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Discussion Starter · #1 ·
I need help. I had a small diesel leak develop on my last trips of the season. I could not track it down before i winterized. I am hoping it is one of the lines, but if it is my tank (20 year old 3/16" alum) I will have to pull an engine to replace it.
Is there a reliable way to test the tank, if I have to bite the bullet and replace it i would want to do it while it is laid up. I am 90% sure it is not the tank, since it only leaks when running, but if I find out in the spring it is the tank I will loose lots of fishing time. Thanks
 

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If its the tank it probably should still be leaking, is it? You could slighly pressurize the tank through the vent tube and see what happens, but I strongly suspect that if it only leaks while running then its not the tank.
 

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Lines First

Lines First.

It does not sound like it can be the feed line. If the feel line had a leak you would suck air and most likely stall the motor. The return line however could leak without any performance problems. Except for the fact that the return just dumps fuel with little or no line pressure.

Check your Racor for air bubbles, If you have a suction leak that is where it will show.

Under load and running I would really carefully examine all fuel filter fittings & the injector pump housing.

What type of a diesel?
 

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Discussion Starter · #4 ·
They are detroit 8.2's
I am trying to isolate the tank one way or the other without running the engines since thry are winterized. If I could run them now, I would be able to diagnose better, but trying to avoid the potential down time
 

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disconnect the fuel lines at the engine and attach fittings that will allow you to caoff one ned, and apply pressure to the other. Do not apply more than a cople pounds of pressure- four is the amount used to test for CG certification, but youy can still blow open a weld at that. Two pounds will be enough for you to sit quiet and listen, and watch for an hour to see if you loose pressure. When you hear a leak, search it out w/ soapy water and a brush- the leak will bubble. It's tough sealing the vent sometimes, and sometimes the fill will leak air.

If you are sure it is a running leak, I would look to the return first, then the feed line, then tank fittings and the filter. Could be that the leak is in the tank, a bit higher than the present level in the tank, and trim or return run-dowm were getting fuel to it.

Paul
 

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the tank and lines were 20 years old and the lines were in decent condition, but it was where the moisture sits on top of the tank where i got the hole which became the size of a nickel when i just tapped it with a screwdriver
 

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Your not alone. Just found out both aluminum tanks leaked diesel after topping off and layup. Dropped the levels down a bit and it stopped. All the line on top of tanks, return fill and vent were dry. Both tanks had the fuel polished in 04 and the bottoms looked good on both during a visual. Both tanks are in the the house so they don't wet. Hoping to find a screw hole leak when they used long self tapping screws to secure the sound insulation to the plywood sides which house the tanks on both sides of the CAT 3126. This ride is 1985 30' SISU.

Good Luck
F/V Irian
 

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Had a leaking tank the year,leaked 24/7 the holes were at the bottom so could not miss it.when i had the tank out i was shocked it was only two small pin holes.Good luck
 

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Tankage

I am mgoing to try to pull my tanks out because I am convinced there is probably a bunch of sediment or something in at least one of them. I don't know how old they are but they seem to be stainless L shaped 125 gallons each. I will have to take my V-Drives out at least. I hope I don't have to take apart the decks. 1970 32' Luhrs.

vsk
 

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ReelTime wrote:
I am mgoing to try to pull my tanks out because I am convinced there is probably a bunch of sediment or something in at least one of them. I don't know how old they are but they seem to be stainless L shaped 125 gallons each. I will have to take my V-Drives out at least. I hope I don't have to take apart the decks. 1970 32' Luhrs.

vsk

You can probably clean your tanks without taking them out of the boat.
 

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Tankage

I may give it a shot if I can't take them out. I would like to see what's going on under them and put some new rubber to cushion them as well. I know there are a few services I can try if I am in a bind.
I have to change the seal on one of my V-drives anyway and the bolts holding the joint together are rusted to round nubs in tight spots.

vk
 
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