Time for Timing Belt ?

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Tex

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I notice that a 12 year old yacht currently for sale had the engine (volvo 50hp) timing belt replaced in 2008.
The engine has (to date) only done 1,100 hours.

At what stage is a replacement timing belt recommended/necessary ?
 
It doesn't really matter whether the engine has done many hours or not, if the recommendation is to replace the belt after a certain time period. Belts deteriorate through age; VP are probably being very cautious in saying 3 years, but it would be sensible to follow their advice.
 
pvb said:
It doesn't really matter whether the engine has done many hours or not, if the recommendation is to replace the belt after a certain time period. Belts deteriorate through age; VP are probably being very cautious in saying 3 years, but it would be sensible to follow their advice.
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I don't quite get that.
So if a dealer keeps a timing belt on the shelf for 3 years it is scrap ?
What's the difference if an engine is not run for 3 years ?
Same difference to me, so why don't timing belts have a 'best before' date ?

Common sense would be number of engine hours or a maximum time limit. I know unused belts that are still good after 10 years, showing no sign of ageing or breakdown. OK after another 3 years of use, it would certainly be time to replace it.

3 years, yes good for Volvo, I suppose they couldn't push for 12 months instead just to be even safer....

If I was buying the yacht and couldn't establish the last time the belt was changed I would change it and then check the new belt every 12 months for cracks and sign of shredding. If it was ok, I would replace after 5 years regardless.
 
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If its any consolation to those with cam belts overdue for a change I last changed the belt in my Volvo car in 1997. :eek:

This thread has reminded me that's its time to change it again
 
claudio said:
Common sense would be number of engine hours or a maximum time limit. I know unused belts that are still good after 10 years, showing no sign of ageing or breakdown. OK after another 3 years of use, it would certainly be time to replace it.

3 years, yes good for Volvo, I suppose they couldn't push for 12 months instead just to be even safer....
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OK, your boat, your choice. Lots of people put off replacing cambelts on their cars. Most of them get away with it without their engines disintegrating; some don't. It's the same with saildrive diaphragms, etc.
 
Tex said:
I notice that a 12 year old yacht currently for sale had the engine (volvo 50hp) timing belt replaced in 2008.
The engine has (to date) only done 1,100 hours.

At what stage is a replacement timing belt recommended/necessary ?
Click to expand...
The MD22 VP engine is what i presume you are talking about. I read in theoriginal VP manual that the belt should be inspected yearly and changed if necessary. This particular engine is the perkins engine which was fitted in maestros and montegos and leyland daf vans. they were are bulletproof. The landrover boys fitted them as an upgrade, more power and improved fuel economy over the lr diesel. I read on one of their forums that the belt, with it being 35 mm wide was almost unbreakable. i changed mine a few years ago, did an article in PBO on how to change it. its pretty easy to do if you hve a modicum of spanner sense.
stu
 
VicS said:
If its any consolation to those with cam belts overdue for a change I last changed the belt in my Volvo car in 1997. :eek:

This thread has reminded me that's its time to change it again
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Wise decision me thinks, not a pretty sight should it disintegrate and damned expensive as well!!
 
claudio said:
I don't quite get that.
So if a dealer keeps a timing belt on the shelf for 3 years it is scrap ?
What's the difference if an engine is not run for 3 years ?
Same difference to me, so why don't timing belts have a 'best before' date ?

Common sense would be number of engine hours or a maximum time limit. I know unused belts that are still good after 10 years, showing no sign of ageing or breakdown. OK after another 3 years of use, it would certainly be time to replace it.

3 years, yes good for Volvo, I suppose they couldn't push for 12 months instead just to be even safer....

If I was buying the yacht and couldn't establish the last time the belt was changed I would change it and then check the new belt every 12 months for cracks and sign of shredding. If it was ok, I would replace after 5 years regardless.
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I think the difference is that a belt, in its original packaging, on a shelf in a warehouse, won't have gone through the same number of heat/cool cycles as one on an engine and is unlikely to have been in a location where oil mist could be present. This obviously applies more to cars than boats, as underbonnet temperatures are generally higher, but other elastomeric components (like tyres) do definitely deteriorate with time as well as use. I can only assume that (again, coming from a car background) there is sufficient throughput of belts in your average dealership to ensure that they're not sat on the shelf for several years. It would be poor stock control for a start!
 
I'm not so sure that under bonnet temperatures are necessarily greater than thos in an engine room. Automotive designs should include getting the airflow from the vehicle's motion and the fan to help cool everything - I could name some notable exceptions where this was ignored. In a boat's engine installation there is little or no airflow, so the ambient temperature is a concern.

Rob.
 
TQA said:
If in any doubt at all CHANGE THE BELT.

WHY

Well if it breaks with the engine running at cruising revs you are almost certainly looking at a new cylinder head and at least 2 new pistons. However it is not at all unusual for an engine to be beyond economic repair after a belt failure.
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I'm not sure what tolerances half the marine diesels have.... Years ago I had a
:rolleyes: cough cough... Cavalier SRI,.....
That snapped a couple of belts, but the head design was probably so old, no piston to valve collision problems....
Just fitnew belt, time it up, and off you went...
 
Robg71 said:
I'm not sure what tolerances half the marine diesels have.... Years ago I had a
:rolleyes: cough cough... Cavalier SRI,.....
That snapped a couple of belts, but the head design was probably so old, no piston to valve collision problems....
Just fitnew belt, time it up, and off you went...
Click to expand...

The pistons may not hit the valves in a petrol engine but they will in a diesel engine!
 
VicS said:
If its any consolation to those with cam belts overdue for a change I last changed the belt in my Volvo car in 1997. :eek:

This thread has reminded me that's its time to change it again
Click to expand...
If the car is worth less than the cost of changing the cambelt fine, but I have (also Volvo) had one go on a belt WITHIN the recommended change interval. Car then scrap, sold on Ebay for parts.
 
Niander said:
They also will in a petrol engine..but not a side valve,
one thing i don't have to worry about then!
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Not always - I can confirm what Robg71 said about no damage in an OHC Cavalier (ca 1990) as an example. Definitely not sidevalve!

I now have a diesel Golf, nearly 8 years old but under 60k miles and I only do about 5k miles a year now. Getting the belt and water pump and idler changed as recommended (80k miles or 6 years officially I think) would cost a good 10% of the value of the car. What's the risk worth? Difficult balance!
 
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Troubadour said:
Not always - I can confirm what Robg71 said about no damage in an OHC Cavalier (ca 1990) as an example. Definitely not sidevalve!

I now have a diesel Golf, nearly 8 years old but under 60k miles and I only do about 5k miles a year now. Getting the belt and water pump and idler changed as recommended (80k miles or 6 years officially I think) would cost a good 10% of the value of the car. What's the risk worth? Difficult balance!
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Its not only the cost verses the value of the car that you have to consider it's the inconvenience, and possible costs, that you will suffer if it fails on a long perhaps important or urgent journey, many miles from home, during the night or in foul weather or on the way to an airport to catch a flight.
 
rob2 said:
I'm not so sure that under bonnet temperatures are necessarily greater than thos in an engine room. Automotive designs should include getting the airflow from the vehicle's motion and the fan to help cool everything - I could name some notable exceptions where this was ignored. In a boat's engine installation there is little or no airflow, so the ambient temperature is a concern.

Rob.
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Even on a modern diesel car, the underbonnet temperature can get close to boiling - especially if you've just been tanking down the motorway on a hot sunny day and all the traffic comes to a sudden stop just as your particulate filter is trying to regenerate itself! The other problem is "heat soak" when you've just done a run and then park up with the sun on the bonnet.
 
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