A CASE OF SQUEAKY MOTORHOMEITUS!
by John Welham
PLUS A BIT OF A RUMBLE
Getting the van ready for a summer outing last year I took it for a run around the local area for a bit of a shake down. After a while I noticed that every time I applied the brakes one of the front brakes squealed loudly. There is sometimes squeaking from the back brakes where the brake dust tends to accumulate more readily, but the front are usually quiet.
Applying a temperature sensor to the front brakes, ie, my hand, I discovered that one of the wheels was very hot, indicating that the brake pads were rubbing against the disc as we drove along. The usual causes of pad contact are either a sticking calliper piston or the floating calliper does not back off when you release the brake. Back home, off came the wheel, off came the pads and calliper, out came the brake cleaning fluid. Having cleaned up all the components, I exercised the pistons and floating slides to make sure they had free movement. All ok, I put it all back together and went for another test run.
Not as hot, but still warm enough to indicate pad contact. At this point I took some advice from my local Fiat man, who had a look at the components. He agreed that every thing was free and functioning properly, but a close look at the pads showed that they were swollen very slightly at the leading edge of the pad, causing to the pad to maintain contact with the disc even when the brakes were released. This swelling, about only 1mm, was caused by corrosion between the pad friction material and the steel backing plate. A new set of pads and the problem was fixed.
Our vehicle was 5 years old; had done about 35000 miles; and the pads were original and only about half worn. If, however, this had been used as a commercial vehicle, in 5 years, the base vehicle would probably have done at least 100000 miles or more, and had the pads changed at least twice in that time and corrosion would not have become an issue. Although our van is well used compared to some motorhomes it did not prevent corrosion starting up over time in a very exposed component.
This was a classic case of a problem developing that was directly attributable to relatively low use that a motorhome chassis experiences compared to a chassis in commercial use.
Whilst I think about it, on the subject of noises, the van has also had a Rumble that took a bit of tracking down.
There was a rumble that appeared to be coming from the front off-side wheel. Running in a straight line, there was a constant rumble. When the steering wheel was turned left, increasing side load on the bearing, the noise increased. Turning the wheel right, unloading the bearing, the noise all but disappeared. This all suggested the wheel bearing was on the way out, and seeing that we were soon to go to Morocco, I took it to the Fiat man. A road test seemed to confirm the front off-side wheel as the source of noise. Front wheel bearings are a known weak point in this vintage of Ducatos, so it was agreed that they would change the bearing.
Once out, the bearing did not seem to be particularly worn, certainly not enough to create the noise level we were experiencing. A new bearing was fitted, and a road test supported that assessment. The noise and its behaviour with steering were still there.
A series of tests on the van followed. This generally involved Fiat man lying on the floor with his ear to the wheel arches as the van was driven around Devon lanes, listening for rumbles. The main source of noise still appeared to be at the front, but it was also present at the rear off-side wheel. Back in the workshop, with the van up on the hoist and spinning the wheels as best can done by hand, the listening stick was used to confirm the REAR off-side wheel as the source of the noise. (Listening sticks can vary from a piece of well worn wood, to big screwdrivers, to stethoscopes, to electronic listening devices.) Out came the rear bearing, and low and behold, a brown mess of grease and water surrounding a roller bearing that might have been ok on a wheel barrow, but was not going to see out a Morocco trip. A new bearing fixed the problem.
The cause of bearing failure was probably a failure of the seal that allowed water into the bearing, leading to poor lubrication and corrosion. Why was the front bearing originally identified as the culprit? The noise was clearly transmitting along the Alko chassis rail that attaches to the cab just under the off-side seat. Seeing that front bearings are a known weak point, it seemed the most likely cause of the problem. Because they got it wrong in the first place, Fiat man offered a reduction in the bill without prompting, which I though was a very fair gesture.
One final point, if you are inclined to change a bearing yourself, be aware that both front and rear bearing are huge compared to anything you will find on a car. I have changed car bearings using suitable hammers, drifts and a freezer, but the Ducato’s bearings are about 10 cm in diameter and 8 cm wide, containing double, tapered roller bearings. You will need at least a 10 tonne press to extract and refit bearings to the hubs.
by John Welham
PLUS A BIT OF A RUMBLE
Getting the van ready for a summer outing last year I took it for a run around the local area for a bit of a shake down. After a while I noticed that every time I applied the brakes one of the front brakes squealed loudly. There is sometimes squeaking from the back brakes where the brake dust tends to accumulate more readily, but the front are usually quiet.
Applying a temperature sensor to the front brakes, ie, my hand, I discovered that one of the wheels was very hot, indicating that the brake pads were rubbing against the disc as we drove along. The usual causes of pad contact are either a sticking calliper piston or the floating calliper does not back off when you release the brake. Back home, off came the wheel, off came the pads and calliper, out came the brake cleaning fluid. Having cleaned up all the components, I exercised the pistons and floating slides to make sure they had free movement. All ok, I put it all back together and went for another test run.
Not as hot, but still warm enough to indicate pad contact. At this point I took some advice from my local Fiat man, who had a look at the components. He agreed that every thing was free and functioning properly, but a close look at the pads showed that they were swollen very slightly at the leading edge of the pad, causing to the pad to maintain contact with the disc even when the brakes were released. This swelling, about only 1mm, was caused by corrosion between the pad friction material and the steel backing plate. A new set of pads and the problem was fixed.
Our vehicle was 5 years old; had done about 35000 miles; and the pads were original and only about half worn. If, however, this had been used as a commercial vehicle, in 5 years, the base vehicle would probably have done at least 100000 miles or more, and had the pads changed at least twice in that time and corrosion would not have become an issue. Although our van is well used compared to some motorhomes it did not prevent corrosion starting up over time in a very exposed component.
This was a classic case of a problem developing that was directly attributable to relatively low use that a motorhome chassis experiences compared to a chassis in commercial use.
Whilst I think about it, on the subject of noises, the van has also had a Rumble that took a bit of tracking down.
There was a rumble that appeared to be coming from the front off-side wheel. Running in a straight line, there was a constant rumble. When the steering wheel was turned left, increasing side load on the bearing, the noise increased. Turning the wheel right, unloading the bearing, the noise all but disappeared. This all suggested the wheel bearing was on the way out, and seeing that we were soon to go to Morocco, I took it to the Fiat man. A road test seemed to confirm the front off-side wheel as the source of noise. Front wheel bearings are a known weak point in this vintage of Ducatos, so it was agreed that they would change the bearing.
Once out, the bearing did not seem to be particularly worn, certainly not enough to create the noise level we were experiencing. A new bearing was fitted, and a road test supported that assessment. The noise and its behaviour with steering were still there.
A series of tests on the van followed. This generally involved Fiat man lying on the floor with his ear to the wheel arches as the van was driven around Devon lanes, listening for rumbles. The main source of noise still appeared to be at the front, but it was also present at the rear off-side wheel. Back in the workshop, with the van up on the hoist and spinning the wheels as best can done by hand, the listening stick was used to confirm the REAR off-side wheel as the source of the noise. (Listening sticks can vary from a piece of well worn wood, to big screwdrivers, to stethoscopes, to electronic listening devices.) Out came the rear bearing, and low and behold, a brown mess of grease and water surrounding a roller bearing that might have been ok on a wheel barrow, but was not going to see out a Morocco trip. A new bearing fixed the problem.
The cause of bearing failure was probably a failure of the seal that allowed water into the bearing, leading to poor lubrication and corrosion. Why was the front bearing originally identified as the culprit? The noise was clearly transmitting along the Alko chassis rail that attaches to the cab just under the off-side seat. Seeing that front bearings are a known weak point, it seemed the most likely cause of the problem. Because they got it wrong in the first place, Fiat man offered a reduction in the bill without prompting, which I though was a very fair gesture.
One final point, if you are inclined to change a bearing yourself, be aware that both front and rear bearing are huge compared to anything you will find on a car. I have changed car bearings using suitable hammers, drifts and a freezer, but the Ducato’s bearings are about 10 cm in diameter and 8 cm wide, containing double, tapered roller bearings. You will need at least a 10 tonne press to extract and refit bearings to the hubs.
