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[Vauxhalloofer]

Hi All in the process of sorting out cylinder head and have loads of oil in the inlet manifold, someone i know said that it could be bottom end pistons pushing up oil, then someone else said its probably valve stem seals.It smokes only at startup not during high revs but has been using loads of oil.With the head out is there a way of testing valve stem seals say filling them up with oil and testing pistons say with fluid.The bores look clean what should i look for.Taking them out not so practical lol.Many Thanks

[omega3000]

Id put money on stem seals 

[Webby the Bear]

Tip head upside down. Fill each chamber with oil. Mine held oil overnight.... if yours don't you have a leak thats stem seals.

You can also remove a couple of valves and look at how much lateral movement you have with one popped halfway back in to the guide.... excessive lateral movement... guides should be replaced also.

[Marks DTM Calib]

Tip head upside down. Fill each chamber with oil. Mine held oil overnight.... if yours don't you have a leak thats stem seals.

Come on then Webby....explain how that one works 

[henryd]

Tip head upside down. Fill each chamber with oil. Mine held oil overnight.... if yours don't you have a leak thats stem seals.

Come on then Webby....explain how that one works 

Lol

[Webby the Bear]

Lol, here we go 

If your stem seals have gone that means they're able to leak oil in tut combustion chamber... agreed?

By turning heads upside down and leaving the combustion chambers filled with oil, if the oil escapes over a period of time then they're nackered surely?

Did this at school on tutors advice.

One awaits post putting me straight 

[Webby the Bear]

ps...fit old spark plugs so it don't leak through there

[Webby the Bear]

sorry I made boo boo. leaking valves I meant 

[Marks DTM Calib]

So a few issues.

1) If the stem seals are leaking then it allows oil into the inlet or exhaust track, not the combustion chamber

2) The test you describe checks how well the valves are sealed against the seats......except it doesn't!. Because you are using a thick liquid such as oil it wont search out the leaks, you need something thin and searching e.g. brake fluid or similar(not water though as it has a 'skin')

Stem seal diagnosis is very much about observation of the exhaust during certain conditions. Mainly looking for short periods of blue smoke following either periods of rest (engine not running)during starting/initial running or during extended periods with the thottle closed (e.g. following idling or periods of coasting) where the inlet vaccum is high and oil can be pulled through the guide.

Only other way to determine it is via direct examination of the seals (at which point you might as well replace them anyway). 

So in this case, given the symptoms described, I would be looking at stem seal replacement

[Webby the Bear]

Yeah, sorry meant valve sealing test. Been a long day already. I'll note what you say about the fluid.

Re the leaking seals...if the oil gets in the inlet then it'll end up being combusted, no? Hence the blue smoke?

[aaronjb]

Yeah, sorry meant valve sealing test. Been a long day already. I'll note what you say about the fluid.

Re the leaking seals...if the oil gets in the inlet then it'll end up being combusted, no? Hence the blue smoke?

Yes - but you can have a perfectly sealing valve in the valve seat (your test) that smokes when cold because of knackered stem seals..

The stem seals let oil leak down the valve stem which then pools on the back of the valve and intake (or exhaust) runner - in the case of an intake valve this won't actually burn until the valve opens as normal.  So it's not the oil leaking past the stem seal into the chamber via the valve, it's oil leaking past the stem seal onto the valve which then gets sucked into the chamber (or onto the CAT in the case of an exhaust valve .. but IIRC it's usually intake seals that will leak due to vacuum in the intake runners as Mark mentioned).

If that makes sense?

[henryd]

Yeah, sorry meant valve sealing test. Been a long day already. I'll note what you say about the fluid.

Re the leaking seals...if the oil gets in the inlet then it'll end up being combusted, no? Hence the blue smoke?

Yes ,generally a puff of blue smoke on start up and increased oil consumption

[omega3000]

Take inlet off , thick with oil ? Then money on valve stems 

[martin42]

Or the seals are not fitted correctly and are moving up and down on the valve stem,like emd's was .

[Vauxhalloofer]

hi people, so went about cleaning up the head, took out valves the stem seals were so shot they were almost falling off!.Looks by the burn patterns and heavy oil it was worst on the exhaust size, seats look clean.Any tips for getting collets back in and also what needs oil on rebuilding it.Thanks