I just got a call from the shop where I took my jeep to have it diagnosised
for engine "strength". The guy told me I have compression of 150 psi per
cylinder with no variance between each cylinder. I'm thinking Great.
However, I looked up the specs in my FSM where they say I should have
between 120 to 140 per cylinder.

Can I have too much compression and what would cause that? Could the test
be done incorrectly which would present a higher number than it really is?

Thanks,

Bill

 

I can only give the advice of an advanced rookie............
I believe that some compression can be due to carbon build up on the top of
the piston or in the combustion chamber of the head - but I think that most
of the difference is probably in the compression gauge. I doubt if any 2
gauges will be that close, especially after banging around in a tool box for
15 to 20 years.
I would still ask around - or wait for more posts from others - but the "no
variance" part sounds good. I would think that if there was a problem, such
as carbon build up, it probably would not be even across all cylinders.
Other possibilities might be a milled head, thin head gasket, different
pistons, etc.
how many miles on the engine ? & what has been done to it ?

--
Carlo F. Serusa, Jr. RPh
carlo.jr at comcast DOTnet
'98 Sahara TJ - '89 YJ - '79 Scout II
O|||||||O
'92 Explorer '65 Mustang


"William Oliveri" <wuji@bigvalley.net> wrote in message
news:bu1c4l$c8dq2$1@ID-193866.news.uni-berlin.de...
> I just got a call from the shop where I took my jeep to have it
diagnosised
> for engine "strength". The guy told me I have compression of 150 psi per
> cylinder with no variance between each cylinder. I'm thinking Great.
> However, I looked up the specs in my FSM where they say I should have
> between 120 to 140 per cylinder.
>
> Can I have too much compression and what would cause that? Could the test
> be done incorrectly which would present a higher number than it really is?
>
> Thanks,
>
> Bill
>
>

 

I can only give the advice of an advanced rookie............
I believe that some compression can be due to carbon build up on the top of
the piston or in the combustion chamber of the head - but I think that most
of the difference is probably in the compression gauge. I doubt if any 2
gauges will be that close, especially after banging around in a tool box for
15 to 20 years.
I would still ask around - or wait for more posts from others - but the "no
variance" part sounds good. I would think that if there was a problem, such
as carbon build up, it probably would not be even across all cylinders.
Other possibilities might be a milled head, thin head gasket, different
pistons, etc.
how many miles on the engine ? & what has been done to it ?

--
Carlo F. Serusa, Jr. RPh
carlo.jr at comcast DOTnet
'98 Sahara TJ - '89 YJ - '79 Scout II
O|||||||O
'92 Explorer '65 Mustang


"William Oliveri" <wuji@bigvalley.net> wrote in message
news:bu1c4l$c8dq2$1@ID-193866.news.uni-berlin.de...
> I just got a call from the shop where I took my jeep to have it
diagnosised
> for engine "strength". The guy told me I have compression of 150 psi per
> cylinder with no variance between each cylinder. I'm thinking Great.
> However, I looked up the specs in my FSM where they say I should have
> between 120 to 140 per cylinder.
>
> Can I have too much compression and what would cause that? Could the test
> be done incorrectly which would present a higher number than it really is?
>
> Thanks,
>
> Bill
>
>

 

I can only give the advice of an advanced rookie............
I believe that some compression can be due to carbon build up on the top of
the piston or in the combustion chamber of the head - but I think that most
of the difference is probably in the compression gauge. I doubt if any 2
gauges will be that close, especially after banging around in a tool box for
15 to 20 years.
I would still ask around - or wait for more posts from others - but the "no
variance" part sounds good. I would think that if there was a problem, such
as carbon build up, it probably would not be even across all cylinders.
Other possibilities might be a milled head, thin head gasket, different
pistons, etc.
how many miles on the engine ? & what has been done to it ?

--
Carlo F. Serusa, Jr. RPh
carlo.jr at comcast DOTnet
'98 Sahara TJ - '89 YJ - '79 Scout II
O|||||||O
'92 Explorer '65 Mustang


"William Oliveri" <wuji@bigvalley.net> wrote in message
news:bu1c4l$c8dq2$1@ID-193866.news.uni-berlin.de...
> I just got a call from the shop where I took my jeep to have it
diagnosised
> for engine "strength". The guy told me I have compression of 150 psi per
> cylinder with no variance between each cylinder. I'm thinking Great.
> However, I looked up the specs in my FSM where they say I should have
> between 120 to 140 per cylinder.
>
> Can I have too much compression and what would cause that? Could the test
> be done incorrectly which would present a higher number than it really is?
>
> Thanks,
>
> Bill
>
>

 

Very few gauges are accurate or will read the same on the same engine.

If they are all even, that's a good thing. Too high can mean carbon
buildup.

Normally carbon isn't a problem until you start to get spark knock or
ping or until it starts dieseling or running on after the key is turned
off.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

William Oliveri wrote:
>
> I just got a call from the shop where I took my jeep to have it diagnosised
> for engine "strength". The guy told me I have compression of 150 psi per
> cylinder with no variance between each cylinder. I'm thinking Great.
> However, I looked up the specs in my FSM where they say I should have
> between 120 to 140 per cylinder.
>
> Can I have too much compression and what would cause that? Could the test
> be done incorrectly which would present a higher number than it really is?
>
> Thanks,
>
> Bill

 

Very few gauges are accurate or will read the same on the same engine.

If they are all even, that's a good thing. Too high can mean carbon
buildup.

Normally carbon isn't a problem until you start to get spark knock or
ping or until it starts dieseling or running on after the key is turned
off.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

William Oliveri wrote:
>
> I just got a call from the shop where I took my jeep to have it diagnosised
> for engine "strength". The guy told me I have compression of 150 psi per
> cylinder with no variance between each cylinder. I'm thinking Great.
> However, I looked up the specs in my FSM where they say I should have
> between 120 to 140 per cylinder.
>
> Can I have too much compression and what would cause that? Could the test
> be done incorrectly which would present a higher number than it really is?
>
> Thanks,
>
> Bill

 

Very few gauges are accurate or will read the same on the same engine.

If they are all even, that's a good thing. Too high can mean carbon
buildup.

Normally carbon isn't a problem until you start to get spark knock or
ping or until it starts dieseling or running on after the key is turned
off.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

William Oliveri wrote:
>
> I just got a call from the shop where I took my jeep to have it diagnosised
> for engine "strength". The guy told me I have compression of 150 psi per
> cylinder with no variance between each cylinder. I'm thinking Great.
> However, I looked up the specs in my FSM where they say I should have
> between 120 to 140 per cylinder.
>
> Can I have too much compression and what would cause that? Could the test
> be done incorrectly which would present a higher number than it really is?
>
> Thanks,
>
> Bill

 

Don't know the mileage as the engine was put in used when the previous owner
poured water on the overheated engine and did something bad. The only thing
other than stock is the Mopar MPI kit.

Bill

"Carlo" <carlo.jr@comcast.net> wrote in message
news:CoOdnV7Z2P8F25ndRVn-iQ@comcast.com...
> I can only give the advice of an advanced rookie............
> I believe that some compression can be due to carbon build up on the top
of
> the piston or in the combustion chamber of the head - but I think that
most
> of the difference is probably in the compression gauge. I doubt if any 2
> gauges will be that close, especially after banging around in a tool box
for
> 15 to 20 years.
> I would still ask around - or wait for more posts from others - but the
"no
> variance" part sounds good. I would think that if there was a problem,
such
> as carbon build up, it probably would not be even across all cylinders.
> Other possibilities might be a milled head, thin head gasket, different
> pistons, etc.
> how many miles on the engine ? & what has been done to it ?
>
> --
> Carlo F. Serusa, Jr. RPh
> carlo.jr at comcast DOTnet
> '98 Sahara TJ - '89 YJ - '79 Scout II
> O|||||||O
> '92 Explorer '65 Mustang
>
>
> "William Oliveri" <wuji@bigvalley.net> wrote in message
> news:bu1c4l$c8dq2$1@ID-193866.news.uni-berlin.de...
> > I just got a call from the shop where I took my jeep to have it
> diagnosised
> > for engine "strength". The guy told me I have compression of 150 psi
per
> > cylinder with no variance between each cylinder. I'm thinking Great.
> > However, I looked up the specs in my FSM where they say I should have
> > between 120 to 140 per cylinder.
> >
> > Can I have too much compression and what would cause that? Could the
test
> > be done incorrectly which would present a higher number than it really
is?
> >
> > Thanks,
> >
> > Bill
> >
> >
>
>

 

Don't know the mileage as the engine was put in used when the previous owner
poured water on the overheated engine and did something bad. The only thing
other than stock is the Mopar MPI kit.

Bill

"Carlo" <carlo.jr@comcast.net> wrote in message
news:CoOdnV7Z2P8F25ndRVn-iQ@comcast.com...
> I can only give the advice of an advanced rookie............
> I believe that some compression can be due to carbon build up on the top
of
> the piston or in the combustion chamber of the head - but I think that
most
> of the difference is probably in the compression gauge. I doubt if any 2
> gauges will be that close, especially after banging around in a tool box
for
> 15 to 20 years.
> I would still ask around - or wait for more posts from others - but the
"no
> variance" part sounds good. I would think that if there was a problem,
such
> as carbon build up, it probably would not be even across all cylinders.
> Other possibilities might be a milled head, thin head gasket, different
> pistons, etc.
> how many miles on the engine ? & what has been done to it ?
>
> --
> Carlo F. Serusa, Jr. RPh
> carlo.jr at comcast DOTnet
> '98 Sahara TJ - '89 YJ - '79 Scout II
> O|||||||O
> '92 Explorer '65 Mustang
>
>
> "William Oliveri" <wuji@bigvalley.net> wrote in message
> news:bu1c4l$c8dq2$1@ID-193866.news.uni-berlin.de...
> > I just got a call from the shop where I took my jeep to have it
> diagnosised
> > for engine "strength". The guy told me I have compression of 150 psi
per
> > cylinder with no variance between each cylinder. I'm thinking Great.
> > However, I looked up the specs in my FSM where they say I should have
> > between 120 to 140 per cylinder.
> >
> > Can I have too much compression and what would cause that? Could the
test
> > be done incorrectly which would present a higher number than it really
is?
> >
> > Thanks,
> >
> > Bill
> >
> >
>
>

 

Don't know the mileage as the engine was put in used when the previous owner
poured water on the overheated engine and did something bad. The only thing
other than stock is the Mopar MPI kit.

Bill

"Carlo" <carlo.jr@comcast.net> wrote in message
news:CoOdnV7Z2P8F25ndRVn-iQ@comcast.com...
> I can only give the advice of an advanced rookie............
> I believe that some compression can be due to carbon build up on the top
of
> the piston or in the combustion chamber of the head - but I think that
most
> of the difference is probably in the compression gauge. I doubt if any 2
> gauges will be that close, especially after banging around in a tool box
for
> 15 to 20 years.
> I would still ask around - or wait for more posts from others - but the
"no
> variance" part sounds good. I would think that if there was a problem,
such
> as carbon build up, it probably would not be even across all cylinders.
> Other possibilities might be a milled head, thin head gasket, different
> pistons, etc.
> how many miles on the engine ? & what has been done to it ?
>
> --
> Carlo F. Serusa, Jr. RPh
> carlo.jr at comcast DOTnet
> '98 Sahara TJ - '89 YJ - '79 Scout II
> O|||||||O
> '92 Explorer '65 Mustang
>
>
> "William Oliveri" <wuji@bigvalley.net> wrote in message
> news:bu1c4l$c8dq2$1@ID-193866.news.uni-berlin.de...
> > I just got a call from the shop where I took my jeep to have it
> diagnosised
> > for engine "strength". The guy told me I have compression of 150 psi
per
> > cylinder with no variance between each cylinder. I'm thinking Great.
> > However, I looked up the specs in my FSM where they say I should have
> > between 120 to 140 per cylinder.
> >
> > Can I have too much compression and what would cause that? Could the
test
> > be done incorrectly which would present a higher number than it really
is?
> >
> > Thanks,
> >
> > Bill
> >
> >
>
>