My car is E39 525i, auto, year 2002, Japan specs. At times when I engage my reverse gear, there is a loud thud and it seems to be coming from the rear. And when this happens, the thud continues when I move the gear to drive and whenever the gear changes. The thud subsides after driving for sometime. I noticed this problem about 2 years back but it happens infrequently. About 6 months ago, the problem became really bad and the thud occured more frequently whenever I engage the reverse gear. I got it to a workshop and the mechanic checked my transmission oil and found that it was low. So we had the oil topped up and the problem was resolved until recently when the problem resurfaced. This time I had the transmission oil and filter changed but the problem is still there but like before, it is infrequent. Anyone out there who might be able to help with this problem?
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Thanks Moots for the quick reply. So you think it is not gear box related? But how does transmission oil affect this problem? The problem went off when I topped up the transmission oil. So this must have an effect. By the way, how much do you think it will cost me with the center support bearing and guibo flex disc?
Your problem is intermittent.My guess is the noise got louder becoz of low gearbox fluid hence the gearbox tend to shift harshly thus exaggerating the knocking sound of the CSB.You can try replicating the sound by shifting to manual gear 2 and give the accelerator a quick jab and see if it thuds.The CSB sits under the rear air louver.
CSB and guibo cost total rm250 approx.workmanship maybe rm100.the exhaust pipes and heat shield needs removing to get to the CSB.
CSB and guibo cost total rm250 approx.workmanship maybe rm100.the exhaust pipes and heat shield needs removing to get to the CSB.
Hi Moots,moots said:
I had my car checked today. Jacked the rear and noticed there was metal clanking sound coming from the end of the drive shaft close to the rear axle. The sound is evident when the rear wheel is spun. I think this is the contant velocity joint (checked it up on realoem). My mechanic told me that the rubber part in there could be worn and this is causing the thud sound when ever the gear changes. Your thoughts?
Howdy Bro....
The inboard CV joint rarely have issues as it moves the least in the X axis.If anything,the outboard CV joints wear first unless the CV joint rubber boot is torn and debris has contaminated the grease.
Which side of the CV jount is making the noise?
What you can do is try to rotate the shaft in quick succession an see if the play is evident.
The inboard CV joint rarely have issues as it moves the least in the X axis.If anything,the outboard CV joints wear first unless the CV joint rubber boot is torn and debris has contaminated the grease.
Which side of the CV jount is making the noise?
What you can do is try to rotate the shaft in quick succession an see if the play is evident.
Hi bro, I am not sure which side of the CV joint in making noise. I will need to check this with my mechanic. But I was seated in the car and was revving the engine while he was underneath checking the shaft. There was a lot of play and I could even feel it sitting in the car. But if it is the case of the rubber boot being torn as you mentioned, would it cause the thud during gear change?moots said:
Hi Moots,
Went to my mechanic and had the drive shaft taken out. The CV joint is hard and difficult to flex. It seemed stuck at certain angle. My mechanic had a look at the drive shaft and said the CSB and the drive shaft in general looked okay (I am not sure if his method of checking the CSB was correct. He just spun the shaft and said it was okay). I did not see the universal joint though. I think that remained on the car. What I saw was a 3 point joint (I think this is fixed to the universal joint). He applied grease into the CV joint and fitted the drive shaft back. Everything was okay when I left his workshop. But I stopped at the gas station on my way back home. And when I started the car and engaged the gear, the thud was there. And as I drove off, the thud occured everytime the gear changed. The only difference this time is the thud is a lot softer and it took a shorter time to subside. Previously the thud would last for a much longer time. Do you think changing the CV joint would fix it for good? I was told it is quite expensive. Or do you think I should also change the CSB and universal joint. Appreciate your advice.
Went to my mechanic and had the drive shaft taken out. The CV joint is hard and difficult to flex. It seemed stuck at certain angle. My mechanic had a look at the drive shaft and said the CSB and the drive shaft in general looked okay (I am not sure if his method of checking the CSB was correct. He just spun the shaft and said it was okay). I did not see the universal joint though. I think that remained on the car. What I saw was a 3 point joint (I think this is fixed to the universal joint). He applied grease into the CV joint and fitted the drive shaft back. Everything was okay when I left his workshop. But I stopped at the gas station on my way back home. And when I started the car and engaged the gear, the thud was there. And as I drove off, the thud occured everytime the gear changed. The only difference this time is the thud is a lot softer and it took a shorter time to subside. Previously the thud would last for a much longer time. Do you think changing the CV joint would fix it for good? I was told it is quite expensive. Or do you think I should also change the CSB and universal joint. Appreciate your advice.
Howdy Bro...dicsitar said:
Let's get into better perspective.The drive train in a rear wheel driven car has the prop shaft and half shaft.The prop shaft is the pic I posted earlier which has a U joint at the rear and center and a guibo (rubber flex disc) at the front.and the half shafts has 2 cv joints at both ends.your description above on what was removed and reinstalled and what was tested is not too clear.
whatever the case may be,cv joints shud not get stuck or be difficult to move.if shud move freely.
i cannot recommend anything as I need to hear the noise and see the prop shaft and half shafts before coming up with a solution.
but i really would recommend you go to optimum auto in damansara kayu ara and see ah foo 012-3081891or ah fai 012-2115679 or their lead mechanic faisal.
removing the prop shaft is a lot of work where the exhaust pipes also requires to be removed and I feel your mech wasted all efforts by just putting grease......
Thanks Bro. Looking at the pic you had sent earlier, it looks different from the drive shaft on my car. I am attaching here the picture, which I got from realoem, of the drive shaft from my car. I think this could have caused some confusion. Anyway your thoughts given this clarification? Thanks so much for your time.
OK.dicsitar said:
That is the prop shaft aka drive shaft.The CV joint as I mentioned shud be smooth to rotate (like how a chamelion's eye moves).
Other than that you have the CSB (#1) and the U joint at the center (after the CSB).
The guibo,if intact and in good nick shud not produce any sound.
The CV joint rarely fails as it moves very minimal in the vertical axis if at all.
Sorry I am not able to help further.Perhaps Optiimum Auto can help?
Hi Bro, the problem recurred and it has become frequent. I went to Optimum Auto last Saturday and the problem was present. They had a look at the shaft and said it was okay. The suspected the knocking problem was coming from the gear box. Checked gear oil and it was sufficient and fine (I serviced it 2 months ago). After doing electronic diagnosis, there was fault with the transmission temperature sensor (I think not functioning) and they said that this is the reason for the knocking. They did a 'reset' and the problem went away. They said need to change the harness and the pair of sensors. Just wanted to get your thoughts before I go ahead. Thanks.
hey bro dicsitar,
wah long time no hear i thought problem solved ady....wow this is a tough one.
knocking due to a temp sensor and resetting cured it...for a while maybe...
well...i really don't know how the autobox work and how the temp sensors relate to the knock but i would go with what they recommend if the knock comes back...if the guys who attended to you was Ah Foo or Ah Fai or Faisal then you shud be good.............
wah long time no hear i thought problem solved ady....wow this is a tough one.
knocking due to a temp sensor and resetting cured it...for a while maybe...
well...i really don't know how the autobox work and how the temp sensors relate to the knock but i would go with what they recommend if the knock comes back...if the guys who attended to you was Ah Foo or Ah Fai or Faisal then you shud be good.............
Yeah bro, temporary fix. The problem came back today afternoon. According to Ah Foo, the faulty temperature sensor is sending wrong information - my gear oil temperature is actually normal but on the diagnostic device, it is showing very high temperature. So the wrong reading / information from the sensors is causing the wrong shifting of gears, hence the knocking.
