Thorneycroft T80

[moodycruiser]

Ihave a T80, (which is really a BMC) and when it idles it emits gert big clouds of blue smoke - this disapears as soon as it is under load. Now, I would have thought that the immediate reaction would be "rings", but it starts at the first turn of the key. Anyone know if it could be anything else, like fuel pump setting, or somesuch, please?

<hr width=100% size=1>Tony

 

[alb40]

I have a 1.5 bmc. even though it has been fully reconditioned incl new injectors, pump etc it smoke at idle but not under load. Most ive seen do the same so guess its just a characteristic of the engine.

However, a good thrashing occasionally does help keep the amount of smoke low so you could try giving it at least half an hour of full throttle to try and clear it. Diesels like to run under load so it always does them good to be stretched occasionally.

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[moodycruiser]

Yep, I also think that I may have been under a misapprehension, thinking that it was only under load - I started her y/day and ran the revs up to 1500 in neutral and it practically disappeared, but it is REALLY smokey at idle, embarrassingly so.
A local spannerman seems to think that there is some sort of idle adjustment (it apparently looks like a bleed nipple, but isn't) and he is going to find out more. Will let you know if I hear anymore.
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<hr width=100% size=1>Tony

 

[brianhumber]

Blue smoke is oil. Oil gets into the combustion space by not being scraped off the cylinders walls ( worn rings, oval cylinder, polished bores) or being sucked down past the valve guides ( worn clearances ) or high crankcase pressure leading to the breather pipe puffing oil droplets into the air inlet manifold. Adjusting the idle speed will alter the partial vaccum in the inlet manifold but its fiddling with symptoms not giving you a cure. These engine are very basic and will run even when in very worn state. They usually failed when thay spewed out so much oil from crankshaft seals/burning that they ran out of oil and seized, but these days its not very PC to have a smoky joe engine.

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