Unless you identify what causes the vibration you may be aggravating the
situation by grinding some of the engine foundation. Conversely if you let
the water pump pounding against the foundation you may end up with a bigger
problem failure at the most inopportune moment. What I have used with
success is a hand rasp. By doing it by hand you have a better control on
the amount of material that you remove and much less dust.
If you have the skill for it you may want to use a 3/4" gouge and remove
exactly the amount you need and finish it off with a rasp and sand paper.
The mini grinder require lots of skill and produce lots of dust. Before
using them you may want to practice of a scrap piece of similar material.
After you are satisfy and feel better about the water pump not hitting the
foundation you have to seal the area with resin and paint after. This is
just a band aid solution you have to find the cause of the vibration.

"Don White" wrote in message
...
Jim Conlin wrote:
Whatever you can make work. Sawzall, jigsaw (carbid grit blades
preferred),
Dremel, or 4" grinder might do the job. My favorites are twist drills,
hole
saws and the Fein Multi-Master.

"Chris" wrote in message
oups.com...

Hi,

I noticed that during idling, my engine vibrates enough
to constantly hit the water pump on the fiberglass engine
foundation. The last two or three big jumps the diesel does
when stopped bang the water pump into the fiberglass really
hard.

So about about half an inch of the engine foundation has to go.
What is the best tool to cut really solid fiberglass, and how
do I do this? Any advice is appreciated.

Thanks a lot,

Chris


I just enlarged 6 thru-hull 3/16" deep holes with my Dremel tool and a
stone gringer. It was hard to make the bigger holes perfectly round,
but all was hidden by the thru-hull flange.
My niece's husband used to work ar Rosborough boats and when he was at
my house last week, said they would use Milwaukie hole saws for same job.