Wayne,
K answered your questions very well, but I'm curious why you think you have
low compression, as that rarely happens on a detroit. I suspect an
underlying story here. Secondly, that engine has been made for 70 years,
there are many variations. Which one do you have? Please note there are many
different cylinder heads as well. The older ones are 2 valve and the modern
ones are 4 enhaust valves per cylinder. I think you should identify symtoms,
if you want meaningful help.
Steve

"Wayne.B" wrote in message
...
Not having made any significant displays of ignorance lately that I
know of, thought I'd give it a try:

Is there any way to measure compression without removing injectors or
other major components on DD671s?

Second question:

Since the DD671 is a 2 cycle engine, I'm assuming there are no moving
valves, just fixed intake and exhaust ports in the cylinder walls.

Anyone know if that is correct?

If so, I'm also assuming that any loss of compression would have to be
from worn rings and/or cylinder bore. Also correct?

On Wed, 25 Jan 2006 00:31:55 +0100, "Steve Lusardi"
wrote:

I think you should identify symtoms,
if you want meaningful help.

It's a 1981 Johnson & Towers marine conversion, supposedly rebuilt
within the last 1,000 hours or so by the previous owner.

My port side engine is taking longer to cold start than it used to,
sometimes needing 8 to 12 seconds of cranking. It used to start on
the first or second turn even when stone cold, and the starboard
engine still does. If it has been run within a day or two it still
starts very quickly. There is very little exhaust smoke at startup
even when cold, and what little there is goes away quickly. The
engine is running well and making full power as far as I can
determine.

"Wayne.B" wrote in message
...
On Wed, 25 Jan 2006 00:31:55 +0100, "Steve Lusardi"
wrote:

I think you should identify symtoms,
if you want meaningful help.

It's a 1981 Johnson & Towers marine conversion, supposedly rebuilt
within the last 1,000 hours or so by the previous owner.

My port side engine is taking longer to cold start than it used to,
sometimes needing 8 to 12 seconds of cranking. It used to start on
the first or second turn even when stone cold, and the starboard
engine still does. If it has been run within a day or two it still
starts very quickly. There is very little exhaust smoke at startup
even when cold, and what little there is goes away quickly. The
engine is running well and making full power as far as I can
determine.


There's a guy at our marina who had a somewhat similar problem for a couple
of years. Turns out he had a very small air leak in the fuel supply line
for one engine. It would run fine after starting, (I assume because the
leak was overcome by fuel, but that is pure speculation), but was hard
starting.

Ain't boats fun?

Eisboch (grandkid #5 is a girl!)

On Tue, 24 Jan 2006 19:17:09 -0500, "Eisboch" wrote:


"Wayne.B" wrote in message
.. .
On Wed, 25 Jan 2006 00:31:55 +0100, "Steve Lusardi"
wrote:

I think you should identify symtoms,
if you want meaningful help.

It's a 1981 Johnson & Towers marine conversion, supposedly rebuilt
within the last 1,000 hours or so by the previous owner.

My port side engine is taking longer to cold start than it used to,
sometimes needing 8 to 12 seconds of cranking. It used to start on
the first or second turn even when stone cold, and the starboard
engine still does. If it has been run within a day or two it still
starts very quickly. There is very little exhaust smoke at startup
even when cold, and what little there is goes away quickly. The
engine is running well and making full power as far as I can
determine.


There's a guy at our marina who had a somewhat similar problem for a couple
of years. Turns out he had a very small air leak in the fuel supply line
for one engine. It would run fine after starting, (I assume because the
leak was overcome by fuel, but that is pure speculation), but was hard
starting.

Ain't boats fun?

Eisboch (grandkid #5 is a girl!)

Congrats! So what's the score now. I've got 4 grandsons, 1 granddaughter.

"JohnH" wrote in message
...

Eisboch (grandkid #5 is a girl!)

Congrats! So what's the score now. I've got 4 grandsons, 1 granddaughter.


Three girls, two boys. Need one more to even up the score.

Eisboch

Eisboch wrote:

"JohnH" wrote in message
...

Eisboch (grandkid #5 is a girl!)


Congrats! So what's the score now. I've got 4 grandsons, 1 granddaughter.



Three girls, two boys. Need one more to even up the score.

Eisboch


The M5 makes it an even score!

Dan

"Dan Krueger" wrote in message
ink.net...
Eisboch wrote:

"JohnH" wrote in message
...

Eisboch (grandkid #5 is a girl!)


Congrats! So what's the score now. I've got 4 grandsons, 1 granddaughter.



Three girls, two boys. Need one more to even up the score.

Eisboch
The M5 makes it an even score!

Dan

Ah! The other "baby". Still working on the mandatory 1200 mile break in
procedure.
Pretty much got the hang of driving a manual without a clutch pedal though.
During break in you have to limit max RPM to 5500, so shifts are done around
4000-4500. After the break in period, max RPM is 8200 RPM with shifts around
6500 - 7000 which is getting into the engine's powerband. Can't wait to try
the "S6" mode. This car is going to get me in a lot of trouble.

Eisboch

On Tue, 24 Jan 2006 19:17:09 -0500, "Eisboch" wrote:

Ain't boats fun?

Eisboch (grandkid #5 is a girl!)

Congratulations! We are still at #0 but both sons are engaged so
that's a good start.

Yes, small air leak is a possibility under consideration. This issue
is fortunately not at a critical state yet but I like to stay on top
of things so I don't get a failure when I'm in the boondocks
somewhere.

"Wayne.B" wrote in message
...
On Tue, 24 Jan 2006 19:17:09 -0500, "Eisboch" wrote:

Ain't boats fun?

Eisboch (grandkid #5 is a girl!)

Congratulations! We are still at #0 but both sons are engaged so
that's a good start.

Yes, small air leak is a possibility under consideration. This issue
is fortunately not at a critical state yet but I like to stay on top
of things so I don't get a failure when I'm in the boondocks
somewhere.


Are your 671s turboed or normally aspirated? It's funny when you get to
know how the various engines sound. I can identify the sound of those 671s
anytime I hear them start up.
A friend has a pair of normally aspirated 671s in a 1972 Hat 38 - actually
a conversion from original gas engines. They have over close to 10,000
hours on them and run like a top. Great engines.

Eisboch

On Tue, 24 Jan 2006 19:50:34 -0500, "Eisboch" wrote:

Are your 671s turboed or normally aspirated?

Naturally aspirated.

It's funny when you get to
know how the various engines sound. I can identify the sound of those 671s
anytime I hear them start up.

You and all of my neighbors. :-)

It's like having a pair of Greyhound busses idling in your backyard.

A friend has a pair of normally aspirated 671s in a 1972 Hat 38 - actually
a conversion from original gas engines. They have over close to 10,000
hours on them and run like a top. Great engines.

They have a reputation of lasting almost forever and can be totally
rebuilt in place with new cylinder sleeves, bearings, pistons, etc.

It's my understanding that in commercial generator service they
frequently go 20,000 hours between overhauls although 4 or 5,000 hours
is more typical for marine service.