removing fuel tank

SJN

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May 30, 2021
37
Catalina C310 Seattle
Buried behind a webasto heater, the autopilot arm and its associated bracing, and I think prohibited from removal without first extracting the water heater, my fuel tank either has a leak or hoses I cannot see or access are loose causing weeping fuel in the bilge when the tank is full. Advice on how to inspect and if needed, remove the tank is appreciated. Feedback and advice is appreciated.
 
D

Deleted member 117556

We went through this fun exercise in 2020 when our fuel tank sprang a leak in the middle of a months long cruise in Florida. It was a pinhole at one of the weld spots at the bottom edge and a bilge full of diesel was our first and only hint. Veey hard to access and even confirm the leak-make sure you use a white cloth like a paper towel because myleak looked like water until i saw the red color on the paper towel. We did a temporary repairwith JB Weld which got us home to GA. Once home i hired a professional to do the replacement although i was next to him the whole time. Attached are some pictures and itis very difficult to access but removing the monstrous, factory installed 20 gallon water heater really opened up the stern area. Even with that, the fuel tank would not come out without cutting off the bottom of the propane locker (see pics). Removed the old tank which was held in place by 8 screws and had an identical replacement fabricated locally. While doi g this we replaced the water heater with a new 6 gallon version which is more than enough and really opens up the lazarette for storage. The tank we pulled out stated it was 17 gallons (specs say 20) and i was hoping to get 20 gallons into the replacement but alas when i filled it 16 gallons was all it took. The propane locker bottom was fiberglassed back on and we were back in business. It was a very expensive projectb but had to be done. New fuel guage sender and new fuel guage does not work very well which is a dissappointment. When full it reads between 1/2 and 3/4 but i am slowly figuring out how it relates to what isin the tank. When first installed the sender leaked like crazy but using liquid gasket material around it has eliminated the leakage. Hope this helps and i wish you luck and maybe it is just a hose... Last picture attached is the new tank.
bob
 

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Tom J

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Sep 30, 2008
2,322
Catalina 310 Quincy, MA
We had the same leak that #1 described. Pin hole leak at the seam weld at the bottom of the tank. We had plans to leave on a cruise soon, so we had a local boat yard pull the tank. They had to remove the aft bulkhead of the aft cabin, and the water heater, but no other surgery was required. Lots of labor involved, since they first tried to remove the tank through the access door. Once the tank was out, I took it to a welding shop and they repaired the leak. This was in 2006, and no leaks since. As an aside, I spoke to Mr. Butler at Catalina about the warranty, but the boat was three years old, so no dice.
To find the leak, I thoroughly dried the tank, and monitored it for a few days. Nothing showed up anywhere on the tank that I could see, but the pan under the tank kept filling up, which left the bottom of the tank as the prime suspect.
 

SJN

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May 30, 2021
37
Catalina C310 Seattle
Thank you for your detailed replies. I feared having to cuts things away to access the tank. I have tightened as many hoses as can be accessed and cleaned around the bottom of the tank. No leaks with a half full tank. I will add fuel a little at a time and check for leaks. I desperately hope the problem is a loose or bad hose!
 
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Feb 20, 2013
52
Catalina 310 Channel Islands Harbor
There is no need to cut anything. The propane bottle holder is easily removed. There are four screws and some sealant holding it in place.
The tank can be removed after removing the hot water heater. It is tight and the fittings on top of the tank also need to be removed for clearance.
IMG_0161.jpeg
IMG_0161.jpeg
 
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Likes: Tom J
D

Deleted member 117556

There is no need to cut anything. The propane bottle holder is easily removed. There are four screws and some sealant holding it in place.
The tank can be removed after removing the hot water heater. It is tight and the fittings on top of the tank also need to be removed for clearance.View attachment 202278View attachment 202278
This is correct but we were unable to remove the propane holder. After removing the screws the sealant used around the holder would not budge and we were very afraid of damaging it beyond repair. At that point it was easier to cut and repair. You do make a great point that i had forgotten about!
 
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SJN

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May 30, 2021
37
Catalina C310 Seattle
Thank you all for your very helpful information. I plan to do the work this spring and will add information at that time.
 
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Likes: Tom J

SJN

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May 30, 2021
37
Catalina C310 Seattle
Update. The comments above were very helpful, providing the path to remove the port propane tank locker to access the fuel tank. With clear visibility of the fuel tank from above, the leak was easily spotted. The Webasto fuel siphon gasket was weeping diesel. It only leaked when the fuel tank was full and either the boat was heeled or temperature was very high during a hot spell in the Pacific Northwest.

Removing the propane tank locker was assisted by a product that weakens caulk. A razor knife was used to scribe around three sides of the propane locker. Scoring the caulked joint next to the transom is not easy. I used a long piece of stainless steel with a sharpened end and carefully tapped it in the joint to release the caulk.

The current siphon gasket was tightened and is not leaking. However, I will replace the gasket before recaulking the propane tank locker.

Thanks to those who provided advice, you saved me from unnecessary work.