Fuel leak woes

[scboolitcaster]

For the last couple weeks, I've been trying to track down a fuel leak.

I'm starting this thread so that maybe down the road, someone can benefit from my experience the way I've done from reading other's posts here.

Initially, I thought what I had was an oil leak. The drips were black. However, after degreasing the engine, the drops are clear and definitely fuel.
Novice mechanic tip number one: Degreaser is your friend.

I changed the oil and oil filters last weekend, and there is no sign of fuel in the oil.

The fuel drips from the fitting that goes to the secondary and final filters from the mechanical fuel pump (part of the injection pump.)
It's a right angle fitting and closest to the firewall. I disconnected the line from it, cleaned the line side of the fitting and the hole it threads into, and re-tightened it. The right angle fitting is really tight; I don't think I could get it off without a vise.

So I figure maybe the leak is higher and just pooling on that fitting before it drips.

I tightened the nuts holding the hydraulic head on to the stated 20 ft pounds from the IP tm. All except for the one closest to the engine and toward the firewall.. I don't see how to get on it without removing the oil filter bracket.

I also checked that the bolt in the center of the HH is torqued at 55lbs.

Both of those last two were prompted by other member's posts (thanks guys!)

My next steps are to try and tighten the hh bolt that I couldn't get to yesterday, and if that doesn't work, put new O rings in the HH and on the fuel shutoff rod. If none of that works, I'm not sure where I'll go next.

 

[Coldpan35]

I have a leak in the same exact area it leaks down on the frame by my steering box and drips on the ground from there. I can't find the exact spot it's coming from though. Any suggestions?

 

[Valence]

I'm not sure if this is even related to the fuel leak that you described, but my nylon fuel lines running to/from the booster pump, to the secondary fuel filters, and then back to the injection pump rubbed together until one (or more) holes formed so I replaced the whole gaggle of fuel lines there. Three nylon and two rubber fuel return lines. The clear(ish) nylon lines were replaced with 3/8" air-brake line (it's the same type of hose, it's just black instead). Most of the fittings were reusable, though one on the nylon lines had a stripped end and I wasn't able to find an exact replacement so I replaced the 90 degree pipe fitting on the "in" of the first secondary fuel filter.

I covered where the hoses would again rub/vibrate against each other in rubber hose to hopefully delay another fuel leak.


What I did was document (via pictures!) and label where each hose ran as I took it off, then I took them all to a local industrial hose shop (Evco, House of Hose) and they sold me new ferrules and inserts and the hose. The larger rubber return lines were new reusable fittings as the crimp style are not reusable. I had to cut and make my new hoses from the lengths Evco sold me, but it was very easy.

You can see the shiny brass 90 degree angle on the "in" of my secondary fuel filters. I located that at a local Ace Hardware store (3/8" compression to 3/8" NPT) to replaced the stripped hex end that used to be there.

 

[scboolitcaster]

I have a leak in the same exact area it leaks down on the frame by my steering box and drips on the ground from there. I can't find the exact spot it's coming from though. Any suggestions?

Are you sure it's fuel? The steering boxes are fairly prone to leaking I think.

 

[scboolitcaster]

I'm not sure if this is even related to the fuel leak that you described, but my nylon fuel lines running to/from the booster pump, to the secondary fuel filters, and then back to the injection pump rubbed together until one (or more) holes formed so I replaced the whole gaggle of fuel lines there. Three nylon and two rubber fuel return lines. The clear(ish) nylon lines were replaced with 3/8" air-brake line (it's the same type of hose, it's just black instead). Most of the fittings were reusable, though one on the nylon lines had a stripped end and I wasn't able to find an exact replacement so I replaced the 90 degree pipe fitting on the "in" of the first secondary fuel filter.

I covered where the hoses would again rub/vibrate against each other in rubber hose to hopefully delay another fuel leak.
View attachment 620104

What I did was document (via pictures!) and label where each hose ran as I took it off, then I took them all to a local industrial hose shop (Evco, House of Hose) and they sold me new ferrules and inserts and the hose. The larger rubber return lines were new reusable fittings as the crimp style are not reusable. I had to cut and make my new hoses from the lengths Evco sold me, but it was very easy.

You can see the shiny brass 90 degree angle on the "in" of my secondary fuel filters. I located that at a local Ace Hardware store (3/8" compression to 3/8" NPT) to replaced the stripped hex end that used to be there.

I'm going to replace all those lines and fittings like you did I think.

I was looking at mine after driving it home from work today and my leak looks like it could be from the base of the hydraulic head, or possibly the fuel delivery valve screw (that's the one in the side of the hh that everyone including me is scared to touch.) It's really hard to see fuel on the hh.

I read in the injection pump tm that the valve under that screw is precision fitted specifically for each individual hh. The tm says to torque that screw to 42 ft pounds, then loosen and retorque two times. I might try it.

First I think I'll tighten that one hh nut that I couldn't get to.
Then all the steel lines at the top of the hh. If it still leaks from the same general area, hh o rings.

 

[rustystud]

Get yourself a half dozen cans of brake clean and hose the whole area down real good ! Then start up the truck and see where the drips come from.

 

[scboolitcaster]

Picked up a couple of sets of the Viton O rings from a shop here in Greenville, and 1/4 and 3/8 OD hose for the fuel lines. Just need to stop by Home Depot for the fittings and hopefully some brake cleaner spray on the way home, and I'm set. Hopefully I can get it all done this weekend.

 

[cattlerepairman]

For what it is worth, my truck had brass inserts in only about 50% of the hose ends. What this means is that when you tighten down on the fitting to stop a leak, the hose gets cut into, making the leak worse. So, when there is a leak, take the fitting apart and check for a ferrule! If there is none and/or if the hoses are the old original ones, replace.

 

[scboolitcaster]

Well, it rained pretty hard Saturday night and Sunday.. My work area turned to mud.
So I didn't get a chance to do any work on it this weekend.

This afternoon after work I may try to pull the HH and replace those viton rings. If I can get home by 6 I'll have about 2 1/2 hours before the sun goes down.
I worry about not getting it back together in time. I hate leaving anything apart overnight. Lots of condensation overnight.

 

[scboolitcaster]

So I got home, unbolted the heater and got it out of the way, marked and removed the injector lines from the hh.. and it dumped down rain.

Covered the hh and buttoned her up till tomorrow.

 

[gimpyrobb]

Just leave the hood up and it'll was away the crud!

 

[scboolitcaster]

Just leave the hood up and it'll was away the crud!

I'm too scared... That crud may be all that's holding the busted knuckle together!

 

[scboolitcaster]

So I got the hh off... Quite the adventure. Mine wouldn't come out with the red/scored tooth lined up with the mark. So I experimented and finally got it out by moving the red tooth just forward of the mark, so the mark was pointing at the valley just behind the red tooth.

My soldier b kept abandoning me (first the wife, then the son). So it took longer cranking the jackshaft than it probably would have otherwise. 15 tries or so bumping the starter didn't work for me. I guess I don't have the magic touch.

So tomorrow new o rings in and put it back together. The gasket around the fuel shut off cover didn't make it. Not quite sure what material to make a new one out of.




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[scboolitcaster]

HH is back in with new o rings. The ports where the lines attach were rusty and dirty. I attached a brass 12ga shotgun bore brush to my drill and cleaned them up. Washed them out with carburetor spray.

Still need to do a few odds and ends but that'll have to wait for tomorrow after work.

I might have pushed to get her stated tonight, but I really want a soldier b in the cab in case I need to block the intake. So tomorrow it is.

As mentioned in a previous post, when I pulled the head I had to put the red tooth ahead of the mark to get the it out.
Putting it back in, it didn't want to go. I found the semicircle cutout over the gear in the ip was not centered (one side of the cutout even looked at little bent.) I straightened it and then turned the jackshaft a little more so that the cutout was centered. HH dropped right in. I'm thinking it must have been off a by a couple of teeth when I took it out.

But it seemed to run pretty good.. just leaked fuel.

I definitely tried with the tooth lined up exactly, then one valley behind, and then it finally came out when I put the red line one valley in front. I'm thinking (based on the state of that semicircle cutout) it might really have needed to be a whole tooth in front.

How much would that have affected fuel delivery I wonder?

 

[rustystud]

HH is back in with new o rings. The ports where the lines attach were rusty and dirty. I attached a brass 12ga shotgun bore brush to my drill and cleaned them up. Washed them out with carburetor spray.

Still need to do a few odds and ends but that'll have to wait for tomorrow after work.

I might have pushed to get her stated tonight, but I really want a soldier b in the cab in case I need to block the intake. So tomorrow it is.

As mentioned in a previous post, when I pulled the head I had to put the red tooth ahead of the mark to get the it out.
Putting it back in, it didn't want to go. I found the semicircle cutout over the gear in the ip was not centered (one side of the cutout even looked at little bent.) I straightened it and then turned the jackshaft a little more so that the cutout was centered. HH dropped right in. I'm thinking it must have been off a by a couple of teeth when I took it out.

But it seemed to run pretty good.. just leaked fuel.

I definitely tried with the tooth lined up exactly, then one valley behind, and then it finally came out when I put the red line one valley in front. I'm thinking (based on the state of that semicircle cutout) it might really have needed to be a whole tooth in front.

How much would that have affected fuel delivery I wonder?

Not delivery but timing. Think of a gas engine and the distributor. Move it forward and you retard the timing, move it back and you advance the timing. The only thing is diesels don't respond to advancing timing like gas engines do. They really like it in just one spot. Give or take a degree .

 

[scboolitcaster]

That makes sense.

Well let's hope I'm not pulling it apart again tonight. This is going to bug me until I see it running (well) again.

Appreciate you guys teaching me stuff. There's a lot in the TMs, but there's a LOT that's not in the TMs.

 

[gimpyrobb]

If you noticed on the harmonic balancer, there is different timing marks. Most of the difference is for turbo or nonturbo. Ive known folks that went from nonturbo to turbo and it still ran well(without changing timing), i wouldn't sstress over it too much.

I have also worked on trucks that had the head come out with the tooth in the valley rather than lined up. You'll be fine.

 

[scboolitcaster]

For reference:

Nuts attaching injector tubes to HH: 23-25 ft lbs (TM9-2320-209-34-2-1 and TM9-2320-361-24-1)
Nuts attaching the injector tubes to the injectors: 23-25 ft lbs (TM9-2320-361-24-1)

Hydraulic head nuts (attaching the HH to the IP): 18-20 ft lbs (TM9-2910-226-34)

Fuel control assy retainer screws : 18-23 inch pounds
(If you tighten these too tight, the fuel control rod will stick!)
(TM9-2910-226-34)

 

[silverstate55]

For what it is worth, my truck had brass inserts in only about 50% of the hose ends. What this means is that when you tighten down on the fitting to stop a leak, the hose gets cut into, making the leak worse. So, when there is a leak, take the fitting apart and check for a ferrule! If there is none and/or if the hoses are the old original ones, replace.

I was just going to post this same thing! My neighbors' Deuce is at my house now getting rebuilt after sitting for 10+ years, and all of the fuel hoses I removed did not have the inserts....I've had experiences with this before as detailed (with pics) in this post. Make sure you have the inserts in the hoses to assure proper compression & sealing of the fuel lines!

Thank you cattlerepairman!

 

[scboolitcaster]

I was just going to post this same thing! My neighbors' Deuce is at my house now getting rebuilt after sitting for 10+ years, and all of the fuel hoses I removed did not have the inserts....I've had experiences with this before as detailed (with pics) in this post. Make sure you have the inserts in the hoses to assure proper compression & sealing of the fuel lines!

Thank you cattlerepairman!

Yeah I bought new hose, sleeves, and inserts.
The two lines from the filters to the HH and the injector return to the IP had the inserts in them. But I will check them all though.
Appreciate the advice guys!