smoke from exhaust

[andy007]

Hi,
I have an old 1975 ford V6 engine in my car, i have had the valve seats hardened about 8 years ago and now on tickover and pulling away from rest i get a little smoke from exhaust, it doesn't smoke when i drive along, any ideas ?

 

[claymore]

Sounds like valve stem oil seals, There is an oil additive you can add to soften up the seals, that might work temporeraly

 

[wizzer]

Wot the compression like? Are you losing power?

 

[andy007]

Hi there is no loss of power, it feels fine. No smoke when i am going along. I just noticed a minute ago something else, i could smell petrol, so i took the air filter off and looked into the webber carb, i noticed the chambers were full of fuel and some was still coming out of the little pipes, the engine was off.

 

[HDi fun]

That could be down to evaporation with an engine that's been turned off and still warm.

Valve stem oil seals seems to be a likely candidate for the smoking. In 1975 this was ignored because all cars smoked a bit anyway. It does at least mean that the oil is getting round the engine so a little bit of smoke is quite admissible.

You could try using a thinner oil (yes, thinner!) as it may well follow the designated oil flow path without needing to seek other routes back into the sump. Thick oil is not the cure all option - it can create too much crankcase pressure which forces it past the guides, rings etc.

 

[obi_waynne]

Is the fuel tank under pressure - does it hiss when you open the filler cap? Could be a blocked breather pipe - this is unlikely to have anything to do with the smoking though.

 

[andy007]

Some one has suggested that i run a return fuel pipe from the webber carb back to the tank, this might help, each time i take off the filter off the carb, i see fuel steaming, evaporating ? I assume running a return will save the fuel and stop it sitting on the engine parts ?

 

[obi_waynne]

Not really sure if it is practical to run a return to the tank. There is so little fuel wasted there is unlikely to be a gain. It's probably just one of those things on carb engines you have to live with.

 

[andy007]

The garage is only charging me £40 for the copper and rubber pipe and i can fit it. It might stop a little evaporation ?

 

[obi_waynne]

Thats not too bad then so I suppose it's worth a go.

 

[andy007]

I will let you know what happens, thanks

 

[HDi fun]

Fuel evaporation is unlikely to cause smoking. The '75 V6 is not likely to have a EGR but there could well be a vent to the atmosphere for the crankcase. In the crappy Montego I had nearly 20 years ago this took the form of a breather pipe that joined the air cleaner to the oil filler cap. It had a silly little wire mesh (brillo pad!!) filter. When that got clogged the crankcase pressures went up and forced oil into all sorts of places where it burnt and caused blue smoking when moving off from rest. A quick wash in petrol sorted all manner of problems.

 

[andy007]

Oh, I don't think there is one of them, but might be a similar type of set up, i wonder what it looks like on the ford engine ? I ran the return pipe, can't see smoke so far but it might be because of the damp atmostphere, will let you all know in a few days. Arn't the fuel pipe clips crap, tighten to hard they dreak, to soft they leak !!!! AHHHHHHH

 

[tegimel]

Hi i found carbon deposits all over my bumper when my valve seals needed redoing, worth checking. I noticed a little change around 4-5000 rpm.

 

[andy007]

No carbon deposits are at rear of car any where. I might try one pot of redex in the tank ?

 

[andy007]

I had hardened valve seats put in about 9 years ago, i've ony done about 9000 miles in it since

 

[HDi fun]

Valve seats and valve [stem oil] seals aren't the same things.

 

[tegimel]

Personnally i think its your valve seals. They only way mine where spoted was when i took it to a rolling road day with kernow cruise.

 

[HDi fun]

I agree with Tegimel, but I wouldn't worry about sorting this very minor bit of smoking anyway. Sometimes it can assist in upper cylinder lubrication, something that will be beneficial in an engine that's been converted to run on unleaded fuel.

 

[andy007]

ok, thanks for all your help, i might leave it then.