Carver Owners Forum

Astonishingly, I find nothing on a search for 'diesel bug' here. My (or, correctly, my Son's) boat has an infestation. Carver's failure to install any sort of inspection hatch in the tanks now prevents me from scouring the tanks of this vile nastiness, and I have to resort to 'treatments', lengthy waits and many diesel/water filters before I can expect relief.

Doubtless, this is isn't an issue which worries too many of the Petrol users, or those who use their boats continuously throughout the year, but we tend to be fair-weather bods who grab a sunny and wave-free day once in a while, and so the fuel festers with whatever condensation drips in the tanks. It's a bugger.

Complaint: No bloody inspection hatches; I can't clean out the tanks without removing the damn things from the boat, or extensive, fiddly messing about with pressure hoses and driers.
Result: Use of feeble anti-bug 'treatments' and many, many expensive changes of filters for the foreseeable future.

Signed; Hacked Off of Northern Ireland.

I don't think anybody puts inspection hatches in the tanks on pleasure boats. Do you have places over there that "polish" fuel for things like diesel gensets for commercial locations? Perhaps they could make a visit to the boat. That may not entirely clean everything up, but at least reduce it to a manageable level. You can also put a couple filters in parallel with a selection switch so you can quickly switch to a fresh filter and continue your journey until you are back in harbor and can change the clogged up one. Are you actually seeing water in the filter or just diesel algae?

Without thorough cleaning (as in by hand, not just pumping around) you are indeed in potential trouble and worry for a long time.

On mine hatches were made at some time in the past. This is perfectly doable. Just do it properly: seal it with something that you can remove and re-use. Not flexible rubber/gasket or crap like that. They did that on my boat.

On mine the wooden floor is made over the tank, the dinette is also half over the tank so it's a big job to have it removed to clean the bilge underneath (diesel was spilled I think, smelly) and to re-work the hatches. They made one by positioning the circular saw half under the steps. Understandable as that is the lowest point and you want to reach that. But they forgot that you need to make holes, thread and put screws in for which you need a bit of space above.... Work gently, do not bend the aluminium as you want a flat surface for the covers.

When you make these openings, do not forget the vertical anti-slosh panels inside. I can just not reach one chamber due to the location of the holes. Which made cleaning even more of a hassle. I have a 1991 26 command bridge / 28 sedan with a 105 gallon tank / 400 liters. I have some pictures somewhere, even in my topic I think. On the other hand, you can do it with only two: one at either end of the tank. This will take a lot of flushing with a powerful pump but less hatches is less work on closing/sealing them later on.

My suggestions after my experience with this are:
- make a man hole (20cm or so) at the lowest point, take into your design the closing. Cork gasket or something diesel-proof (don't know what that would be) and stainless screws all around. Preferably more than on hole. depending on where you can reach the tank.
- clean out the tank: pump it out and then rinse, mop, and so on. Messy and smelly but do it right once and you're ok for a long time. and you can keep track of the condition of the tank by opening a hatch rather than just by examining the filters after problems.
- clean the filter housings and remove the filters of course. flush the hoses
- replace the filter at the engine too of course, depending on the state of the separator/filter before that one you could postpone this a bit to make sure it runs for a while on new diesel through the hoses. Then replace and from now on monitor the tank and the filters.

Of course: check every possibility that water got into the tank in the first place. Mine had none that I could find but did have years old diesel in the tank.

Fill and add anti-diesel bacteria poison in the right amount. Consider switching or adding synthetic diesel (GTL / HVO or whatever names they give it). Less smoke, less smell and no bacteria.


While you are at it, you might want to do a bit of plumbing and create a bypass so you can switch to a bypass tank (jerrycan) in case of trouble (just remember to insert the return too).
and perhaps a way to switch filters (double filter install) en route quickly. Didn't get round to do that on mine due to limited time and material at hand.

PossiblyPaul wrote:Source of the post ....Carver's failure to install any sort of inspection hatch in the tanks..... Complaint: No bloody inspection hatches.....

I'm curious, was the diesel install original from factory or was this a repower by a previous owner from an original gasoline build? There were two TAMD31 models in production prior to your production year but I was surprised to see them installed in your particular model.
While I've come across many diesel applications with tank cleanout ports, I've also seen just as many without them in just about every brand. It may be preferable for some but there's a few reasons why most opt not to install them.

Unfortunately the toxic soup is a downside to using diesel but only if you don't follow some basic measures of prevention to begin with. Certainly being a dock queen and barely ever going out increases your chances of having older fuel which doesn't help. Treatments have their place and help as a proactive measure but they can't perform miracles with conditions that have been left unchecked for years.

for the record: I have AD31B Volvo Penta units with duo prop sterndrives. 1991. The tank is the original (with green sticker on it) and the hatches were sawn in later. The Racor separators have American text on them.

How would I recognise a change from petrol to diesel engines? I find the fuel line installation messy but that may have been caused for other reasons during its lifetime.
I think it's been converted because it has (had) the ventilators in de engine room, hanging about and ducting loose. Perhaps these were installed early, before a choice for fuel was made.

The water tank is positioned on a small wooden platform over the valves for the head's hoses, can't imagine that being original. How was the watertank mounted (location is the same as on a plan I found) originally?

PossiblyPaul wrote:Source of the post Astonishingly, I find nothing on a search for 'diesel bug' here. My (or, correctly, my Son's) boat has an infestation. Carver's failure to install any sort of inspection hatch in the tanks now prevents me from scouring the tanks of this vile nastiness, and I have to resort to 'treatments', lengthy waits and many diesel/water filters before I can expect relief.

Doubtless, this is isn't an issue which worries too many of the Petrol users, or those who use their boats continuously throughout the year, but we tend to be fair-weather bods who grab a sunny and wave-free day once in a while, and so the fuel festers with whatever condensation drips in the tanks. It's a bugger.

Complaint: No bloody inspection hatches; I can't clean out the tanks without removing the damn things from the boat, or extensive, fiddly messing about with pressure hoses and driers.
Result: Use of feeble anti-bug 'treatments' and many, many expensive changes of filters for the foreseeable future.

Signed; Hacked Off of Northern Ireland.

That used to be the scourge of all the sailors at the club. They spent the entire year bragging about never using the engine and, "I only used 2 litres of fuel the whole season." Then they spent the off season trying to get the tank and system cleaned of algae.......

Ya nasty stuff if you let it get out of control.

PossiblyPaul, my curious mind wants to know....

The tale to date has involved an inspection with a little camera on the end of a long wiry thing, shock and horror, and no real solution other than to fire a bottle of Diesel 16 into the tank and let it kill everything in there. As I said above, this means lots of filter changes, but I suspect that - after only a couple of runs of the engine - the gunge has clogged up the second filter on my stbd engine and it won't start. I should really stop whining at this point, but anyone with a couple of TAMD31s in his or her boat will recognise what comes next; getting to the bloody filter (let alone the little pump arm) and changing it. Half the boat has to be dismantled first (a slight exaggeration, but it's a lot of sweat and pain) and the exhaust tube must be removed if you don't want to knife off half your arm to get there.

Wish I had petrol engines now.

uhm.. add a pre-filter between tank and engine? Perhaps it's not standard, mine has water separator / filters and then the fuel goes through the filter on the engine. Clogged up the separator ones two times and not so much the engine one. Changed that only after the tank and first filter was clean. Did help a smoother idling engine so there was some reduction in flow.

The flakes floating around in my tank were way too much to pump out by running the engine, it even clogged the pick up tube. After the cleaning I put the poison in for prevention. Didn't change the filters yet as the engines are running fine for 100 liters of fuel till now.

What I also did to get the air out that may have entered when the filters were off was to suck the fuel through the fuel lines towards the filters with a somewhat oversized pump (noticed the oversizedness when seeing it slush around with great enthusiasm...oohps). In hindsight, I should have flushed those fuel lines longer. And perhaps later in the sequence: at the engine.

About the filter and the manual little lever pump: I filled the filter and screwed it on, then pumping worked on one engine (bit of fuel coming out of the vent screw) but on the other one nothing came out, felt like it didn't pump at all. But I only had to unfasten the fuel lines slightly to vent the trapped air and that was it. Didn't ask any more questions on the 'why' of that

I'm going with Phrancus's advice on this now; alongside the Marina's magical marine diesel Expert (who only sails now, the swine) who got the engine going beautifully today, I saw the effects of the vile Bug on my fine filter. This coming winter will see the two tanks out of the boat and thoroughly scoured out - or even replaced with smaller, collapsible (?) plastic (?) ones, together with a couple of hatches installed on top. I don't use the boat for more than a few hours weekly, so there's plenty of opportunity for the bug to infest and procreate, given the moisture conditions in there. Bloody annoying, or what?

Edit: I discovered why I'd spent most of an hour pumping the little lever to no effect after consulting the Manual, by the way; apparently a half-turn on the camshaft with a hammer wrench solves that issue. (I have anger issues sometimes).