Leaking injectors

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450FiveString
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Leaking injectors

Post by 450FiveString » Sun Dec 06, 2020 8:00 pm

I've got a straight 450 crawler that is leaking fuel where the injectors fit in the head. When I found it was leaking I asked a friend who does a lot of heavy equipment repair and he said it was more likely leaking from the return lines and suggested replacing the rubber O rings for the return lines although I was pretty sure the leak was coming from where the injector fit in the head. But it was a cheap and easy try. It didn't help. So... since this machine is 50 years old and I didn't know if the injectors were original I decided to replace them. Put in 4 new ones I got from a very reputable diesel repair shop but they leak as bad as the ones I took out. Any ideas to stop the leaks?

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LeonardL
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Re: Leaking injectors

Post by LeonardL » Mon Dec 07, 2020 9:37 am

I really think your friend is right on this. I think you have an issue with the seals or the nuts. Are you sure you have them installed correctly and they are tight enough? If it was me I would be looking at the nut and seal that fits on the barrel of the injector itself. I'm thinking you either don't have those installed correctly or they're not tight enough. The nuts themselves could be cracked or damaged in some way.

The only injectors I ever found that leaked at the base where they are close to the cylinder head were cracked where the line fits to the injector barrel. Then it was only a single injector not all of them. I have a hard time thinking that you would have all eight of these injectors with the same issue. Especially the four new ones. It's virtually impossible for these to leak where you say they are leaking. I'm not saying it's impossible because that always bites me on the butt when I say it. But I still have a hard time seeing this as being your issue.

Make sure the nut and seal on the barrel itself is down past the lock nut at the top of the injector. Then make sure your "T" is down far enough so that the seal is tightening around the barrel of the injector and not the lock nut at the top.
40 plus years working on JD 350s, 400Gs, 450s and other equipment both Ag and Construction.

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Lavoy
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Re: Leaking injectors

Post by Lavoy » Mon Dec 07, 2020 10:09 am

It really shouldn't be able to leak fuel from out of the head, because the fuel is way down in the combustion chamber. To leak any fuel there, you would have to be leaking compression as well.
Lavoy
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450FiveString
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Re: Leaking injectors

Post by 450FiveString » Mon Dec 07, 2020 4:01 pm

Thanks for the replies. I'll check them again. The original injectors were leaking somewhere so I put new grommets on them but that made no difference. So I bought new injectors with new grommets. The leak is still there. Everything is tight. Is it possible that the return line is blocked causing back pressure?

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gregjo1948
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Re: Leaking injectors

Post by gregjo1948 » Tue Dec 08, 2020 3:32 am

Does the machine run as it should? Is there a check valve on the return line that may be faulty?
JD 350B diesel 6way blade, Case 580B Loader/backhoe, Farmall 504 high crop w/ flail boom mower, International 404 , International 284 diesel w/belly mower, 1972 Ford F600 dump truck, Galion 3-5 roller, Allis Chalmers D17, 1620 Ford

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Re: Leaking injectors

Post by Lavoy » Tue Dec 08, 2020 10:07 am

There is just no scenario that I can think of that would have fuel at the location you are saying. If the return is plugged, it won't leak where the injector goes into the block.
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450FiveString
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Re: Leaking injectors

Post by 450FiveString » Tue Dec 08, 2020 4:26 pm

The crawler starts and runs fine but fuel is puddling at the base of the injectors and running down the side of the engine. I just pressure washed the engine and I'm going to start it tomorrow and watch it to see it I can find the source of the leak.

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gregjo1948
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Re: Leaking injectors

Post by gregjo1948 » Wed Dec 09, 2020 2:53 am

Could it be the connections where the fuel line connects to the injectors? Seems like those round connectors are soldered to the fuel line and if they get tweaked while installing or removing, they will leak.
JD 350B diesel 6way blade, Case 580B Loader/backhoe, Farmall 504 high crop w/ flail boom mower, International 404 , International 284 diesel w/belly mower, 1972 Ford F600 dump truck, Galion 3-5 roller, Allis Chalmers D17, 1620 Ford

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Re: Leaking injectors

Post by B Town » Wed Dec 09, 2020 6:31 am

You said you replaced the o-rings on the return lines, do you have the original style fittings with the compression fitting/nuts that have to be tightened on each side of the injectors? You can upgrade to the rubber T fitting that use the constant pressure spring clamps. These new style T fittings are much better.
Best regards, Bruce

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450FiveString
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Re: Leaking injectors

Post by 450FiveString » Wed Dec 09, 2020 8:51 pm

Didn't get a chance to look at it today but hopefully will tomorrow. I'll give an update on what I find and maybe a picture.

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450FiveString
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Re: Leaking injectors

Post by 450FiveString » Thu Dec 10, 2020 7:32 pm

Checked out my crawler today and think I found the problem. I disconnected the return line at the first injector and fuel started running out which made me wonder if that should happen. Then I blew air into the line toward the fuel tank. I could hear the air going into the tank and when I stopped no air came back out of the return line which didn't seem right. I started unscrewing the fuel cap and could tell there was pressure on it but as I loosened it air began to come out of the return line. So when I got the fuel cap off I looked at the gasket. I recently bought a new one which is thick soft rubber and the ID is small enough that it covers the return line vent and soft and flexible enough that it seals it off. I marked the cap when tightened on the tank and notched the gasket there and it appears to have cured the leak. We'll watch and see.

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gregjo1948
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Re: Leaking injectors

Post by gregjo1948 » Fri Dec 11, 2020 3:18 am

I understand that you were building pressure due to the vent problem but, where was the fuel actually leaking?
JD 350B diesel 6way blade, Case 580B Loader/backhoe, Farmall 504 high crop w/ flail boom mower, International 404 , International 284 diesel w/belly mower, 1972 Ford F600 dump truck, Galion 3-5 roller, Allis Chalmers D17, 1620 Ford

Jim B
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Re: Leaking injectors

Post by Jim B » Fri Dec 11, 2020 6:43 am

I'm a bit confused by your description of this and a fuel return vent line. I believe your return fuel line goes in the bottom of the tank, a few inches to the left of the supply line to the transfer pump. It is a submerged dump, not atmospheric, so you wouldn't get air back out of it, or fuel, if the point in the line you were putting air pressure in was above the fuel level in the tank. If the tank wasn't venting to atmosphere and you you pressurized it with air, it should have pushed fuel out the line to you when the air was removed. I think the tube you see in the filler neck is the tank vent and exits the bottom of the tank. It is just a tube that gives an atmospheric vent to the tank, so the cap can be tightly sealed so as to prevent slopping fuel on the operator when working. The cap gasket would need to be real, real thick to block the vent tube in my 450E tank, if we are looking at the same tube. Those tubes do get plugged at the bottom of the tank and you may need to run a wire down through it to open it, air pressure from a shop hose might clear it as well. Stan did a post on his 350C tank a while back which is similar to mine and I expect yours is as well. Does yours look similar to the tube in these pictures? (A straight 450 didn't have the drain sump at the bottom that is on later series tanks.) You might have had a blockage in the return line or where it entered the tank which you disturbed by blowing back through the return line. Just my thoughts.
Jim
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