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Engine Specific Info and Questions => IDI Engine => Topic started by: sgnimj96 on January 30, 2013, 07:22:54 pm
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I just got a 1.6 n/a. Previous owner was not good to it, but the engine is still healthy. After fixing various things I still have this return banjo leak that is perplexing: new copper washers, return line seems clear (blew air through it), rubber hoses are good and tight, engine runs fine. However, when I ran a short fuel line from the return banjo straight into a bottle the leak is much less. It idles fine, but leaks a steady drip from the out banjo. I'm really not happy about having to take that banjo bolt off- I've never seen torqued copper washers leak so easily. The PO had rigged a lot of stuff ridiculously wrong. The idle adjustment screw is gone and I was told the fuel screw was turned up. ???
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I would make sure both copper washers are clean and not cracked or something. I would make sure the banjo isn't cracked either. A guy on here says he sands the copper washers with fine sandpaper and then heats them to blue with a torch. He said they seal better for him. I personally haven't had an issue or used this method, but would give it a shot if you have that bad a leak.
Also, if you reused the cloth line after pulling it off, then that is your problem. Replace those as they leak always.
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thanks for the reply
I'll try cleaning and heating the washers, I was starting to worry the pump was over pressuring the return with the odd fuel/idle set up. It's a 81' scirocco that someone put a diesel in. Then someone else got it and thought it would be faster with an electric fuel pump and the fuel screw turned up. There is a long list of dumb stuff. Good thing he sold it.
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Hey now, don't be dissing the electric fuel pump.. ;) It is my first modification when I start working on one of these bad boys. That and clear fuel lines, best things to do if you haven't
(http://i299.photobucket.com/albums/mm307/J_holubek/88%20Jetta/20130102_203411.jpg)
Also, yes it could be ridiculously high internal pump pressure.. he may have tinkered with it if he has done some other funky stuff. I'd be checking it, by making one of these;
(http://i299.photobucket.com/albums/mm307/J_holubek/84%20Jetta/20120801_233505.jpg)
However, before you do any of that.. when you remove your OUT bolt, make sure it is not gunked up inside.. that will cause stupid high pump pressures, and sooner or later you will start blowing seals out.
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8V you forgot to tell him about the tiny screen inside the OUT Bolt and the teeny tiny hole in it where the return line goes. Both of these need inspection and air through them.
Nice gauge set up but again, tell him where it goes to measure the IP pressure.
You may be correct on the PO pounding in the regulator on the front part of the pump. Refer to the sticky from the home page that has the diagrams and such in it so you can get started on understanding where the fuel comes and goes in these critters.
I have a take off on the out bolt that provides me with IP pressure. The gauge is inside the car with all the others. Lots of others.
Good luck, I hate leaks like that.
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Ahh yes, my apologies.
My second picture is an air tank gauge (yes it is broken, they should sit at zero). The bolt on the left is a drilled and tapped OUT bolt. When you take yours out you will see that there is a very small hole on the side of it above the threads. It is this small hole that regulates the internal pump pressures by the way of being a restriction. You need to make sure the screen is free of debris, and gunk.
As can be seen here, I have the gauge in my out bolt. With separate testing lines in to a jug of 2-stroke oil.
(http://i299.photobucket.com/albums/mm307/J_holubek/84%20Jetta/20120803_153913.jpg)
And here (http://www.youtube.com/watch?v=_wzm_VIJxUA) is a video of said excursion. My pressure was WAY LOW, as I had some internal pump issues.. but you're looking for around 45-47psi at warm idle I believe.
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About washers-
I sand them with fine sandpaper, like 1000 grit by laying the sandpaper on a smooth surface and moving the part back and forth in an figure 8 motion.
I don't heat them though, I tried that once and it melted the washer.
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I don't heat them though, I tried that once and it melted the washer.
Too hot.. lol
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The copper washers and banjo fitting seal around the outside of the OUT bolt and so are not under any pressure at all, ever, unless there is a blockage in the return line to the tank.
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IIRC he has blown through the fuel lines.
I think you just may have to crank it down a little tighter. You have to crush that copper washer for it to seal.
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electric primer/lift pumps are a GREAT IDEA on these old cars..
i, as well, add an electric pump to any new cars as well.. they really DO help out..
plus, if/when you run out of fuel, all you have to do, is turn the key on, and let the inj pump re-fill, then hit the key..
that eliminates the need to crank for minutes at a time to re-prime your fuel system..
have you confirmed that it IS INDEED the out banjo leaking, and not the throttle shaft seal? they are both on top of the pump, and in close proximity..
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I use the figure 8 pattern as well but when heating I only use the tip of the torch flame not the internal blue tip. It takes like seconds to turn them blue and then they smash better. Clean extremely well on all sides of all parts. Why embed a bit of dirt and make it leak again?
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I hang the washer from a screwdriver, and heat it over a burner on the stove till it just starts to glow.
Doesn't take much.
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IIRC he has blown through the fuel lines.
I think you just may have to crank it down a little tighter. You have to crush that copper washer for it to seal.
The injector jumpers and return line to the tank are similarly on the outside of the OUT bolt and so are not under any fuel pressure at all unless there is a restriction to the line to the tank.
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They still utilize a crush washer for a reason, no? To be crushed lol.
You can't tell me there is 0psi on the return, it does not just trickle back to the tank. The pump forces it back there.
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If I undo my out bolt, the return drains down by gravity.
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My sedans siphon the fuel in the return line away from the IP, as does the supply line (unless there are no air leaks). So, in a manner of speaking, there is negative pressure. :P
But, if there is a split in an injector return jumper, it can spit fuel with each pulse of the injector pintle.
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If I undo my out bolt, the return drains down by gravity.
While running? And having fuel pushed out of the IP?
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If I undid it while running, fuel would go everywhere, and the line would still drain down.
Drainback is prevented by air not having any way to get into the pump, but if you pump leaks, if you park your car, it will be drained back in the morning.
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Yeah I know.
However what you are getting at does not pertain to what I said earlier. We are not talking about over night drain back, we are talking about a leaking OUT banjo.
There is pressure in that line while running.. The fuel pump is pushing nearly as much fuel back to the tank as it brought from it in the first place.
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Off topic somewhat, but where does one find replacement copper washers, my import supplier could not find the ones I need for my oil return thanks.
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Off topic somewhat, but where does one find replacement copper washers, my import supplier could not find the ones I need for my oil return thanks.
Anneal themas mentioned earlier in this thread, try a turbo or hydraulic shop.
Yeah I know.
However what you are getting at does not pertain to what I said earlier. We are not talking about over night drain back, we are talking about a leaking OUT banjo.
There is pressure in that line while running.. The fuel pump is pushing nearly as much fuel back to the tank as it brought from it in the first place.
Sure, but the line is more than big enough. No clamp, and it doesn't leak, though the braided ones will if they are too old.
If there was appreciable backpressure, it would ruin your dynamic advance.
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Consider the diameter of the orifice in the OUT bolt and the ID of the return line itself.
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Consider the diameter of the orifice in the OUT bolt and the ID of the return line itself.
I am just saying, regardless without a crushed washer.. there is no seal.
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The crush washer is upstream of the out bolt, and has little to do with the return line.
It sees full case pressure at all times, and must be sealed.
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That is incorrect. The crush washers are outside the OUT bolt and so see zero pressure. The oil pan gasket is similarly under no pressure. In either case, if there is a hole it will leak and make a mess I'm not trying to say the crush washers are unimportant. They need to seal. They just aren't holding back internal pressure (or any pressure at all for that matter) and neither are the injector jumpers and so although leaks are not uncommon, it doesn't take much to make them seal. If the OUT bolt screen were plugged and internal pressure went through the roof, the likelihood of the crush washers leaking would not be increased any. If there is an issue of increased pressure at the injector jumpers or crush washers then it is due to a restriction in the return line.
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That is incorrect. The crush washers are outside the OUT bolt and so see zero pressure. .....
I don't think so. The threads of the out bolt leads directly to the inside of the pump and sees internal fuel pressure.The copper washer's job is to seal the out bolt threads.
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Libby is right, but I wonder if worn threads affect internal pressure?
Even so, the plunger one seals way more pressure without being all that tight.
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The OP needs to come back and tell us what is up. I suggested the copper washers as he hinted at them first post. My thinking is if you don't tighten the out bolt the fuel will come up the threads of the bolt and leak out a bit. He may have fixed it by adding new line like I told him could be the problem and is just embarassed to post up as it was simple.
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I was referring to the copper washer between the pump case and the bolt/pedestal. If you take that bolt/pedestal out, you see internal case pressure. How can that copper washer not see pressure unless the threads forms a perfect seal? Help me out please!
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The pedestal is on less than 1% of the pumps and the copper washer under it has nothing at all to do with the banjo fitting except that it is in the vicinity... Obviously I wasn't talking about the copper washer under the pedestal, if you happen to be one of the very few who even has one. I was talking about the two around the OUT banjo (note thread title...). Further, you even state that 'the threads of the OUT bolt lead directly into the case' and so in that instance you couldn't have been talking about a pump equipped with a pedestal/standoff.
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The pedestal is on less than 1% of the pumps and the copper washer under it has nothing at all to do with the banjo fitting except that it is in the vicinity... Obviously I wasn't talking about the copper washer under the pedestal, if you happen to be one of the very few who even has one. I was talking about the two around the OUT banjo (note thread title...). Further, you even state that 'the threads of the OUT bolt lead directly into the case' and so in that instance you couldn't have been talking about a pump equipped with a pedestal/standoff.
My car as well as my spare engine has the pedestal. I may have used out bolt and pedestal interchangeably but I meant pedestal (I was half asleep so please excuse me). My previous post was in response to a post from you which was deleted before I was able to quote it where you stated the the copper washer under the pedestal is not under pressure. Maybe you did not say that, hey I was half asleep. :)
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Off topic somewhat, but where does one find replacement copper washers, my import supplier could not find the ones I need for my oil return thanks.
any industrial supply or hydraulic shop should have what you seek..
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Furthermore, for the same reasoning I gave for the pedestal washer, it would also apply to the banjo/ out bolt washers. i.e. if you remove the out bolt, you see internal case pressure at the pump opening. Put it back and the copper washers see case pressure, unless the out bolt threads form a perfect seal. Help me out but I can't see it any other way.
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To the OP, a good way to find the source of your leak is pressurize your pump and squirt soapy water in suspect areas and look for bubbles.
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To the OP, a good way to find the source of your leak is pressurize your pump and squirt soapy water in suspect areas and look for bubbles.
pressurize it with AIR, not fuel, just to clarify..
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A sure way to test if there is pressure behind the out bolt copper washers is to loosen the out bolt a little while the engine is running. If there is no pressure, fuel should not squirt out. If there is (around 60 psi at idle), you should get a pretty good squirt so wear goggles and take precautions.
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I did not delete any posts that you replied to. I did delete one post where I reiterated what I had said previously, but in the interest of reducing redundancy I deleted it to reduce redundancy.
I guess you are asking for more redundancy and so I will accommodate you because you are asking for more redundancy. The copper washers of the banjo are outside the threads of the out bolt. I haven't even made any attempt to do the calcs on how much fuel flows up the gap of the threads of the OUT bolt but I certainly believe it to be significantly less than what flows out of the orifice of the OUT bolt. The area of the return line is many times larger than the combined area of the orifice and whatever minuscule gap there is in the threads of the out bolt/case and so there is not internal pressure outside the case threads or orifice of the out bolt. The boundary of the internal pressure is the vane pump and pressure regulator on the inlet side (no pressure on that banjo either) and the OUT bolt itself on the outlet side. The banjo and copper washers are BEYOND the OUT bolt and so are not under any pressure. The copper washers do not seal the threads of the OUT bolt. They seal the top of the banjo to the bottom of the head of the OUT bolt and the bottom of the banjo to the case. If you believe that the copper washers are under internal pump pressure then you must also believe that internal pump pressure extends down the return line to the fuel tank and through the tank vent to atmosphere...
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A sure way to test if there is pressure behind the out bolt copper washers is to loosen the out bolt a little while the engine is running. If there is no pressure, fuel should not squirt out. If there is (around 60 psi at idle), you should get a pretty good squirt so wear goggles and take precautions.
That's a terrible test. Gravity coupled with the fact the fuel weighs more than the air that displaces it will cause fuel to flow out if there is a gap.
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A sure way to test if there is pressure behind the out bolt copper washers is to loosen the out bolt a little while the engine is running. If there is no pressure, fuel should not squirt out. If there is (around 60 psi at idle), you should get a pretty good squirt so wear goggles and take precautions.
That's a terrible test. Gravity coupled with the fact the fuel weighs more than the air that displaces it will cause fuel to flow out if there is a gap.
x2
fuel is going to leak out when you loosen the out bolt, no matter if the return line is clogged or not...
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I did not delete any posts that you replied to. I did delete one post where I reiterated what I had said previously, but in the interest of reducing redundancy I deleted it to reduce redundancy.
I guess you are asking for more redundancy and so I will accommodate you because you are asking for more redundancy. The copper washers of the banjo are outside the threads of the out bolt. I haven't even made any attempt to do the calcs on how much fuel flows up the gap of the threads of the OUT bolt but I certainly believe it to be significantly less than what flows out of the orifice of the OUT bolt. The area of the return line is many times larger than the combined area of the orifice and whatever minuscule gap there is in the threads of the out bolt/case and so there is not internal pressure outside the case threads or orifice of the out bolt. The boundary of the internal pressure is the vane pump and pressure regulator on the inlet side (no pressure on that banjo either) and the OUT bolt itself on the outlet side. The banjo and copper washers are BEYOND the OUT bolt and so are not under any pressure. The copper washers do not seal the threads of the OUT bolt. They seal the top of the banjo to the bottom of the head of the OUT bolt and the bottom of the banjo to the case. If you believe that the copper washers are under internal pump pressure then you must also believe that internal pump pressure extends down the return line to the fuel tank and through the tank vent to atmosphere...
I will have to dig out my spare pedestal/out bolt and have a look. I just can't see there is zero pressure behind the copper washers.
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What do you find confusing in my explanation?
Imagine just an out bolt bolted all the way into a pump, no banjo or washers. If it is run that way, internal pressure will still be maintained by the bolt/orifice. Outside that boundary there is no internal pressure regardless of whether the washers or banjo are present. Granted fuel will squirt out of the orifice a weep a little around the threads, but that leakage is metered and accounted for by Bosch in the design of the pump. Beyond that point, when banjo, washers and hose are present, gravity pulls the fuel back to the tank.
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Wow. I just got back. I tightened the banjo one more time and then had to drive it on the interstate to get back home with the car - a long drive. As it turns out, I had a restriction in the line coming from the tank. It was quite a drama: first I thought it was just an air leak in the clear line coming from the fuel filter to the IP, so I refit and tightened that and off I went down the highway (with the out banjo leaking). Funny how real fuel flow problems happen after time at highway speeds, just when you don't want them to happen. KInda scary and dangerous things like that can be. I thought I just had a leak.
So I lost power on the interstate; made it to an exit (luckily), popped the hood and found the clear line full of air. All hoses are tight. This car has an electric fuel pump, which IS cool, so I turned it on and left it on (didn't think I needed it while driving but it helped so I continued on). 30 minutes later I lost power again, barely made to an exit and coasted into a truck stop sputtering- in the middle of nowhere. Disconnected the electric pump out hose, checked it, still pumped fuel (but seemed kind of weak). Then disconnected the other end of that fuel hose (at the filter) did a blow test. I should have done this in the garage- main line from the filter to the tank (disconnected at both ends) is clogged. LUCKILY I had some 1/4" clear fuel line, had to heat it with a lighter a little but managed to push it onto fuel filter inlet and ran it to the electric fuel pump (in the back of the car). Used the electric fuel pump to push the air out of new fuel line (out the bleeder on the filter)- although it took it a while, which seemed odd. So with a new fuel line off I went down the interstate on my long journey. Like an hour or two later, middle of the night, loses power! Hit the fuel pump switch and it helped but not for long. Sputtering and feathering the pedal (it actually died a couple times) but I managed to restart with clutch with my leftover speed and finally coast into convenience store off the highway somewhere in Louisiana. Feeling lucky, but stupid. Last ditch effort- bypass the electric fuel pump. A police SUV is casually hanging out watching me. I ran the fuel pump a little more to see if it would get some of the air out of the clear line to the IP and it did a little but was now basically worthless. I had nothing to connect the hoses together to bypass the electric pump but... Luckily! in my toolbox I had a 1/4" deep-well socket (1/4" drive) that would fit with a little forcing (actually worked pretty good because they were two different sized hoses) Managed to start her back up. After a bit all the air was purged and I was out of there.
I drove from Texas to Florida, and For some reason, the out banjo on the IP doesn't seem to be leaking anymore after that or is just hard to notice (I made a lot of stops checking things) KInda neat having a clear fuel hose running across the passenger seat where you can keep an eye on it. NOT!
Is that missing leak just a coincidence?
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Since the car is relatively new to you, it is hard to know what went into the tank. I would give it a healthy dose of Power Service 911 to help dissolve any wax or foreign oil that the PO might used that could be blocking the tank screen or pump. Bypass/remove the water separator, if it is still in line.
I'd ensure the return line is flowing freely with light application of compressed air and listen for bubbles in the tank.
As for the leaking banjo, a fine scratch on the IP case or bolt can create a dribble. It may self-seal for awhile, but come back later. Close inspection with a magnifier might reveal potential leaks. A very very light smear of sealant on the washers might resolve a lingering drip.
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When I had something similar happen to me, I just ran a clear fuel line from the fuel filter through the top rear of the hood, back into the passenger front window, out the rear passenger window, then into the gas tank through the filler neck, thus bypassing the fuel pickup in the tank.
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I may have to open the top of the tank and look inside. When I took the outlet line off the tank fuel didn't run out very fast- poked a stiff zip tip end in it, made no difference. That poor electric fuel pump had a lot of resistance to work against, pushing and pulling. Its own filter seemed clogged when I checked on the road but you can't bypass it without a threaded adaptor. It was the green Mr. Gasket Diesel pump. Still comes on. At least now I can drive my other car in the meantime. I will be running biodiesel in it when it gets straightened out (they sell B99 here). I got a lot to do before I can get back to the banjo leak. Thanks for all the posts. It was amazing to get back and see the good discussion that had started about the possible causes of return banjo leaks. :)
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Return line pressure readings:
(https://lh6.googleusercontent.com/-sAYddaFlYOE/UQ1YpxyxZTI/AAAAAAAAA-Y/h7OIRWiQtBo/s0/ReturnLinePsi.jpg)
1985 Jetta, 1991 ECO engine w/ 1989 TD IP.
That's an air/gas gauge.
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Thanks for the test. Your gauge is weird, tho. It looks like 10 marks between 10 and 15 psi but only 8 marks between 0 and 10. It looks like you're counting the marks as 1 psi each doesn't make sense in either case. Regardless, apparently there is slightly more flow from the OUT bolt than will bleed back to the tank by gravity alone, unless you have a bit of restriction in your return line somewhere.
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OP, you might also want to consider running a biocide fuel additive.
My boost gauge is like that too, but has honest numbers that start at 2.
might be to stop chattering on the peg at near 0, or to mask poor calibration at 0.
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Not too surprising that 500ml/sec flow from the out bolt to the tank would generate some pressure, albeit quite small compared to typical fuel line pressures. I would have expected slightly higher pressures at 3000rpm.
Had I known the pressures were in that small of a range, I'd have found a more appropriate gauge.
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...sounds like all new fuel lines is in order for this. I do have some Killem biocide I can put in the fuel after.
Nice pics with the gauge on to see actual normal pressures! :)
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Off topic somewhat, but where does one find replacement copper washers, my import supplier could not find the ones I need for my oil return thanks.
I got em from Autohauz. You might want to get some other stuff while your at it.
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DIY manometer, ATF for the fluid.
(https://lh3.googleusercontent.com/-8WZLXOuMn-A/URF0VTSAPiI/AAAAAAAAA_8/WhqlBI4dG0Y/s800/IMG_9234.JPG)
Tee into the return line, mostly level with the raintray, since about 4 feet of fuel will push into the tube.
(https://lh3.googleusercontent.com/-UQhtNJNE2to/URFzaLbpPXI/AAAAAAAAA_0/nxMQBjya_Iw/s640/imagejpeg_9.jpg)
Engine off: Negative pressure from the weight of the fuel trying to flow back to the tank.
(https://lh4.googleusercontent.com/-S20P6D0P9IQ/URFzY0JDGSI/AAAAAAAAA_s/jEtJUGRRvVA/s640/imagejpeg_8.jpg)
1000 RPM:
(https://lh6.googleusercontent.com/-Aoe9weVLzj0/URFzWBpgd5I/AAAAAAAAA_k/_29SRe-dpw0/s640/imagejpeg_7.jpg)
2000 RPM:
(https://lh4.googleusercontent.com/-M7rDYbl_94A/URFzUVEZ7GI/AAAAAAAAA_U/qznlThplo2w/s640/imagejpeg_5.jpg)
3000 RPM:
(https://lh4.googleusercontent.com/-ngfSCe_993w/URFzPjXc3dI/AAAAAAAAA_A/y5Gv6kWfjWI/s640/imagejpeg_2.jpg)
Keep in mind that the reading is including the negative pressure the flow the line to the tank is creating; but that resulting sum (the reading) is the pressure the OUT banjo encounters.
So it would appear the Watts gauge is a bit inaccurate at low pressures. lol
The u-tube manometer is quite accurate if there are no leaks. It is a common "primary standard".
For those who like math, the specific gravity of ATF is ~0.87.
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Nice science project. The pressure you measured is after the banjo bolt orifice. Now measure it before the orifice from the outside of the copper washer with the banjo bolt loosened.
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Nice science project. The pressure you measured is after the banjo bolt orifice. Now measure it before the orifice from the outside of the copper washer with the banjo bolt loosened.
Lol... I'll let you handle that one.
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Pressure :).
From 12 with the engine off to over 40 at 3000rpm. It rose the liquid in the manometer by 28 what I am guessing are inches?
Care to go a bit further in to detail TD? Interesting.
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Ja, them is inches... inches of ATF.
40 inches of ATF should be about 46" of water ("WC). (40/.87)
46 / 27.7 = 1.66psi. So, the banjo outlet is handling ~1.7psi.
12/.87 = 13.8" of vacuum due to the tank means the IP out bolt orifice is actually outputting 59.8" WC of pressure, or 2.2psi... but the tank vacuum lowers the pressure in the fitting.
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Right on, I learnt about it in the times between our reply but I came to some different pressures. Being that it was not my experiment I don't have accurate readings of what you had there.. so it probably threw it off.
Is 2.2 psi enough to cause a leak between those copper washers and the aluminium if not crushed? I think so.
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Is 2.2 psi enough to cause a leak between those copper washers and the aluminium if not crushed? I think so.
I rekon so too... Every time I leave that fitting loose, it leaks just fine.
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Now measure it before the orifice from the outside of the copper washer with the banjo bolt loosened.
...while doing a handstand, riding backwards, blindfolded, on a horse...
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Td your troubleshooting techniques amaze me more and more every time.
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I'm just happy to have found a use for the vinyl tubing that I'll never use for fuel lines.
As for the pressure at the bolt threads, a bit of poking around the webz reveals there are NPT threads, BPT threads, Metric Pipe Threads and the Germans have a unique thread also.
http://www.engineeringtoolbox.com/thread-standards-d_776.html
It is my impression that the threads seal most of the IP internal pressure from the banjo fitting.
(https://lh3.googleusercontent.com/-NhzL7Cpb9tA/URHXxUjQ5JI/AAAAAAAABAM/aZetvY9CmNU/s400/banjo1.png)
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Just for the record, after a couple of months of doing other stuff i found... my ip return banjo WAS actually cracked (a micro crack at the small tube for the injector returns). I replaced it with a banjo fitting (single tube) from a fuel line replacement kit and added a stainless T fitting (1/4 1/4 1/8) for the injector returns to meet into the return hose.
Definitely is a low-pressure fitting or fuel would have been spewing everywhere when I was driving around with that. ::)
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Ja, them is inches... inches of ATF.
40 inches of ATF should be about 46" of water ("WC). (40/.87)
46 / 27.7 = 1.66psi. So, the banjo outlet is handling ~1.7psi.
12/.87 = 13.8" of vacuum due to the tank means the IP out bolt orifice is actually outputting 59.8" WC of pressure, or 2.2psi... but the tank vacuum lowers the pressure in the fitting.
Your math might be a little off. A lower specific gravity (0.87) will result in the higher reading, no? Mercury has a much higher specific gravity than water and an inch of mercury is proportionately more pressure than an inch of water... Shouldn't the 40 inches of ATF be multiplied by the specific gravity rather than divided by it? That would mean 1.26 psi rather than 1.66 psi. Regardless, the pressure is minuscule.
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Yes, quite right!