Hi Jeff
had some personal experience with this last week. While replacing the fuel filter on my 60 series, 24v through out (except the radio connections) I must have got a huge air lock in the pump because it took an age to bleed. Predictably the batteries got run down, but luckily we used a 12v tractor to jump onto one of the batteries and we were able to bleed the system through from the power this supplied. I'm sure this isnt exactly good for the batteries but it got everything running again.
As for why 24v on a landcruiser I have no idea. I worked in agriculture for years and nearly all tractors are 12v and they employ some fairly hefty diesels. I only really saw 24v on eastern european tractor, and what a delight they were!
James
hi Christopher
thanks for the explanantion.im sure its been covered before but i must have missed it..you said that the starter uses 24 volt, which i understand, but what about the rest of the electrics in an 80 are they 12 volt, and if so how,
and if i try and jump another (12 volt) car using the left hand battery (as i look into the bonnet) does it deliver 12 volts?
I suspect thats it someting to do with batteries connected in seres or parrallel but ive no idea what that means
regrads
jeff
From: "Christopher Bell" <[Email address removed]>
Reply-To: [Email address removed]
To: <[Email address removed]>
Subject: RE: [ELCO] direct injection diesel / huge starter motor
Date: Tue, 24 Jan 2006 09:47:59 -0000
Jorgen
Apologies if you already know the below, but here is a brief explanation of diesel engine starting.
Diesel engines are "compression ignition", meaning that the heat generated by compressing the air in the cylinders is enough to ignite the diesel when it it injected. You can feel this for yourself if you pump up a bicycle tyre using a hand pump: the end will get hot, and if you do it vigorously enough it can be too hot to touch - the mechanical work of compressing the air is turned into heat. So diesels don't need, and don't have, spark plugs.
Some diesel engines have glow plugs, which literally glow red hot due to electric current, to help with starting when they are cold; but these are usually "indirect injection" engines, in which there is a small cavity above the cylinder where the fuel is injected. Typically they glow for a few seconds before starting to warm things up, and turn off automatically a few seconds after the engine has started.
"Direct injection" engines, in which the fuel is injected straight into the cylinder, don't normally need glow plugs as the heating effect from compressing the air is enough to start the engine. However it does mean that direct injection engines need powerful starter motors, and the Euro spec 80 series diesel has a huge 24 volt starter for this purpose - hence my comment. (I don't know its exact rating, but it is around 2kW which is about 3hp.)
I don't know anything about the D-4D engine other than that it is direct injection, but if yours has a manual gearbox I should think it will bump-start OK. When I had battery trouble I bump-started my 80 series very easily in 2nd gear. If you have an auto box don't even think about it!
Again I don't know about diesel catalysts, but so long as you don't squirt masses of unburnt fuel down the exhaust I don't see that it will be a problem. So as long as it bump-starts reasonably quickly it should be fine.
Christopher Bell
From: [Email address removed] [mailto:[Email address removed]] On Behalf Of Jorgen Gronberg
Sent: 23 January 2006 22:07
To: [Email address removed]
Subject: [ELCO] direct injection diesel / huge starter motor
Hi Folks,
My eye caught the e-mail from CB mentioning direct injection
and a huge starter motor.
Does that also imply that I for example shall be able to bumpstart
my LC3 D-4D 120KDJ ?, does the engine start on the heat generated from
the compression only, and thus ready to fire when the injection happens?
If a bump start is used, will that cause any problems with the catalytic
converter if the engine does not fire-up immediately?
Regards Jorgen KDJ120 UK
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