sticky engine valve

[jonhall88]

Ser 3 v12 E type
Have had a niggling problem for a while which seemed to go away but now back. I have a miss on one cylinder. Fitted new plugs and leads along with dizzy cap and checked for a good spark on all 12 cylinders which there was. No fuel starvation to any cylinder. No real signs of blue smoke but a little on startup so I am thinking about a sticky valve. regulary serviced with new oil and filter but have been using supermarket fuel and am thinking maybe better not being a cheapskate and put in premium fuel. Is there any way to clean the valves without all the aggro of removing the heads ie spray cleaner into to intakes or even get the engine internals cleaned with one of these new fangled injector machines. do they work
any advice more than gratefully recieved
ta
jon

[abowie]

What do you mean by sticky valve?

[jonhall88]

going down the road you get a misfire from one cylinder as all the fuel system and electrics are ok i suspect an exhaust valve is not opening or closing as it should hopefully caused by carbon build up and nothing more serious. Car runs fine but holds back a little when accelerating more annoying than anything else. thinking about it I have a compression tester which is probably the next step
jon

[abowie]

thinking about it I have a compression tester which is probably the next step
jon

Good idea. Get back to us with results.

Cheers.

[christopher storey]

Sticking valve is not the first thing I would think of, because it usually produces symptoms of banging in the exhaust etc, or backfiring through the carbs . A burnt valve is a more likely candidate, which a compression test will reveal . If you suspect gumming, then redex in the petrol, and trickling redex into each carb whilst the engine is idling, is a good tactic . Another thing you can try is running the engine in the dark and looking for blue halo/tracking effects on dist cap and leads and plugs . Even with new equipment there can be faults . Look for the simple things first .

[PeterCrespin]

Congrats on noticing something wrong. A V12 running on 11 is very easy to ‘miss’. Even running on ten is not that obvious.

Doing a compression test on a Series 3 is not trivial, and at best will only give you an indication of a problem rather than pin point its cause. For the same amount of work a leakdown test will diagnose the problem more precisely. Since these testers are not normally in constant use, a friendly local garage may loan you one?

[jonhall88]

Thank you for the invaluable advice. Will let you know how I get on
jon