Low knocking noise after CVT R&R
Hi guys. I'm hoping someone has some experience with a problem like this who can shed some light on the situation.
I removed the CVT assembly (AWD) to replace the rear main seal. The job went fairly smoothly except when I was separating the transmission from the engine block the torque converter was stuck to the flex plate and I had to gently pry it away. I didn't use much force to free it so I'm not thinking I bent the flex plate. The converter was out of the pump when I got the trans out so I reinstalled it, fully engaged, and reinstallation of the trans went smoothly.
While road testing the vehicle, it now has a loud, low, rhythmic knocking noise coming from under the vehicle only when accelerating from a stop. The noise goes away once driving down the road. The noise can also be heard while power braking in drive. I don't hear the noise free revving in park or neutral. It kind of sounds like a bad thrust bearing.
Another thing I'll mention is that both of the front CV axle inner boots are torn and the joints looked pretty dry, but I've never heard an inner CV joint make a noise like this. The customer declined to replace the axles because they weren't covered by the warranty company.
Any help or insight with this will be greatly appreciated.
Are the torque converter bolts tight? Did you bend the flexplate a little going in or out? Just some random 1st thoughts
Thanks for the response. The torque converter bolts are tight. The flex plate I'm a little worried about because of how I had to pry it away from the converter. I didn't use much force, just used a small flat blade screwdriver, but that flex plate is very thin and flimsy. Do you think a bent flex plate could make a noise like that, even when the noise isn't present in park/neutral?
They are really thin for what they do..... If it is a CV joint that came apart that might be easier to find and to repair . Good luck.
I suspect that one of the inner CV boots got stretched too far and one of the rollers fell off of the spider in the tulip joint. Had it happen to me a while back.
Thanks for the response. I'm really hoping this is the case, since I recommended replacing them based on the torn inner boots. I just finished this job at the end of the day, so now I get to stress about it all weekend. I've never heard an inner CV joint make a rhythmic knocking noise like that.
Yep bad cv joint I have had this happen to me
Thanks, maybe I shouldn't let this ruin my weekend.
No do not ruin your week end . Have a great week end . Monday is just another day . It sucks customers say it did not do it before . Have a great week end . What do they say here guido lol
Don't do that. It will be there on Monday.
I had a noise like this before similar. Remove the rear driveshaft and see if the noise goes away. I have seen faulty rear differentials causing this type of noise and or transfer case issue. If I remember it could be duplicated on slow take off or power braking.
I assume you checked for A bad thrust bearing? I’ve seen one torque converter stuck and it was because of excess crank play
Not yet. I had to leave the car immediately after road testing it yesterday. I will check on monday.
You said the noise can be heard when power braking. Is that with the car stopped, or just using the brake to put a load on it while moving? If you hear it while stopped the cv joint doesn't make sense. Also if it's the flex plate the noise should correspond to the rpm's of the engine. If it's the axle the noise should correspond to the axle revolutions. Good luck and have a great weekend.
I pretty much agree with you. The axle inner joint would have to extremely loose to hear the noise while power braking with the vehicle stopped.
Hearing the noise while power braking, vehicle not moving right? That eliminates the axles since they aren't moving. Did you test drive the vehicle before the repairs so you are sure the noise wasn't there before you worked on it? This sounds like a vehicle with an owner who will overlook everything that isn't covered under warranty. Turn the radio up louder. Use a set of chassis ears to…
Yes, power braking with the vehicle stopped, the noise is there. I road tested the vehicle before and the noise was not there. In my mind that almost rules out the axles and thrust bearing. I think you're right about the flex plate. That's about the only thing that seems logical. Going over the procedure again, I overlooked the part about aligning a guide pin tool for indexing the torque…
If the noise is there when power braking then its not the axles, at least not the noise, I would not think it would be the flex plate but it is possible, will it make it power braking in revers?, I have a set of mechanics ears and they are a life saver to help in these kind of situations.
it does sound like possibly a flexplate issue? we do a lot of these and they are bad about the pilot of the converter sticking in the crank. when you were prying did you pry between the outside of flexplate where the converter bolts up or the inside on flexplate where it bolts to the crank? (we always try to get thin prybar up between crank and pilot to pry it out) I've had a lot of these…
Hi Mike. I pried with a small flat blade screwdriver between the flex plate and the torque converter once I had the trans a couple inches away from the block and noticed the converter wasn't free from the flex plate. The flex plate was flexing a bit but I didn't feel that I bent or damaged it in any way. Next time I do one of these I'll try to free the converter from the flex plate through the…
Hi Alex: I'll give you 2 things to think about. You may like the first but will hate the second. 1: Put a dial indicator on the ring gear and rotate the engine. If there is very little runout then it stands to reason that there is even less with the body of the flex plate. (Since the engine starts, I doubt that the signal plate is coming loose though you should see this with a scope if it…
Thanks Anthony. I did check for thrust play when I had the flex plate nuts off. There was no movement. I have a new flex plate in hand. I’ll pull the trans again today or tomorrow and let you guys know what I find.
Thanks to everyone who replied. I removed the trans again and rechecked everything and didn't find any problems. I put everything back together and closely listened to the noise again with a stethoscope. The noise sounds louder toward the middle of the engine oil pan. At this point I'm leaning toward a possible jumped timing chain and/or balance shaft chain. It's possible that when holding the…
I had to remove the engine from this vehicle to physically check the timing marks. The timing marks were all perfect. The 2014 Altima 2.5 cam/crank waveform wasn't exactly the same as the 2014 Rogue 2.5. I also noted that the Altima 2.5 has intake and exhaust cam sensors while the Rogue only has an intake cam sensor. When I removed the oil pan and timing cover, I found extreme engine sludge and…