[grease line]

Went for a drive up a long hill today...as I came back down in first gear, using the engine as a brake, I noticed I was blowing some lighter colored smoke...not black.

went away as soon as I accelerated...it just occured when I was not touching the pedal, crawling downhill. The engine was very cool...head was barely warm to the touch.

It is the 2.4 turbo diesel in a first gen surf, 160 k.

Is this normal? Sign that something is worn?

Cheers

 

[steve604]

that is usually a sign of leaking valve seals. rolling down a hill in high rpm's causes alot of vacuum which sucks the oil out of the top end into the combustion chambers.

the lighter coloured smoke could be oil smoke from this happening.

i used to get this on a gas engine with leaky fuel injectors. the fuel got into the gas and thinned it out so it would easily run past the valves under high vacuum.

 

[grease line]

It was actually pretty low rpms...mostly 1500, max 2000, but I was in first gear low...what you said makes sense.

Is this bad for the engine if I do it occasionally? Or is it something I should try to avoid?

 

[steve604]

nothing wrong with doing it. just keep in mind that you are consuming oil doing this so make sure to check the oil regularly during long trips. you could try running thicker oil.

if what i said is actually what is happening then this means you are losing some compression through your valve seals under normal driving too.

 

[grease line]

Thanks for the responses.

I just put on 31 inch tires, had 245 75 r15s before...I wonder if this made a difference, as I've never noticed this problem before?