Does diesel go off ?

[composimmonite]

I know unleaded has quite a short a "shelf life" but what about diesel ?
My Mahindra is always difficult to start (it's a project and not on the road) despite new starter, battery and glowplugs. Engine has only done 77000 miles and has good compression. The diesel in the tank is probably nearly 10 years old but I assumed it doesn't go off like unleaded.
I now intend draining the tank and putting a gallon of fresh fuel in but just wondering if old diesel could be a reason for poor starting ?

Paul H

[willowandmikey]

I didn't think anything effected those engines :-) I was in India once and the driver of the mahindra ran out of diesel so he used parrafin

[optimusprime]

Yep. it can 'go off'.
Bear in mind also that diesel also contains a certain amount of water, and given the right circumstances,it can absorb more,therefore making combustion harder ....

[murdock]

Diesel doesn't go off in the same way that petrol does and generall has a much longer storage life then petrol, however as mentioned before water mixing with it can be an issue, but also over time the 'cetane' rating of the diesel will decline, making combustion more difficult, you could drain the tank, or you can add a cetane additive to restore the fuel, which would be less hassle.

en.wikipedia.org/wiki/Cetane_number

[composimmonite]

Thanks.
After reading this -
www.bp.com/liveassets/bp_internet/australia/corporate_australia/STAGING/local_assets/downloads_pdfs/f/Long_Term_Storage_ADF.pdf
it looks like there can be problems - especially after 10 years !
I've a parts washer so can find a use for the old diesel so will try draining and fresh fuel.

HNY

Paul H

[Deleted]

the bacterial/algae growth can block filters and fuel lines so they may need cleaning/replacing as well.

[colnerov]

Dec 30, 2013 16:46:30 GMT @chip said:

the bacterial/algae growth can block filters and fuel lines so they may need cleaning/replacing as well.

Whilst that is true 10 yr old diesel is unlikely to be Bio-diesel.

I don't think it is any one thing, any un-used engine will be down on compression because the rings will be dry. Maybe not by much but on a diesel it does not take much coupled with as suggested too higher water content in the fuel. Fuel tanks should ideally be kept as full of fuel as possible. Less air > less humidity > less condensation. Drop the filter bowl and see if there is any water in it. If you are going to keep useing it infrequently it might be an idea to fit an agglomerator bowl.

Good luck!

Colin

[MrSpeedy]

Gas oil (red diesel) can certainly go off and depending on the age of the engine will affect in varying degrees.

As said, it loses its cetane rating a few points, so wI'll become less effective as a fuel.

Having worked on many an aged boat, believe me the smell of old stale diesel is something else compared to fresh!!

[waveman1500]

I know someone who works as a facilities manager for several large city buildings, which have diesel backup generators in the basement. He told me that the diesel in the tanks of one of the buildings was past it's shelf life and went off, so they had to get it all pumped out (10,000 litres) and replaced!