft carrier for the transaxle? Is it attached to the CV axle? I'm trying to look for a diagram.

Much thanks to both of you for replying! :)
 

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ddm2k: Where is the output shaft carrier for the transaxle? Is it attached to the CV axle? I'm trying to look for a diagram.

Much thanks to both of you for replying! :)
I just mean where it comes out of the transaxle. Can’t think of any other words to describe. I’m dealing with the SAME thing.


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Has anyone inspected the rear tire for damage? Could it have hit the same rock after the front did?
Bingo!!! - We have a winner

Buying new tires in pairs is always the best idea - Usually either a front pair or a rear, but in this case, the pair on the damaged side would be most apropos

All these problems from a triangular rolling rock! - Those are the worst kind!!

Don
 

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Has anyone inspected the rear tire for damage? Could it have hit the same rock after the front did?
Besides inspection, if rotating the tire to a new position also moves the bump bump bump...
 

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Discussion Starter · #8 ·
I’m dealing with the SAME thing.
Did you ever figure out what was causing your wobble problem?

Current status of mine:
- Suspension shop checked hub/bearing and said it looked fine, as well as all other components supporting the RF wheel.
- They found a very minute bit of play in the new CV axle they had installed and so did a warranty replacement to see if it fixed the problem. It did. For a while.

The wobble seems to be coming back.

Since the last time I posted, all four rims were checked for round and twist. All were found to be good and tires were rebalanced.
The tires were rotated around to get the new rim off that corner.

The only things left to check would be:
- Damage to the output shaft carrier for the transaxle (where the CV axle comes out of the transaxle).
- Brake system (unlikely since the wobble happens on coast as well as acceleration?)
- Steering system
- Suspension system

Please correct me if I'm off on these checks.
I'm all ears for any other ideas.
 

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Discussion Starter · #9 ·
Would a broken engine mount feel like an intermittent wobble?
 

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Does applying the brakes make any difference when you are getting the bump/vibration? If it makes a difference check brake rotor / wheel bearing. It is possible for the wheel bearing to start failing but still not have play. With wheel off the ground and car in neutral any roughness in the bearing when spinning the tire by hand.
Very unlikely problem is with the output bearing on the transaxle. you would have an oil leak from the seal if it was bad.
The cover that ripped off is more for aerodynamics than for protection. Be good to replace it but I would not lose sleep over it.
If you can jack up the front of the car check to see if the tire runs true on the car. I know the wheels were checked and are good. but when mounted on the car do they wobble? That would tell you if the hub is bent My guess they will as it would have shown up when you had the alinement done. But does not hurt to check.

Bottom line is if I were to wage money on it my guess is the wheel bearing is failing but not wiped out yet but on it's way to fail. The test is if it feels rough when spinning by hand. You will not get any play until it fails when a ball or roller falls out of it because it failed. This is because it has to wear down the steel races and the ball or rollers enough to create the space to allow the play. You will feel the roughness and or the trail from the grease that leaked out to the bearing first.
 

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Discussion Starter · #12 · (Edited)
Thanks Daferris.
There is no difference when brakes are applied.
I will try hand spinning the wheel.
I got a fender insert/lower FR engine cover that I need to install, so I can do the check then.
 
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