Joined: Aug 2017 Posts: 138 Threads: 28
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Location: New Forest
Car type: 27 Chummy
Hello All
In the post "Books and lubricants" Dave Mann mentions an oil causing the exhaust valves to stick.
Is this a common problem and what is the cure?
I think I have an engine that exhibits the signs, a regular misfire after a short run even after changing the entire fuel and ignition system.
Many thanks
Adrian.
Joined: Aug 2017 Posts: 1,666 Threads: 46
Reputation:
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Location: Auckland NZ
Car type: 36 Nippy, 31 RM, 38 Special, 24 Works Rep
Use your car more! Sorry if that sounds a bit flippant but the valve stems are lubricated by oil mist alone, if you only use your car occasionally and on short runs very little oil will make it to the valve stems. I guess some oils will have better clinging properties so will be less inclined to drain away between use than others, but the more use a car gets the better it runs in my experience.
Black Art Enthusiast
Joined: Oct 2017 Posts: 1,390 Threads: 44
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It's happened on two Sevens when using a straight non detergent oil, on the first I removed the valve and cleaned it and the guide of carbon and changed to a detergent oil. On the second I just changed the oil. Do I assume using the car daily isn't frequently enough? Both engines had less than 5000 miles after rebuild which included new valves and guides.
Joined: Mar 2015 Posts: 5,186 Threads: 223
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Location: Scotchland
We suffered a sticking valve issue in my father's car whilst touring the north west coast a few years back - on stripping there was a quantity of sticking tar-like substance, we wondered at the time if it was the new fuel mixtures?
After cleaning and reassembly it hasn't reoccured and we are really none the wiser as to the exact cause...
Joined: Aug 2017 Posts: 138 Threads: 28
Reputation:
2
Location: New Forest
Car type: 27 Chummy
Hello Ruairidh
We could only put the sticking valve down to using a different ethanol treatment as the same engine had done many thousand miles without any trouble. Maybe a dodgy fuel mix could have been to blame.
I hate not being able to positively identify a resolution.
Adrian.
Joined: Mar 2015 Posts: 5,186 Threads: 223
Reputation:
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Location: Scotchland
His engine has not suffered the same symptoms before or since, like you say, annoying not to pinpoint why.
Joined: Aug 2017 Posts: 1,808 Threads: 99
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Hi Ian,
I beleive you are right, as we know any car apreciates regular use.
Sadly today, modern life makes us to busy to give old cars regular use.
I had a sticky valve on the supersports when I first had it, again it had been in minimal use.
When I stripped it down, it was number 8 valve. The hot end of the engine. So for me no need to analyse it to much. Just put it down to querky old cars and owners.
I replaced all 8 valves and guides, and used it again.
Tony.
