Sticking valves

[Adrian Payne]

I have noticed there have been a few posts lately mentioning sticking valves and even a suggestion that some oils may contribute to this problem.
What are the factors that lead to sticking valves? and how to cure them?
Adrian.

[Tony Betts]

Hi adrian,

The first time had a valve sticking on the supersport was 15 years ago. Again at the scottish rally.

We got around ok. But the car wasnt happy at lower revs.

When I stripped it down, number 8 valve was burning out and not sealing the valve.

I thought little of it, at number 8 is the valve that usually sticks first. As the rear of the engine is the hottest place.

I wasnt happy with the sloppy pistons then, but I had only had the car 12 months. And didnt want to be in for a rebuild. Also I couldn't afford to loose the time.

This time the car felt different. But when stripped down, you could see the soot was spreading over half way down the valve. Making it sticky, on all 4 exhaust valves. This can only be down to to much oil, and to much petrol.

Stripping the engine, showed all the other problems that added to the job needing doing.

Tony.

[Adrian Payne]

I guess the answer is - stop going to Scotland? Perhaps the Scottish brew is too strong for our English cars!
Adrian.

[Tony Betts]

Hi adrian,

I see the joke.

But I think it's more that I need to do less on austin 7 parts for others. And take more time to do upkeep on my csrs.

Tony.

[Malcolm Parker]

I've run various Austin 7's for almost 50 years and have never had a sticking valve.   I have always used cheap oil, changing it every 1000 miles or so.    Most of my engines have run on SU carbs and I think having a correct mixture must help.

[Dave Mann]

I've experienced sticking valves twice, number 8, the first time after I ran out of Duckhams Q20/50, a detergent oil, and used Castrol classic 20/50, a non detergent oil, within 50 miles of the oil change. So I removed and cleaned the valve and guide and changed the oil to Unipart 20/50, another detergent oil, with no more bother till Unipart 20/50 was no longer available and number 8 stuck again when I used a non detergent oil. I changed the oil to Halfords classic 20/50, a detergent oil, didn't touch the valve and within a mile the valve freed up.

[Ivor Hawkins]

I’ve stripped my motor three times in the past two weeks due to sticking valves and all were covered in a really gummy brown deposit under the valve heads but the stems were clean.

I’ve nor reamed the lot and after initial start up and a re start everything seams okay, but I think I’ll change to Halfords Classic 20/50 before taking it on a long run.

[Steve kay]

And talking of oil, this is what one of the sponsors recommended fifty years ago. No I can't get the damn thing to go back to portrait format, can we have detailed instructions please. 

   

[Charles Levien]

Don’t worry too much about that as a tap on the screen puts the image right way up.

[Steve kay]

Charles, so it does!