VDO Fuel Senders Woes! - Zenith Aircraft Builders and Flyers2024-03-29T11:57:25Zhttps://zenith.aero/forum/topics/vdo-fuel-senders-woes?commentId=2606393%3AComment%3A745075&feed=yes&xn_auth=noHi All,
I see that several of…tag:zenith.aero,2023-08-21:2606393:Comment:9113012023-08-21T14:29:23.723ZJohn A. Minatellihttps://zenith.aero/profile/JohnAMinatelli
<p>Hi All,</p>
<p>I see that several of us continue to have sender issues. As you can see above I took John Austin’s advice and installed the vans units now nearly 2 years later and no issues whatever. I did this by removing the wing root top skins which was easy to do and gave me great access to get the replacement done. The VDO senders I took out were in terrible shape and thus I am glad that I switched to the vans units. Despite all this even with matching VDO level indicators and with…</p>
<p>Hi All,</p>
<p>I see that several of us continue to have sender issues. As you can see above I took John Austin’s advice and installed the vans units now nearly 2 years later and no issues whatever. I did this by removing the wing root top skins which was easy to do and gave me great access to get the replacement done. The VDO senders I took out were in terrible shape and thus I am glad that I switched to the vans units. Despite all this even with matching VDO level indicators and with using a model to bend the float wire I only get 75% readings on full tanks, never the less I never rely on these gauges anyway and use the Cessna dip stick before each flight instead. This is a very accurate method of fuel management and I keep a log book for each measurement. When the install was complete with empty tanks I simply added 2 gal. Increments to one of the tanks, too the dip stuck reading and recorded it until full, then I made chart which provides the amount at each dip setting. I have had no leaks and no issues since this change. When you use the sealant be sure to get very little on the inside of the tank but apply liberally to the external mating surface. John</p> This is an old posting (3 yea…tag:zenith.aero,2023-08-20:2606393:Comment:9112212023-08-20T19:42:15.249ZNorm Neulshttps://zenith.aero/profile/NormNeuls
<p>This is an old posting (3 years ago) of what I did with the same problem. </p>
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<p><a rel="nofollow noopener" href="https://zenith.aero/forum/topics/fuel-sender-access-covers?xg_source=activity" target="_blank">https://zenith.aero/forum/topics/fuel-sender-access-covers?xg_sourc...</a></p>
<p>This is an old posting (3 years ago) of what I did with the same problem. </p>
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<p><a rel="nofollow noopener" href="https://zenith.aero/forum/topics/fuel-sender-access-covers?xg_source=activity" target="_blank">https://zenith.aero/forum/topics/fuel-sender-access-covers?xg_sourc...</a></p> Same problem with mine. Unfor…tag:zenith.aero,2023-08-20:2606393:Comment:9112772023-08-20T13:46:02.381ZDr. Randall Haneyhttps://zenith.aero/profile/DrRandallHaney
Same problem with mine. Unfortunately, the center popped out while I was looking at it and I got a fuel shower on my back. Has anyone else replaced these things? I’m guessing the best way is to remove the top root skin or at least part of it. Mine are less than two years old.
Same problem with mine. Unfortunately, the center popped out while I was looking at it and I got a fuel shower on my back. Has anyone else replaced these things? I’m guessing the best way is to remove the top root skin or at least part of it. Mine are less than two years old. I know what you mean. I agre…tag:zenith.aero,2021-10-29:2606393:Comment:8515152021-10-29T03:27:19.177ZBill Bearhttps://zenith.aero/profile/BillBear
<p>I know what you mean. I agree and would have done the same having known what I know now. I, too, bought a partially built project and the side mounted VDO senders were already installed. Top mounted senders would have been the way to go.</p>
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<p>Bill</p>
<p>I know what you mean. I agree and would have done the same having known what I know now. I, too, bought a partially built project and the side mounted VDO senders were already installed. Top mounted senders would have been the way to go.</p>
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<p>Bill</p> There's certainly pros and co…tag:zenith.aero,2021-10-28:2606393:Comment:8513282021-10-28T13:53:15.093ZJohn Austinhttps://zenith.aero/profile/JohnLAustin
<p>There's certainly pros and cons of ProSeal vs gaskets! Apparently, the SW senders are very reliable, so it's unlikely the sender itself will fail. If sealed with ProSeal and a leak develops, you usually can get away with simply slathering-on more ProSeal and seal the leak. If you use gaskets, the possibility of a leak developing as the rubber ages is there, but as you point out, it's possible to neatly and cleanly replace the sender and/or gasket. As the old saying goes, "You pays your…</p>
<p>There's certainly pros and cons of ProSeal vs gaskets! Apparently, the SW senders are very reliable, so it's unlikely the sender itself will fail. If sealed with ProSeal and a leak develops, you usually can get away with simply slathering-on more ProSeal and seal the leak. If you use gaskets, the possibility of a leak developing as the rubber ages is there, but as you point out, it's possible to neatly and cleanly replace the sender and/or gasket. As the old saying goes, "You pays your money and you takes your choice!"</p>
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<p>Quite frankly, in the unlikely event of an early failure with the SW sender sealed with ProSeal as I did, I'd likely just abandon the sender, seal off the entire area with ProSeal for good measure, and cut an access panel in the top of the wing and install a sender (probably one of those with a vertical tube and has a float that goes up and down the tube) in the top of the tank and use a gasket - easier to access and easy to replace a gasket. I would have done that 10+ years ago during my build except I bought a partially completed project and the previous builder had already cut the sender holes in the side of the tank, plus, I didn't know then about the leaking problems with the VDO senders. "If I only knew then what I know now!" LOL!</p>
<p>John</p> John, I did some soul searchi…tag:zenith.aero,2021-10-25:2606393:Comment:8512552021-10-25T16:53:04.237ZBill Bearhttps://zenith.aero/profile/BillBear
<p>John, I did some soul searching about the ProSeal and discussed it with an A&P who has built two experimental aircraft. He convinced me to not use ProSeal. If for any reason I would need to remove those senders again, it would be a big job and a mess to accomplish. He recommended better access and just use Fuel Lube which I did. I guess time will tell if I made a good decision or not.</p>
<p>Bill</p>
<p>John, I did some soul searching about the ProSeal and discussed it with an A&P who has built two experimental aircraft. He convinced me to not use ProSeal. If for any reason I would need to remove those senders again, it would be a big job and a mess to accomplish. He recommended better access and just use Fuel Lube which I did. I guess time will tell if I made a good decision or not.</p>
<p>Bill</p> Looks great, Bill! Van's rec…tag:zenith.aero,2021-10-25:2606393:Comment:8512502021-10-25T16:08:20.824ZJohn Austinhttps://zenith.aero/profile/JohnLAustin
<p>Looks great, Bill! Van's recommends installing the SW senders with ProSeal (or ChemSeal) only and no gaskets, but since you have added the top access cover, it won't be difficult at all to change out a gasket if you eventually developed a leak - but let's not think like that! LOL!</p>
<p>If I had it to do over again, I'd definitely modify the bends similar to what you did. However, I now think that my sender arm wasn't binding against the tank as much as it was just stiff from being new. …</p>
<p>Looks great, Bill! Van's recommends installing the SW senders with ProSeal (or ChemSeal) only and no gaskets, but since you have added the top access cover, it won't be difficult at all to change out a gasket if you eventually developed a leak - but let's not think like that! LOL!</p>
<p>If I had it to do over again, I'd definitely modify the bends similar to what you did. However, I now think that my sender arm wasn't binding against the tank as much as it was just stiff from being new. After very little flying, what with the fuel sloshing around and giving the float arm a good work-out, it began moving very freely and works great. </p>
<p>John</p> John,
Thanks for the detailed…tag:zenith.aero,2021-10-25:2606393:Comment:8510822021-10-25T04:48:06.497ZBill Bearhttps://zenith.aero/profile/BillBear
<p>John,</p>
<p>Thanks for the detailed description. I have replaced my VDO senders with the SW senders as you have. However, I modified the bends and angles of the sender arms to eliminate the possibility of binding with tank structure. The float position appears to be located the same place as yours. I used Fuel Lube on all screw threads, both sides of the new gaskets, and one side of the backup plate. After 36 hours, no leaks ! I've included an adequate access panel to the top inboard…</p>
<p>John,</p>
<p>Thanks for the detailed description. I have replaced my VDO senders with the SW senders as you have. However, I modified the bends and angles of the sender arms to eliminate the possibility of binding with tank structure. The float position appears to be located the same place as yours. I used Fuel Lube on all screw threads, both sides of the new gaskets, and one side of the backup plate. After 36 hours, no leaks ! I've included an adequate access panel to the top inboard wing skins to access the senders if needed in the future. I find it easier to work from above than from below. Pix below.</p>
<p>Bill Bear</p>
<p><a href="https://storage.ning.com/topology/rest/1.0/file/get/9733987665?profile=original" target="_blank" rel="noopener"><img src="https://storage.ning.com/topology/rest/1.0/file/get/9733987665?profile=RESIZE_710x" class="align-full"/></a></p>
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<p><a href="https://storage.ning.com/topology/rest/1.0/file/get/9733988460?profile=original" target="_blank" rel="noopener"><img src="https://storage.ning.com/topology/rest/1.0/file/get/9733988460?profile=RESIZE_710x" class="align-full"/></a></p>
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<p><a href="https://storage.ning.com/topology/rest/1.0/file/get/9733989055?profile=original" target="_blank" rel="noopener"><img src="https://storage.ning.com/topology/rest/1.0/file/get/9733989055?profile=RESIZE_710x" class="align-full"/></a></p>
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<p><a href="https://storage.ning.com/topology/rest/1.0/file/get/9733988701?profile=original" target="_blank" rel="noopener"><img src="https://storage.ning.com/topology/rest/1.0/file/get/9733988701?profile=RESIZE_710x" class="align-full"/></a></p> I doubt they were intentional…tag:zenith.aero,2021-09-30:2606393:Comment:8489132021-09-30T11:58:21.107ZJohn Austinhttps://zenith.aero/profile/JohnLAustin
<p>I doubt they were intentionally designed to be side-mounted (I suspect they are intended to be a replacement for the VDO's, which are actually mounted on top of the tank in OEM applications like the old VW bugs), but as I've said elsewhere, apparently they're much more resistant to gas leaks as they have a totally different central terminal and resistance wiper design while maintaining the exact same diameter and bolt-hole pattern of the VDO.</p>
<p>If replacing the VDO sender with the SW,…</p>
<p>I doubt they were intentionally designed to be side-mounted (I suspect they are intended to be a replacement for the VDO's, which are actually mounted on top of the tank in OEM applications like the old VW bugs), but as I've said elsewhere, apparently they're much more resistant to gas leaks as they have a totally different central terminal and resistance wiper design while maintaining the exact same diameter and bolt-hole pattern of the VDO.</p>
<p>If replacing the VDO sender with the SW, you'll definitely have to bend the float arm to get a complete range of motion that mimics what the VDO sender had. However, the arm pivots on the side of the mechanism on the SW and pivots on the end of the VDO mechanism, so the pivot points are different and thus the bends will not be exactly the same.</p>
<p>John</p> John,
On the SW senders you u…tag:zenith.aero,2021-09-30:2606393:Comment:8490112021-09-30T11:24:23.078ZJimmy Younghttps://zenith.aero/profile/JimmyYoung
<p>John,</p>
<p>On the SW senders you used - are they designed from the get-go to be side mounted, thus no bending of the float arm is required? </p>
<p>John,</p>
<p>On the SW senders you used - are they designed from the get-go to be side mounted, thus no bending of the float arm is required? </p>