Ok bit of a story,
My 1968 Columbia
36 is soon to be splashing again after spending winter on the hard
. I bought her last fall and motored her a couple hours to new marina, without any issues with engine
has a 12-15 year old Yanmar 3gm30
that seems to be in excellent shape. I am assuming at the same time they installed a new diesel
tank (poly tank) that is mounted on a shelf in aft cockpit
locker. They self is roughly same height as cockpit
floor so the diesel tank is mounted higher up then the engine
. This winter I noticed that the self (raw plywood) was half rotten so this winter I simply replaced the shelf with epoxy
. I didn't want to go re-engineering diesel tankage. So the quick and easy solution was to simply replace the shelf with new plywood
. Figuring it worked well for previous owner so........
Today I completed that task, re-installed the diesel tank (about 28 gallon tank), connected the supply and return lines. And that is when the problems started....... Those lines feeding into the engine compartment (which again is lower then the tank. Bottom of tank is roughly same height as cockpit floor and obviously engine is under the same floor. So supply line first goes into a shut off valve that is attached to a Racor
filter and water
separator. So when supply lines are full of diesel they are syphon gravity feed down. So normal process to change the Racor
would be shut off valve open bleed valve and bottom drain. Reassemble and reopen shut-off valve and bleeder which siphon fills the everything. Unless you run out of diesel system primes by gravity feed. So I guess the Racor pump
probably hasn't been used in a very very very long time. It was siezed and once freed didn't pump
anything to get flow started. After a bunch of testing and figuring this out I actually used air to pressurized the tank just enough to get the diesel flow started and eventually got everything bleed. So Yanmar
is back to funtional and operating the same way it has for a long time.
However, now that I fully understand the system I am debating options and possible problems. First a fuel
leak would siphon empty the diesel tank into bildge..... That would of course be bad, so I will be very careful about turning off the shut-off valve, but I do have to move stairs, open hatch
, lay on floor, turn valve... You get the point. I will also mention that there is also a water
tank on other side of boat
to balance against the weight of diesel on port side. There are of course some positives like once you get the supply line full of fuel
gravity takes care of priming systems (no little pumps to worry about) Now I do need to fix or replace the Racor so pump works, pressurizing tank worked but isn't great solution if I ran the tank a little too, but it got me ready to splash in the next week or so.
My hope is to simply use system like it is now for this season, get some good experience on the boat before I go making any major system changes. That seems OK to me, but hoping for a sense check from the community. What potential risk am I not thinking of with diesel tank mounted so high up and having a gravity fed system?