Biodiesel compatibly

[Seadoc777]

I have a 1977 CT41 with a Perkins 4108. I have been using Biodiesel B100 for the last four years. I just discovered fuel in the bilge after adding fuel thru the deck fill pipe. Investigation found the fill pipe where it bends to meet the fuel tank is very soft and gummy and is the source of the fuel leak. My question, has anyone had a similar experience with Biodiesel compatibility and any problems with engine components; lift pump, injector pump, filters and/or aux fuel pump, and engine oil?

[Lepke]

The only issue I know of is biodiesel acting like a solvent, rapidly dissolving sludge and clogging filters. Washing State or BC ferries were using about a 50/50 mix and were having filter problems. I know several people using 100% bio and no issues with standard diesel hoses, pump seals, etc.

[Steve Bean]

For several years I used vegetable oil from restaurant fryers as fuel in two 1980 diesel Mercedes. It was successful, but at first the primary filter clogged repeatedly with gunk from the tank and fuel lines. I learned to swap out that filter in five minutes. That oil, and biodiesel, can also dissolve some rubbers.

[a64pilot]

Up to B20 can have some advantages if your system can handle it.
However due to the very real problem of “bugs” growing in the fuel, I’d avoid it in my boat.
One of the biggest problems with Bio Diesel is there is no standard, and there are several different ways to create Bio with different problems.

I know this from going through the process to certify an aircraft to fly with Brazilian Bio Fuel. One issue was that you can have no brass or copper in the fuel system as that will change the fuel chemically.

John Deere at the time had the best, most scientific driven papers on the issues, look for their literature.

A quick Google came up with this, it may be good reading
https://www.deere.com/en/engines-and...ore/biodiesel/

[Aloha_float]

Pure biodiesel has a very high acid number so is unstable in terms of ability to remain in storage for any length of time. Degraded biodiesel has a black honey like consistency and is relatively insoluble so can cause a lot of issues with filtration and pumps. It can degrade hoses as well.

Blended biodiesel also has some issues but anything below B7 is relatively ok. However, you will still encounter small spherical contaminant that is degraded biodiesel that has fallen out of the fuel.

There are other cold flow issues but probably not worth discussing here.

On the plus side, it the presence of biodiesel does improve lubricity.

Biodiesel can hold up to 10x more water than ULSD and this increases the likeliness of microbial contamination.