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strange hissing noise? http://4g61t.org/forum/viewtopic.php?f=6&t=15718	Page 1 of 1

Author:	waxie1 [ Fri Nov 04, 2005 6:12 am ]
Post subject:	strange hissing noise?
Boys i need your advice.... I had just finished installing my timing belt and was doing the standard 6 turns clockwise to check all the timing marks were lined up. Now as I turn the crank there is this strange hissing noise... So I removed all the spark plugs and at TDC air seems to hiss out of the piston 4 park plug hole. I realise some air would be normal as this is the only piston with the all the valves fully closed. The thing is, I've never heard this noise before and think i may have screwed a valve when i was turning the cams with out the belt on, to realign with the crank. I can't see how though as I was very delicate when I was rotating the cam to make sure there was no sudden smack of the valves against the pistons... At a loss... What could i have done?

Author:	slowx2 [ Fri Nov 04, 2005 7:42 am ]
Post subject:
i dunno about the '63 but when i have been too lazy to take out the spark plugs to do valve clearances or something, the air always makes a hissing noise as i turn the crank. Dont forget that when the engine is not running, there is no pressure to force the piston rings out against the cylinder walls, so the seal is crap, and air gets past. Also when you turn the crank with the plugs out, you are pushing 1/2 litre of air out through the small plug hole, so you will probably hear or feel it, especially if the valves are closed for that cylinder. your engine is not my area, so maybe see what other people say.

Author:	Skrenos [ Fri Nov 04, 2005 9:06 am ]
Post subject:
Do a compression test. It's either rings, valves, or spark plug.... or worse, but we wont go there.

Author:	waxie1 [ Fri Nov 04, 2005 1:46 pm ]
Post subject:
It's not the rings cos I only recently did a rebuild and this has only just started after i was rotating the cams with the belt off and the crank not on TDC. Haven't run the engine at all. Do you think I could of damaged a valve doing this?

Author:	pma1123 [ Fri Nov 04, 2005 2:11 pm ]
Post subject:
If everything was running fine before the belt, and the teeth all line up on the crank and cam gears with the new belt, I would fire it up without the PS/alternator belts on just to make sure everything is ok. Without witnessing what is happening myself, I would say that it sounds like youre just hearing compression leaking as you turn it, which is normal.

Author:	waxie1 [ Tue Nov 22, 2005 1:45 am ]
Post subject:
All good!

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