philipj Posted March 23, 2018 Share Posted March 23, 2018 Does anyone have a photograph of the original style sending units for these cars or know the operating ohm range? Thank you. Link to comment Share on other sites More sharing options...
DonMicheletti Posted March 23, 2018 Share Posted March 23, 2018 Here are some photos of the sending unit. I dont know the resistance Link to comment Share on other sites More sharing options...
philipj Posted March 24, 2018 Author Share Posted March 24, 2018 (edited) Thank you very much for the photos. Would you consider selling it? This is what I have, frozen solid. Edited March 24, 2018 by philipj (see edit history) Link to comment Share on other sites More sharing options...
Bloo Posted March 24, 2018 Share Posted March 24, 2018 Is that original for 38? I have worked on a 37, and 37 is like DonMicheletti's picture. Either way, resistance is 0-30 ohms, with 0 ohms being empty. Link to comment Share on other sites More sharing options...
MCHinson Posted March 24, 2018 Share Posted March 24, 2018 1 hour ago, Bloo said: Is that original for 38? I have worked on a 37, and 37 is like DonMicheletti's picture. Either way, resistance is 0-30 ohms, with 0 ohms being empty. No, that is not original for a 1938. The 1938 one looks identical, or nearly identical to the 1937 one. That looks like some of the reproduction ones that I have seen advertised. Link to comment Share on other sites More sharing options...
philipj Posted March 24, 2018 Author Share Posted March 24, 2018 (edited) Thank you for confirming the OHM range, very important factor to find a replacement.. Are 37 and 38's interchangeable? I cannot even find the fuel sender I had with the bent tube; it definitely has been reworked to fit... The tube is bent and the holes are elongated. The length of the arm is 7" to the middle of the float. It always read 1/4 tank since it is stuck, so I have no way of knowing how accurate it was.. Almost looks like a 39-56 unit from oldbuickparts.com.. The 58 might be more difficult to modify, (fuel tube points opposite direction) but the arm is straighter... Edited March 24, 2018 by philipj (see edit history) Link to comment Share on other sites More sharing options...
philipj Posted March 24, 2018 Author Share Posted March 24, 2018 (edited) Hello Don, Would you please measure the length of the supporting bracket under the sending unit as well as the length of the arm? Thank you. Edited March 24, 2018 by philipj (see edit history) Link to comment Share on other sites More sharing options...
philipj Posted March 24, 2018 Author Share Posted March 24, 2018 (edited) This website has quite a few, some even look like the original style, but would have to match the depth... http://www.classiccarautoparts.com/gastank_sending_units2.html But this may work better, 0 to 30 Ohm for $39.00... If the length is ok it may be an option. Waiting for a reply regarding measurements. You will have to bend the tube though... https://www.summitracing.com/parts/tnk-b1-s/overview/ Edited March 24, 2018 by philipj (see edit history) Link to comment Share on other sites More sharing options...
Bloo Posted March 24, 2018 Share Posted March 24, 2018 (edited) 41 minutes ago, philipj said: I cannot even find the fuel sender I had with the bent tube, Bent tube? Those tubes often need to be replaced anyway, due to cracking or holes worn where the tube clamps to the top of the sending unit. It is 5/16 copper tubing, a size most hardware stores don't have, but I did eventually find some. I suspect you could also use NiCopp brake line, or steel brake line. You do have to solder it. I suspect NiCopp would solder but I haven't tried. The bends in this piece are way too tight for any normal tubing benders. I started with extra length, crimped and folded over an end, and filled the tubing with salt, then I packed the salt in tightly with a punch and crimped the other end, folding it in such a way that it tightened the salt more. No matter what you do it is never tight enough,and you have to keep tightening it more as you work. I made the bends with a combination of cheap tubing benders and various size pipes and steel bars, working in a vise, usually with a pipe or something clamped in the vise. The tubing really wants to collapse. It is also a bit challenging to get the bends in the right paces. When I had it right, I cut the ends to length with a tubing cutter, dumped the salt out, and soldered it to the clamp and fitting. I didn't get the bends right on the first try. Buy more tubing than you think you need. It least one rivet will have to go away to get the clamp off. I don't think you could solder it while assembled because there is a cork gasket under there. I had the whole thing apart anyway due to problems with the resistor. Theres another gasket under the resistor housing. I had to make the rivets from hobby store brass tubing, The rivets at the hardware store were close, but not close enough. If you were only taking the pickup tube off, and not disassembling the rest, I think you could get away with just leaving that one rivet out. Edited March 24, 2018 by Bloo (see edit history) Link to comment Share on other sites More sharing options...
philipj Posted March 24, 2018 Author Share Posted March 24, 2018 What I meant by bent tube is the fact that this sending unit had a straight tube originally and was bent to work for this car... I suppose that what I have could be rebuilt for about $75,.00-$150.00 but I don't know how right it was in the first place, so it is a big gamble.. It is totally frozen now. http://tristarrradiator.com/Services Page/Services.html Link to comment Share on other sites More sharing options...
DonMicheletti Posted March 24, 2018 Share Posted March 24, 2018 I'll measure the length of the float arm OK, I'm not sure what you mean by support bracket. Is that the vertical piece where the pivot attaches? Link to comment Share on other sites More sharing options...
philipj Posted March 24, 2018 Author Share Posted March 24, 2018 Hello Don, Thank for the information... Yes, the vertical piece where the pivot attaches... Link to comment Share on other sites More sharing options...
Spinneyhill Posted March 24, 2018 Share Posted March 24, 2018 (edited) I would probably fill the tube with dry sand rather than salt when bending it. Sand doesn't crush as easily as salt. As the salt crushes, it occupies less volume (the smaller particles fill the spaces between the bigger ones). P.S. silica sand, not coral sand! Edited March 24, 2018 by Spinneyhill (see edit history) Link to comment Share on other sites More sharing options...
DonMicheletti Posted March 25, 2018 Share Posted March 25, 2018 Here are a couple of photos. I hope they help. I can take more if you wish Link to comment Share on other sites More sharing options...
Bloo Posted March 25, 2018 Share Posted March 25, 2018 6 hours ago, Spinneyhill said: I would probably fill the tube with dry sand rather than salt when bending it. Sand doesn't crush as easily as salt. As the salt crushes, it occupies less volume (the smaller particles fill the spaces between the bigger ones). P.S. silica sand, not coral sand! Good advice I think!. I have only sand bended much larger things, and someone suggested salt for small tubing. It worked, but not as well as I had hoped. The part came out nice, but there was sure a lot of retightening the salt!. I will definitely be trying it with sand next time. This one is a 36 Pontiac. I made a 37 Buick one too, but don't have a pic handy. The differences are small. Link to comment Share on other sites More sharing options...
Bloo Posted March 25, 2018 Share Posted March 25, 2018 (edited) 14 hours ago, philipj said: What I meant by bent tube is the fact that this sending unit had a straight tube originally and was bent to work for this car.. OH! I thought you meant you had another unit laying around that just had a mangled tube. I think they all have a mangled tube. If it were me, I would try to source an original one and rebuild it or get it rebuilt. I am thinking you are probably going to take the tank out a bunch of times getting a modified one really right. It is bad enough trying to get the stock one right. At least the 37 Buick was much easier to drop the tank out of than the 36 Pontiac. The Buick filler neck unscrews. A few years ago when I was trying to learn what makes these gauges tick, I kept seeing forum posts all over the web about 55-57 Chevrolets. They have 0-30 ohm gas gauges, as do most (all?) GM cars through about 1964. Apparently by now most 55-57 Chevys have aftermarket senders. The complaints about them are truly endless. Some of the most common ones are: 1) Gauge wont go to "e" because sender doesn't get anywhere close enough to 0 ohms. 2) Non-Lineaarity 3) Sender goes way over 30 ohms on full, so the tank has to burn way down, maybe to 3/4 or 1/2, before the needle comes off of full. 4) Needle waving all over the place. If a 37-38 Buick owner in here can suggest an aftermarket sender that is known to work, I'm all for it., otherwise I would start looking for an original to rebuild. I do like that sock filter on the sender in the picture. I am a believer in those, and I added socks to both the Pontiac and the Buick sender. I tried to use Mopar-style rigid socks, but they don't fit through the hole on these old GM tanks. The GM one fits, but is too long. I shortened the sock, and melted the end back together. As made, the GM socks are long enough that they could climb up and get caught in the gears. Edited March 25, 2018 by Bloo (see edit history) Link to comment Share on other sites More sharing options...
philipj Posted March 25, 2018 Author Share Posted March 25, 2018 Hello Don, Thank you very much for the additional photos. I can use them for reference if I find that style pump... I can see that it would get more steady readings than the one I had by the design... As for repairs or soldering, I can weld, but somehow I cannot solder anything! Bloo, wish you were here for a tutorial but I do not want to get off topic. Link to comment Share on other sites More sharing options...
MCHinson Posted March 26, 2018 Share Posted March 26, 2018 If you want to see how to repair an original one, check out post 377 in my 1938 Century Restoration Discussion: Link to comment Share on other sites More sharing options...
Dynaflash8 Posted March 28, 2018 Share Posted March 28, 2018 The '39 does not have the screen on the bottom. I have one that is NOS here. Link to comment Share on other sites More sharing options...
philipj Posted March 29, 2018 Author Share Posted March 29, 2018 I am sorry Dynaflash 8, did you say that you have a NOS 1939 sending unit available? I don't care if it does not have the screen at the bottom... Link to comment Share on other sites More sharing options...
DonMicheletti Posted March 29, 2018 Share Posted March 29, 2018 A '39 unit will have to be modified to work Link to comment Share on other sites More sharing options...
philipj Posted March 30, 2018 Author Share Posted March 30, 2018 I am willing to investigate... What kind of modification? Link to comment Share on other sites More sharing options...
DonMicheletti Posted March 30, 2018 Share Posted March 30, 2018 The screw holes are a different bolt pattern - not the same as '38. You have to bend the fuel line a bit, but it worked for me and I was able to use the original flared fittings The biggest headache is the top mounted electrical connection. It wants to hit the trunk floor. I put a thick piece of plastic insulation over the screw head to keep it from shorting out. Link to comment Share on other sites More sharing options...
philipj Posted March 30, 2018 Author Share Posted March 30, 2018 Sounds like quite a bit of aggravation... I would hate to have to pull the fuel tank down because of problems, so I might try the one from Summit Racing... https://www.summitracing.com/parts/tnk-b1-s/overview/ I have no other choice that seems reasonable right now. For the price, I am willing to give it a try... Link to comment Share on other sites More sharing options...
MCHinson Posted March 31, 2018 Share Posted March 31, 2018 Phillip, Do you have an original fuel tank sending unit? They are actually easy to repair. Link to comment Share on other sites More sharing options...
philipj Posted April 6, 2018 Author Share Posted April 6, 2018 I so wish I did... I just received the one from Summit Racing ($40 plus shipping) that I will use... It looks ok however, the tube does not have a support for the base or the female fitting. It is 5/16 though, which I will have to clamp to the rubber hose coming from an additional filter under the car... I will also have to bend the tube 90° luckily, the tube is long enough and 0 to 32 ohms, in range... It will be more accurate near empty, as tested. Link to comment Share on other sites More sharing options...
philipj Posted April 29, 2018 Author Share Posted April 29, 2018 (edited) For any of you interested in this sending unit from Summit Racing, I would say that for the money it worked out great with minor effort... The mounting holes had to be elongated a little and the pickup tube cut short... I initially bent the tube to a place that made sense, but once trying to fit in the car it would hit the rear cross member... It needed to be bent down again, but with the gas tank resting on my legs, it was not an easy task! The result was a kinked tube which I had to cut short as indicated before. By the way, in order to bend the tube without kinking it before I inserted a piece of 30 G copper wire which fit perfectly inside the tube. I figured it would be easier and cleaner than sand... You can see the photos of the bend and the actual final install that made it for a perfect fit... I should also let you know that Moyer's fuel tank renu did a nice job on the original tank despite being a little bit pricey... The one pipe going down after the small section of rubber hose just had a 90° bend that runs along the length of the tank to another inline filter... Edited April 29, 2018 by philipj (see edit history) Link to comment Share on other sites More sharing options...
Bloo Posted April 29, 2018 Share Posted April 29, 2018 21 minutes ago, philipj said: By the way, in order to bend the tube without kinking it before I inserted a piece of 30 G copper wire which fit perfectly inside the tube. I figured it would be easier and cleaner than sand... Can you elaborate on that? What is 30 G? (IIRC 30 gauge is super fine like hair). I am just imagining to myself right now how well that probably worked. The 2 pickups I made with the sand method came out nice, but it was fiddly, long winded, and just barely worked. Link to comment Share on other sites More sharing options...
philipj Posted April 29, 2018 Author Share Posted April 29, 2018 My apologies for the typo! The wire size used was 8 AWG... The only thing I would do different would be a little grease or vaseline for ease of wire removal. Also don't go too far past your bend point or it might be harder to remove... I was very surprised how nice it came out. If you have some spare 5/16" tubing pieces try it out. It does require a little bit of force but it works. You will be pleasantly surprised! 1 Link to comment Share on other sites More sharing options...
DonMicheletti Posted April 29, 2018 Share Posted April 29, 2018 For safety sake (and headaches), put a piece of tough insulation over the sender terminal. The original was very low profile and your new one may want to hit the floor of the trunk, short out and give a continuous "E" reading Link to comment Share on other sites More sharing options...
philipj Posted April 29, 2018 Author Share Posted April 29, 2018 Thank you for the advice, Don I will get a rubber cap over the terminal... Link to comment Share on other sites More sharing options...
Gingerbread Posted October 11, 2021 Share Posted October 11, 2021 This is great info, thank you all. Have our ‘37 Pontiac Sedan fuel sending unit. It’s frozen, and am finding it difficult to find a suitable replacement. You mentioned following you on post #344 ? But for an hour ,now I can’t figure out how to find that post, or any numbering system for the post. I am very interested in rebuilding the ori sending unit. Thank you for any help in this matter. Ginger 1 Link to comment Share on other sites More sharing options...
Bloo Posted October 11, 2021 Share Posted October 11, 2021 I don't see where post 344 was mentioned, but post numbers went away on this site long ago. Got pictures? How bad is it? I fixed a couple for a 36 Pontiac and 37 Buick some time ago. Both were very similar in construction to DonMicheletti's picture in the second post. They were both made from the same basic parts, but there were differences, like the pickup tube was longer on the 36 Pontiac for a deeper tank, and the bend was in the opposite direction. The assembled unit appeared to be a near mirror image of the 37 Buick. The fittings were different too, threaded sleeve on the Pontiac and double flare on the Buick. I sand-bent new copper pickup tubes. It got the job done but was tedious and didn't work as well as expected. Next time I will try philipj's method. I would also want to use CuNiFer brake line instead of pure copper if you can solder to it. I wonder if you can? I have not tried. Pure copper work hardens, and you will probably find cracks where the line is clipped into the steel retainer on top, and maybe inside the tank as well. CuNiFer doesn't work harden. Be sure to get new sealed cork floats. The old ones cannot be trusted. Bob's Automobilia has them. I disassembled my sender, which you must do if you are going to fix the brake that keeps the float from waving around too much when you go over bumps. For somewhat of a lesser repair, you might be able to just derust the bottom non-electric portion in evaporust. I didn't. I drilled the rivets out to get the resistor off the top, and unsoldered the shaft at the bottom to get the brake washer out. Then, I electrolytic-derusted the whole remaining mechanism, straightened it, and plated it with zinc. The zinc is sacrificial, to slow down future rust. That all sounds hard, but is actually pretty easy and can be done at home with no exotic chemicals, just stuff from the grocery store. Putting the sending unit back together can be the tricky part. Post back if you plan to tackle this. I might have a picture or two but I'll have to dig for them. Link to comment Share on other sites More sharing options...
Gary W Posted October 11, 2021 Share Posted October 11, 2021 4 hours ago, Gingerbread said: You mentioned following you on post #344 ? This from Matt's Century Restoration. I'm pretty sure this is the correct post concerning the sender rebuild. Matt does address the sending unit / gas tank in posts before and after this one, but this will get you in the ballpark: 2 Link to comment Share on other sites More sharing options...
Gingerbread Posted October 11, 2021 Share Posted October 11, 2021 Thank you, I would definitely need to replace both corks,and filter bag. Gears are rusted together, will wire brush , maybe Swiss files , to see if I can get things moving. No bends, nor visible holes, will do a light pressure test when clean, to ck for pin holes. Are there any cautions, that I should be aware of ? Have volt meter, but unsure as to what to meter ? 0-3- ohms, is the requirement, I believe. Link to comment Share on other sites More sharing options...
Bloo Posted October 12, 2021 Share Posted October 12, 2021 (edited) My guess is you could get that sender freed up by just dunking the lower half in some evaporust for a day or two. That sender is in far better shape than mine was. I am intrigued by the filter sock. I think it might be original and I have never seen one before. Next time you are working on the sending unit, would you mind posting pictures from a couple more angles? Maybe with a ruler so we can see what size it is? The resistance is 0 ohms empty (or very near) and 30 ohms full. At low resistances like that, if you are using a digital meter, you will also be measuring the test leads. Short them together and hit the "delta" button to bring the meter to zero before you measure the sender. If your meter does not have a "delta" button, then note the reading with the test leads shorted together. Subtract that number from the readings you get on the sending unit. Edited October 12, 2021 by Bloo (see edit history) 2 Link to comment Share on other sites More sharing options...
Gingerbread Posted October 12, 2021 Share Posted October 12, 2021 Great news, there is slight movement, from a gear ,yeh ! Watched some videos, on how they are to work. If replacing the corks, how will I know if a different type of float will work the same ? Actually the bag looks/feels of plastic. 1 Link to comment Share on other sites More sharing options...
MCHinson Posted October 12, 2021 Share Posted October 12, 2021 On my 1938 Buick, I used two modern floats sold by Model A Ford vendors for Model A Ford gas gauges. The original corks were the same size as the Model A Ford, but the Buick required two instead of one like a Model A Ford. https://www.brattons.com/GAS-GAUGE-FLOAT/productinfo/13550/ 2 1 Link to comment Share on other sites More sharing options...
Bloo Posted October 12, 2021 Share Posted October 12, 2021 (edited) Bob's Automobilia has floats listed for Buick, and that is what I used. I was not aware of the model A floats at the time. I would re-use those big washers no matter what comes with the floats. They probably prevent damage to the sealer if the floats should touch the tank. They really shouldn't touch the tank. Thanks for posting more of the sock. I agree it could be something modern. I am a believer in sock filters, and I added them to the two units I rebuilt. I wanted to use the Ford or Mopar style barrel shaped ones, but they will not fit through the tank hole next to the sender. I used a GM style, like the one in philipj's pictures above, but had to shorten it. The socks come in 3/8" or 5/16" at the tube end, and these sending units take 5/16". The sock is long enough that it looks like it could climb up the pickup tube and jam the gears, so I cut it off and re-melted the end. I crimped a piece of brass shim stock over the cut end, and heated it with a huge soldering iron until the ends of the plastic sock mesh melted together. Then, I peeled the brass off. Edited October 12, 2021 by Bloo (see edit history) 1 Link to comment Share on other sites More sharing options...
Gingerbread Posted October 13, 2021 Share Posted October 13, 2021 Thanks so much, for all of the advice. Ordered 2 corks,from Bob’s. And a sock filter from Jegs. Still PB soaking, and working on getting both gears moving. Using a feeler gage to push/dislodge the rust. Working up to getting emory sheet in there. There is at least a pint of rust chunks/powder in tank. Soaking and cleaning the tank, while looking for a replacement. I am that much closer to ‘Beep, Beep” !! 1 Link to comment Share on other sites More sharing options...
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