abcandjrc
Well-known member
- Joined
- Oct 10, 2010
- Messages
- 363
- Fluid Motion Model
- C-24 C SE
- Hull Identification Number
- FMLT2160D707
- Vessel Name
- Little Lady (2007)
We have grown some bugs in our diesel over the years. Our first experience was in moving our Crealock 37 down the Tenn-Tom Waterway to salt water after lying idle in Lake Guntersville for much of a winter. We had treated the fuel with a biocide, which brand I do not recall, so my skepticism of those is alive and well. I started to see large fluctuations in the tach as the fuel filter started grabbing the bugs out of the fuel. We made it to a marina which had a shop and I asked about having the fuel "polished" which was coming on strong as a solution at the time. An expensive solution.
The owner said to just replace the filter, and keep a few on hand. I knew what he told me, but it didn't really connect until he 'splained it to me. Diesels move more fuel through the filter than the engine consumes. The balance is returned to the tank. That means there is continuous "polishing" of the fuel going on. The only trick is to keep spares on board, and know how to change one and bleed the air from the lines if necessary.
The Crealock had an electric pump installed in the line. That is one addition which is a real help. Ours was in-line but was valved to allow fuel to flow through when it was not running. We kept it turned off during normal operation to reduce wear-and-tear on it. The pump we used as a #EP12B, a common OEM pump, which is available at most auto parts stores. When changing filters I could just turn it on for a minute or two and the system would self-bleed. Yanmars are pretty forgiving of small amounts of air as long as they did not die of total fuel starvation.
We did stir up the bugs which had been in hiding (sticking to the bottom and baffles) in large numbers once while crossing to The Bahamas in heavy seas. I was able to change a filter in minutes so just dove into the engine compartment, swapped one out, and we were eating conch burgers in a couple hours. Dual filters with a change-over valve would have been quicker, of course. But if real-estate was at a premium I would go for the electric pump as my first choice as an addition.
Our Atlantic 44 had Ford-Lehman engines and Lehman did recommend using Marvel Mystery Oil in the fuel. That sounds about like snake-oil to me, but those folks knew engines. We did use it all the time we had the boat. It was a top-end lubricant, not a biocide, of course.
RE the comments about filters, the Atlantic did have large, switchable, primary fuel filters. I never had to switch them. How's that for irony?
As to concerns that the vent is always open so bugs grow faster, see my solution to that at:
gallery2.php?g2_itemId=28091
The owner said to just replace the filter, and keep a few on hand. I knew what he told me, but it didn't really connect until he 'splained it to me. Diesels move more fuel through the filter than the engine consumes. The balance is returned to the tank. That means there is continuous "polishing" of the fuel going on. The only trick is to keep spares on board, and know how to change one and bleed the air from the lines if necessary.
The Crealock had an electric pump installed in the line. That is one addition which is a real help. Ours was in-line but was valved to allow fuel to flow through when it was not running. We kept it turned off during normal operation to reduce wear-and-tear on it. The pump we used as a #EP12B, a common OEM pump, which is available at most auto parts stores. When changing filters I could just turn it on for a minute or two and the system would self-bleed. Yanmars are pretty forgiving of small amounts of air as long as they did not die of total fuel starvation.
We did stir up the bugs which had been in hiding (sticking to the bottom and baffles) in large numbers once while crossing to The Bahamas in heavy seas. I was able to change a filter in minutes so just dove into the engine compartment, swapped one out, and we were eating conch burgers in a couple hours. Dual filters with a change-over valve would have been quicker, of course. But if real-estate was at a premium I would go for the electric pump as my first choice as an addition.
Our Atlantic 44 had Ford-Lehman engines and Lehman did recommend using Marvel Mystery Oil in the fuel. That sounds about like snake-oil to me, but those folks knew engines. We did use it all the time we had the boat. It was a top-end lubricant, not a biocide, of course.
RE the comments about filters, the Atlantic did have large, switchable, primary fuel filters. I never had to switch them. How's that for irony?
As to concerns that the vent is always open so bugs grow faster, see my solution to that at:
gallery2.php?g2_itemId=28091