To convert or not

[Johnnojack Senior Member Find all posts View Profile Close Johnnojack]

I have been running my Mercedes 190D for over a year on a blend of vege and petrol. Often not quite enough petrol as was shown this week when the temp dropped to 5degrees and I couldn't start it at all. Heated up manifold and top of injectors the with heat gun for few minutes but after a mild splutter no go.
Was late meeting a tradie after having to transfer to the Jackaroo, which started instantly BTW?
I've never been too comfortable with starting on cold oil or using petrol but am sure the Merc would start under any conditions if it had diesel to start on, so is it worth a simple conversion? I'm thinking a tank in boot with a facet pump for diesel, leave return as is and switch Vege off and on with gas solenoid. Any thoughts?

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: To convert or not

JJ, Try one of these valves.
They are available as 2 wire (you need a double pole, double throw switch wired as a reversing switch) 3 wire, (a single pole double throw switch will do) or 5 wire (which is like a 2 wire with indicator switches to show when operated to either state).
The one I linked to is a 20mm BSP thread so you just need some 20mm BSP hose barb adaptors to make it connect to your system.
No Pump needed as the lift pump on the IP will bring the fuel from the selected fuel tank.


I would prefer a separate fuel filter for each fuel so you do not need to purge the filter when changing to diesel at the end of the day.

Tony

PS, I used 20% misfuel (basically petrol with a little bit of diesel in it - from people who fill up their diesel with petrol) with veggie in winter in my Musso (OM662 2.5L 5 cylinder turbodiesel)

[fattima Junior Member Find all posts View Profile Close fattima]

Re: To convert or not

Different engine but I'm going to convert my Land Rover Discovery 300tdi.
It is getting harder to start in the cold Melbourne winter even with a 10% petrol mix and some extra diesel mixed in. I have heating so it is all good once the engine is up to temp.
Will be running two filters as per Tony's post and an electric lift pump as the Land Rover ones are known to fail.

[Captaincademan Senior Member Find all posts View Profile Close Captaincademan]

Re: To convert or not

Johnno,

if you stuck starting a diesel due to low temperatures (insufficient glow heat) you can always create a rough start with a can of deoderant. the propellant will self ignite like diesel under compression. of course the ignition timing is a little off (I think its a bit early) and it is a bit rough, but you will probably find that it will generate enough heat in the cylinder to support normal combustion within a few OTTO cycles.

I have started quite a few diesel engines for people (including my own) with deoderant. It is very effective if your glow system has failed either through failed plugs or some other electrical problem. Of course there is the "start ya bastard" and "aerostart", but deoderant works just fine too. Sometimes you may need a second person to stay on the spray can while you crank.

I find the best place to squirt it is in the PCV pipe where it enters the air cleaner box. very easy to get to with out tools.

[Johnnojack Senior Member Find all posts View Profile Close Johnnojack]

Re: To convert or not

Things went from bad to worse this morning. Jumped into the Jackaroo with frost on the windscreen, gave it a couple of glows and cranked her over but no go. Then discovered I hadn't flushed the night before. Oh no! This is not good. Trouble with running one car with single tank and the other with dual tanks after a period in the single tank car you forget what the procedure is in the other and do half the trip on diesel or forget to flush at the end. Ok so I had to get it going, got the heat gun and gave the manifold, intercooler, injectors, lines and IP a good 10 minutes of blessing. Still no go, bit hard to put petrol rag down the inlet like I did with the Merc so more waving the heat gun around for about 20 minutes final blast over the intercooler and quick dash to the drivers seat, a quick glow and crank. Started with enough blue smoke to alert the local fire brigade then after a minute settled down to steady idle. Won't be forgetting to flush for a while I can tell you.
Cade I did start the Merc with a bit of petrol on a strip of rag pegged in the inlet but not something I'd like to do on a regular basis.

Question for anybody who have or have had a Merc with a conversion, How long (distance) would you need to flush for for an easy start the next (cold) morning?

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: To convert or not

JJ, On my 300D, I went to 20% misfuel in the veggie blend for winter, otherwise no changes and no conversion necessary.
For a 2 tank system, purge time depends on whether you are purging the fuel filter as well as the IP.
If just purging the IP, about 2 minutes or less. depending on the engine power delivery (our driveway is 160m long and 15m elevation in that distance, so flick back to diesel at bottom of drive and drive up to the house, engine ready for cold start tomorrow)
I had to slowly pour a kettle of boiling water over the IP and injectors on one occasion with my first 300D (2 tank conversion) when I forgot to purge.

[Johnnojack Senior Member Find all posts View Profile Close Johnnojack]

Re: To convert or not

Fattima I've always liked the design of the 300tdi and it should be a good engine to convert. Purge times should be short as well. You plan sounds good. Try to minimise the length of unheated oil pipe before the IP. I did it by swapping the oil filter to where the diesel filter was, and moving the diesel filter back to the firewall, different engine though.

[Johnnojack Senior Member Find all posts View Profile Close Johnnojack]

Re: To convert or not

Thanks Tony, I will use another filter for diesel and tee it in just before the IP. While the factory lift pump would work for both fuels, it makes it impossible to use seperate filters that's why I planned a Facet in the boot.
Haven't been able to procure any misfuel yet, the Holden and VW service centres both have my number. Will call at Automasters I think.

[Johnnojack Senior Member Find all posts View Profile Close Johnnojack]

Re: To convert or not

Ok the time has come to go 2 tanks. Despite having a 20 km highway commute and never doing short cold engine trips the condition of my engine has become intolerable. Missing on starting which worsened to missing on idle when hot as well. An interstate run last weekend of 900km made no difference.
Had day off today with idea to take out injectors but hadn't socket to fit and no means to get to tool shop.
So started on conversion. No room for solenoid valve between filter and IP so it has to go between lift pump and filter. Teeing new line in to short hose between filter and IP from new diesel filter in front of Facet pump. Pump in engine bay to make it simpler to plumb and wire.
Going to try to decoke the motor by eliminating cold oil starts while gathering tools and supplies for possible injector clean

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: To convert or not

Ok the time has come to go 2 tanks. Despite having a 20 km highway commute and never doing short cold engine trips the condition of my engine has become intolerable. Missing on starting which worsened to missing on idle when hot as well. An interstate run last weekend of 900km made no difference.
Had day off today with idea to take out injectors but hadn't socket to fit and no means to get to tool shop.
So started on conversion. No room for solenoid valve between filter and IP so it has to go between lift pump and filter. Teeing new line in to short hose between filter and IP from new diesel filter in front of Facet pump. Pump in engine bay to make it simpler to plumb and wire.
Going to try to decoke the motor by eliminating cold oil starts while gathering tools and supplies for possible injector clean

JJ, Here is something you can do to reduce coking in the engine. I have had a lot of success with doing this in my Mercedes W123 300D.
With a hot engine at a fast idle, spray a mist of water across the air inlet (remove air cleaner). If a turbo-diesel, disconnect the air line from the intercooler and spray across that. continue spraying for 20-30 minutes, then stop spraying while leaving the engine running for a few more minutes. reconnect the disconnected inlet air plumbing and take the car for a good hard flog and see if it makes any difference. You need to get the exhaust really hot to evaporate the condensed water from it.
Check cold starting. I believe it should be much better.

Then get your injector socket and check the injectors for carbon build up and spray pattern. Rebuild injectors if needed.

Tony

[Johnnojack Senior Member Find all posts View Profile Close Johnnojack]

Re: To convert or not

Question. Since my 'conversion' hasn't extended to looping the return or changeover solenoids on the return, will I lose much diesel back to the oil tank when switched to diesel? Will this be made worse by having an electric pump? I'd prefer not to use up half a litre of diesel every time I start the engine.

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: To convert or not

JJ
Can you measure the return line flow (re-route the return line into a 5 litre can) and run the engine for 1-5 minutes to see how much you are pumping down the return line. You can then see how much you would be sending to the veggie tank. Adding a return line solenoid valve is much easier than adding one in the supply line as you do not have the pumps and filters in the way.

[Alga Senior Member Find all posts View Profile Close Alga]

Re: To convert or not

Johnno, have found it much easier to have both a return line and recycle line, that way can flush the system and yet when running recycle the oil. Also have a switch to turn of the inline pump under the bonnet, so just a matter of switching from the 5lt dino/bd tank to vo and back. You could also add either 2 stroke or ATF to your starter tank, that cleans out the crud in in the fuel system, especially if you are recycling as it is pretty hot by the time it come back round and works best that way.

On my 1hdt, it will go through a 5lt tank in a couple of minutes when using the return line. I run 1lt through then switch to recycling the fuel and when starting already have some dino/bd. so it's easy to switch when staring and you get a combination of dino and vo as the engine warms up. If you don't care how much dino you have in you vo tank then just use a return line, but have found when I recyclable vo on the road, have a bit more power for some reason an my inline filters don't crush up as they do sometimes.

Tony's idea works really well, but can be a trial, if yo add 2 stroke or ATF into every second tank of starter fuel, it tends to keep the system pretty clean.

[Johnnojack Senior Member Find all posts View Profile Close Johnnojack]

Re: To convert or not

Tony I did a rough check and found that about 0.5 litres per minute returned from the pump at idle, I suspect some even when the car was ready to start, ignition on and facet pump ticking away. When running probably faster even more than half a litre. Started with 9 litres and with priming air out, cranking the motor etc for about 10 minutes until I got the car to run again after having the fuel lines off I had only 5 litres in the diesel tank. So will have to do something. Probably 2 solenoids from a Tee in the return line, one returning to diesel inlet side (looped) and one to oil line returning to main tank.
Tony I don't have room for one of those big 2 way valves you linked to, a smaller one may work.

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: To convert or not

Search for motorised bvall valve DN15. I have seen some which are only a few inches long and high. Would they be too big for your vehicle?