Need diesel tank access



My super maramu (not 2000) has, I believe, no access to clean the tank.  I know my tank is dirty since after 25 hours running the volvo the cleaned injectors are dirty again.

The volvo is out of the boat for a rebuild (2300 hours, but internal oil leak) so this is an ideal opportunity to create access hatches to the tank and clean it.  Does anyone have the tank specification, in terms of is it a single tank or are there separate compartments, and specifically where should the access hatches be cut?

As a side question, if I installed a day tank would that be a suitable alternative?


Eamonn Washington

Travel Bug SM 151

Cleopatra Marina, Greece

smiles bernard

i'd be really interested to hear other people experience with this question of how to access/ clean diesel tanks

I have a maramu 1985 and was wondering how i would ever clean the tank if needed

I assume it has baffles to add a spot of complexity!

On my old boat I cut an inspection/cleaning hole. Not the nicest job in the world, upside down in the bilges in 40+ degrees on the hard in Venezuela with a reasonably blunt hack saw blade. Happy days none the less :)

All the best



Hi Eamonn,

I have just cleaned (it was a try) as much as possible my diesel tank this summer by a dieselist from perkins La Rochelle. My SM isn't either a 2000. The access was only possible from the bottom of the tank. He took out the valve and put a new one in. When it was deinstalled I could try to cratch the black stuff out. You will never get all out! For this I have a big filter (300 micro meters) and a second one with 30 micros meters.
Before the dieselist let clean the dirty diesel by pumping out into a clean temporary tank with anti bug and push it back after have been holding through the night in the cleaning tank.

Hope this helps for the first time.

Good luck in Cleopatra Marina. I was there in 2000 during winter. Good price and good service.

Fair winds,

SM 124, Félicie, Switzerland



If you search the file section of the forum you will find an Amel drawing of the fuel tank for a Super Maramu that will help you understand what the internals of the tank look like. The drawing apparently is not 100% exactly as built, but it is close.

 If your tank is contaminated with water, you can extend a tube down the fill pipe to reach the deepest part of the tank to pump it out with a hand pump.

After enough time, even the cleanest diesel tanks accumulate hard, black "coke" on the bottom from the slow, unavoidable,  oxidation of the fuel. When this breaks loose it can cause all kinds of problems.  As far as I know the only way to clean it is to mechanically remove it.

I did this on my old boat, cutting holes in the tank, and using these to patch them up again: 

Be really, really careful cutting holes in the tank.  This might be best done by an experienced professional.  Diesel fuel and fumes are not very flammable, but a mistake can cause the tank to explode.  I know someone who came very close to dying when this happened to him!

Bill Kinney
SM160, Harmonie


Thanks for all the helpful replies.

I decided to do exactly what Bill suggested, mechanical removal via cutting access holes and welding back the holes again.

I removed the insulation, and by tapping the full tank it is obvious where the 3 baffles are separating the 4 compartments.  A professional marine steel worker will cut the 4 access holes and weld them closed again at the end.  All the fuel will be removed by another company and cleaned (if possible) and this other company will clean the tank too.  (I would like to get my hands dirty, but I simply won’t be around along enough for the job to be finished.

I mentioned the danger, cutting with diesel fumes, but I will mention it again.  He said he woud not do it if the engine was there, but I think that was mainly for the physical access to the tank.  (The volvo is in a workshop.)

4 Vetus insulation panels (60 x 100 cm) will cover the tank.

I will Also take the opportunity to install a second feed from the bottom of the tank and a second return tube at the other end in order to install a fuel polishing system.

Eamonn Washington
Travel Bug SM 151