Veg Oil/Diesel Mix in the Cold

pistonbroke · Post by **pistonbroke** » Thu Dec 20, 2007 9:05 pm

I've been running on a 33% (ish) mix for a couple of months now and have been happy with the results; no loss in performance/consumption and the feeling I'm able to buck the tax system in a small way. However, after filling up with 40 litres diesel and 18 of rapeseed Wednedsay evening, Freda wouldn't start this morning for the first time in the 13 months since I've owned her. Ususally she starts first time with only the briefest turn of the engine. There has been no previous indication of any problem. I can't imagine all four glowplugs have gone at the same time and there's plenty of oomph in the battery. I wonder whether the veg oil has gelled in the cold weather and clogged the fuel system up. I am considering siphoning the tank out and refilling with 100% diesel. Any other suggestions?

mikeonb4c · Post by **mikeonb4c** » Thu Dec 20, 2007 10:28 pm

it does seem unlikely that veg oil has gelled. I've got 10 bottles of rapeseed oil in my freezing garage and the stuff looks as clear and runny as when it was in the shop. Mind you, that doesnt mean to say the veg oil / diesel mix might not be harder to ignite when everything is so cold. Just started a thread on kerosene / diesel blending and came across this table:

Oil type.....Ignition Point (oC).....Gross Calorific Value (MJ/kg)
Jatropha....340..........................39.65
Palm.........314..........................39.54
Rapeseed..317..........................40.56
Sunflower..316..........................39.81
Kerosene...50 - 55.....................43.50
Diesel........55...........................45.00

It seems to suggest that rapeseed is quite a bit harder to set alight than diesel fuel. Out of interest (and assuming it isnt the fuse - it would be great if it was), what about trying one of those (alcohol is it?) sprays for the inlet manifold that people use in cold weather. Might be worth considering. It the engine does catch, it tells you there is probably an ignition point problem and/or glowplug system that is not up to the job in hand (and cold weather has found it out).

Good luck - keep us posted.

Mike

pistonbroke · Post by **pistonbroke** » Thu Dec 20, 2007 11:35 pm

Thanks John; thanks Mike. Just tried an alcohol spray myself so now going to bed. Will try a bigge hammer in the morning and let you know how things go.

dandywarhol · Post by **dandywarhol** » Fri Dec 21, 2007 12:19 am

I'd only use that spray as a last resort - it really gives the pistons a hard time

pistonbroke · Post by **pistonbroke** » Fri Dec 21, 2007 10:18 am

When I turn the key, there is a click and the dashboard lights come on as usual. The glowplug light goes out as normal, but there is no click a there usually is. Tried the fan heater thing and playing my paint stripping gun over the pipework, filter etc yesterday to no avail. Will bypass the fuse and check glowplugs today. The more I think about it the less I feel its a fuel issue, more a component failure. The problem didn't develop gradually. It all worked, then it didn't. Thanks again for everyone's input.

dandywarhol · Post by **dandywarhol** » Fri Dec 21, 2007 11:50 am

After the glowplug lamp goes out the relay/plugs stay on for around another 15 seconds if the key isn't turned to the start position.
If the engine does start the relay will click on and off depending on engine load - it's controlled by pressure from the turbo.
If the engine doesn't start then I reckon you'd need to turn the key back off then on again to repeat the procedure.

ronhud · Post by **ronhud** » Fri Dec 21, 2007 2:53 pm

Another thought - theres a fuse under the dash which is described as 'Engine' - replacing this solved a dead situation for me. I assume it controls the fuel pump.
Ron

ronhud · Post by **ronhud** » Fri Dec 21, 2007 3:53 pm

I put rapeseed oil in my freezer overnight and it came out like your phots. However I have posted elsewhere viscosity tests on Morrisons and Lidls oils down to -10c and though they ran slower they werent gelled. At this stage I cant say whether the gelling is the result of more time spent at a given temp ( say -10c) or having reached a lower temp than -10c. Ill put my thermometer in the freezer now and see what it reads in 6 hours.
Ron

pistonbroke · Post by **pistonbroke** » Fri Dec 21, 2007 8:25 pm

Wow........Thanks for everyone's interest. I've not a great deal to report - we're still not running. Removed the wire 'fuse' and ran a test lamp through it - it's fine. Removed two glow plugs & tested - they're fine. The other two are stuck and currently soaking in WD40 to get them out prior to testing. To be honest, I don't really know what I'm looking at. It's not a petrol V8, is it? It's a bl**dy diesel and therefore not 'proper' and belongs in a tractor. That's a bit harsh I suppose - I am coming round to the world of the oil burner, but still have a little way to go.

Freda's currently in my mechanic's garage. If anyone can get her going he can. His view is that it probably is a fuel issue and that some siphoning will be necessary. We'll see. He closes for Christmas, but is coming in in the morning to get me back on the road. Diamond, or what? Hope so 'cos we are booked into a site for our New Year and would rather no cancel.

BTW Miss F, he also says that, in the old days, he used to add petrol to their diesels (about a gallon/4.5 litres to a Bopngo-sized tank) to help cold weather starting and give it a bit of zip).

Surprised (and grateful) for all the interest shown. Will update.

Ralph · Post by **Ralph** » Fri Dec 21, 2007 9:05 pm

Would not think petrol would help with starting,
quite the opposite, I have come across 2 or 3 Diesels
that have had petrol put in by mistake and non were
very happy.

BongoMTBer · Post by **BongoMTBer** » Fri Dec 21, 2007 9:25 pm

The reason that they do not like the petrol on it's own is because it compresses and combusts before it reaches the top of the compression stroke, ignites and tries to push the piston the wrong way. A bit likee over advancing the ignition in a petrol engine.

However, the pertrol mixed with diesel works on two counts. It lowers the CFPP temperature. It also increases the volatility of the fuel helping the starting process when the cold fuel cannot be atomised and or vapourised so well by the injectors.

Ralph · Post by **Ralph** » Fri Dec 21, 2007 9:55 pm

Re petrol not convinced better you than me.

dandywarhol · Post by **dandywarhol** » Fri Dec 21, 2007 11:46 pm

An xmas cracker says your fuel filter is choked. Has it ever been changed since you first started using veg mix?
Veg tends to clean out the system - tank, pipes etc. and the filter should be changed earlier than usual the first time mix is used.

dobby · Post by **dobby** » Sat Dec 22, 2007 1:26 am

If it's the fuel filter - which sounds very likely, could it also be the metal strainer jobby that's fiddly to get at? i.e. as per this thread:

http://www.igmaynard.co.uk/bongo/forum/ ... t=strainer

Hope you get it fixed in time for the hols

bigdaddycain · Post by **bigdaddycain** » Sat Dec 22, 2007 1:43 am

paul9 wrote:i use veg 50/50 during the summer,i am down to 80/20 diesel veg now at this time of year,came across a drum of veg KTC finest,with a couple of litres left in today,so i thought i would pour into a spare petrol can to save space.
started to pour but nothing came out,this is why.

drum had been in back of car for a few weeks with just a few litres left in

it seemed to have set like treacle

these are the blobs of oil when it finally came out

i am wondering if it could set like this in your tank,and it wasn't particulary cold up here in lancashire today.
this ia straight veg oil with nothing else,it is the few litres left from topping my bongo up a few weeks ago,drum was in the back and not left outside.

Woah!... Thats not a good look

I have a few litres of neat veg in a plastic container out back, i'll check that in the morning for any signs of gelling...we only live a few miles apart paul,so if my oil is ok,its not looking too promising for the costco stuff (both oils have been in the cold in close proximity of each other)