worn engine ?

[gatewright]

Hello, can anyone advise why my otherwise well performing 35000 mile engine (1600) seems to have a lot of back pressure , if you take the dipstick out whilst engine is running you can easily see splashes of oil coming out and puffs of fumes. it is a bit over filled with oil at moment would this make difference or do you think it is worn.
Alan

[rossocorsa]

Be surprised if there is wear. Could be the breather for the enclosed crankcase ventilation is blocked, do the revs increase significantly if you take off the oil cap? if it does i would suspect either a blocked breather (not uncommon if it has been stood around and had very infrequent oil changes in the past) or possibly a broken piston ring but with that it probably wouldn't idle, wear on a twin cam is very unlikely at that mileage they were extremely well made and well able to withstand even Italian driving. The breather is at the front of the car you should be able to trace the breather pipe from the air cleaner back to it, unfortunately not very easy to access when everything is assembled though!

[gatewright]

I took the large pipe off the air cleaner while engine was running and you could see the fumes coming from it so i pressume breather not blocked, but small pipe from air cleaner to carb was disconnected at carb so re attached and engine seems to run slightley better, i suppose there would always be some back pressure so perhaps mine is not excessive, funnily on tickover when you remove dipstick you can see some oil escaping but when you rev engine no oil escapes its as if back pressure reduces, im confused.
but engine runs really well so maybe its normal and im worrying too much.

[rossocorsa]

Possibly you are, could be worth cleaning the crankcase ventilation anyway as it costs nothing except time to do it

[lukasdeopalenica]

Do you also observe a drop of power? Maybe some of piston rings are just blocked. The best suggestion is to measure the engine compression pressure, then you can pour a bit of engine oil into each cylinder, let it soak the rings then measure again and compare the results. If the oil improves the compression significantly the problem may be of bigger sort...

[gatewright]

thanks for knowledgeable replies, i will try your suggestions,
Alan.