valve stem oil seals

[david lewis]

hi all,

i have a 1969 13/60 fitted with a mk 3 spitfire head with double valve springs.

the engine is giving puffs of blue smoke after idling for a bit or after the overun so i believe the inlet  valve stems are the culprit so i would like to fit seals but according to canleys web site they cannot be fitted to double valve spring guides.

has anyone got a solution to this problem apart from fitting new guides.

cheers

[JohnD]

There are other possibilities to cause 'puffs of blue smoke'.

In any case, it's probably due to the high vacuum in the inlet ducts while idling, as the throttles will be closed.   This will draw more gas from the crankcase, which is, of course, loaded with oil vapour and droplets, which will be burnt as the throttle opens.  Check that your crankcase vent, usually from the rocker cover, is not partly blocked by deposits as some covers have a partly open metal box welded inside the vent that was filled originally with wire wool as a crude filter.  The wool can now be corroded and/or filled with carbon from burnt oil.    It could also be due to excessive blow-by due to leaky piston rings.   A compression test is indicated, and do not omit the 'teaspoon test', a teaspoonful of oil into the spark plug hole after doing the standard test, to exclude ring problems and reveal valve leak.

 

For so much oil to get into the chambers via the valve guides that blue smoke ensues, the guides must be severely worn.   To check for wear, dismantle the head and 'wiggle' the valve stem in the guide.  ANY side movement indicates excessive wear.  No movement, that the guide is tight enough!

 

Hope that helps,

John

[Pete Lewis]

And if it has the dreaded external rocker feed .....take it off

 

pete

[Clive]

You can just throw away teh inner springs, you won't notice any difference....

[david lewis]

thanks for your replies--just a thought i know i overfilled with a bit too much oil would this cause the smoke?

cheers

[JohnD]

Damn right it would!

And you ask us about valve stem seals.

 

John.

[Pete Lewis]

and another thing I have come across is wrong dipsticks 

 

always worth on an oil change to add 3 pints   check the stick for a low marking  then add the last 1.5 pts and check its up to the full mark 

   we had one that allowed 2 pnt overfill

 

  juats a check you can do when ever 

 

Pete

[david lewis]

when i mentioned my overfilling i am talking about a 1/4 inch above the full mark - is that enough to cause problems,

do i have to go on the naughty step for talking about valvestem oil seals ?

cheers

[dougbgt6]

I clumsily overfilled to that much once in the past, didn't seem to have any consequences. But as Pete says if you've got the wrong dip stick..................

[Pete Lewis]

dont think 1/4" will upset any of us  ...............

 

but if you can drop some out and see if the problem improves wont hurt to try

 

as for the naughty step there's a few Tee shirts around for that prized position !!!!

 

are you sure  the blue is not from overfilled carb dampers , this spills into the manifold and gets sucked in on shutting the throttles , open her up and Puffff!

a shot of blue appears 

just a thought ... love the cheap idea's first

 

          Pete

 

 

Pete