Valve clearance adjustment
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From: Scotty on 22 Apr 2010 05:30 "John_H" <john4721(a)inbox.com> wrote in message news:ih20t51fndaeagc0om46rknckjn07q2okq(a)4ax.com... : Scotty wrote: : > : >Blow by is through the rings or valve stem seals? : : Blow by is the combustion pressure (gas) that gets past the rings : (unless there happens to be a hole in a piston). : : -- : John H Excuse my ignorance but would it also come past the stem seals? Thats why I commented on if you put oil down the bore and it still shitty compression that it may be valve seals? Tell me if Im wrong so I can learn a bit here.............. after all aint that why this NG is here.
From: atec7 7 ""atec77 " on 22 Apr 2010 05:38 Scotty wrote: > "John_H" <john4721(a)inbox.com> wrote in message news:ih20t51fndaeagc0om46rknckjn07q2okq(a)4ax.com... > : Scotty wrote: > : > > : >Blow by is through the rings or valve stem seals? > : > : Blow by is the combustion pressure (gas) that gets past the rings > : (unless there happens to be a hole in a piston). > : > : -- > : John H > > Excuse my ignorance but would it also come past the stem seals? > > Thats why I commented on if you put oil down the bore and it still shitty compression that it may be > valve seals? > > Tell me if Im wrong so I can learn a bit here.............. after all aint that why this NG is here. > > ring will still sorta function with quite a gap , they do allow gas and oil past though indicated by smoke and or low compression , the stems/guide and seals have a much closer tolerance which when exceeded allow oil past and the valve to rock knocking the guides and seats about but the amount of gas allowed past the stems would be minimal predicated mostly by oil puffs on over run and sometimes low cylinder preasuers someone else can finish it off
From: Noddy on 22 Apr 2010 06:08 " Scotty" <scoter1(a)warmmail.com> wrote in message news:4bd002bc$0$6094$afc38c87(a)news.optusnet.com.au... > Blow by is through the rings or valve stem seals? Rings. If it was through the valve stem seals the engine would be in *very* serious trouble. -- Regards, Noddy.
From: Noddy on 22 Apr 2010 06:18 " Scotty" <scoter1(a)warmmail.com> wrote in message news:4bd01730$0$12142$afc38c87(a)news.optusnet.com.au... > Excuse my ignorance but would it also come past the stem seals? In short, no. > Thats why I commented on if you put oil down the bore and it still shitty > compression that it may be > valve seals? It'd be the *valves* themselves, or a head gasket or damaged piston or some other fault. > Tell me if Im wrong so I can learn a bit here.............. after all aint > that why this NG is here. Valve stem seals aren't designed to do anything other than limit the amount of oil that finds it's way up to the top of the engine to lubricate the rocker hear from travelling down the valve guide and entering the combustion chamber. They don't completely eliminate oil from getting inside the valve guide, as some oil is necessary to keep the valve stems lubricated, but they're generally intended to prevent bucket loads of oil running down the valve stem. The sealing of the cylinder is done in three key areas: The piston rings, the head gasket and the valves themselves, and all three can fail causing a compression loss. It would actually be impossible for compression gas to be lost through valve stem seals in a conventional engine, as they would first have to get past the valve seats and the minute they do they'd be vented into either the inlet or exhaust manifold. -- Regards, Noddy.
From: D Walford on 21 Apr 2010 02:53
On 20/04/2010 10:10 PM, hippo wrote: > John_H wrote: >> >> Jason James wrote: >> >>> Did you take the readings for each cylinder? Done with a >>> compression gauge rated to 250 psi. Gauge either has a large tapered rubber >>> knozzle to fit in the plug hole,..or a screwed fitting. Its imperative you >>> hold open the throttle (wide-open) while someone cranks the engine for at >>> least 8 revs. What were the figures? >> >> And you've forgotten one absolutely vital requirement... any idea what >> it is? :) >> > > Umm... anything to do with the HT lead on the coil? > Disconnecting the HT lead is good idea but I don't think that's the answer John was looking for, my guess is you need to warm the engine to operating temp before doing the comp test. Daryl |