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Junior Member
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Discussion Starter · #1 ·
I've got an old NTC-350 in a dumptruck. The truck is an 88, the motor is a 73, or so it says on the tag. It's been transplanted from some other truck (I suppose). Anyway, this thing gets used VERY little, and I'll probably sell it when the current stickers expire on it.
However, it adds fuel into the oil in large quantities. I don't know what it holds (oil), or how much fuel was in the oil when I got it, but the level on the dipstick has gone up several INCHES since I have it. I assume that's in the area of 3-5 gallons? I also assume that it's the seal on the pump shaft that's leaking. But what to do? Can I pull the pump and replace the seal, have somebody that knows something replace the seal, or does the entire truck have to go to the shop for the seal replacement?
Motor runs well once it's going. It takes large amounts of ether to start it when it's cool (say below 50 degrees). Doesn't seem to have a lot of blow-by. I think that it sat unused for quite a while - it leaks, it smokes, etc, etc....

Rebuilding the pump is out of the question, unless it can be done extremely cheap. My goal is to spend as little on this POS as possible. I'd rather not spend any money on it, but it has to stop putting fuel in the oil. It won't much longer like that, I suspect..... So how do I go about this?
Also, how do I know what this thing is??? I hear about big cams and small cams..... Would it actually say that on the info plate? I assume this to be an extremely early unit - has compression release, CPL 0021, family 093, build date of 11/28/73.

Rodney
 

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The other guy
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Pop the valve covers off and run the engine. Look around the injector where it goes into the head for fuel leaking out. If there is none, look at the injector where the plunger rod goes in for fuel there. It should be one of the two. If it’s around the bore, pull the injectors and replace orings. If it comes out past the plunger, replace the injectors. Get Pro Diesel injectors from a local pump shop for $40 apiece. That should cure the fuel in oil and the hard start at the same time. Set the injectors at 7in.lb non-OBC (old style), as they are not top stock injectors…T BTW, it's an early small cam NTC-350 (N=4vlv, T=turbo, C=W/J aftercooled)
 

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Junior Member
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Discussion Starter · #3 ·
So you're thinking that the problem lies in the injectors and NOT the pump??? I didn't think they'd flow enough fuel, but then I think about the 6-71 detroit we have, and that has a LOT of return fuel flow....

Is there anything special to be concerned about with injector removal - drain water partially, maybe copper washers that need replaced?

With any luck I'll get a shot of warm weather to bring this thing inside to work on it..... in the 30's tomorrow = no chance of getting it to run.

Rodney
 

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The other guy
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No concerns. Pop em out, no washers or anything. it will have cast injector hold downs with 5/16" 12pt bolts. Torq is 120 in.lb. Don't over torq, it'll break the hold downs...T
 

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Discussion Starter · #5 ·
Sounds like a plan. Seems like the weather will cooperate soon, and I can fire this thing up and bring it to the shop to work on it.

Thanks,

Rodney
 

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Junior Member
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96 Posts
Discussion Starter · #6 ·
So I popped the center valve cover today, fired the critter up, and all I saw was oil, and lots of it. All over everything now.



I took a few pics while it was running. I could plainly see where the injector was at, and the way the engine sits, the oil seems to collect near the rear of the valve train, and the rearward injector was covered with oil. I could see the movement was causing oil droplets to fly upwards, but didn't really see any fuel. Now, I ONLY popped off the center cover, so I have 4 other injectors to look at, but that has to wait for a day when I have time to roll this thing outside. I should mention that this is in a Ford L-9000, so the engine does sit in this thing on an angle towards the side I need to see. Is that going to prevent me from seeing what I need? If fuel is leaking from the injectors or the o-rings, it HAS to come up through the top, correct?

Rodney
 

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The other guy
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Rodney R said:
So I popped the center valve cover today, fired the critter up, and all I saw was oil, and lots of it. All over everything now.



I took a few pics while it was running. I could plainly see where the injector was at, and the way the engine sits, the oil seems to collect near the rear of the valve train, and the rearward injector was covered with oil. I could see the movement was causing oil droplets to fly upwards, but didn't really see any fuel. Now, I ONLY popped off the center cover, so I have 4 other injectors to look at, but that has to wait for a day when I have time to roll this thing outside. I should mention that this is in a Ford L-9000, so the engine does sit in this thing on an angle towards the side I need to see. Is that going to prevent me from seeing what I need? If fuel is leaking from the injectors or the o-rings, it HAS to come up through the top, correct?
Rodney
Yep, need to pull the other two. Yep, it`s a mess but can`t be helped. Wash the engine as best you can before any more tear down, from the top down. Use only cork valve cover gaskets as you have aluminum boxes (with no Jakes, cool). The oil is normal, just watch for fuel, and it will only be at the top. If it has a cracked cup, it`ll show in the rad...T
 

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Discussion Starter · #9 ·
I resurected this thread, cause today I had this POS outside, setting on a hill, and the valve covers were off, and it was running. Well, I didn't take the rear cover off, cause it required removal of the doghouse, the breather pipe, etc, etc, and I probably still couldn't have seen what I needed to see. I don't know how much fuel I should be seeing, but I didn't see any. I'm really leaning away from the o-rings/injectors, but y'all seem to think that's where the trouble lies. Does the injector hold down sit flush with the head - would the fuel be coming out BELOW the hold down???? I saw nothing on the top side, and nothing seemed to 'pool' around the injector.

Back to the pump...... Could this just be the seal on the pump shaft? What is required to fix that? Anything special to pull the pump? Must I take it to a rebuilder to have the seal put in, or can I do it?

You may ask why it was on a hill - a sidehill...... This thing is in an L-9000 Ford, and it sits tilted to one side...... the side that has the injectors. I think I'd almost have to roll the truck to make to the motor level, but it wasn't too bad. Would fuel float on oil, or would it mix right away?

Rodney
 

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the fuel wil mix. i beieve that it is possibe for fuel to leak from the pump into the pan. just unbolt the pump and take it to an injection shop. dont mess with it.if it has problems , they are better to be rebuilt by a shop.
 

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The other guy
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Rodney R said:
I resurected this thread, cause today I had this POS outside, setting on a hill, and the valve covers were off, and it was running. Well, I didn't take the rear cover off, cause it required removal of the doghouse, the breather pipe, etc, etc, and I probably still couldn't have seen what I needed to see. I don't know how much fuel I should be seeing, but I didn't see any. I'm really leaning away from the o-rings/injectors, but y'all seem to think that's where the trouble lies. Does the injector hold down sit flush with the head - would the fuel be coming out BELOW the hold down???? I saw nothing on the top side, and nothing seemed to 'pool' around the injector.

Back to the pump...... Could this just be the seal on the pump shaft? What is required to fix that? Anything special to pull the pump? Must I take it to a rebuilder to have the seal put in, or can I do it?

You may ask why it was on a hill - a sidehill...... This thing is in an L-9000 Ford, and it sits tilted to one side...... the side that has the injectors. I think I'd almost have to roll the truck to make to the motor level, but it wasn't too bad. Would fuel float on oil, or would it mix right away?

Rodney
I'd still check under the last cover. If it's an injector leak of any kind, you'll see it plain as day, whether it be from the top oring or the plunger. If not, check to see if the compressor "pan" (bottom) has a pipe plug in it. One that old should. Make sure your oil is full, pull the plug out and screw a fitting in that you can put a hose on. put the hose in a clear bottle and run the engine. If it's the pump seal, you'll see fuel in the bottle very easy. If so, pull the pump and take it to a shop. Cheap fix but you want it done right. He!!, a ReCon's only $500 for a new pump...T
 

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Discussion Starter · #12 ·
OK, this sounds good. I wasn't sure if I'd be able to see, with the engine leaning like it is..... And I like the sure-fire method of seeing if there's a leak @ the pump. I'm gonna attack this this weekend.

Many thanks,

Rodney
 

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Discussion Starter · #13 ·

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The other guy
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You be right. No plug, but check the bottom of the accy drive too. I guess now it’s how far do you want to go into it (after checking the last injectors)? The first step I’d guess is to go to Cat or Cummins with a small pill bottle or whatever and “borrow” some fuel dye (bright red powder). It’ll be in a 50lb cardboard bucket, and most places will just dump some in your bottle for you. Now you have something to hit with a flashlite or UV lite. I suppose being you don’t have an A/C comp, the easiest check is to remove the four accy drive to compressor bolts, pull it back on the drive sleeve about an inch, put 10psi of air to the #10 fuel inlet into the filter, and leave it on for hours (maybe overnight, who knows, under the 150psi rail pressure it has running) or til you see fuel running out. No fuel there, drop the pan and find the trail. Cylinder wall, injector tip or lower oring with a bad copper; passenger side of block, pull the covers back off. You missed it in there somehow. No sign anywhere, pull the pump off the compressor on the bench and take it in. It only leaks running. Hope that helps. Good luck bud…T
 

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Ol Dirt Contractor
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What ynot said plus maybe a long shot I've had happen to me with an NTC motor. The crosshead guide pilot hole sets right on top of the internally drilled pressure fuel galley in the head. I had one rebuilt head out of a set of 3 that I purchased with the pilot hole drilled into the fuel galley. After a week of running the fuel moved the guide up enough to leak fuel around the guide raising the oil level. I pulled the valve covers off and ran it thinking injector o-rings were leaking. I spotted the fuel bubbling up around the guide. Pulled the crosshead off and lifted the guide out of the pilot hole with my fingers.

The rebuilder would only exchange the one bad head and no money for labor so I pulled the other two off and put them on the parts counter and said credit me for these 3 phony heads or I no pay bill that month. Got the credit and went to Cummins for 3 recon heads.. Shop gets screwed every time..:damnit I found a new parts supplier also.
 

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Discussion Starter · #16 ·
Oh No...... I removed the doghouse, breather tube, and finally got that last valve cover off, parked it on my sidehill, had it running, and..... all I saw was oil. #5 cylinder wasn't too easy to see (from either side), but I wasn't seeing any fuel bubbling up. For sake of staying clean, I didn't rev the engine real fast, but I let it idle quite a bit, before the cover was off, and while the cover was off. I had it running while I took the cover off, so as not to 'lose' the trail of fuel I was hoping to see....

I'm not 100% certain that I read this right.... You said to take 4 bolts off the accy drive, and pull it back on the sleeve..... Do you mean to take out the bolts holding the pump, and slide it back a little, pressurize it, and watch for a fuel drip?

Rodney
 

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The other guy
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Rodney R said:
I'm not 100% certain that I read this right.... You said to take 4 bolts off the accy drive, and pull it back on the sleeve..... Do you mean to take out the bolts holding the pump, and slide it back a little, pressurize it, and watch for a fuel drip?

Rodney
You can break it loose at the pump, but my suggestion was to break it loose between the accy drive and the compressor. The oil return (or fuel leak) will run from the pump front thru the oil pan on the comp, thru the bottom of the accy drive, and down the front cover. Any place in there will show the leak, and it can only be from the pump. I suggested the air comp cause it's the easiest to bust apart (usually), but play it by ear...T
 

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Discussion Starter · #18 ·
Ok, so either one will work, it's just which ever one is easiest. I now have a project for the upcoming week.... I'll report back when I get some sort of findings.

Rodney
 
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