pistonbroker
Active Member
hi, yes all good in that regard, also no rumbling and no excess free play - although defining excess when moving something by hand is always subjective! Thanks.
Volvo D4 Belt Slipping (Have Changed and Tensioned Belts)
- Thread starter pistonbroker
- Start date
pistonbroker
Active Member
Problem now solved and hopefully this may help others with a similar issue.
So just to recap the belts were slipping on one motor each time the bow thruster or anchor windlass were operated. I originally thought it was the belts at fault as I didn't know the history on this newly purchased boat. I tried re-tensioning them, did all the pulley and tensioner checks and cleaned them all and still had issues. The belts were actually in really good condition when compared with new but I changed them anyway on both engines and followed the Volvo manual to the letter. I still had issues with the new belts. So here is what I found:
1. I own up, I was a numpty in part as despite tensioning the new belts, running the engines up warm and then re-tensioning as per the manual, I didn't do it on load, i.e. take the boat out. It was done on tickover. The manual does not specify how, but my past experience with older cars should have made me think more! So I found the belts on both engines tonight "fairly loose" which didn't help. Lesson learnt again, always run the engine on load and then check the tension. A re-check over the the coming weeks will ensure all is good and any new play well and truly out.
2. Whilst the belts were loose they were not the root cause of the problem. As suspected it was a battery issue, but not one that was obvious. The batteries are reasonably new (dated last year) and appear well maintained with the correct fluid levels and greased up terminals, however on further inspection a couple of them, including the bowthruster and windlass battery, had corroded cable clamps when I removed the cable clamps from the posts. I.e. the outside of the clamp looked fine, but the inner part that contacts with the battery posts were very poor. I guess the previous owner had the batteries all replaced due to problems but the clown that replaced them didn't clean the clamps properly, if at all. Whilst not my fault it is once again (from car ownership) a lesson learnt! I wonder what else lay in wait for me....
3. So after re-tensioning the belts, cleaning, greasing and re-clamping the battery terminals the engines were run up and bingo all resolved. I have concluded that the alternator was placed on so much load that it was trying to deliver most of the current demand, rather than the battery (due to the poor termination), this slowed it down due to the increase in flux density and eventually couldn't keep up with the engine speed via the belt. The alternator pulley is now nice and shiney
On reflection it was all down to bad maintenance and the basics really do matter. Also the bowthruster and windlass are current hungry and it seems odd that the battery is the furthest away it can be in a stern engine room. I'm sure there are volt drop issues at play here. The windlass is 800w which would draw 66A but with a voltage drop this would cane the battery. Never mind a job for another day.
Thanks for the comments and help and hope this assists someone else in the future.
So just to recap the belts were slipping on one motor each time the bow thruster or anchor windlass were operated. I originally thought it was the belts at fault as I didn't know the history on this newly purchased boat. I tried re-tensioning them, did all the pulley and tensioner checks and cleaned them all and still had issues. The belts were actually in really good condition when compared with new but I changed them anyway on both engines and followed the Volvo manual to the letter. I still had issues with the new belts. So here is what I found:
1. I own up, I was a numpty in part as despite tensioning the new belts, running the engines up warm and then re-tensioning as per the manual, I didn't do it on load, i.e. take the boat out. It was done on tickover. The manual does not specify how, but my past experience with older cars should have made me think more! So I found the belts on both engines tonight "fairly loose" which didn't help. Lesson learnt again, always run the engine on load and then check the tension. A re-check over the the coming weeks will ensure all is good and any new play well and truly out.
2. Whilst the belts were loose they were not the root cause of the problem. As suspected it was a battery issue, but not one that was obvious. The batteries are reasonably new (dated last year) and appear well maintained with the correct fluid levels and greased up terminals, however on further inspection a couple of them, including the bowthruster and windlass battery, had corroded cable clamps when I removed the cable clamps from the posts. I.e. the outside of the clamp looked fine, but the inner part that contacts with the battery posts were very poor. I guess the previous owner had the batteries all replaced due to problems but the clown that replaced them didn't clean the clamps properly, if at all. Whilst not my fault it is once again (from car ownership) a lesson learnt! I wonder what else lay in wait for me....
3. So after re-tensioning the belts, cleaning, greasing and re-clamping the battery terminals the engines were run up and bingo all resolved. I have concluded that the alternator was placed on so much load that it was trying to deliver most of the current demand, rather than the battery (due to the poor termination), this slowed it down due to the increase in flux density and eventually couldn't keep up with the engine speed via the belt. The alternator pulley is now nice and shiney
On reflection it was all down to bad maintenance and the basics really do matter. Also the bowthruster and windlass are current hungry and it seems odd that the battery is the furthest away it can be in a stern engine room. I'm sure there are volt drop issues at play here. The windlass is 800w which would draw 66A but with a voltage drop this would cane the battery. Never mind a job for another day.
Thanks for the comments and help and hope this assists someone else in the future.
Last edited:
Portofino
Well-Known Member
Nice write up .
I try and remove , emery paper inside the clamps , posts , etc every year .
Its not just the V out , but the charger / alternator in .
Turn them off first .
I try and remove , emery paper inside the clamps , posts , etc every year .
Its not just the V out , but the charger / alternator in .
Turn them off first .
