jenevers Posted September 14, 2020 Report Share Posted September 14, 2020 I've noticed my 4LW doesn't start first time after a dinner break although it's still hot from a morning's cruise. Any suggestions? Link to comment Share on other sites More sharing options...
Tracy D'arth Posted September 14, 2020 Report Share Posted September 14, 2020 Compression falling due to oil thinning when hot? Have another cup of coffee whilst it cools a bit? Link to comment Share on other sites More sharing options...
Rob-M Posted September 14, 2020 Report Share Posted September 14, 2020 Don't stop for lunch ? Link to comment Share on other sites More sharing options...
jonesthenuke Posted September 14, 2020 Report Share Posted September 14, 2020 (edited) How is your oil? No sign of oil thinning due to dilution with diesel? Just thinking about the first comment above. Edited September 14, 2020 by jonesthenuke Typos! Link to comment Share on other sites More sharing options...
dmr Posted September 14, 2020 Report Share Posted September 14, 2020 My vw camper used to do this, I think your petrol is vapourising, or have I got the wrong engine ? .................Dave Link to comment Share on other sites More sharing options...
jenevers Posted September 15, 2020 Author Report Share Posted September 15, 2020 7 hours ago, jonesthenuke said: How is your oil? No sign of oil thinning due to dilution with diesel? Just thinking about the first comment above. The oil's fine. If there was lack of compression due to hot, thin oil, on start up, would the engine stop running? Link to comment Share on other sites More sharing options...
Tony Brooks Posted September 15, 2020 Report Share Posted September 15, 2020 2 hours ago, jenevers said: The oil's fine. If there was lack of compression due to hot, thin oil, on start up, would the engine stop running? Not in the initial stages because the faster the engine runs the more compression leaks it can cope with. Less time for the air to leak out of the cylinder. There is a large speed difference between cranking and idle. Personally I am less convinced by the oil thing but would check the valve clearances as soon as you stopped it in case one is closing up when hot. A wet and dry compression test should give an indication of bore wear. Link to comment Share on other sites More sharing options...
jenevers Posted September 18, 2020 Author Report Share Posted September 18, 2020 On 15/09/2020 at 08:28, Tony Brooks said: Not in the initial stages because the faster the engine runs the more compression leaks it can cope with. Less time for the air to leak out of the cylinder. There is a large speed difference between cranking and idle. Personally I am less convinced by the oil thing but would check the valve clearances as soon as you stopped it in case one is closing up when hot. A wet and dry compression test should give an indication of bore wear. Maybe it’s because I always knock the decompression lever over when I switch off and start up under decompression. Suppose I should start under full compression? Link to comment Share on other sites More sharing options...
David Mack Posted September 18, 2020 Report Share Posted September 18, 2020 16 minutes ago, jenevers said: Maybe it’s because I always knock the decompression lever over when I switch off and start up under decompression. Suppose I should start under full compression? Assuming this is not a hand start, why would you start a warm engine with decompression? Link to comment Share on other sites More sharing options...
Tracy D'arth Posted September 18, 2020 Report Share Posted September 18, 2020 ER, that will be why. Why do that? Link to comment Share on other sites More sharing options...
Tony Brooks Posted September 18, 2020 Report Share Posted September 18, 2020 54 minutes ago, jenevers said: Maybe it’s because I always knock the decompression lever over when I switch off and start up under decompression. Suppose I should start under full compression? No harm in letting the starter spin up with the decompressors set because the engine will probably spin faster but then knock them off when p to speed. Probably less strain on the starer & battery and probably an easier start. Link to comment Share on other sites More sharing options...
jonesthenuke Posted September 18, 2020 Report Share Posted September 18, 2020 If we have not run the engine for more than a week or so I turn it over with the decompressor applied. Otherwise, I always start with full compression. This is what Gardner specified in the manual. The decompressor is for hand starting. I suggest the OP should try this and at the same time check that the starter and battery is capable of attaining cranking speed immediately. The Gardner book says that the engine should start on the first or second compression stroke. This is how ours behaves, the engine starts immediately after pressing the start button. Link to comment Share on other sites More sharing options...
jenevers Posted September 18, 2020 Author Report Share Posted September 18, 2020 3 hours ago, Tony Brooks said: No harm in letting the starter spin up with the decompressors set because the engine will probably spin faster but then knock them off when p to speed. Probably less strain on the starer & battery and probably an easier start. That’s why I do that, but I’ll try with full compression next time. Link to comment Share on other sites More sharing options...
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