Smoke Problem

[110v8]

after going down a long hill on overun, feet off, and i start to push the go pedal when on the level i get clouds of smoke for 2-3 minutes normal running then i stops. i also have a good deal of smoke when i accelerate hard in second. the engine is a 3.5v8 running on gas, anybody know if fatal thanks

bob

[Wally]

It sound like your engine is worn, especially if the smoke has a blue tint to it. When you run it for some time under "high" vacuum in the inlet manifold /combustion chamber such as when you go down hill with your foot off the accelerator you tend to suck in oil through the inlet valve stem seals. That is if they are worn. Once you put your foot on the accelerator the vacuum dissapear and the combustion temp goes up, thus burning off the lub oil accumelated in the chamber. When you accelerate hard the oil rings on the pistons do not seal that well and the oil which stay behind on the cylinder walls then gets burned off or gets blown into the inlet manifold through the vent pipes.

Check the following:

- See if your inlet manifold is covered in oil on the inside - if yes problems

- Does your oil level in the sump decrese fast - if yes problems

- Does the oil in the sump smell like petrol on the dipstick - if yes problems

- How old / used is the engine - if milage is high problems

By looking at these you might be able to see if you need to overhaul the engine.

[110v8]

thanks for the reply and very helpfull ,,and depressing it was lol. i have a pair of fairly good efi heads waiting to go on with new guides and seals which i hope will solve the vacuum problem, as to the rings i can do that at the same time. but . i have had the heads off in the past and cannot see any marks on top to indicate size ie +10-+20 only thing i can see is what looks like an mod arrow on top, is the oversize marking supposed to be easy to see? as i am running almost permanently on gas would it be worth fitting some 10,5 pistons i happan to have stashed away as i understand that gas overcomes the pinking problem with high compression pistons.

[110CSWDEFENDER]

Hi.

If the engine is left to stand for several hours, does it produce a lot of smoke on starting ?.

If so this suggests that the oil is getting into the cylinders past the valve oil seals rather than the pistons.

Oil will creep past the oil seals due to gravity while the engine is standing, but not past the piston rings.

Don