Diesel puzzle - enzyme additive?

[pvb]

I know very little about these additives frankly. I don't think most of us do. For that you need a chemist. I have however worked in the filtration industry and can talk with some authority on that.

What strikes me is that lots of enzyme based products have come on the market that appear to break down the biological sludge into something that will pass filters.

That's not what enzyme additives generally do. Diesel bug tends to produce a rather nasty sticky jelly-like deposit, which rapidly blocks filters. The enzyme additives are supposed to eat up the jelly-like stuff, leaving a scale-like deposit which has far less effect on filters.

 

[Marsupial]

The idea of a filter is clear, if anything can pass through it then it wont harm the engine. IF the engine is harmed by something that passes through a filter then see the engine designer for a refund.

My experience with the dreaded bug spans several decades, the first case of many involved tank removal, steam cleaning and poison; it failed to eradicate the bug, to be sure it was failing we stupidly repeated the process several times. Removing a fuel tank is no mean feat - we did it three times - and the bug came back within a month (each time we used new fuel) - cant remember what the poison was but it was a biocide that was supposed to clear up the bug.

Treated the fuel with fuel set and the bug went and had not returned up till the boat was sold several years later.

A vessel with a similar problem to to OP was treated with fuel set and left for a month, on returning to the boat no sign of the bug. Fuel is clear even though the tanks were not drained, the engine has now done several thousands of hours with no further fuel issues so less than 5 micron bits of dead bugs passing through filters and engines may not be a problem.

 

[boatmike]

That's not what enzyme additives generally do. Diesel bug tends to produce a rather nasty sticky jelly-like deposit, which rapidly blocks filters. The enzyme additives are supposed to eat up the jelly-like stuff, leaving a scale-like deposit which has far less effect on filters.

Well I thought that was in effect what I said, but to be clear you are correct that the ensymes attack the sludge but there must indeed be some sort of end product unless it's all given off as gas and this has to go somewhere so one assumes it passes through the filter. In fact if you read the Soltron publicity that's what they claim.

I also agree with the poster who suggested that anything that passes the filter should in theory do no harm but we should remember that the final filter is usually 5 to 7 micron nominal and I have indeed seen these additives cause the primary 15 micron filter to pass particles that then clog the final filter. However, as I said, I don't object to additives in principle. I just think that efficient filtration should remove the problem unless it has become extremely bad and something like a Racor centrifugal filter should make enzyme treatment unnecessary. Many boats rely on a simple filter and some don't even have a water seperator.

 

[RichardS]

ever since Dr. Blair of the Mech. Eng. Dept. at QUB (remember RaY McCulloch winning on his racing motorbikes?) published a very convincing report on it back in the nineties.

Was that the QUB Seeley - I remember reading about it in MCN in the late 1960s!

Richard

 

[Marsupial]

following on from my previous posting, my boats have always had fuel set from new and so far no sign of the bug, when they were young I removed the filters at the prescribed intervals and cut them open to see what they had trapped - the 5 micron filter had nothing in it with the exception of a small amount of red sand. I continue to treat with fuel set and dont bother to change the filters so often.

 

[boatmike]

following on from my previous posting, my boats have always had fuel set from new and so far no sign of the bug, when they were young I removed the filters at the prescribed intervals and cut them open to see what they had trapped - the 5 micron filter had nothing in it with the exception of a small amount of red sand. I continue to treat with fuel set and dont bother to change the filters so often.

In a previous post I said "When you have done, by all means add one of the many preventive treatments that will effectively prohibit new biological contamination but in my opinion avoid the ensyme treatments entirely if you can".

Fuel set is one of the preventive treatments I was talking about. In fact I use it myself in conjunction with a primary Racor 15 micron and 5 micron final filter and have never had a problem. Prevention is certainly better than cure. One other thing to watch for however is water which can come about due to condensation in a half empty tank subject to large temperature variations especially in winter. Keep your tank full to reduce the air space and if possible close all vents by covering with an oily rag.