Volvo B5TL engine low compression issues

[Brio17]

We have a few B5TLs with low engine compression on 2 to 3 cylinders. They are 16 reg and have done about 100k on the clock. This is a known fault with the engines. I have heard that many operators in the UK have got into trouble when they had to scrap the engine and get a new one.

 

[randyrippley]

What's the actual cause? Surely it's fixable?

 

[Trnsprt4Sctlnd]

What's the actual cause? Surely it's fixable?

I would guess that these engines would’ve went through fairly extensive testing before they would’ve been used in any heavy vehicle.

 

[PG]

I have heard that many operators in the UK have got into trouble when they had to scrap the engine and get a new one.

Who got them into trouble? Or am I taking you too literally?

Edit: BTW welcome to the forum

 

[dodecahedron67]

Coastliner have had continuous problems with the engines being underpowered

 

[computerSaysNo]

Coastliner have had continuous problems with the engines being underpowered

I wouldn't say that was a "problem" as such: the engine is/was advertised as being a (roughly) 5 litre engine with x amount of power, and the weight of the body is also known, so it's not like operators didn't know what they were buying. Other, higher-powered double deck vehicles are available such as the Streetdeck when specified with the 7.7L engine, the integral E400MMC with its 7.7L (from memory; couldn't quickly find a reference to confirm) engine or the Scania/ADL E400MMC which has a 9L (again from memory) engine.

However if the engine is routinely being worked at the top end of its power rating and/or isn't being properly maintained as per manufacturer instructions, then this may obviously impact it's reliability.
I'm sure if there were any major reliability issues that Volvo would design and offer to retrofit a fix.

 

[Trnsprt4Sctlnd]

I wouldn't say that was a "problem" as such: the engine is/was advertised as being a (roughly) 5 litre engine with x amount of power, and the weight of the body is also known, so it's not like operators didn't know what they were buying. Other, higher-powered double deck vehicles are available such as the Streetdeck when specified with the 7.7L engine, the integral E400MMC with its 7.7L (from memory; couldn't quickly find a reference to confirm) engine or the Scania/ADL E400MMC which has a 9L (again from memory) engine.

However if the engine is routinely being worked at the top end of its power rating and/or isn't being properly maintained as per manufacturer instructions, then this may obviously impact it's reliability.
I'm sure if there were any major reliability issues that Volvo would design and offer to retrofit a fix.

Lothian Buses of Edinburgh had B5TLs from new way back back in 2014, they then took delivery of another batch on 17 plates then more again on 21 plates.

I can only assume there isn't any major ongoing or unfixable problems with the engine.

 

[dodecahedron67]

I wouldn't say that was a "problem" as such: the engine is/was advertised as being a (roughly) 5 litre engine with x amount of power, and the weight of the body is also known, so it's not like operators didn't know what they were buying. Other, higher-powered double deck vehicles are available such as the Streetdeck when specified with the 7.7L engine, the integral E400MMC with its 7.7L (from memory; couldn't quickly find a reference to confirm) engine or the Scania/ADL E400MMC which has a 9L (again from memory) engine.

However if the engine is routinely being worked at the top end of its power rating and/or isn't being properly maintained as per manufacturer instructions, then this may obviously impact it's reliability.
I'm sure if there were any major reliability issues that Volvo would design and offer to retrofit a fix.

Sorry, I maybe should've said Coastliner have had continuous problems due to the engines being underpowered (and thus the buses not actually suitable for the routes)

I hope that explains it a bit better?

 

[richw]

Lothian Buses of Edinburgh had B5TLs from new way back back in 2014, they then took delivery of another batch on 17 plates then more again on 21 plates.

I can only assume there isn't any major ongoing or unfixable problems with the engine.

They are a good and efficient engine in the right environment. They are suited to low speed city work where there is limited hills.
They are not suitable to high speed intercity running in hilly terrain

 

[Trnsprt4Sctlnd]

They are a good and efficient engine in the right environment. They are suited to low speed city work where there is limited hills.
They are not suitable to high speed intercity running in hilly terrain

Despite the likes of Volvo, Daimler & Cummins offering relatively small 4-cylinder units, particularly when they're tuned with high horsepower outputs relative to their size, you most likely would run into durability issues if used in particularly challenging scenarios where the engines are continually stressed.

With a Volvo D5K engine with 240hp versus the D8K which can be had with 280hp, only 40hp more, it’s likely the smaller unit has to work a little harder overall to achieve its output.

Where diesel vehicles are concerned at sustained higher speeds or where the route has continual hill climbs it should be preferable that you choose a vehicle with a larger unit with more torque, such as a Scania N250/280UD chassis with the 9ltr 5-cylinder unit. Scania purposely fit these with longer 5.13 rear differentials for sustained higher speed routes; this approach keeps engine rpm around 1500rpm@90kph(56mph).

The Volvo B5TL & B8L tri-axle are fitted a standard with a 6.20 rear differential, meaning you’d be at around 2000rpm at only 80kph(50mph) on high speed work.

For comparison's sake, an ADL Enviro 400MMC is generally fitted as standard with a 5.74 rear differential and Voith gearbox, another configuration that isn’t particularly suitable for high speed or work where there is continued stress on the engine. Even at 50mph you're still talking 1800rpm at a cruise; with a ZF Ecolife it would drop to around 1550rpm.

 

[Brio17]

Who got them into trouble? Or am I taking you too literally?

Edit: BTW welcome to the forum

It all started with one bus having low compression on 1 cylinder. After a couple of weeks it was a non start (engine wouldn't fire and low oil pressure). When we checked the compression it showed 3 cylinders with less than 50%. When we pulled down the sump, the bearing were scoured.
This soon followed with another 3 buses with the same issue ( excessive smoke and no power). Done the oil analysis and it was good.

Volvo reckons the engines have no known issues but won't comment as to why the bearings were scoured nor why the issue of low Compression.