Update November 16th, 2006
Please note that since this install I have found out that the galvanized tee used in the video and installation is harmful to the engine and will damage it over time. This is due to galvanized metal's reaction to petrol fuels. Do not use galvinaized pipe as shown in the video and installation. Simply substitute black iron (gas) pipe or Brass for the galvinaized items.

September 4th

Today I moved the Vegtherm, installed a temp gauge & an on/off switch for the Vegtherm. I guess taking more then a week to do the initial install before helps speed it up the second time around - such as pulling the dash apart!

These things are all related

Vegtherm moved off the injectors. Previously I had installed the Vegtherm on top of the injectors (& in contact with them). Today I moved it to where Plantdrives suggest it be placed on Jetta installs (and does so on their installs). The reason I placed it on the injectors initially was to try and get as much heat from the vegtherm as possible. I thought if I attach it to the injectors I will at least get some additional heat transfer to the injectors that would normally be lost . I had read about signifacant tempature fall off after the IP and I thought why not get some last possible heat?

There were several concerns I had about doing this the more I thought about it.


  1. It makes the fuel line very long. By changing the position I was able to trim at least 2' off the fuel loop. This is better for shorter purge times and less oil being dumped into the diesel tank upon purge. I have a looped return
  2. It heats the diesel fuel.. Once the engine is at normal temp the vegtherm is doing exactly what I wanted it to do by attaching it to the injectors - transfering heat. The problem is when I purge, and even though the Vegtherm is then off, the engine heat must surely be keeping the vegtherm hot and by conclusion heating the diesel fuel. Now obviously this is a short period while purging but what about all those short trips I do and even though the engine is at switch over temp I don't do it because I will only be purging in a short time.
  3. It's really hot here in the summer. I'm concerned that in 100º+ temps and the vegtherm attached to the injectors it is too hot for the IP. I'm coming to the conclusion that it will get plenty hot enough.

Temperature gauge added. This is something that most people recommend doing as it tells you the temp of your oil at some point along the way. I based it on Dana Linscott's Little Angel plans that you can download for free. I wanted to tackle this project this weekend and simply went to Kragen Auto parts for a temp an electrical temperature gauge. It was $16 plus tax. I wanted something a little more stylish but this is all they had in stock.

The temp gauge kit, as most do, includes several size threads for the sender for various applications. You simply need to match one to a galzanized "tee" you purchase at a hardware store in the plumbing dept. You then need to install the sensor into the oil line somewhere along the way, wire the sender, wire the gauge & mount it. Everything was included in my gauge.


The sender wire was something I was not looking forward to since I would have to diassemble part of the dash and get the wire through the firewall. Again since I had done this before it was much easier this time around. I had already used the hole in the firewall that is used for the main wiring harness to pass the wires for the Pollak swicth though, so I used that opening. Someone pointed out an unused grommet higher up but I was familar with this one. I'm hoping to mention that one in the main install directions

The gauge needs to be wired so it only gets power while the key is on. On my inexpensive gauge there were 2 additional wires for the light inside the gauge. I just wired it so the light was on to make my life easier then trying to hook it up to the headlight swicth (nightmare). Conveniently the fuse box is right next to the location I picked for the gauge. I pulled power from the fuse for wiper blades or wiper wash, as I now they don't come on unless the key is on. You should always double check with a volt meter. On the '02 Jetta the wiper fuse is #24 and is located in the left most corner in the square portion of the housing. I then grounded the negative wire to a chasis bolt that was accessible via the fuse box. Both can be seen in the photo.

With my set up, no HIH(metal veggie line w/engine coolant jacket) & very liittle HOH (hoses together w/ insulation over them) , the temp gauge is only effective when the vegtherm is switched on and flowing through the system, as opposed to a strickly coolant based system which you could monitor the temperature before switch over as the oil is being heated while in line (HIH) all along it's path. Another complication for me with the Vormax in the trunk is that initially I have all that oil in the line past the Vormax and before the Vegtherm that is more or less unheated. Part of the reason I used aluminum under the car was to try and transfer some of the heat from the coolant loop to the the oil line. If the Vormax was installed in the engine bay the journey & quanity of cold oil would be much less


Plantdrive says the Vegtherm will raise the oil to 160º from room tempature in a very short time. This is because it is an electric based system and heats imediately after turning on. The idea is that this when used with a looped return allows for early switch overs to vegetable oil.

On my maiden voyage with the new temperature gauge, the car's OEM water temp gauge arrived at 190º (operating temp) in about 7 minutes. Generally speaking it always takes this long for it to get to this temp where I live. On this day it was 100º+ outside. Once the car reached 190º I threw the switch to veggie, as I ususally do. From there the car took about another 10 minutes for the new Veggie oil temp to show 160º.

I initially thought that the new gauge was being affected by the large galvanized tee that it is installed in (causing it to wait until the metal tee was also heated) but I think that the gauge is fairly accurate because when I return to diesel the tempature drops quite rapidly, so if the galvanized tee was effecting the sensor it would have to do the same when cooling off. I've since driven it at night when it is cooler and it takes much longer for the temperature gauge to reach 160 (upwards of 25 minutes). I'm hoping to keep a better log here.

So basically the oil is not getting as hot as quickly as I thought when the Vegtherm is turned on and when I switch over. This is disappointing and a problem but:

  • I'm more concerned with the engine temp then the oil temp. The oil will thin soon enough but we don't want to switch before the engine is at temp to prevent "coking" of the engine block or polymerization of the engine oil. These are the issues that trash an engine over time
  • As I understand it the cold oil is a viscosity issue for the IP and the strain it puts on the IP. A benfit of the looped return is to lessen the strain on the IP.
  • On the otherhand, I would also think that the injectors would have a different spray pattern because of the thicker oil.

    • I need to come up with a solution

    The temp gauge leads me to . . .


    On/off switch for the Vegtherm installed. Craig at Plantdrive intially suggested this. I asked him early on what if I go further then a tank of oil. How do i fuel the vechicle? I asked if I could put diesel back into the main tank. He said I could but I should turn off the vegtherm. (A better idea he suggested was to simply fill up -buy new veggie oil- at Costco and/or Smart & Final, etc.)

    On the origianl install I was so overwelhemed with everything else that I simply decided to make sure I could access the fuse for the Vegtherm. That way I could pull the fuse and turn off the Vegtherm if needed. Besides I wanted to try the systems as it was supposed to be before modifying. The only problem with this is that the pollak is in the oil position if I pull the fuse. Not a problem on a long trip if I need to put diesel back into the main tank but practical it's not.

    Again the ambient tempature plays a role. It's been incredibly hot here and on longer trips with the outside temp around 100º in a black car after a while I could probably turn off the Vegtherm.
    1. This lessens the strain on the electrical system
    2. less the chance of the oil getting too hot - if possible in these extremely hot conditions

    Today I took the car out as mentioned above. It was over 100º and the oil reached 180º in about 15 minutes of freeway driving. After that I turned the Vegtherm off and the oil maintained a temperature of 178-180º according to the new gauge. So this implies to me that in this mild enviorment , So Cal, I can turn off the Vegtherm when driving for extended periods once the Vormax gets up and running, if the temp is this hot outside. I will find out as it gets cooler here how it will affect my temperatures

    As for the install. Again I had removed the dash before so it went quicker this time but the whole lower portion of the dash must be removed to acces the upper dash where I installed the switches. After removing the lower dash the radio & cup holder can come out as one unit, although the climate controls need to be left in the console. Once accessible simply pop the punch outs out and install the swicth of your choice.

    The wiring was relatively easy as I just ran one wire from the switch to the brown wire on the Bosch relay and the other to the Vegtherm red wire. Both wires were 12 gauge and had to go through the firewall. I then grounded the swicth to the chasis

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