From: The Raven on
"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.


From: Scotty on

"The Raven" <swilson150(a)yahoo.com.au> wrote in message
news:4bd034cc$0$6090$afc38c87(a)news.optusnet.com.au...
:" 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.
:
:

Thanks for your honest input.


From: Jason James on

"John_H" <john4721(a)inbox.com> wrote in message
news:kr0vs5hfh7mnpr5mgb7l0uf23ip9eoplge(a)4ax.com...
> Scotty wrote:
>>
>>Isnt adding oil into the bore a 2nd test? At normal temp the correct
>>reading will be gained. If low
>>compression on one pot then add oil. If the reading gets better then its
>>most likely worn rings.
>>
>>Am I wrong in this?
>
> The blurb that comes with the compression gauge probably says so...
> but why bother when the quick, easy (and far more effective) check for
> blow by is to remove the oil filler cap while the engine is running.
>
> Takes about five seconds, and even if you're deaf and blind you'll
> still be able to smell it if it's bad enough to show up in a
> compression test. :)
Dont forget to block off the PCV valve and any other lines from the
crankcase to intake (atmospheric and inlet-vac). Usually the PCV is all you
need to do.

Jason


From: Scotty on

"John_H" <john4721(a)inbox.com> wrote in message news:kr0vs5hfh7mnpr5mgb7l0uf23ip9eoplge(a)4ax.com...
: Scotty wrote:
: >
: >Isnt adding oil into the bore a 2nd test? At normal temp the correct reading will be gained. If
low
: >compression on one pot then add oil. If the reading gets better then its most likely worn rings.
: >
: >Am I wrong in this?
:
: The blurb that comes with the compression gauge probably says so...
: but why bother when the quick, easy (and far more effective) check for
: blow by is to remove the oil filler cap while the engine is running.
:
: Takes about five seconds, and even if you're deaf and blind you'll
: still be able to smell it if it's bad enough to show up in a
: compression test. :)
:
: --
: John H
:

Blow by is through the rings or valve stem seals?


From: John_H on
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
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