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From: John Boy \ (no email)
Date: Tue Sep 23 2003 - 09:10:31 EDT
With regards to Jose's 3208 idle/uneven RPM problem, which I agree is probably
air entry from the supply system, I thought I'd mention a tool I've used for
years to diagnose "air-in-fuel" problems.
The product is a sight-glass incorporated into a brass fitting, (normally AN)
that is attached at the inlet of the transfer pump. (You don't want any
fittings after this, as they could be the problem child.) As one of the
members pointed out, it is very easy to observe if any air is entering the
"negative pressure" side of the system. This tool is inexpensive and is of a
quality that can be permanently installed on the engine. This, along with the
vacuum gage mounted down-line of you fuel filters, can make fuel system
diagnosis underway much easier. These sight gages are available from many
diesel supply/tool companies. I got mine from Caterpillar, because I was
working there at the time, but Cummins, Snap-On, hydraulic supply houses, and
many others have them available. I think they should be standard equipment on
any new installation. Having a valve installed, prior to the return line check
valve, that allows for diversion of the return fuel into a container via a
clear line can also be of great help. BTW, another sight gage could also be
installed in the return line. This setup allows for easy observation of the
fuel delivery/return system while underway and during loaded conditions
without any tools or disruption of the components.
IMHO, Anything that can help diagnose a component problem, has no moving
parts, dosen't require power, can be used underway and is inexpensive I think
is a reasonable addition to the system.
I don't believe your pump/s need rebuilt Jose. The main down fall of Cat's
sleeve metering system was the ingression of water. If you let water get into
that pump, as well as any of the Stanadyne/CAV pumps, it will kill it. These
pumps, as well as some others, use the fuel passing through the "pressurized"
houshing to lubricate the mechanical parts of the pump. Unfortunately, the
water settles to the bottom of the pump and "STAYS". The Cat sleeve-metering
system is worse than the rotary pumps as it has a large area, basicly a sump,
that can't really be drained. Any water ingression tends to be cumlative and
can build up till it finally gets to the camshaft lobes/journals (the lowest
part of the system) and kills it. Fuel additives attempt to bind with the
water, on a molecular level, and pass it through the system, but this can only
remove very small amounts of moisture and I don't think these additives are
present in marine fuel either at all, or in quanties that will help much.
Again IMHO, If I bought a used 3208 engine, I would get a new top cover gasket
and remove the fuel houshing top cover and inspect for the presence of
water/foreign material. It's an easy opperation and only requries making sure
you line up the governor control links when you reinstall the cover. Refer to
servied manual.
Hope this wasn't to long a post,
BTW, it's good to be back in the States where I can do this, as well as many
other things.
John Stone & Susan Demesquita
Aboard MY "Mariah"
Gwynn's Island Trawler,62
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