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| Fuel leaking from vent | Rate Topic |
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| Posted: 08-11-2020 09:35 pm |
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1st Post |
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Jagwire64 Member
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Stock Stromberg 175 cd2. The carbs appear to be in good order. was told they were recently rebuilt. The car ran well when i drove it home. It was smelling of gas in the garage. The carb nearest the bulkhead/firewall has fuel running out of the air intake side. I believe it is coming from a vent hole (brass fitting hole at 10 o'clock) Fuel starts coming out as soon as the fuel pump is powered. I looked through shop manuals and internet. Does the carb need rebuilt again. This vent, vents fuel (right onto the starter) when something is blocked? Also, I am not sure if the throttle return springs? are right and proper (the long spring that is hooked on the air intake). There are 2 long springs on the throttle shaft..they don't look right? What spring should be there and how are they connected? Not sure if the picture is uploading? https://drive.google.com/file/d/1acDKT2NqbSpubpDK6TczCwQ_6HbBPHG-/view?usp=sharing Thanks Last edited on 08-11-2020 09:45 pm by Jagwire64 |
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| Posted: 08-11-2020 10:28 pm |
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2nd Post |
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Jagwire64 Member
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Upon further troubleshooting, The piston has higher damping force to push it up compared to the other. It doesn't fully come down and seat on the bridge. Could the piston not fully seated on the floor cause the fuel leak? Not sure if the needle is dirty, it was more a brassy color compared to the clean silver of the front carb. I did try to clean the needle. and the top end of the carb. I am assuming the needle is getting hung up in the jet? the diaphragm appears to be in good condition. Everything looks clean. Maybe it is the wrong needle? Any idea or tips on what i can check or clean to sort it out? Last edited on 08-11-2020 10:35 pm by Jagwire64 |
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| Posted: 08-12-2020 07:43 am |
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3rd Post |
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subwoofer Member
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If fuel is coming out when the pump is running the needle valve in the float chamber is not closing properly. Could be a bad valve, could be a sinking float. Either way, DO NOT DRIVE THE CAR UNTIL SORTED! There is a great ignition source right underneath the carbs, and fuel leaks have claimed the lives of many a Jensen Healey. I see a carb rebuild in your immediate future. -- Joachim
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| Posted: 08-12-2020 07:48 am |
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4th Post |
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Tom Bradley Member
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The first thing I would check is the fuel pressure at the carbs. This should be less than 3.5 PSI. More than this and the fuel could be forcing its way past the inlet needle valves. Less than 2.5 PSI I think is better. Depends on the condition of the inlet needles. Other possibilities are: The float set too low, making the fuel level too high. Nowadays I set this to 17mm or even a bit higher. The fuel inlet jet(s) are leaky and need to be replaced. Other things you mentioned probably are not the main issue, however... The damping force when pushing the damper up depends on the oil in the damper. Make sure they are topped up with 20W50 oil. If one of the dampers does not fall all the way back down, it may be slightly misaligned. Try loosening the screws holding holding the top on and see if the damper will drop down. You may have to move it around a bit. Once you find a good position, carefully tighten the screws a bit at a time to keep the top from shifting position. The throttle return springs are not that critical. As long as they are strong enough to consistently get the throttles to close back to the stop position they should be OK.
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| Posted: 08-12-2020 01:58 pm |
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5th Post |
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redracer Member
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Agree with Tom & Joachim: please DO NOT EVEN ATTEMPT TO START CAR;; could be INSTANT FIRE
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| Posted: 08-12-2020 03:29 pm |
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6th Post |
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Jagwire64 Member
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No i'm not driving it. Which is sad because I just bought it and haven't driven it much. Been trying to sort out the little niggles, which seem to be compounding. As soon as one is sorted you find another. PO was using the wrong fuses, had a positive earth voltage reg. that wasn't grounded so the temp and fuel read high, and the belt was only at 70lbs tension. That stuff is all fixed. I was hoping to take the wife to a winery this weekend to show her what a great purchase I had made....sigh I'm surprised it didn't catch fire when I tried to start it before noticing the fuel leaking. One of the first things I did was purchase an auto fire extinguisher after reading all the stories about the car catching fire. Going to go through the carb today and see if I can figure this out.
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| Posted: 08-12-2020 06:11 pm |
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7th Post |
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Jagwire64 Member
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I think it is the metering needle? if exchange air pistons, the problem follows. I don't have the tool to change just the needle. The cylinder and bore faces look ok. The needle that hangs up is marked B1CM, which Delta lists as the proper needle. The Needle that functions properly is marker B1AF that Moss lists for the TR6. I'm thinking I need the B1AF. Since that is what seems to be functioning properly. Don't know the history of the car or the carbs. When i bought the car it wasn't running properly and the PO changed the carbs with some spares he had (which he said were recently rebuilt). Maybe these are from a TR6 and the jets are sized for a different needle the B1AF? Any insight would be helpful. Thanks. Can't find much info on needle sizes.
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| Posted: 08-12-2020 07:23 pm |
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8th Post |
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redracer Member
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B1CM needles were used ONLY in the '72 $ '73 cars with B1DK used in all the later ones. A "dirty" needle would have nothing to do with a leaking carb, so please check you're float valve(gasket could either be broken or not tight enough, or too much fuel pressure as Tom mentioned.
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| Posted: 08-12-2020 08:19 pm |
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9th Post |
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Jagwire64 Member
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The fuel pump is not an SU, but is black plastic and says "Auto Pump made in NZ"...not sure how to test the pressure, without a specific tool for the job. The fuel is leaking out of the vent hole at 11 o'clock, if i plug that it comes out of the hole at 1 o'clock. That hole has a fitting to the vacuum lines on the outside of the carb. PO did remove the Charcoal canister. Is there a pressure regulator I could install? Not sure if i should put in a regulator or a different pump? The fuel starts running out when the pump is on, car not running. The needle valve in the float chamber should stop the flow of fuel once full? I'm guessing the leak is either high fuel pressure or the float needle valve is stuck open? If it were high pressure wouldn't the other carb be leaking? Last edited on 08-12-2020 08:52 pm by Jagwire64 |
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| Posted: 08-12-2020 09:01 pm |
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10th Post |
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redracer Member
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Jag: as Jaochim stated earlier, you WILL DEFINITELY need to remove the carbs. 1)a vacuum.pressure gauge is needed; this is a standard item for most home mechanics(along with a compression gauge) 2) the other carb doe not necessarily leak since the pressure is relieved by the leaking carb(just like hose) 3)yes, the float valve MAY be stuck open(ecpecially if the engine has not run in a long time, maybe 6+ months) but much more likely for one of the other reasons I already stated 4)hopefully there is a shop or mechanical friend nearby who could help you with this btw, I've rebuilt at least 150+ pairs of Strombergs; I use GROSE jets and not the needle valves that come with the kits)
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| Posted: 08-12-2020 09:02 pm |
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11th Post |
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Tom Bradley Member
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When you switch the needle and damper assembly do you also switch the spring? I think the springs for a TR6 are significantly softer than those for the JH. Check to make sure both of yours require the same force to compress. (This is not a subtle thing. When you squeeze them by hand it should be obvious if they are different). This could be why one of the dampers is not closing all the way. Though I don't see why this should cause fuel leakage unless there is another problem (or two). The needle should be easy to replace. There is a hole in the side of the damper which holds a spring-loaded pin that holds the needle in place. On my carbs this can be unscrewed with a slotted jewelers screw driver, which are cheap and easy to get. Supposedly, some require an Allen key, but I have never seen that. Once this is unscrewed, the needle can be pulled out the bottom. When re-installing, make sure the slot in the needle assembly is lined up with the holding pin. If the JH-spec needle is causing the problem, maybe it was installed incorrectly. Either the old or newer JH needles should work OK, but they should both be the same. IDK about TR6 needles in a JH.
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| Posted: 08-12-2020 09:04 pm |
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12th Post |
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Jagwire64 Member
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Purchased the car 3 weeks ago maybe. It ran well. Drove it 1.5 hours home...no problems. The different metering needles and the function of the piston is a problem but apparently unrelated to the leak. should I replace the needles with B1DK does it make a difference? I am ordering a pressure gauge. I will need to take this carb apart. I did switch springs and damper rods too. Tried all combinations. The springs look the same to me. The piston does take more force to compress. Last edited on 08-12-2020 09:12 pm by Jagwire64 |
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| Posted: 08-12-2020 09:10 pm |
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13th Post |
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Tom Bradley Member
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The quickest way to solve the fuel pressure question is to install a pressure regulator close to the carbs that has a readout dial. That way you have a visual check that it is correct, not just trusting the setting and can verify the pressure right where it matters.
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| Posted: 08-12-2020 09:14 pm |
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14th Post |
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redracer Member
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Since an incorrect needle was used, I would be VERY suspicious of whomever did the last rebuild. I normally take 5-6 hours for rebuilding with a few tricks involved; these are simple carbs(constant depression, like SUs) but from the few remarks I have read so far, you would best have someone more knowledgeable do the work. There were just 3 return springs used for Strombergs; Red, Blue, and Natural. Both the J-Hs and TR6s used the same (Blue) . The rubber diaphragms are the more likely culprit for different return rates or possibly a somewhat dirty air valve causing resistance on the side wall.
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| Posted: 08-12-2020 09:19 pm |
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15th Post |
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Tom Bradley Member
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If the car was running OK and you did not smell any gasoline when running, my guess is that the leak is small, possibly leaky jets. If you are going to open up the carbs, I would replace them just in case. I also like GROSE jets: I have only been using them for a couple of years, but the design seems to be more reliable than the original variety. They are also available at Moss. Look under TR6 carbs.
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| Posted: 08-12-2020 09:33 pm |
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16th Post |
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Jagwire64 Member
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The car did not smell of gas when running. The garage did smell strongly of gas. I will look into these Grose jets. After finding a variety of things wrong, I'm starting to suspect everything. In rebuilding the carbs I see various kits some with more than others, "service kit" rebuild, master rebuild kit" which kit do you all get? Not sure if the $22 walker kit is sufficient or I need a kit closer to $80?
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| Posted: 08-12-2020 09:42 pm |
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17th Post |
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redracer Member
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here's a start from ROCKAUTO: https://www.rockauto.com/en/catalog/jensen,1974,healey,2.0l+l4,1312383,fuel+&+air,carburetor+repair+kit,5964 I make up my own kits which include Grose jets and the large "O" ring the mounts on the back plate-y=to-intake manifold; but again, I would strongly advise finding a knowledgeable mechanic.
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| Posted: 08-13-2020 06:20 am |
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18th Post |
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Tom Bradley Member
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What to buy at this point depends on how much of a hurry you are in and what kind of shape the carbs are in. The least expensive route is to just get the things you know you need: fuel pressure gauge, the correct needles and the tools for tuning and balancing the carbs. Then look at it again and see what you need. One thing to look at is the condition of the big rubber diaphragm on the damper. If this is in good shape, still flexible and no sign of stiffening up or cracking, then the rest of the rubber bits and gaskets are probably also in good shape. If not, then I would go for a basic rebuild kit. If you want to cover all bases at once, then also getting Grose jets and new floats (preferably nitril if you have gasohol in your area). At this point it seems entirely possible that main problem could be simply due to a fuel pump putting out too much pressure. Resolving this first and then seeing if this is a problem may keep you from having to go to all the trouble of carb rebuilds at this point. While waiting you might also try wiping the dampers and carb inside with carb cleaning fluid and see if that helps with the sticking. I see no problem with going the do-it-yourself route at this point. We were all pretty ignorant when we first started on these cars. You seem to be ahead of where I was when I bought my first British roadster. I still did almost everything myself anyhow and both car and I survived the experience. Being able to fix these things myself and get it back on the road is a big part of what I like about these. Can't do that with most modern cars nowadays.
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| Posted: 08-13-2020 01:17 pm |
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19th Post |
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Jagwire64 Member
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I have ordered the pressure gauge. Going to check that first. The diaphragms look good, and so do the carbs in general. I did try some cleaner on the pistons. The surfaces look clean and feel pretty smooth. The little spring on the needle itself is also alot stiffer in action then the other. Not sure if that matters. I'm going to order a new needle as well. Having two different needles can't be good. I haven't decided if I should order 2 JH stock needles or just replace the one needle that appears problematic. The Grose jets look good and will put them in if and when the carb needs to come apart. I am very diy and the most mechanically inclined person I know. I can fix just about anything. I will get the car fixed, eventually, but I am definitely trying to save time and money. You guys have been very helpful. While I can't enjoy driving the car yet we are getting to know each other intimately.
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| Posted: 08-14-2020 01:19 am |
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20th Post |
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Tom Bradley Member
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I would definitely replace the TR6 needle. I doubt either of the needles are the main problem, but the JH engine was a major departure from traditional British engines like the TR6, so I would expect the needles to be significantly different. That cannot be helping things. Unfortunately there is a trad-off between quick and cost. The quickest solution is to buy everything you think you might need. The lest expensive is to order only what you know you need and then see if you need to order anything else. That means things are sitting more. If you don't have a Stromberg manual, you should get one. These carbs are not as difficult as they are made out to be, but there are issues that are not that obvious. You can get one on Amazon: https://www.amazon.com/Zenith-Stromberg-Haynes-Repair-Manuals/dp/156392157X/
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