Re: Compression tests
 

no_account wrote:
> May be when you want to buy a used car?
> "ILJ" <res1kumh@verizon.net> wrote in message
> news:tJYSb.8763$9a4.3978@nwrddc01.gnilink.net...
>> What is the point of a compression test? I know what it measures,
>> but if you get a poor compression ratio, how do you fix it?

I always check compression when buying a new car. If a 4 cyl, I'll check all
of them. A 6 or 8, I would do enough to satisfy me that there is not a high
"range".

Re: Compression tests
 

no_account wrote:
> May be when you want to buy a used car?
> "ILJ" <res1kumh@verizon.net> wrote in message
> news:tJYSb.8763$9a4.3978@nwrddc01.gnilink.net...
>> What is the point of a compression test? I know what it measures,
>> but if you get a poor compression ratio, how do you fix it?

I always check compression when buying a new car. If a 4 cyl, I'll check all
of them. A 6 or 8, I would do enough to satisfy me that there is not a high
"range".

Re: Compression tests
 

On Fri, 30 Jan 2004 20:43:46 -0800, "CaptainKrunch"
<nothing@nobody.com> wrote:

>It is like any other test. Like an EKG. It takes somebody that knows what
>they are doing in order to interpret the results correctly. Depending on
>whether overall compression is low or just an isolated cylinder or two would
>determine the fix.
>
>Pertaining to the other poster I have never heard of a running compression
>test. In as much as connecting a psi gauge to a cylinder and running the

Compression 1 2 3
4
Cranking 178 175 170
175
Idle 60 60 40
60
2000 RPM 40 40 20
20

May indicate valve or flat camshaft problem on #3.

In conjunction with a cylinder leakdown test, is very helpful for
identifying problems.

You may not be able to peform running compression tests on all
vehicles. Especially OBD-II which will catch the misfire, unless you
can disable the individual cylinder.

>engine minus that spark plug. If indeed this is the case that makes no
>sense because you would have a misfire with that cylinder and it would set
>off codes in the computer that would need to be reset. Mostly compression

Only on OBD-II Lots of pre-OBD-II cars out there which won't bat an
eyelash on a running compression test.

>tests are just done while cranking the engine over and disabling the engine
>so that it temporarily doesn't fire.

And disconnecting power to the fuel injectors.

__________________
Note: To reply, replace the word 'spam' embedded in return address with 'mail'.
N38.6 W121.4

Re: Compression tests
 

On Fri, 30 Jan 2004 20:43:46 -0800, "CaptainKrunch"
<nothing@nobody.com> wrote:

>It is like any other test. Like an EKG. It takes somebody that knows what
>they are doing in order to interpret the results correctly. Depending on
>whether overall compression is low or just an isolated cylinder or two would
>determine the fix.
>
>Pertaining to the other poster I have never heard of a running compression
>test. In as much as connecting a psi gauge to a cylinder and running the

Compression 1 2 3
4
Cranking 178 175 170
175
Idle 60 60 40
60
2000 RPM 40 40 20
20

May indicate valve or flat camshaft problem on #3.

In conjunction with a cylinder leakdown test, is very helpful for
identifying problems.

You may not be able to peform running compression tests on all
vehicles. Especially OBD-II which will catch the misfire, unless you
can disable the individual cylinder.

>engine minus that spark plug. If indeed this is the case that makes no
>sense because you would have a misfire with that cylinder and it would set
>off codes in the computer that would need to be reset. Mostly compression

Only on OBD-II Lots of pre-OBD-II cars out there which won't bat an
eyelash on a running compression test.

>tests are just done while cranking the engine over and disabling the engine
>so that it temporarily doesn't fire.

And disconnecting power to the fuel injectors.

__________________
Note: To reply, replace the word 'spam' embedded in return address with 'mail'.
N38.6 W121.4

Re: Compression tests
 

On Fri, 30 Jan 2004 20:43:46 -0800, "CaptainKrunch"
<nothing@nobody.com> wrote:

>It is like any other test. Like an EKG. It takes somebody that knows what
>they are doing in order to interpret the results correctly. Depending on
>whether overall compression is low or just an isolated cylinder or two would
>determine the fix.
>
>Pertaining to the other poster I have never heard of a running compression
>test. In as much as connecting a psi gauge to a cylinder and running the

Compression 1 2 3
4
Cranking 178 175 170
175
Idle 60 60 40
60
2000 RPM 40 40 20
20

May indicate valve or flat camshaft problem on #3.

In conjunction with a cylinder leakdown test, is very helpful for
identifying problems.

You may not be able to peform running compression tests on all
vehicles. Especially OBD-II which will catch the misfire, unless you
can disable the individual cylinder.

>engine minus that spark plug. If indeed this is the case that makes no
>sense because you would have a misfire with that cylinder and it would set
>off codes in the computer that would need to be reset. Mostly compression

Only on OBD-II Lots of pre-OBD-II cars out there which won't bat an
eyelash on a running compression test.

>tests are just done while cranking the engine over and disabling the engine
>so that it temporarily doesn't fire.

And disconnecting power to the fuel injectors.

__________________
Note: To reply, replace the word 'spam' embedded in return address with 'mail'.
N38.6 W121.4

Re: Compression tests
 

On Fri, 30 Jan 2004 20:43:46 -0800, "CaptainKrunch"
<nothing@nobody.com> wrote:

>It is like any other test. Like an EKG. It takes somebody that knows what
>they are doing in order to interpret the results correctly. Depending on
>whether overall compression is low or just an isolated cylinder or two would
>determine the fix.
>
>Pertaining to the other poster I have never heard of a running compression
>test. In as much as connecting a psi gauge to a cylinder and running the

Compression 1 2 3
4
Cranking 178 175 170
175
Idle 60 60 40
60
2000 RPM 40 40 20
20

May indicate valve or flat camshaft problem on #3.

In conjunction with a cylinder leakdown test, is very helpful for
identifying problems.

You may not be able to peform running compression tests on all
vehicles. Especially OBD-II which will catch the misfire, unless you
can disable the individual cylinder.

>engine minus that spark plug. If indeed this is the case that makes no
>sense because you would have a misfire with that cylinder and it would set
>off codes in the computer that would need to be reset. Mostly compression

Only on OBD-II Lots of pre-OBD-II cars out there which won't bat an
eyelash on a running compression test.

>tests are just done while cranking the engine over and disabling the engine
>so that it temporarily doesn't fire.

And disconnecting power to the fuel injectors.

__________________
Note: To reply, replace the word 'spam' embedded in return address with 'mail'.
N38.6 W121.4

Re: Compression tests
 

In article <mcpo10tvsqugjmejmt9g5r41ukcpclejmd@4ax.com>, nntp@spamsack.org
wrote:

> On Sun, 01 Feb 2004 01:35:21 GMT, "ILJ" <res1kumh@verizon.net> wrote:
>
> >What is the point of a compression test? I know what it measures, but if you
> >get a poor compression ratio, how do you fix it?
>
> A cranking compression test is a measure of whether the cylinder is
> operating normally. If the cylinder can't compress air, it won't
> produce power. A running compression test (idle and 2000 RPM)
> sometimes helps point to camshaft and valve problems. All this
> combined with a cylinder leakdown test allow you to identify or rule
> out engine problems.
>
> The fix for low compression can be valves, rings, engine replacement..
>
>
> __________________
> Note: To reply, replace the word 'spam' embedded in return address with
'mail'.
> N38.6 W121.4

Excellent post--I was going to say some of these same things--but you done
it better and included more details than I would have included. Keep up
the great work.

Re: Compression tests
 

In article <mcpo10tvsqugjmejmt9g5r41ukcpclejmd@4ax.com>, nntp@spamsack.org
wrote:

> On Sun, 01 Feb 2004 01:35:21 GMT, "ILJ" <res1kumh@verizon.net> wrote:
>
> >What is the point of a compression test? I know what it measures, but if you
> >get a poor compression ratio, how do you fix it?
>
> A cranking compression test is a measure of whether the cylinder is
> operating normally. If the cylinder can't compress air, it won't
> produce power. A running compression test (idle and 2000 RPM)
> sometimes helps point to camshaft and valve problems. All this
> combined with a cylinder leakdown test allow you to identify or rule
> out engine problems.
>
> The fix for low compression can be valves, rings, engine replacement..
>
>
> __________________
> Note: To reply, replace the word 'spam' embedded in return address with
'mail'.
> N38.6 W121.4

Excellent post--I was going to say some of these same things--but you done
it better and included more details than I would have included. Keep up
the great work.

Re: Compression tests
 

In article <mcpo10tvsqugjmejmt9g5r41ukcpclejmd@4ax.com>, nntp@spamsack.org
wrote:

> On Sun, 01 Feb 2004 01:35:21 GMT, "ILJ" <res1kumh@verizon.net> wrote:
>
> >What is the point of a compression test? I know what it measures, but if you
> >get a poor compression ratio, how do you fix it?
>
> A cranking compression test is a measure of whether the cylinder is
> operating normally. If the cylinder can't compress air, it won't
> produce power. A running compression test (idle and 2000 RPM)
> sometimes helps point to camshaft and valve problems. All this
> combined with a cylinder leakdown test allow you to identify or rule
> out engine problems.
>
> The fix for low compression can be valves, rings, engine replacement..
>
>
> __________________
> Note: To reply, replace the word 'spam' embedded in return address with
'mail'.
> N38.6 W121.4

Excellent post--I was going to say some of these same things--but you done
it better and included more details than I would have included. Keep up
the great work.

Re: Compression tests
 

In article <mcpo10tvsqugjmejmt9g5r41ukcpclejmd@4ax.com>, nntp@spamsack.org
wrote:

> On Sun, 01 Feb 2004 01:35:21 GMT, "ILJ" <res1kumh@verizon.net> wrote:
>
> >What is the point of a compression test? I know what it measures, but if you
> >get a poor compression ratio, how do you fix it?
>
> A cranking compression test is a measure of whether the cylinder is
> operating normally. If the cylinder can't compress air, it won't
> produce power. A running compression test (idle and 2000 RPM)
> sometimes helps point to camshaft and valve problems. All this
> combined with a cylinder leakdown test allow you to identify or rule
> out engine problems.
>
> The fix for low compression can be valves, rings, engine replacement..
>
>
> __________________
> Note: To reply, replace the word 'spam' embedded in return address with
'mail'.
> N38.6 W121.4

Excellent post--I was going to say some of these same things--but you done
it better and included more details than I would have included. Keep up
the great work.