Mod to eliminate HIH termination inside tank?
June 10, 2011 - 12:53pm
I've been running veggie for 7 years and maybe 80-90k miles on Frankenstein systems, and I have never had good success with HIH's not leaking (probably a reflection on me more than the concept of HIH), so when I got a used Greasecar spare tire tank the other day, I was concerned to find that the HIH terminates inside the tank.
Can I replace the Tank Bulkhead Tee Assembly with a second Straight Bulkhead Assembly to just have a straight heat exchanger, then terminate my HIH outside the tank? The HE coil looks like one side is longer than the other, so it wouldn't line up. Has anyone developed a modification for this? How difficult would it be to bend an aluminum coil to make it line up properly? Does anyone else sell an aluminum HE that wouold fit right in there (i.e. spaced properly and fit in a 24" round tank)?
Alternatively, is there a foolproof* way to plug that tee without any special tools or relying on some sort of compound that could eventually be worn away or softened by hot oil?
I did do quite a bit of searching on this forum for the answer. Sorry if it's something that has already been addressed, but I've only ever seen people expressing concern and others assuring them that the HIH hasn't leaked for them. I know it works for lots of people, but I would rather work around the in-tank termination if possible.
* I may actually be a fool
December 29, 2011 - 6:49pm
#2
I added a pickup screen. I was surprised to find it difficult to locate one for sale that plugs into a 5/16" hose and keeps a low profile, so I had to figure something out, and it turned out to be pretty simple with a little creative thinking.
It's just an in-line fuel filter, the kind with the replaceable insert screens. If you take off the "in" side of the housing and remove the glass, it's a nice little pickup screen for your fuel tank.
Plug it into the 5/16" hose, and you've got a pickup screen.
View your shopping cart.
Greasecar Kits and Products
User login
Skype: greasecarsupport
Greasecar Customer Profiles
Who's online
There are currently 0 users and 153 guests online.
I worked out my own pretty simple modification that might be useful for you to think about if you're considering the same kind of thing.
1. straight bulkhead connectors
I bought the Greasecar straight bulkhead assembly and the aluminum in-tank heating coil (though I suspect the copper would have worked just as well if you're into copper - I like being able to run my tank close to empty without negative consequences of air meeting copper and oil).
I simply bent the in-tank coil by hand to make the flared ends line up to where they need to go to attach to the bulkhead assemblies. That meant that the coil was pretty ugly (just a weird, tangled shape), but nobody has to look at it, and it doesn't interfear with my sending unit or modified fuel pickup (see below). If you do this, be very careful only to make small curves. Kinkingthe tubing even a little will produce a weak spot that could likely develop a leak under heat and pressure. The flared ends need to be about 9mm apart (center-to-center measurement), and they need to line up evenly and straight, which is not how the coil is designed since it is meant to connect a straight assembly on one side and a tee assembly on the other).
Then, of course, I just removed the tee bulkhead assembly and replaced it with the straight one I had bought.
At this point, I just had a tank with a heater coil in it, and no way to get fuel out.
2. fuel pickup (and return)
I bought the following from McMaster: Miniature Brass Tube Fitting, 1/4" NPT Bulkhead, Packs of 2 (5454K87)
When the bulkhead fitting arrived, I took one to a local hardware store and looked for regular electrical gromments that fit snugly around them (and I do mean snug). I got 1" vinyl ones made by Noble Wire out of Oregon (1129D).
Next, I took the wonderfully large access panell off my tank and drilled a hole big enough to just squeeze the grommet into it. I used a step drill bit like this one, which I happened to get used just for tis purpose (well worth the purchase - I used to for lots of things in this installation).
After squeezing in the grommet, I hooked the desired fittings onto my minature brass bulkhead fitting. It has 1/4" pipe thread both on top and on bottom, so on top I added an MPT to 3/8" hose barb elbow and on the bottom I added an MPT to 5/16" straight hose barb (it should've been 3/8", but I didn't have any extra ones). I then added a short piece of hose to the bottom hose barb, just long enough to reach the bottom of the tank. It would be good to add a pickup screen, but I didn't. I also added a fuel return line port the same way because I pump fuel directly into my tank through it and because it's a lot less hassle than a looped return.
Top view of the pickup I added.
Bottom view:
The tank in the trunk (too big for my doughnut spare tire well):
Additional comment:
I tried to reuse the tee fitting I took out of the tank as just an outside-the-tank terminal for the HIH, but I cross-threaded the compression fitting and it leaked like crazy. It's not Greasecar's fault I am a bumbling idiot, but I am sure glad this happened outside the tank instead of inside. Further in GC's defense, there are other factors likely contributing to this cross-threading mishap. First, it was a used system, so maybe the previous owner had messed up the threads or something. Second, I did this with aluminum tubing instead of PEX. Maybe PEX would have seated better and made it easier to get that fitting on there straight.
In the end, I decided to use HOH (because I am bad with HIH) and make everything much simpler and safer. I don't have to worry about terminations inside or outside the tank anymore, and my system gets plenty hot thanks to my in-tank coil, a Frybrid style heated filter, and a vegtherm (later, I will add injector line heaters just for fun).
That's all. Thanks.
Mike