MTFCA Forum

The two photos show a new sediment bowl I am have installed on the gas tank for my 1927 coupe. I hand tightened it to the position shown. I filled the tank with gas to check for leaks, and left it set for a couple of days. No tank leaks, but there is seepage at the bowl threads.

As can be seen, the bowl is not in a vertical position. How do you get a sediment bowl in vertical position and still have it tight enough so it does not leak at the threads?

Sorry, the last photo had to be rotated for it to be accepted!

Permatex 2A

Not sure, is it possible to shorten the thread, champer it and try again?

Use Gasoila thread sealant

it is a national pipe taper...cutting it off will only make it short AND still not threaded in far enough to align

not knowing how tight it is right now, it is impossible to correctly or safely say to tighten it more...however, with an expensive die, you can apply 1/2 turn more on the die and tighten with the sealant I mentioned above, or just use the sealant and not tighten as much as it is now, and simply leave it aligned where it belongs (which is what I would do, and have done, and things were just fine)

it is a national pipe taper...cutting it off will only make it short AND still not threaded in far enough to align

Thanks Scott, we will scratch that idea!

Well, second thought is wrapping the thread with pte tape (plumbers tape) - that would thicken the thread and it would not turn as many times, so lining up?

Pipe threads have a spiral leak path and will leak unless a sealant is used. My favorite is the same as Scott C’s, Permatex 2A; fuel and oil proof, and doesn’t harden to the point the joint can’t be disassembled. If it’s good enough for airplanes, is should be good enough for Model T’s.

If it was any further past the optimal orientation, I would not trust just sealant. Backing it off further than you have to will leave it loose on the thread. I presume from your photo that it is a reproduction cast in brass. That would make tinning the thread a simple task, and would make a tighter fix on the thread.

Allan from down under.

Hello.
I have the tank under the seat, but the principle will be the same. I had to install a new sediment bowl because the old one was total crap. It had a cast-iron bulb with brass parts screwed in, but some super smart guy drilled it up from tank side (through the petcock, too) and soldered in a piece of copper pipe... So the tank had no shut-off valve anymore, this I wanted to be solved...

I bought this sealing product years ago. Product "Ulith 240"/"TWINEFLON". Plumbers swear on it.
It is a thin thread of Teflon but not as smeary as usual Teflon tape. It is absolutely resistant against gases, oil, and most chemicals. Temperature range from -200°C - +240°C (should be sufficient ). I am pretty sure you find something similar in your local DIY market.
https://www.babo-team.de/Verbrauchsmitt ... -175m.html

I decently roughed the thread on outside of the bulb by dragging a file edge across the thread in 90deg, then I wound up this sealing thread and turned in the bulb.
The connection is 100% proof even after 1 year, I am pretty sure this will last forever.

If you want to screw the bowl deeper into the tank (to make the thread vanish), I would not recommend that. Simply turn in the bowl without any sealant until it is in place and doesn't go further, then measure the gap width. Find a brass muffle in a DIY market and cut a ring in previously measured width from it. You can also take a piece of pipe or a flat G1/2" nut, but the muffle will be easier to get and has a round outer shape.
If this ring doesn't go all way up on bulb thread, use a file and increase inner diameter until it does. There is no need to make it proof!

Finally use the sealing tape of above and put things together. The Teflon will fill the joint (so it will sit now strong) and you will get a perfect look and 100% proof joint.

Rainer

The permatex 2A will work. If you decide to use thread tape make sure it’s good for gasoline. this stuff works. It’s a blue colored tape.

If you've gotten it to the orientation shown "by hand", (assuming that means hands only, and no wrench), you should be able to run it in further with sealant and a wrench to get it in the proper position.

If it is only hand tightened to that position you should easily be able to get it to the correct position with some sealer as a lubricant and a Stilson wrench. Protect the sediment bulb from the teeth with a thick rag. The sediment bulb is correctly threaded at the factory to achieve the proper position. Keep in mind you must install the cowl tank in place prior to installing the sediment bulb. I have installed several sediment bulbs and have never had a problem. Jim Patrick

You may have to use a backup wrench of some sort on the tank fitting to get it in the right position if it’s necessary. But that depends how tight you have it now. If you have a vise grip wrench you might try to open the jaws enough to get it on the tank fitting with a thin piece of leather or rag and try to move it in position that way. The rag or whatever will keep it from scarring the tank fitting.
BUT make sure your using the backup wrench and let your hand take the stress instead of the tank fitting when tightening. DO NOT put the stress on the tank and fitting. It can be done that way and it’s in the way you do it.

Here is some more information on the situation with the sediment bowl.

I just removed the bowl, cleaned the threads in the tank with a dentist type of pick and lubricated the threads. I reinstalled the bowl by hand, and it reached the same previous position. There are eight threads on the bowl. Three turns gets it to that position, and 2 3/4 turns gets it to vertical. I think it needs to penetrate the tank more than that.


I am pretty sure tightening it by a wrench would not get it to a vertical position.

now that we know it is tight as photographed, then you need to run a die onto the valve and give it somewhere around 1/2 turn or so like I mentioned above

your car originally appeared as "like new" before restoration and the tank threads obviously are still in very good shape. Folks don't realize that many times repro parts must fit an entire gamut of cars from nearly totally shot, to (in rare instances) "like new". Parts with NPT threads are a great example. If you were to give that valve to someone else with a worn set of threads in his tank, it might well run nearly all the way in...Given that, you're going to have to run the thread up the valve just a bit...since it is a tapered thread, it will reduce the diameter just a tad and once you do that, it will run up into the mating tank thread just that little bit more to align your part. Sometimes you have to do a little fitting of things considering it is 100 years old, or thereabouts.

DO NOT ALTER THE TANK IN ANY WAY during the fitment of the valve. If there is strong cause to "chase" the tank threads, have someone KNOWLEDGEABLE WITH NPT taps do the job. Simply running the tap in will ruin things...NPT threads have a definite minimum/maximum they want to go in and other than perhaps a little oxidation you can be CERTAIN that the gas tank is correct. It is the valve which needs to be altered.

Scott, Thanks. What you have said makes sense.

Could you give me information about the "die"; that is, size needed, availability, etc. I will check with the local machine shop to determine if they have dies, and if they would do this for me.

BLB27 wrote: ↑

Sun Jun 19, 2022 4:53 pm

Scott, Thanks. What you have said makes sense.

Could you give me information about the "die"; that is, size needed, availability, etc. I will check with the local machine shop to determine if they have dies, and if they would do this for me.

Its a plumbing thing, not likely to find @ a machine shop. In the old days there were dies that would do the job. (1/2"NPT)

The Permatex way definitely wont work??
What about some string & Permatex??

I see there are large hex rethread dies available. Wasnt aware they were common over 1/4". Thank you Scott.

If memory serves me correctly it is 1/2 NPT. If I am remembering correctly, then this means it is 1/2-14 (1/2" nominal pipe x 14 threads per inch...tapered). The outside of the pipe would measure somewhere around .84" in diameter.

Believe it or not, your local old-time plumber will be far more likely to have a die for this than a machine shop...he will know exactly what it is just by looking.

Don't go crazy...look at it's orientation now...add enough "twist" on the die relative to how much MORE twist you want onto the tank. Ideally, it will thread on by hand and stop at around "3 or 4 o'clock" to that later, where when you put lubricant/sealant on it, a pipe wrench will easily twist it another 90 degrees and it will be where you want it. Your plumber may even have advice for you in this regard.

Or....do it yourself...this die is made to work with a wrench and does not need a special die holder. Since you already have threads cut, you don't have to worry about starting it straight. Just clamp the sediment bowl in a vise padded with wood and give it ever-increasing twists until you try the thing in your tank and you're happy... https://drillsandcutters.com/1-2-14-npt ... -qEALw_wcB

this die is carbon-steel and not High Speed Steel. That's why it is pretty cheap...it is a re-work die and not made for constant use making new threads from scratch...it is plenty good for your use and is an economical alternative to a higher-quality die. Also, the hexagonal Carbon Steel die does not require an expensive die holder that High Speed Steel dies require. Economics again...Myself, I only buy High Speed Steel tools when I can, but then again, if I own a tool, then I use it pretty frequently so the expense is easily amortized over the many projects it will support. You have pretty much a one-time use and for that this is fine.

Finally, because it is tapered, there is only one way to thread it on to start!

Good luck

I don’t believe it needs to be tapped and am certain you can get it to vertical with a wrench, since, in the first photo, where the bottom of the sediment bulb is at the 9:00 position, it is only hand tightened. If you are determined to tap the female threads, make certain to use a tapered pipe tap. If you use a regular straight tap, it will remove the taper and ruin your tank. Before tapping, put a little oil on the threads and turn the sediment bulb. You only need to go 3/4 of a turn to reach the 6:00 position, which can easily be attained with a wrench. Jim Patrick

Clean out the threads with a tap to clean out old thread sealant, install new sediment bulb with Gasoila thread sealant... You will get the extra 3/4 turn that you missed.

Scott, What tells me that the die you showed (SKU DWTHXNPT12) is tapered? Or, if I ordered it, do I just specify a tapered die?

Scott. In your 1:24pm post I read that you believe that the sediment bulb is fully tight at the 9:00 position. In Bruce’s first post he said the bulb that is pictured, is only hand tightened at the 9:00 position. I have never had trouble getting 3/4 of a turn or more from the point where a tapered pipe fitting was only hand tight. I am worried that Bruce is going to damage his tank beyond repair if he taps the threads unnecessarily. If your advice is based upon the erroneous perception that the bulb is fully tight, it is wrong. As pointed out in Bruces first post, it is only hand tightened. Please reconsider. Bruce seems to be leaning toward your position. Jim Patrick

Jim

I somehow missed that point and agree that it should tighten OK with a wrench and lubricant/sealant. That is my mistake.

I don't think any harm would have come to the tank as I had directed the sediment bulb be modified if necessary and not the tank...so there is that

Bruce

put some sealant on the thing, pad the jaws of a pipe wrench sufficiently and tighten it down...my advice to modify the sediment bulb was based on thinking that it was TIGHT in your first picture. My apologies for being less than careful in my reading

Reminder: Bruce, in John Kuehn’s 9:03am post, he suggested using a stilsen wrench or vice grips (protect the fitting from the teeth with a rag) to hold the stationary tank side female threaded fitting in the opposite (counter-clockwise) direction as you tighten the male threaded sediment bulb. Good advice. That will prevent the tank side fitting from receiving too much stress while tightening which could cause the tank material around the fitting to buckle or the rivets to loosen. Don’t forget that the tank must be secured up in the cowl before installing the sediment bulb. It is easiest to install the tank after the dash is installed but before the body is lowered onto the chassis. Jim Patrick

I tried to tighten the bowl with a wrench. It moved to the position shown here. It turned very hard. There is no way that I will get it to the vertical position with just using a wrench.

I believe I should try using a "die' on the bowl threads, being careful not to overdue the amount I turn the die. Scott was clear that I should not use a "tap" on the tank threads.

I appreciate the comments and suggestions I have received. I welcome any additional ones.

How are you attempting to hold the tank while tightening the sediment bulb ? As recommended & posted above - tank installed in the car makes less objects to try & hold !

You still have more than 1/2 a turn on a very coarse thread, so the thread needs chasing. If that is a new reproduction outlet, it most certainly needs some work on the thread. Your local old time plumber is your new friend. He should have the die necessary to do the job. Less is better. Tell him you need 1/2 a turn more, and trial fit. You can always go back for a bit more.
Keep in mind that the receiver in the tank is cast iron, it is riveted in place, and it is sealed with solder. Too much moxie on any wrench may compromise the fitting. Fitting is the word here, not forcing.

Allan from down under.

A person holds the tank down.

Bruce. There is something seriously wrong if you can’t turn the sediment bulb any more than 1/4 of a turn from hand tight! It should easily turn 3/4 of a turn from hand tight. In your first picture, the exposed threads look new. Did you recut the threads? If so, did you use the correct TPI (threads per inch) tapered pipe tap? All I can think is that you, or someone used the incorrect tpi tap. Scott, what do you think the problem is?

I would take both the tank and the sediment bulb to a plumber and explain the problem then tell him “fix it”. I think it is probably beyond your experience and a good plumber should have the proper tapered pipe fittings with which to do the job. Jim Patrick

Jim, I have done nothing to the threads on the bowl or tank, except using a dentist type of pick to clean the threads in the tank. Those threads look good.

I want to clarify "hand tight". It is not just turning the bowl to where some slight resistance was felt and then stopped. I used gloves and really turned the bowl hard.

NPT = National Pipe Tapered

Carefully chase the threads in the tank with a tap and be done with it! Running the tap by hand (no tap handle/wrench) will likely do it. Take the tank to a plumbing shop if you don't have the 1/2 NPT tap. Any shop that installs black iron gas pipe will have this tap. Don't bugger up the new thread on the sediment fitting, good luck jb

Bruce, let us know of your progress....thanks

I took the sediment bulb to a machine shop. The machinist used a 1/2 npt die on the threads, not much but it worked. I used lubricant and got it to the vertical position with a wrench.

Yeah !!!!! Finally fixed

Good job! I am still confused as to why you could not get your sediment bowl in the proper position. I am posting a picture of your firewall before you removed the sediment bowl back in April, 2021 showing it in the proper downward position. That is why I was so adamant that you should be able to tighten it to the proper position. It would be nice to know why you couldn’t. Do you think you might have cross threaded it! That is a possibility. A note of caution. When threading, go slow, making sure the fitting is going on straight. If you feel it is crooked and tightening far too soon, back it off, straighten it an try again. Jim Patrick

jiminbartow wrote: ↑

Sat Jul 30, 2022 10:57 am

Good job! I am still confused as to why you could not get your sediment bowl in the proper position. It would be nice to know why you couldn’t. Do you think you might have cross threaded it! Jim Patrick

Jim

The reason is that was the original Ford bulb, he used a Reproduction new bulb, today's NPT is just enough different, or else the repop thread lead began at a different point than the Ford part, NOS Ford parts work best

BTY, had similar issue with the under tank new repop bulbs into a repo new tank, the thread won't quite align, but isn't too big an issue with the under seat tank, and you can curve the fuel line to make up the difference of position of that bulb. Permatex #2 to the rescue.

At the rate the Ford shops were running to keep up with production the folks probably had it down just right when machining parts. Probably having the bulbs fixed in the lathe or threading machine every time in the same position and so on. When you were doing boxes full of bulbs you got the knack of it and knowing the exact position where to jig the parts up every time.
Just guessing !

Jim, Dan has the reason it would not go vertical.

I had a new petcock for my new radiator that would not screw on more than a few threads. I took the radiator to the machinist, and he used a tap on the radiator threads to get the petcock on.

Question.... don't you put the tank in first and then install the sediment bulb on a '26-'27 cowl tank?
Pic shows installed out of car.

Professor ... Maybe he was anxious with that new part to see if it fit his tank ?

Yes Dan. On the 1926-‘27 cowl tank, the sediment bulb can only be screwed on after the tank has been installed. The tank cannot be installed with the sediment bulb installed. Jim Patrick