I am planning to run my Mercedes 709d on SVO- I used to an old 307d on it and it purred smoother than on diesel..

I will only be using a single tank and will be attaching a heat exchanger. At times I will be running the vehicle on 100% diesel. Does it matter that the 100% diesel will be pre-heated by the heat exchanger before being combusted. Will it adversely effect performance or damage the pump/engine?

I am fairly confident it won't but just wanted to double check.

Cheers Mike

Heat exchangers are often used on 100% diesel using vehicles as very cold diesel is problematic.
Coolant heated heat exchangers cannot heat fuel hotter than the coolant and when the engine is fully warmed up the fuel will reach this temp anyway.
Hot distillate does not lubricate as well as cold distillate or as well as biodiesel or as well as vegetable oil so regardless of whether a heat exchanger is used or not it is advisable to add a little vegetable oil to your distillate to improve lubrication.
Electric heaters are another thing altogether.

Magic 98Troopy

Thanks for that advice! I am going to running it 100% SVO most of the time- except on start-up but will sometimes need to run it on 100% diesel, particularly in the couple of weeks before the merc has to go through its MOT.

Either add a valve in the coolant plumbing to the heat exch or add 1L of oil to each tank of diesel.

The Valve will allow you to turn off the heat to the heat exhanger.
The oil will improve the lubricity of diesel - significantly better than cold diesel.

Regards,
Tony

How will you be starting on diesel if you only have a single tank conversion?

Also why do you need to use diesel for your MOT test? There's nothing illegal about using WVO in UK, as it is excise exempt up to a certain limit (not that it would concern an average mechanic anyway). Are you concerned it won't pass the emmissions test with WVO?

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Sean

Hi Pangit

I use one tank which has a diesel-SVO mixture which I vary. The van won't start on 100% SVO from cold but it will run fine on it when warmed up. So I will leave roughly 40% Diesel 60% SVO/WVO for cold starting. When its warmed up I fill it up with enough SVO/WVO to get to my destination and slip a bit of diesel in just before I get there to bring it back up to 40-60.

Its passing the emissions test I am concerned about. When I used to run my 307D on SVO the emissions readings were off the scale partly I think because the sensor was picking up a lot of unburnt oil.

Anybody else had this problem with emissions?

Here in NSW the annual roadworthy test (equivalent to MOT) is a lot less strict that the UK and we don't have to do an emissions test.

I'm not sure about other states in Oz but I think they are even less strict. e.g. in Victoria I think you don't even need to do it every year, only when the vehicle changes ownership (somebody correct me if I'm wrong).

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Sean