The Marston Sunbeam Club & Register Forum

General Category => Technical Discussion Forum => Topic started by: oggers on October 31, 2022, 03:30:58 PM

Title: Decompressor/exhaust valve lifter
Post by: oggers on October 31, 2022, 03:30:58 PM
Gents

Dumb question perhaps so apologies. I removed the cable at the lever end of the decompression/exhaust valve lifter, but the lever now refuses to return to the correct position of arond 6 o clock. It remains at around 3 o clock - horizontal. It now does not want to go past 3 o'clock depsite me turning the engine I did not pull the lever off, though I did rotate the shaft and lever in order to pull the cable off.

How do I return the lever to its correct downwards/6 o'clock position please.
Title: Re: Decompressor/exhaust valve lifter
Post by: Thomas on October 31, 2022, 04:07:40 PM
Machine and year?
Title: Re: Decompressor/exhaust valve lifter
Post by: oggers on October 31, 2022, 05:21:15 PM
Model 9 1931
Title: Re: Decompressor/exhaust valve lifter
Post by: singleminded on October 31, 2022, 10:20:12 PM
I'm guessing that the inside part of the decompressor lever has gone vertical and won't go back under the valve lifter. You could try getting the valve fully open to see if it will rotate back to where it should be or try removing the outside arm by undoing the nut and then see if the shaft will rotate anti clockwise till it is back under the valve lifter and refit the  external arm..You can see the arm in the picture.
Title: Re: Decompressor/exhaust valve lifter
Post by: oggers on November 01, 2022, 09:31:15 AM
Yes, it does seem as if lever has gone vertical and won't return under the lip or ear of the exhaust cam - I think that is how it works. I have indeed tried rotating the engine - and thus the exhaust valve as you say - no joy. The next move may well be to remove the arm and rotate the shaft of the valve lifer, but that arm is very firm on the shaft! 

Title: Re: Decompressor/exhaust valve lifter
Post by: singleminded on November 01, 2022, 05:06:54 PM
Just slacken the nut a turn or so and tap theend of the shaft is should release it, try not to damage the thread though.