Plantoil/diesel conversion basics
Sign up Latest Topics Chat
 
 
 


Reply
  Author   Comment  
danalinscott

Moderator
Registered:
Posts: 934
Reply with quote  #1 

One of the most valuable gauges you can install in any conversion is a VO fuel pressure/vacuum gauge.

This will not only warn you that your VO filter may be plugging long before you are forced to change it...it will help identify most fuel system problems much more easily.

One of the least expensive pressure/vacuum gauges is a "boost gauge" normally used to monitor the pressure from a super or turbo charger. Like this one from Summit.

For safety a pressure isolator should be installed in the line to the gauge.

It is also handy ..especially on a new conversion (either DIY or a kit) to have some way of monitoring VO fuel temp. If you only have a single VO fuel temp sensor/probe in your conversion it should probably be mounted either in the VO filter outlet or just prior to the IP inlet.

A temp probe (and dash display) in the VO fuel filter outlet will allow you to easily determine if the VO filter is sufficiently heated enough to be able to flow hot VO. If VO filter temps take significantly longer to reach the desired temp than the engine does to reach operating temperature you may want to add more VO fuel filter heating. If the VO fuel filter outlet temps fall to lower than desired while at highway speeds you may want to add more VO heating components to your conversion. 

The simplest temp sensor/display is an indoor/outdoor type thermometer like the one shown here.


The sensor must be well insulated with foam to get close to accurate readings on surfaces but it is relatively simple to zip-tie it to nearly any surface under an insulating foam sheath. These thermometers are usually accurate to +-3° but are limited to a maximum temp of 155°F in most cases.  In most cases this is more than sufficient.


They are more and more difficult to find...so if you DO find a good source for them please pass it along and I will link to it so others can easily find them.

Another option is to use an automotive coolant temp probe and gauge and install the probe in the filter-head outlet by tapping in a threaded port similar to that in the GoldenGlow heated filter head. Alternatively a tee can be installed in the VO line where ever you want to  monitor the fuel temp using the "Little Angel" adapter. This can be easily fabricated using the free "How-to" file available HERE.  When choosing a coolant temp gauge it is best to find one that has a range from 100°F or lower though these are much rarer than the normal gauges that have a lower limit of 130°F.


 

__________________
Dana danalinscott@yahoo.com
FloydTG

Registered:
Posts: 1
Reply with quote  #2 
Dana,

would you be willing to elaborate a little on these vacuum/pressure gauges and why they are useful?  I appreciate your recommendation in incorporating them in a conversion system, however, if i installed one i wouldn't even really know what to look for or how to interpret its readings. 

also, do you have recommendations for other types of senders/temp probes/guages?

thanks very much
tim

danalinscott

Moderator
Registered:
Posts: 934
Reply with quote  #3 
Quote:
Dana,

would you be willing to elaborate a little on these vacuum/pressure gauges and why they are useful?  I appreciate your recommendation in incorporating them in a conversion system, however, if i installed one i wouldn't even really know what to look for or how to interpret its readings.  
 


In conversions that have a positive pressure between the VO filter and IP a pressure gauge is used. Conversions that normally  have a negative pressure between the IP and VO filter use a vacuum gauge. Both type of gauges are installed by teeing in the sensor tube of the gauge to the VO line between the VO filter and the IP.

Most commonly both types of gauges are used to determine if the VO fuel system is operating properly or if there is a blockage at the VO filter due to contaminant accumulation or overly high VO fuel viscosity.  By noting/marking on the gauge face the "normal" operating pressure that is present when a fresh filter is in place and the operating pressure when a filter is so contaminated it must be replaced one can use a pressure or vacuum gauge to warn of when a filter will soon need replacing.  As the filter element becomes more and more clogged with contaminants the gauge needle will creep farther and farther from the gauge zone it does with a clean filter element. 

I use a thin triangle of green tape to mark the gauge where the needle points to at highway speeds when a clean filter has been installed. A second red triangle is placed on the gauge face where the first signs of fuel starvation is noticed or at the minimum pressure the IP requires. A third yellow triangle is placed at 25% of the distance from the red triangle to the green one.  If I notice the gauge reading in the "yellow zone" I change the filter at the next convenient opportunity.


They can also help identify if there is insufficient VO heating taking place prior to the filter since too cold VO fuel will be more viscous than sufficiently warmed VO fuel. If unusually low pressure/high vacuum is noted it may indicate that one of the existing heating components has failed...or that additional VO heating may be needed.

In some cases particular IPs require a minimum positive pressure in order to operate without incurring internal damage. In these cases an audible alarm and flashing dash light are smart additions to a pressure gauge.

Generally pressure gauges should be chosen that have a range that is around double  what the expected operating ranges will be.  For example if the expected operating range is around 8psi a 0-20 psi gauge is appropriate. The gauge is best mounted where it is easily observable..and preferably has internal lighting that can be connected to  the stock instrument cluster so is lighted when the instrument cluster is lighted.

Quote:
also, do you have recommendations for other types of senders/temp probes/gauges?
 

Yes...and I  wiil post those recommendation in the top post of this section ASAP.


__________________
Dana danalinscott@yahoo.com
forbey

Registered:
Posts: 21
Reply with quote  #4 
The specks for the Summit gauge linked to in the first entry in this thread indicate the sending unit is not enclosed. Do you have a link for the sending unit as well?

One option, I'm researching, is to install one before the filter and one after the filter so that the difference can be noted at a glance.

Jay
Previous Topic | Next Topic
Print
Reply

Quick Navigation:


Create your own forum with Website Toolbox!

This forum is brought to you by A proud sponsor of Invest in the future.