Can't bed down cause of noise out back of bus

[shea]

Just got my engine rebuilt last week, straight after putting the engine in I did 150 miles in my bus no problem(first time I'd driven the bus for more than 10 minutes), well apart from doing 15 mpg if I go by the gauge but that's another thread.

I've been driving around Dublin since doing the first 150 mile trip and a noise has started out back, it sounds like a jack hammer in the distance, or a metal hitting metal tapping. It only happens when the the clutch is engaged. And only starts after I've been driving for a few minutes.

If I rev the engine with the clutch in it sounds fine, same thing if I go round to the engine and rev it.

I'm just after putting in new cv boots last month, when I start hearing the tapping noise and I stick my head out the window I can no longer hear it, same for passenger side. Also turning slowly in circles in a carpark in both directions I don't hear anything from the cv's.

The gearbox is a bit knackard, I can only get into first gear when I'm fully stopped and there is a lot of gunk around it. I also slightly bent one of the teeth on the clutch assembly when fitting the engine but pried it back into place.

So now that you know all the above any ideas on what the noise could be? I'm at a complete loss as to what's causing this and have to do the 150 mile trip again at the end of the week.

Thanks!
Shea.

 

[Trikky2]

Just got my engine rebuilt last week, straight after putting the engine in I did 150 miles in my bus no problem(first time I'd driven the bus for more than 10 minutes), well apart from doing 15 mpg if I go by the gauge but that's another thread.

I've been driving around Dublin since doing the first 150 mile trip and a noise has started out back, it sounds like a jack hammer in the distance, or a metal hitting metal tapping. It only happens when the the clutch is engaged. And only starts after I've been driving for a few minutes.

If I rev the engine with the clutch in it sounds fine, same thing if I go round to the engine and rev it.

I'm just after putting in new cv boots last month, when I start hearing the tapping noise and I stick my head out the window I can no longer hear it, same for passenger side. Also turning slowly in circles in a carpark in both directions I don't hear anything from the cv's.

The gearbox is a bit knackard, I can only get into first gear when I'm fully stopped and there is a lot of gunk around it. I also slightly bent one of the teeth on the clutch assembly when fitting the engine but pried it back into place.

So now that you know all the above any ideas on what the noise could be? I'm at a complete loss as to what's causing this and have to do the 150 mile trip again at the end of the week.

Thanks!
Shea.

The most important information is this. Does the tapping noise rise and fall with engine rpm or with road speed? For instance, when you hear the noise in fourth gear, change down to third, does the noise get faster or stay the same?

 

[shea]

I'm 90 % sure when I say this but it rises and falls with road speed. I'll recheck when I drive home from work to confirm.

 

[Trikky2]

I'm 90 % sure when I say this but it rises and falls with road speed. I'll recheck when I drive home from work to confirm.

Ok, well if its road speed related then its not the engine or the clutch.

Check the bolts securing the CV joints.

While its jacked up check the wheel bearings for wear by waggling the wheels top and bottom and side to side.

Check the hub nuts are tight.

When its making the noise see if it stops or changes when you apply the foot brake.

Do the same again but with the handbrake.

Hopefully these checks/tests should help you isolate the problem.

Ps. I had a friend who had a similar problem and asked me to have a look, turned out there was a big screw in one of his rear tyres :lol:

 

[slow-lane-Matt]

I had what may be a similar problem - at certain speeds there was a heavy clanking from somewhere indiscernible at the back.

It turned out to be one of the circlips on on of the drive shafts (CV joints) wasn't there.

The drive shafts should move in/out about 5mm, without the circlip they moved about 30/40mm - giving the
drive shaft too much play - and making a load clanking when under load - mainly when starting to decelerate through the gears.

(I think I had to jack the back up to feel the extra play)

 

[Trikky2]

I had what may be a similar problem - at certain speeds there was a heavy clanking from somewhere indiscernible at the back.

It turned out to be one of the circlips on on of the drive shafts (CV joints) wasn't there.

The drive shafts should move in/out about 5mm, without the circlip they moved about 30/40mm - giving the
drive shaft too much play - and making a load clanking when under load - mainly when starting to decelerate through the gears.

(I think I had to jack the back up to feel the extra play)

Good point - forgotten about that one

 

[shea]

OK so I took bus home and the noise started again, I braked while keeping the accelerator at the same position, the noise did not stop, just slowed down as the bus started slowing. Same goes for the handbrake. I got underneath the bus and checked the drive shafts the drivers side (lhd) seems to have the correct amount of play but the passenger side has a lot more! actually feels like the boots are what's limiting its travel. So hopefully you guys are onto something, I've realised I broke my adapter for my wrench to take the m8 triple square bit last time I installed the cv boots. I'll get another tomorrow and take the drive shaft off and let you guys now the results.

Thanks again!