Fuel tank leak (gas)

[Chuck in WA]

Howdy all.

So I went to check on the boat recently and found a bilge full of fuel (gasoline) - UGH!!!! The marina contracted with a company to pump it out the next morning (at considerable expense to me), and one of the techs identified a small hole in the Stbd tank due to corrosion.

I'm just starting to research this, but it's my understanding that, unlike diesel tanks, gas tanks can't be repaired/patched, so it looks like I'll need new tanks made. So, I'm looking for suggestions for: 1) someplace that will fabricate new tanks and 2) a yard to do the work.

After reading many fuel tank threads on this most excellent forum (thanks to all of you btw), it sounds like I may have two options: Either cut the tanks apart (after purging of course) and replace with a series of smaller tanks, or pull both engines and R&R the old tanks with similar new ones. Either way, this looks to be a large project.

The boat is a 1985 Tollycraft 40' Sundeck, and I'm located in the Puget Sound region. The boat should still be usable running on the one good tank via crossover valves, so I can travel. I haven't tested or run this way yet however.

Any and all suggestions welcome, thanks in advance!

PS - if there's a bright spot to my predicament, it's that this didn't happen while out cruising, but rather while still on the hard at the marina yard for winter. Also, during my annual spring and fall testing of my bilge pumps, I found one to be faulty so I removed it. The replacement is sitting on my gally countertop - thankfully I hadn't installed it yet!

 

[tiltrider1]

Gas tanks can be repaired but most likely it will cost the same to repair as to replace. The only way to repair is to weld and the cleaning process in order to weld is expensive.

Since you are gas, R&R the engines is pretty easy due to the light weight. I usually pull the engine and tranny as one unit. I don’t like cutting up gas tanks, very dangerous. I like to pull the tank out whole. This gives me the best picture on what I am getting into and what sizes the replacement tank should be.

I don’t usually haul out to do a fuel tanks.

Just about any yard and most engine shops are capable of doing this job. Shopping around will get you the best price.

You could call Gallery Marine and Yacht Performance in Seattle as a starting point. Haven Boat works out of Port Townsend is also a possibility.

 

[sunchaser]

Wow!!!

Nearly 40 year old tanks and gas. Replace the “good” one too and all the fuel lines, valves etc. Aren’t those Al tanks? The bilge smell may take awhile to dissipate.

 

[rslifkin]

Having a gas boat with 37 year old aluminum tanks, this is my single biggest fear. Fortunately, I had my tanks moved out of position for water tank access about 1.5 years ago and also replaced the senders in them, and from everything I could tell, they're still in good condition.

As far as replacement goes, I agree that moving the engines is likely to be the best way to do it. Getting the tanks free of vapor to cut them up safely would be a pain, and you can't link multiple tanks together with gas (as all fittings have to be on the top of the tanks). So replacement with multiple tanks per side would complicate fuel management.

 

[Pete Meisinger]

This is a subject which gets about as much travel as anchors and singles vs twins.

I have a tiny leak in my starboard tank right now which has been patched with JB weld (diesel) I have not tested it yet as I really don't need that much fuel. I balance with my water tank level. I intend to do a better patch this summer. the JB was to get me through the last season.

I am lucky, I can sort of get to the tank leak. It is a pain, literally. I have to remove all my batteries and wiggle like a worm to get to it.

Anyway, if I were you.. knowing what bilges look like with twin engines, knowing you have gas tanks and knowing you are a millionaire (LOL) . Bite the bullet, pull the engines and replace both tanks.

pete

 

[luna]

I would caution you about running on only one tank. To do so safely, one would need to ensure that all (at least 99.999% of it) of the fuel has been removed from the leaking tank and that the crossover system is not contributing any new fuel into the leaker. How do you know that the crossover valve is not slowly leaking? Perhaps its best to remove and seal the crossover plumbing to the leaker.
Neither of these is easy especially the fuel removal without any large access openings into the tank.

If you chose to replace with the like tank route, the original tank will may still have a label (mine do) on the top that was installed by the manufacturer which indicates the size, capacity, test pressure, material type, etc. If they exist still, they may prove helpful.

Above all, be safe.

 

[Comodave]

I would not try cutting up gas fuel tanks. How do you figure how long to purge the tank? And what if you are wrong and there is still some fumes left when you put the sawsall or grinder to it. When I was in the Navy we used to purge the aircraft fuel tanks with compressed air for several days before working on them and that wasn’t even cutting them. I would pull the engines. We pulled the engines in our previous boat one at a time. I reinforced the deck under the remaining engine and set the pulled engine above the remaining engine. It took me a couple of hours to set up the crane and unplug and remove fuel lines, etc. then about 2 hours for 3 guys to hoist the engine and block it in place over the remaining engine. And these engines were diesel so they weighed almost 1,400 pounds. Gas engines will be a lot lighter and easier to move. We did it DIY and it was fairly easy. I was going to replace the fuel tanks as a preventative measure but my back went out so I didn’t get to replace the tanks. I did clean up the engine room so it was worth it. Unfortunately for the new owner one of the fuel tanks did start leaking about a year after we sold the boat.

 

[rslifkin]

Assuming the engines are 454s, expect to be about 1100-1200 lbs for a fully dressed engine/trans combo. Pulling the trans, manifolds, etc. will reduce weight if needed.

 

[Comodave]

Assuming the engines are 454s, expect to be about 1100-1200 lbs for a fully dressed engine/trans combo. Pulling the trans, manifolds, etc. will reduce weight if needed.

That would be easy to lift. When I built the crane I made sure ever component was rated at least 2 times the weight of the engine.

 

[Larry M]

If you are going to remove the tanks, you may still have to cut them to get them out. That was the situation on our last boat. The tanks were installed then the deck added. Not a big deal for gas tanks. I was in the gas tank removal business back in the 80s/90s and probably removed 100 plus gas tanks and also cut them open to clean for disposal/recycling. We used dry ice at a ratio of 25lbs/1,000 gallon tank capacity. The carbon dioxide displaces the oxygen. With a meter you can check the oxygen content and lower explosion limit so the tank(s) can safely be cold cut.

I’m not suggesting you do this your self but there are companies in your area that does this regularly. Good luck.

 

[Comodave]

I like to DIY on my boats. For many years, like 50+ I would never let anyone work on my boats except me. Now since I am old, turned 70 in March, I am revising that policy.

 

[Chuck in WA]

Thanks for the responses all, very helpful. Just to re-iterate - I won't be doing this work myself.

Sunchaser - yes, the tanks are aluminum. And perhaps surprisingly, the gas smell dissipated quite quickly once the fuel was removed. It was very strong initially, and when I first went below to investigate, I had to egress quickly to avoid being overcome!

Rslifkin - good point about linking multiple gas tanks. I guess I should have been able to put 2+2 together when reading up on this but didn't. So new single tanks are the answer.

Luna - good comment re: backfeeding the bad tank. Safety first!

I'm starting to warm up to the idea of pulling the engines (probably don't have a choice anyway). In the end, I'd probably save some billable yard hours, as this would likely be the fastest method. I would also have the option to have the engines sent out for rebuild. While they still have great compression and purr like kittens, they are getting long in the tooth (approaching 4000 hours).

Thanks again all.

 

[rslifkin]

I would also have the option to have the engines sent out for rebuild. While they still have great compression and purr like kittens, they are getting long in the tooth (approaching 4000 hours).

What engines are they specifically? Not a lot of people manage to keep gassers healthy for 4000 hours, so it's good to know what the engines are and what kind of use they've seen to get there.

 

[Comodave]

At 4K hours on gas engines I would seriously think about rebuilding them at the same time if it is in your budget. If they have been run easily they may be fine but itq looks like your boat is a big one and if it has seen much time on plane they probably could use a rebuild.

 

[Chuck in WA]

They are Crusader 454s. I’ve had the boat for almost 9 years (where does time go?). In that time, I’ve run WOT maybe 3 times, and for periods of only a few minutes. The rest of the time I loaf along at 7 knots. Maybe 8 if I’m in a hurry

However, as we use the boat mostly as a fair weather weekender rather than distance cruiser, the majority of hours were logged before my ownership. The prior owner passed away before I took possession, so I don’t have much in the way of older maintenance logs.

If anyone has a rough idea of rebuild cost, I’d love to hear it. And I suppose the Velvet Drives too, sigh……

 

[tiltrider1]

They are Crusader 454s. I’ve had the boat for almost 9 years (where does time go?). In that time, I’ve run WOT maybe 3 times, and for periods of only a few minutes. The rest of the time I loaf along at 7 knots. Maybe 8 if I’m in a hurry

However, as we use the boat mostly as a fair weather weekender rather than distance cruiser, the majority of hours were logged before my ownership. The prior owner passed away before I took possession, so I don’t have much in the way of older maintenance logs.

If anyone has a rough idea of rebuild cost, I’d love to hear it. And I suppose the Velvet Drives too, sigh……

First, I am impressed that the engines have 4000 hours. However, it’s possible that the engines have been rebuilt with out the hour meters being replaced,

If the engines are not using oil or blowing blue smoke. I don’t think I would invest in a rebuild at this time. If you are going through a quart of oil every 10 hours then it’s probably a good time to rebuild.

 

[Comodave]

No idea what a rebuild would cost. But if you have to pull the engines to get to the fuel tanks I would certainly check and see what it costs because you would save a lot of labor cost for the removal and replacement. Once you have an idea what the costs are then you could make an informed decision. The transmission could be done at a later time since they are usually easier and cheaper to pull out.

 

[rslifkin]

You mentioned having done a compression test. What kind of numbers did you come up with? And how much variance between cylinders? If the compression numbers are truly good, oil pressure at hot idle (after a hard run) is good, and oil consumption isn't excessive, then they may not be due for a rebuild yet. The heads will likely need to be gone through before the bottom end is tired.



One of my 454s is up to just under 1900 hours and still checks out healthy. It burns a little more oil than the other one, but still not much. Mine were likely run much harder than yours for much of their life though, so I'm not sure I'll see 4000 hours out of them.

 

[Amy J]

With 4,000 hours you may want to consider new GM crate engines over rebuilds. I put one in a hot rod I built 20 years ago, fairly inexpensive considering they are brand new.
It still runs great and I have never had a single issue with it.

 

[Chuck in WA]

Thanks again all. Engines burn no oil to speak of (and don't smoke), and compression on all 16 is a low of 88 and high of 95psi (with most being 90, although this was a few years ago). I suppose it's possible that they have been rebuilt and the hour meters weren't changed, but boy I'd be upset if I were the one to foot the bill for that and NOT change the meters. And as I mentioned, the previous owner passed away and I didn't find any paperwork in "the stack" to indicate a rebuild. But who knows.

I was contacted by 2 other owners of my boat model who were able to remove tanks by cutting up part of the floor. I'll have a look at the feasibility of this when I next visit the marina. At least I know it's been done, and therefore an option to consider.

 

[rslifkin]

If those compression numbers were taken with the throttle held open and ideally with the engines warm, then they're quite low for a 454. Based on that, I'd say they're definitely tired and could use a rebuild. Although if the numbers were stone cold with the throttles left closed, they might be fine. If in doubt, get the engines at least lukewarm and re-test (with the throttle held open and all spark plugs removed for faster cranking speed).

 

[tiltrider1]

If you can replace the tank without removing the engine then do it. Save the engines for a different project.

Odds are if one tank is leaking the second tank is only 1 to 3 years behind. Pull the bad tank first. If you can identify a true one of a kind failure such as a cracked weld or a drill hole then pulling the second tank is not necessary. Odds are you will find a hole from corrosion. In this case pull the second tank as well.

 

[Chuck in WA]

Thanks gents. I guess when I mentioned my compression being "good", I should have said "mostly even" across the cylinders, i.e. nothing catastrophic indicated. That, and the mechanic doing the test said they checked out good - but I'm not an engine expert, so yes probably worthy of another test. I wasn't able to attend during most of his inspection due to other commitments, so I'm not sure about his testing methodology.

I'm pretty confident the leak is due to corrosion (I am able to get eyes on it), so I'll definitely be doing both tanks.

 

[Chuck in WA]

Quick update: I was finally able to get to the yard today, for the first time since posting this thread. Good news, after some quick/rough measurements it appears the tanks can likely be removed without disturbing the engines (save for possibly the outboard riser on each, to allow for rotation). I'll be meeting with a yard rep later this week for more info.

Also, and this is somewhat embarrassing to admit, the engines are pushing 3k hours, not 4k, after looking at the meters today. It's been a long winter I guess.....

 

[Comodave]

Well that is a good thing, but 3K hours on a gas engine is still pretty high.

 

[rslifkin]

Based on that, I'd pull the tanks and take care of those. Being that the engines are running well and your compression numbers are pretty even across the cylinders, I'd run them for now. When it's convenient, do a warm, open throttle compression test to get better absolute numbers. Monitor oil consumption, and next time you run them hard, check oil pressure at idle with them good and hot. If that all checks out, then I'd call them "still healthy" and not worry about a rebuild yet.

 

[heysteve]

Back in the day, there used to be a guy who specialized in removal of aluminum fuel tanks from boats. Apparently, his trick was to put a vacuum on the tanks to reduce their size. Might be an interesting experiment if you had access to a pump.