motor compression - when is low, just too low
 

Howdy fellow boat enthusiasts,

I'm trying to make some judgment calls on a motor I have on my project boat,
and need your help.

It has some obvious electrical problems currently, however, it also has low
compression last I checked.

Some history on this motor (1972 80HP Merc) is that it did sit for 8 years
without running, and since then it has started a couple times running
briefly in a barrel (not even sure if it was firing on all four cylinders
though).

When checked (in the period after it had started and run a couple times) the
compression was even, but noticeably low, very low. Does anyone know what
the compression should be low to high for a motor like this which would
make it still worthy to fix up?

I really don't want to put hundreds of dollars into this old motor if its
bound to check-out in a short time. A newer used motor would likely be a
better choice I believe.

C.

On Mon, 2 May 2005 17:08:24 -0400, "Chris"
wrote:

~~ snippage ~~

I really don't want to put hundreds of dollars into this old motor if its
bound to check-out in a short time. A newer used motor would likely be a
better choice I believe.

We have a lot of really good Merc guys here.

Give 'em some numbers to work with and a few more specifics.

Later,

Tom

Get a can of "Mercury Power Tune" and use it as directed only let it sit
twice as long.

If it helps at all, do it a couple more times till compression is over 120.

Stuck rings are VERY common in those Merc inlines.

I rebuild those powerheads on a daily basis. For short money compared to
new.


-W

C.C. Marine
Lake Hartwell S.C.



"Chris" wrote in message
.. .
Howdy fellow boat enthusiasts,

I'm trying to make some judgment calls on a motor I have on my project
boat,
and need your help.

It has some obvious electrical problems currently, however, it also has
low
compression last I checked.

Some history on this motor (1972 80HP Merc) is that it did sit for 8 years
without running, and since then it has started a couple times running
briefly in a barrel (not even sure if it was firing on all four cylinders
though).

When checked (in the period after it had started and run a couple times)
the
compression was even, but noticeably low, very low. Does anyone know what
the compression should be low to high for a motor like this which would
make it still worthy to fix up?

I really don't want to put hundreds of dollars into this old motor if its
bound to check-out in a short time. A newer used motor would likely be a
better choice I believe.

C.