Is it really hot enough?
Moderator: Fatmobile
Is it really hot enough?
How do you know when your oil is really hot enough? What happens when it's not? I've read alot on this topic and still wonder. With my Caddy running on used veggie, the temperature sensor I have mounted on the pump intake fitting( copying Fatmobile's idea) reads up 2 notches on the dash guage. That's the best I can get. Mounting a small insulated tank that holds 12 liters by the engine, heating the tank( filter submerged) with a coil, then sending this oil back through one of the 3' heater lines just does not seem to get that pump real hot. It's like a cooler in itself, that pump, and how is the oil supposed to stay warm going through those steel injector lins with the cold air blowing over them. I've tried running my return back to the tank, back to the pump, and heating it with a small exchanger, then to the pump. My pollocks are right next to the pump, mounted on my tank. Harder starting in the morning, occasional uneven idling has really got me wondering. Sign me puzzled.
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Fatmobile
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cold oil
Dear Puzzled,
Uneven idling is what I've noticed when the oil is too cold.
If I'm reading this right, your heat exchanger (other than the oil being warmed in the tank and the filter being in the oil) is a 3' HIH.
That doesn't seem like enough. You tried adding a small heat exchanger and that didn't help?
A return to tank probably just made it colder.
The pump usually adds heat to the oil and in the winter I insulate the metal injector lines but oil doesn't give up it's heat as quickly as water.
When my coolant was only reading 2 notches up on the gauge (thermostat issue), it ended up being around 160F when measured at the resevoir with a boiler gauge) ... that should be enough to keep it idleing right.
How's your timing? It works better for me to have it plenty advanced ... seems to smooth out the idle.
Harder starting in the morning would be because it isn't flushed long enough on shutdown. There shouldn't normally be any cold vegy in the pump when you go to start it up. You said Pollack's so you probably have one on the return line, instead of the lame "one solenoid return to the front of the pump" setup that takes 13 miles to flush to get a good start.
With my looped setup I flush for a mile and a half in the winter (at 55mph in high gear).
Sign me Wondering
Uneven idling is what I've noticed when the oil is too cold.
If I'm reading this right, your heat exchanger (other than the oil being warmed in the tank and the filter being in the oil) is a 3' HIH.
That doesn't seem like enough. You tried adding a small heat exchanger and that didn't help?
A return to tank probably just made it colder.
The pump usually adds heat to the oil and in the winter I insulate the metal injector lines but oil doesn't give up it's heat as quickly as water.
When my coolant was only reading 2 notches up on the gauge (thermostat issue), it ended up being around 160F when measured at the resevoir with a boiler gauge) ... that should be enough to keep it idleing right.
How's your timing? It works better for me to have it plenty advanced ... seems to smooth out the idle.
Harder starting in the morning would be because it isn't flushed long enough on shutdown. There shouldn't normally be any cold vegy in the pump when you go to start it up. You said Pollack's so you probably have one on the return line, instead of the lame "one solenoid return to the front of the pump" setup that takes 13 miles to flush to get a good start.
With my looped setup I flush for a mile and a half in the winter (at 55mph in high gear).
Sign me Wondering
I've been flushing the system for about 1 mile at 20mph down a sideroad, we've been wondering about that distance, since on start-up I'm sure I smell veggie. Truck is in the garage so cold start is 32F. The timing advance makes little difference at that temperature, even if I'm only running on diesel, but I've never tried it warm and idling on veggie. It only idles unevenly once in a while on veggie, but I can always tell I'm on it by the idle. Maybe I'm on the fringe here for temperature, need to get an infra-red gun. My tank has 6' of 1/2"copper pipe wound in a 6"coil around the filter and the whole tank gets really hot under the insulation. The veggie supply line entering the pollock is very hot to the touch. The original idea was to have the cab and box free of any tank but I'm realising now that the long run of HIH is hard to beat. The copper is short term, I heard it's a mistake to use it. I will try flushing for a longer period, insulate around the pump and go from there. Signed feeling better.
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Fatmobile
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return line
Yeah the smell of vegy at startup means it wasn't completely flushed out. That's trial and error.
Where is your return line going to?
Where is your return line going to?
My return line is going back to the tank now. I've tried looping directly back into the pump; then I tried using the overflow line( with exchanger) to heat the loop going back to the pump. That gave me the 2 notches on the heat guage and it didn't run too bad that way. Yesterday we tried the 'back to tank return', that gave me only one notch on the temp guage and a very loopy idle. That proves what you said so now I know I got a heat problem. It was great though to drive for 3 hours north to Algonquin park and back for free, what a feeling. I guess my biggest concern is that the rings don't gum up. I think I will consider a tank in another location but it's been fun trying. 
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Fatmobile
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loopy
You might not need to move your tank.
It is very important to heat the loop.
You looked at my site so you know I have a fuel select solenoid on the input and one on the output of the injection pump.
I also designed a backflush setup.
My first backflush setup had the return line hooked to the vegy line just before it went into the input fuel select solenoid. I figured this way all the stuff I flushed from the pump would go backwards up the vegy line ... from the fuel select solenoid back. This way the whole vegy line in the engine bay would be filled with the thinner flushings as they were purged from the pump on shutdown. First vegy, then vegy/diesel, then diesel, if the pump was fully purged, would be pumped backwards down the vegy line ... from the fuel select solenoid back.
What I found was that when idling at 35F, or driving through town at 18F, the fuel temp would drop off.
The diesel is so efficient at idle that it hardly uses any fuel. The only heat getting added was in the fuel being used and added to the loop, which wasn't much.
I fixed this by connecting the return line to the output of the vegy filter (while on vegy). Now the fuel coming out of the pump was being run through a section of HWH (Hose Within a Hose) that runs from the filter to the IP.
I once figured that for every 5 cups of fuel going into the pump, 4 came back out the top. Much more is being circulated than is being used by the engine. By putting a section of HWH in the loop this fuel was being repeatedly heated.
After this change I was able to idle at 35F and drive in town at 18F without losing fuel temp.
You can probably figure out a way to heat this loop, maybe a little bigger heat exchanger than you had before.
The return to tank setup can work the pump much more than you realise. I would suggest you put a vacuum gauge in the place of your fuel temp sender (pictures of both are on the same page).
If you want a temp sensor (and since you already have the wiring there for it), I'd move the fuel temp sender to the return line. You could use a 1/8" NPT "T", put a couple barbed fittings on the straight through and tap the "T" to 10 M 1 so the stock VW temp sensor will screw into the "T". You'll have to make sure the "T" has a good ground to make the sender work right ... I'd solder a ground wire to it.
The input banjo bolt works great for a vacuum gauge connection, it let's you know how things are working on both diesel and vegy ... it also keeps me from having to "T" into the input fuel line ... things are also kinda crowded at the front of the pump with the fuel select solenoid and termination of the HWH going on, I didn't need to try fitting a temp sensor "T" in there as well.
Yeah driving on vegy is like a dream. Hard to believe it's real, possible and that I am doing it ... but I know it's not a dream, because if I smiled that big in a dream, I'd wake up.
I keep wondering why my friends keep buying those damn gassers.
It is very important to heat the loop.
You looked at my site so you know I have a fuel select solenoid on the input and one on the output of the injection pump.
I also designed a backflush setup.
My first backflush setup had the return line hooked to the vegy line just before it went into the input fuel select solenoid. I figured this way all the stuff I flushed from the pump would go backwards up the vegy line ... from the fuel select solenoid back. This way the whole vegy line in the engine bay would be filled with the thinner flushings as they were purged from the pump on shutdown. First vegy, then vegy/diesel, then diesel, if the pump was fully purged, would be pumped backwards down the vegy line ... from the fuel select solenoid back.
What I found was that when idling at 35F, or driving through town at 18F, the fuel temp would drop off.
The diesel is so efficient at idle that it hardly uses any fuel. The only heat getting added was in the fuel being used and added to the loop, which wasn't much.
I fixed this by connecting the return line to the output of the vegy filter (while on vegy). Now the fuel coming out of the pump was being run through a section of HWH (Hose Within a Hose) that runs from the filter to the IP.
I once figured that for every 5 cups of fuel going into the pump, 4 came back out the top. Much more is being circulated than is being used by the engine. By putting a section of HWH in the loop this fuel was being repeatedly heated.
After this change I was able to idle at 35F and drive in town at 18F without losing fuel temp.
You can probably figure out a way to heat this loop, maybe a little bigger heat exchanger than you had before.
The return to tank setup can work the pump much more than you realise. I would suggest you put a vacuum gauge in the place of your fuel temp sender (pictures of both are on the same page).
If you want a temp sensor (and since you already have the wiring there for it), I'd move the fuel temp sender to the return line. You could use a 1/8" NPT "T", put a couple barbed fittings on the straight through and tap the "T" to 10 M 1 so the stock VW temp sensor will screw into the "T". You'll have to make sure the "T" has a good ground to make the sender work right ... I'd solder a ground wire to it.
The input banjo bolt works great for a vacuum gauge connection, it let's you know how things are working on both diesel and vegy ... it also keeps me from having to "T" into the input fuel line ... things are also kinda crowded at the front of the pump with the fuel select solenoid and termination of the HWH going on, I didn't need to try fitting a temp sensor "T" in there as well.
Yeah driving on vegy is like a dream. Hard to believe it's real, possible and that I am doing it ... but I know it's not a dream, because if I smiled that big in a dream, I'd wake up.
I keep wondering why my friends keep buying those damn gassers.
Well that reply really took a while to think through. Had to draw it out but wow, what an idea! I'm picturing 80% of that fuel going back into the supply line, coming to that tee, logically it would flow back and draw the rest from the tank. So I got to thinking, if it worked for you, why not move that tee before my section of heated line. I almost ran out to the garage to change it, but it will have to wait till morning.
Moving the sensor is a good idea, for some reason I thought it should be at the supply side, but why not know exactly how hot the pump is. It's so tight between the pollock and the pump, I didn't want to put a tee in for a vacuum guage, but the hole where the sensor was is perfect for it. Got to pick one up at the hydraulic hose place.
So what is your timing delay with the 2 selector switches, changing over and changing back?
Moving the sensor is a good idea, for some reason I thought it should be at the supply side, but why not know exactly how hot the pump is. It's so tight between the pollock and the pump, I didn't want to put a tee in for a vacuum guage, but the hole where the sensor was is perfect for it. Got to pick one up at the hydraulic hose place.
So what is your timing delay with the 2 selector switches, changing over and changing back?
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Fatmobile
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flush time
Yeah, it took awhile to type too .
By timing delay I figure you mean how long till I switch to vegy after startup and how long of a flush.
In the summer I switch to vegy before I turn the key. the injection pump is full of diesel and the filter is backflushed and filled with the thinner flushings so even though I'm in vegy mode it's about 90% diesel and gets more vegy as it warms up.
In the winter I drive about 7 miles, when it's below freezing. Then I flip the switch and watch the vacuum gauge. If it rises higher than 5 inhg. I do a 1 second backflush (purge mode) which sends fuel back down the vegy line. This gives the vegy line a little pull/push action and gets stuff flowing. I can always pull over and idle it to keep the vacuum down and still get stuff moving but I usually just do the 1 second backflush till the guage stays below 5. It will drop down from there as things warm up.
Flush is about 1 mile at 55mph (or 1 1/2 minutes at idle)... then I tried something new this summer and instead of returning to the diesel tank after the flush, I put it back into vegy mode. This meant I shut down on about 90% vegy. It started OK so I did that most of the time this summer. Rarely returning anything to the diesel tank, the return line was almost always connected to the vegy line.
In the winter I flush for 1 1/2 miles at 55 or 2 minutes at idle, then return to the stock configuration of returning to the diesel tank.
.By timing delay I figure you mean how long till I switch to vegy after startup and how long of a flush.
In the summer I switch to vegy before I turn the key. the injection pump is full of diesel and the filter is backflushed and filled with the thinner flushings so even though I'm in vegy mode it's about 90% diesel and gets more vegy as it warms up.
In the winter I drive about 7 miles, when it's below freezing. Then I flip the switch and watch the vacuum gauge. If it rises higher than 5 inhg. I do a 1 second backflush (purge mode) which sends fuel back down the vegy line. This gives the vegy line a little pull/push action and gets stuff flowing. I can always pull over and idle it to keep the vacuum down and still get stuff moving but I usually just do the 1 second backflush till the guage stays below 5. It will drop down from there as things warm up.
Flush is about 1 mile at 55mph (or 1 1/2 minutes at idle)... then I tried something new this summer and instead of returning to the diesel tank after the flush, I put it back into vegy mode. This meant I shut down on about 90% vegy. It started OK so I did that most of the time this summer. Rarely returning anything to the diesel tank, the return line was almost always connected to the vegy line.
In the winter I flush for 1 1/2 miles at 55 or 2 minutes at idle, then return to the stock configuration of returning to the diesel tank.
I tried the return line modification you mention and it works perfectly. I'm up to the 2nd line on the guage and that was only a short trip; it idles perfect. Hope to make more improvements to the heated line soon now that I have a better idea whats going on. Too bad you couldn't patent some of these ideas. I have saved your posts to my VW file. Thanks
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Fatmobile
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there you go
I don't mind helping people get their system running right. Especially when they have the whole thing put together and are so close.
At least that way I know they aren't just wasting my time dreaming about a sytem they will never build.
I was the first one to suggest a filter backflush setup and the first to stick a vaccum gauge on a VW diesels fuel line.
The vacuum gauge is the standard on VW vegy systems now and I think most people move toward a filter backflush setup after they see the problems associated with the return to tank and looped to the front of the pump systems.
On my website, I do promote a booklet and follow-up support (for a $10 minimum donation) for anyone trying to convert their VW diesel to run on vegy but I wouldn't want to patent any of the info, even if I could.
I could probably sell system components like control panels and wiring. I found some DPDT rotary switches
Vacuum gauge setups would probably sell better because they should be in almost every VW diesel not just those converted to run on vegy.
Some gasser VWs also have a variable vaccum switch that can be put on the vacuum gauge line and control a beeper or light when the vacuum gets too high ...so people don't have to pay much attention to the gauge.
At least that way I know they aren't just wasting my time dreaming about a sytem they will never build.
I was the first one to suggest a filter backflush setup and the first to stick a vaccum gauge on a VW diesels fuel line.
The vacuum gauge is the standard on VW vegy systems now and I think most people move toward a filter backflush setup after they see the problems associated with the return to tank and looped to the front of the pump systems.
On my website, I do promote a booklet and follow-up support (for a $10 minimum donation) for anyone trying to convert their VW diesel to run on vegy but I wouldn't want to patent any of the info, even if I could.
I could probably sell system components like control panels and wiring. I found some DPDT rotary switches
Vacuum gauge setups would probably sell better because they should be in almost every VW diesel not just those converted to run on vegy.
Some gasser VWs also have a variable vaccum switch that can be put on the vacuum gauge line and control a beeper or light when the vacuum gets too high ...so people don't have to pay much attention to the gauge.
Sorry for the late reply. I mounted the tank between the timing cover and the inner fender. My tank follows the shape of the headlight holder in the front, sits on the frame on the bottom and follows the slope of the shock tower in the back. On the top it follows the line that the fender bolts to and on the inside it is 3/4"from the timing cover. Since I don't have a mig yet, I used 1/8"plate, so it is heavy. If I did it again I would use much lighter material. An access plate holds the filter which drops down inside the coil.