bobk
Legendary Member
- Joined
- Aug 27, 2005
- Messages
- 4,097
- Status
- OWNER - I own a Hatteras Yacht
- Hatteras Model
- 48' MOTOR YACHT-Series I (1981 - 1984)
I gave it away in the title, but thought I'd post this problem in case some one else runs into it.
I've been chasing a mysterious intermittent fuel leak for almost a year. It would appear after refuelling and initially showed up on the battery shelf in front of the starboard engine. We were pondering a fill hose leak because that was the closest source of fuel, but we ruled that out! In desperation I took a mechanic out for a check ride this week. First I stoppped for a fill up, then ran about five miles at speeds from idle to 2000 rpm. Nada. No leak. We tied up and went about getting dinner. Later we smelled diesel. There was a puddle behind the starboard engine. WTH?
Following another careful inspection, there was still no obvious source. We had already changed the fuel manifold valves and the sleeves on the Westerbeke injection pump (both minor leak sources). So I began taking close up pictures all around the engine space and viewing them on the computer. I was surprised to find the thin plastic tubing from the Hart gage to the aft tank had fuel in it. Double WTH, this tube should only have air in it, but this gage had failed on that tank and I never worried about it. The mechanic dissasembled the tank fitting and blew back on the tube and found a chafed area right above that battery shelf. The hole was quite large on this small tube.
It sure looks like the fuel ran down the formica battery shelf into the dead space below and then aft via a glassed in pipe to the bilge compartment behind the engine. The only explanation we have for fuel in the tube is after a run, the heat in the ER warmed the fuel and airspace in the tank and pushed fuel up into the tube and started a siphon. The vent is clear, but probably has a puddle of fuel in it which could allow just a bit of pressure to develop in the tank system. When everything cools after a few days, the contraction in the tank would pull the fuel out of the line. Leak stops.
While on the subject of the Hart monitor, the tank fittings on the holding tank are poorly designed/engineered. Mine have corroded apart and failed three times in five years. This brass and waste are not compatible. The monitor for the water tank is also acting strange and I'm planning to change out all the tubing in the whole system as soon as I can locate a source for the right tube.
Bobk
Chateau de Mer
1981 48MY
I've been chasing a mysterious intermittent fuel leak for almost a year. It would appear after refuelling and initially showed up on the battery shelf in front of the starboard engine. We were pondering a fill hose leak because that was the closest source of fuel, but we ruled that out! In desperation I took a mechanic out for a check ride this week. First I stoppped for a fill up, then ran about five miles at speeds from idle to 2000 rpm. Nada. No leak. We tied up and went about getting dinner. Later we smelled diesel. There was a puddle behind the starboard engine. WTH?
Following another careful inspection, there was still no obvious source. We had already changed the fuel manifold valves and the sleeves on the Westerbeke injection pump (both minor leak sources). So I began taking close up pictures all around the engine space and viewing them on the computer. I was surprised to find the thin plastic tubing from the Hart gage to the aft tank had fuel in it. Double WTH, this tube should only have air in it, but this gage had failed on that tank and I never worried about it. The mechanic dissasembled the tank fitting and blew back on the tube and found a chafed area right above that battery shelf. The hole was quite large on this small tube.
It sure looks like the fuel ran down the formica battery shelf into the dead space below and then aft via a glassed in pipe to the bilge compartment behind the engine. The only explanation we have for fuel in the tube is after a run, the heat in the ER warmed the fuel and airspace in the tank and pushed fuel up into the tube and started a siphon. The vent is clear, but probably has a puddle of fuel in it which could allow just a bit of pressure to develop in the tank system. When everything cools after a few days, the contraction in the tank would pull the fuel out of the line. Leak stops.
While on the subject of the Hart monitor, the tank fittings on the holding tank are poorly designed/engineered. Mine have corroded apart and failed three times in five years. This brass and waste are not compatible. The monitor for the water tank is also acting strange and I'm planning to change out all the tubing in the whole system as soon as I can locate a source for the right tube.
Bobk
Chateau de Mer
1981 48MY
