8 replies to this topic

[Tinkerbelle]

Hello,

Got around to starting removing my engine today to diagnose a smoking problem.

When I took the inlet manifold off there was a pool of oil at the bottom. I took lots of photos but just lost them when my pc just died (harddrive failure) - great!

The oil was also in the inlet ports. No.3 and 4 piston crowns and combution chamber in head are very dirty and carbonised ( if thats a real word?). Engine had not been run for a week before dismantling.

Photos would have been handy!

My thoughts:
1, valve seals gone- nearly new and intact.
2, carbs leaking oil -nearly new and full of oil still, are they known to leak?
3, oil from pushrod tubes beng broken into when head flowed - maybe but its not obvious.
4, another oil leak, such as a perforation affecting inlets only.

I will get the head pressure tested to check 3 and 4. Has anyone anymore ideas extra to the above.

Thanks

Matt

[bmcecosse]

Some oil can get drawn down the valve guides (so fit new ones!) - but mostly your problem will be rings/pistons/bores - all worn !

[Tinkerbelle]

I'm not positive but I don't think it is the valve guides as these were replaced about 500 miles ago when engne was rebuilt.

Worn bores is a likely culprit as when I rebuilt it about 500 miles ago I honed and put in new rings as did not have the money to rebore and new pistons.

Could that much oil get into the inlet tract from worn bores? It is a sizeable amount say 10ccs+ in each of the manifold ports?

Matt

Edited by Tinkerbelle, 25 March 2011 - 11:53 PM.

[Tinkerbelle]

Anyone else got any ideas?

[johnatandy]

Do you have any of the oil mist traps connected to the carb, or from the rocker cover.

Had a mini once which was doing the same thing and it was pulling oil through the oil traps into the carbs and engine.

Just a thought.

John

[Tinkerbelle]

Good idea but no, they both (clutch and timing cover) vent to air through breathers.

[bmcecosse]

You should vent the breather through the carb - to minimise crankcase pressure. Oil can really only get in the inlet tracts from the guides...... But your 'smoke' problem could very possibly be eased by drawing the fumes away into the carb.

[cooperrodeo]

You will always find 'oil' in the inlet manifold. It comes from the additives put in petrol. If you have smoke and the oil is not coming from the breather then it sounds like valve guides or rings.

[Tinkerbelle]

Thanks for the help. The head and block are with Rob Walker Engneering now to check and sort out.

Thanks Rob for comng in on saturday and showing me around your latest 'projects'.

Matt