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MG TD TF 1500 - Fuel Line Leak at Carbs
|I'm looking for some suggestions.|
I just got my carburettors back from Joe Curto, after he rebuilt them and I also put new lines from fuel pump to carbs and carb to carb that came from Moss. I get some leakage from the banjo fittings and Joe supplied me with new red gaskets that go on the bango bold. I keep tightening them up but still get some fuel leakage.... Any Ideas?
60 MGA Coupe
61 MGA Roadster
56 LeMans Healey
|They have always been a major pain for me to get them to stop leaking. The fiber washers seem to need re-tightening every few days for a while, and I have seen some washers over the years that just never would seal. Make sure there are no radial scratches on any of the mating surfaces- the brass of the banjos as well as the float bowl lid fitting. All of the mating surfaces should also be close to perfectly smooth. Lastly, make sure the banjo bolt is not bottoming in the threads, so it seems tight but is not. George|
|George is correct, and for more complete advice, here is a link to Skip Burns' advice on SUs. You can read all his great advice here (there are two parts):|
But I cut and pasted his information specific to leakage here, so, per Skip:
Leaks Around the Carbs: When the carbs have been rebuilt and reinstalled, the bane of the rebuilder is leaks that occur where the banjo bolts and the bolts that attach the float bowls to the carbs are located. Because of the hazy line between getting it just right or over-tightening and stripping the threads, stopping these leaks is more an art than science. Over the years, I’ve developed a technique that almost always works.
To begin with, when reinstalling the carbs, studiously avoid overly tightening the banjo bolts that connect the fuel lines to the float bowls and the bolts that attach the float bowls to the carbs. Your objective is the middle ground between stripping any threads and stopping leaks. That said, and assuming you’ve properly renewed all the associated washers and they’re in the correct order, and that you haven’t overly tightened the bolts, turn on the ignition switch and check for leaks. Run your finger under the banjos and under and around the float attaching bolts. Usually, you’ll find leaks. Not to worry. Just don’t retighten the bolts right away unless the leak is really bad. Let the fuel pump run for a few seconds to thoroughly soak the fiber washers with fuel. After a few seconds, turn off the ignition and using a ˝ Whitworth or 9/16 BS wrench, tighten the banjo bolts (if they’re leaking) only a slight amount. If needed, do the same for the lower float bowl bolts using a 3/8 Whitworth or 7/16 BS wrench. Turn on the fuel pump again and recheck for leaks. If any are found, retighten again, but only a little, repeating the process until you think the leaks have stopped. What you’re doing is tightening in increments. Quit for the day and come back the next day and repeat the checks. Almost always, the next day will reveal yet more leaks, albeit minor ones; but remember, the objective here is to completely stop all leaks without stripping threads. Repeat the process carried out the day before, again being careful not to apply too much torque on the wrench. Itty-bitty, incremental turns of the wrench is what you seek. When you’ve done this for two, three or four days—or whatever time it takes, come back and check the lines in a week. They should be leak free.
|The banjo bolts are by far the most prone to leak, but I would recommend that you also check the hose connections to the banjo bolts, if those are not tight enough, or are a bit off center, you can get leakage from them that will flow around the banjo fitting, dripping off the bottom and looking for all the world like the banjo fitting is leaking. Loosen the nut that holds the fuel line to the banjo fitting and rock the line back and forth a bit to insure that it is centered in the concave end of the banjo fitting and then tighten the nut down well. I am looking into a source of Dowty washers for the carburetors and fuel pump banjo fittings and will let people know when I find them. Dowty washers are similar to Stat-O-Seals for those who know what that is. They are an aluminum washer with 'O' ring fused to the inside diameter. The advantage to this type of a seal is that it doesn't have to be tightened to just shy of stripping the threads to insure a good seal. Cheers - Dave|
|David, I've run into this before. It's caused by a wrong parts issue. The banjo connections require properly sized fiber washers to work properly. The washer that the banjo bolt first goes through has to have a small enough outer diameter to fit into the recess in the outer side of the banjo fitting. The washer that is placed between the fitting and the float chamber can have a larger o.d. with no problem. I ran into this problem a couple of years ago (7/04). The o.d. of the gaskets that I had received was .885". The originals were .867". Joe Curto sent a new set to me that measured .877" o.d.. Problem solved.|
I will go over all your suggestions. None of my other cars leak because the fiber washers have been on for some time. I undo the bango bolts every year to clean out the screen filter and don't have much of a problem. I guess its because the TD has new washers.
|Also, check the float bowl lid for small cracks around the banjo sealing surface. One of my lids had a very small crack that leaked. I applied JB Weld to the area and sanded smooth. The repair has worked for 2+ years and isn't visible.|
(Sorry for not logging in. On the wife's computer.)
Give me a call at the office - I may have something that will help in the future.
This thread was discussed between 24/02/2008 and 26/02/2008
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