Valve clearance adjustment
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From: The Raven on 22 Apr 2010 07:36 " Scotty" <scoter1(a)warmmail.com> wrote in message news:4bd01730$0$12142$afc38c87(a)news.optusnet.com.au... > > "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? The valve seal (as in the sealing effectiveness) could be poor, which you should be able to hear when the engine is running. As for the valve stem seals, they are separated from the compression gasses by the valve itself (if it's sealing). Even if the valves themselves are leaking (aka burnt valves) any gasses that make it past the valve stem seals are the least of your problems. > Tell me if Im wrong so I can learn a bit here.............. after all aint > that why this NG is here. Trying to be helpful.
From: The Raven on 22 Apr 2010 07:40 "Noddy" <me(a)home.com> wrote in message news:4bd0217a$0$903$c30e37c6(a)exi-reader.telstra.net... > > " 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. > If he's getting lots of smoke just on acceleration (for a few seconds) it could be valve stem seals. Easiest way to test is drive at a steady speed, back off the throttle (change down a gear perhaps), then hit the throttle several seconds later. Lots of smoke on throttle application indicates bad valve stem seals (and or valve stem to head clearance).... oil is being pulled from down into the intake ports from the top side of the head. Had this on a old Mazda 929.
From: The Raven on 22 Apr 2010 07:41 "The Raven" <swilson150(a)yahoo.com.au> wrote in message news:4bd035b7$0$24251$afc38c87(a)news.optusnet.com.au... > "Noddy" <me(a)home.com> wrote in message > news:4bd0217a$0$903$c30e37c6(a)exi-reader.telstra.net... >> >> " 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. >> > > If he's getting lots of smoke just on acceleration (for a few seconds) it > could be valve stem seals. Easiest way to test is drive at a steady speed, > back off the throttle (change down a gear perhaps), then hit the throttle > several seconds later. Lots of smoke on throttle application indicates bad > valve stem seals (and or valve stem to head clearance).... oil is being > pulled from down into the intake ports from the top side of the head. > > Had this on a old Mazda 929. "valve stem to head clearance" should be more correctly "valve stem to guide clearance". It's late and I've had a few....
From: Jason James on 23 Apr 2010 02:39 "The Raven" <swilson150(a)yahoo.com.au> wrote in message news:4bd0c873$0$10009$afc38c87(a)news.optusnet.com.au... > "bugalugs" <bugalugs67(a)netscape.net> wrote in message > news:hqqgvm$471$1(a)news.eternal-september.org... >> On 22/04/2010 11:40 p.m., The Raven wrote: >>> "Noddy"<me(a)home.com> wrote in message >>> news:4bd0217a$0$903$c30e37c6(a)exi-reader.telstra.net... >>>> >>>> " 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. >>>> >>> >>> If he's getting lots of smoke just on acceleration (for a few seconds) >>> it >>> could be valve stem seals. Easiest way to test is drive at a steady >>> speed, >>> back off the throttle (change down a gear perhaps), then hit the >>> throttle >>> several seconds later. Lots of smoke on throttle application indicates >>> bad >>> valve stem seals (and or valve stem to head clearance).... oil is being >>> pulled from down into the intake ports from the top side of the head. >>> >>> Had this on a old Mazda 929. >>> >>> >> >> Or oil is being pulled up passed worn rings. > > Easier to pull oil down into the intake and then cylinders (given intake > vaccum) than pull oil vapors up from the sump (which is generally at a > lower pressure anyhow - PCV etc). > > I don't disagree it could be the rings, but the valve stem seals will > generally show that behaviour first. The rings would have to be really > rooted....in which case smoke all the time. Ring-pumping on long down-hill runs.The rings move up and down while oil passes behind the rings up into the comb-chamber. Ring-grooves need to be worn pretty bad. Jason
From: John_H on 21 Apr 2010 06:00
Denis wrote: >The compression test was done at Ezygas, the guy said there was a >problem with cylinders 2 and 4 and that I need the valve clearances >adjusted. He probably didn't say 'bad compression' I may have just >assumed that myself. He also said it would cost $300-$400 to have it >done. Ironically I've just had the car at the auto electrician to have >a wiring fault looked at, he said the same thing (the valve clearances >need adjusting) I asked if they were able to do that sort of thing >there and he said "Sure, no worries" and quoted me $88-$132 max. The valve clearances and the compression are separate issues. Both the mechanic and the auto electrician would've based their valve clearance diagnosis on the noises caused by excessive valve lash... which ought be dead obvious to any mechanic, but possibly not to the average wood duck. If it's had previous head work whoever assembled it probably never set the clearances properly, which isn't unusual. He most likely would've told the previous owner to bring it back for a final adjustment after it settled in (which is bullshit, but common practice all the same). You probably should get the valve clearances adjusted by a competent operator but I wouldn't be losing any sleep over a compression test, which may or may not have been done properly. If compression really is an issue the 'competent operator' who adjusts the valve clearances should pick it up without being prompted. -- John H |