BAC Forum
General Boards => Technical Support => Topic started by: Adam Hicklin on August 04, 2019, 08:29:58 PM
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I have a small drip from the fuel line (in photo of tank fittings, the middle line with the compression fitting). There is about 12 inches of exposed line from the fitting to where it disappears in to the frame rail. I’m assuming this is the supply line. The leak is right where it was tied with a tie wrap. Several questions here: if possible, can that line be cut and repaired with a barbed coupling? (That’s how I repaired the return line leak in the same spot) Is it under pressure? If it can’t be spliced, I guess I would have to run a new line externally. Any thoughts on that? Does it go straight to the primary filter? Regardless of how it’s fixed, it will need to be purged of air, correct? (That will be another discussion!) Last question, What it the bigger hose with the pipe fitting? A vent maybe?
Thanks in advance.
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That fuel supply line is a flare fitting and it looks a lot like a Aeroquip reusable hose fitting. It can be removed from the hose and re-installed. Look up Aeroquip hose fittings and how they are assembled. This is the suction fuel line to your motor in the rear and it will not have any pressure in it but fuel will drain back out once disconnected. Once the hose is repaired the Cat mechanical lift pump will suck fuel all the way to your water separator. Your motor should fire right up as the fuel filters will still be full of fuel.
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Adam and Lee, I do not think that looks like a fuel line to engine. We did have some problems with a fuel line about 5 feet long from primary fuel filter to the fuel transfer pump that was a Gates Hydraulic
Hose that had leaking issues. If perhaps this is the hose in question replacement hose should be
ID hose .500 with one end 1/2 JIC female on end and a 5/8 female on the other end of 5 foot hose.
Dave Atherton Retired Cat Mechanic
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Adam, Here is a pic of the hose Dave is referring to. I would NOT have looked for this hose, but Dave alerted us who have this configuration of the pending failure. As you can see, mine was leaking! It is the 5 foot hose from the output of the primary fuel filter to the fuel pump on the front lower corner of the C-12 engine. Not sure what hose is leaking on your coach. Perhaps you can remove and splice a repair? Fred
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Adam, I did something wrong with the photo, so I will try again. Fred
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Thanks guys. Yes, I’ve read about the line from the primary filter to the transfer pump. That’s on my list to change. The line I’m referring to connects to the tank outlet at front of coach and runs down the frame rail to the back. I’m assuming this is the supply line to the primary filter, I know the smaller line in my picture is the return line to the tank. I don’t know what the bigger line is with the pipe fitting. I’m guessing that is the vent line.
My leak is in that middle line (supply/suction?) about 8 inches from the fitting, before it disappears in to the frame rail. My question is, can I cut out the pinhole leak and join the two ends with a barbed coupling connector and hose clamps? If this is the supply line, would it be 1/2” ID? Them if that is the fix, would I just be able to start the engine and it will bleed off the air in the line by itself, or will there be a procedure for that.
As an aside, my primary filter does not have any black particles in the sight tube so I’m assuming the integrity of the hose is intact, at least for now. I may change over to the CAT primary filter set up at the same time, but I need to make sure I solve one problem at a time, as not to confuse the issues.
Thank you.
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Adam, you cannot splice the suction hose from fuel tank to primary fuel , the suction hose in
Question is hydraulic hose with steel braids, note a regular rubber hose would restrict fuel flow.
The hydraulic hose we are talking about is on the discharge side of primary fuel filter to suction
Side of fuel transfer pump which is a gear pump and hydraulic hose inside break down would go
I think the secondary fuel 1R-0749 and into fuel manifold on C-12 engine. Dave Atherton Retired
Cat Mechanic
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Adam, Almost any of these hoses can be spliced you just have to find out what kind of fittings to do it with. That hose end looks a lot like a Aeroquip reusable hose fitting. There are all kinds of stuff out there to make up or repair hoses. Once you figure out what the make up of the hose is you can get fittings to repair it. Aeroquip is a good place to start, back in the day trucks used a lot of aeroquip hoses and fittings and I've done tons of them. There are many others besides Aeroquip just do some searching.
http://aeroquipperformance.com/
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Adam and Lee , the hose in question is the middle hose in the picture. If that is correct of which
It should be is a 2 ply hydraulic hose with a JIC female fitting that is machine crimp to hydraulic
hose. Have found many on Monaco and beaver motorhomes. The mfg name on hydraulic hose is
Gates. Yes there is a hydraulic fitting that will thread into splice is there is room to work. What
Problem that has happened is condition of the inside rubber liner, If connection will not leak.
The reason when ieaking has occurred to outside has indicated inner rubber liner is end of its
life and rubber liner is cracking and hydraulic hose is hard and stiff. Again several hydraulic fuel lines
between the primary fuel filter and fuel transfer pump has shown area of failure. Also if this
mfg brand Gates, follow up on information printed in white on hydraulic hose is not rated for BIO
Fuel . I have several pictures with camera of inside liner missing and person can see the Steel
Braids instead of rubber liner. Dave Atherton Retired Cat Mechanic
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So Dave, you would suggest replacing the entire line from the fuel tank to the primary filter? Are we all in agreement this is the suction line? I don’t see any other hoses coming off the tank, but that doesn’t necessarily mean there aren’t any. Could the suction line come from the top of the tank? I can’t see any marking on the hose as to the brand, but I have no trace of the black particles in the primary filter sight glass, like the pictures Fred B has shown. As I see it all those particles came from the line between the tank and the primary, not from the hose from primary to fuel transfer pump. Would that be correct? Lee, if I had the room to work, would one of those Aeroquip couplings work on this line? Dave, what do you think? Any idea what size the line is? Would it be 1/2 inch ID?
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Adam, yes that is a 1/2 inch line. The one in the middle will look same at primary fuel filter
inlet. Have one question where can I see the leak as per photo. The reason mfg used hydraulic hose versus regular rubber hose the hydraulic hose will kink. If there is no room to install non-crimp
JIC fittings because you will need two hands and two wrenches to install into the 2 ply steel braided
hydraulic hose. These non- crimp fittings work good except in steel braided hyd hose which can
be very interesting to install. Here is my suggestion, make sure that you have a fuel leak coming
from primary fuel filter. That can be hard starting because fuel drain back to tank from primary
fuel filter. Has the hose started leaking in bracket or just leaking with nothing around hose. What
that will tell you condition of hydraulic hose if it is wet and see fuel drops on outside of hose.
With that will tell you condition of hydraulic hose, replacement or repair. Again if hydraulic hose is wet with diesel fuel and nothing would indicate damage caused from outside to hose, than repair
Is just a running band-aid that will keep moving along hydraulic hose. Last if you feel and
Replacement is required, I would suggest going with 5/8 plastic air line hose along with Brass
air lines fittings. Very large savings of money versus hydraulic hose. The later motorhomes
use 5/8 plastic air line for there fuel system. Dave Atherton Retired Cat Mechanic
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Thanks Dave. I will try to get a picture of the leak. It appears to be a pinhole right where there is a plastic tie wrap bundling together some other hoses. I can see a wear mark where the wrap has indented the fuel line. It doesn’t appear that the whole section of line is seeping fuel as line break down would indicate. It’s a drip coming from a specific spot. About a drop every couple minutes. Either way, if it’s repaired or replaced, along with replacing the primary filter outlet line to the transfer pump, is there a procedure to purge the air in the line? Last question: should it be driven, for instance, if I just drove it to have it repaired, would it/could it, cause damage?
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Adam, what you are telling there is a little damage to the outer hydraulic hose rubber . Than there is
a small pin drop fuel leak. As I explained your hydraulic hose make up starting from center of hose.
You have a hose within a hose with 2 braids of wire covering the inner hose on the outside. Than
you have a outer rubber hose that is the protection cover. Point to remember as hose over time gets
older the outer takes lot of external wear. The inside rubber hose wrapped in a woven steel wire outer
cover. As I indicated and you answered what in my above post ( over time inside hose starts cracking )
and than will leak to outside. Reason old age of hose and BIO fuel causing break down of hose. The
answer remember hydraulic hose is under suction which indicate the center of the fuel line has failed
Where it’s dripping on its own without any pressure applied. Suggestion it will not hurt to keep
running as you indicated just a few drops no stream of diesel fuel coming from hose. In addition
to this statement the fuel transfer pump will over come any diesel loss and not affect engine operations. Just wrap so you do not get big mess. Last at some point would suggest to change out
your fuel line with plastic 5/8 plastic air line and brass air line fittings. Dave Atherton Retired Cat Mechanic
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Adam, sorry forget to answer your question , bleeding air after hose replacement. The bleeding
of air will not be nessary being you are not changing out the secondary 1R-0749 fuel filter. Engine
will start right up.
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Thanks. After looking at all the options, it looks like I will change the whole line. And while I’m at it, I’ll change over to the CAT primary filter and replace the fuel line between the primary filter and the fuel transfer pump. Went to CAT today and they were helpful. I think there is a lot of “Ask Dave” and “Ask the Forum” in my future. First question: has anyone run a new fuel line from the tank back to the primary filter on a Magnum era coach? Ideas?
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Here come the questions: has anyone replaced the fuel line from the tank to the primary fuel filter? There’s no way to remove the old line and run the new line through the frame rail. It will need to be re-routed and it looks like I can route it fairly protected (behind slide, etc.) for most of the distance. There is about 6 feet that will need to drop down and be run along the bottom of the coach, exposed to the road. I can’t see any way around it. Any suggestions? Question 2: went to CAT and they suggested using a CAT rubber, heat resistant fuel line. Does that sound correct? The line in use now is a hydraulic line. Dave A. Suggested an air line. Thoughts? Question 3: is it worth the trouble changing over to the CAT primary filter set up? It’s much larger and will take significant modification in my fuel bay, if it can even be done. My current Racor set up works fine. Not sucking air. Sight glass and screen seem to be in good condition. Thoughts? Thanks in advance for the input. I’m flying blind here but excited to get this behind me.
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Adam,
When it comes to routing a fuel line, you should be able to route the hose through the basement along the outside of the frame, and above your holding tanks. This would get you into the engine compartment where you could terminate at the primary fuel filter. However, if your fuel hose is in good condition other than the end connection, I would investigate the possibility of splicing a short section onto the end instead of replacing the entire line. There are hydraulic hose connectors available to repair a line that if installed properly, will not leak fuel out at the connection or air into the fuel stream.
One of the issues in the use of hydraulic hose for a fuel line is that a few of the applications, after many years of use have experienced a failure of the rubber lining in the hose (probably a reaction to the diesel fuel) resulting in rubber pieces in the fuel stream. If this happens in your case, the rubber pieces will be very obvious in the primary fuel filter prescreen sight glass. The biggest problem with getting these rubber pieces in the fuel stream is if it happens after the primary filter and clogs the engine fuel transfer pump that is located before the secondary filter.
When it comes to the Racor primary fuel filter, that has been discussed in depth on the forum. So do a search on it and read the numerous opinions that were previously expressed.
Gerald
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Thanks Gerald. I’ve been waiting for your opinion! I do not have any indication in the pre-screen sight glass that my hose is deteriorating. I heard different opinions in this thread about the possibility of repair. It’s my understanding that this is just a suction line. It holds no pressure, correct? I may just try a repair first. It’s very tight, but maybe worth a try. What’s the easiest way to cut a hydraulic line?
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Adam,
Yes, the fuel line from the tank to the engine, including the primary filter, is a suction hose that normally runs under a slight negative pressure, and that is why you have to be very careful to prevent any air leaks. The negative pressure in the fuel line will vary with the fuel level in the tank from almost 0 with a full tank to moderate with the tank close to empty.
The negative pressure at the Racor filter is the root of the problem with it if it is not properly maintained. The O rings on the slight glass column will loose their sealing ability over a very long period of time and cause an air leak into the fuel stream. This can cause a no start condition if excess air gets into the fuel or a runability problem and injector wear over time. Leaking O rings will also usually manifest themselves with a slight fuel seepage at the O ring when the tank is full and the engine is off for several hours. This O ring issue is the reason that Dave Atherton suggest replacing the Racor system with a Cat primary filter.
Cutting hydraulic hose is difficult. In tight quarters, I use a hack saw or a small cutoff tool. The issue is that you will fill up the hose with debris. There are several commercial hydraulic companies that have the smooth knife saws and crimping tools to do the job right at a reasonable price to insure that the repair will have no leaks. If you do not have any experience with hydraulic hoses or the tools to repair one, I would suggest you look into having the repair done by a professional hydraulic hose company.
Gerald
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Thanks again Gerald. I’ll try calling a mobile repair and see what they say. When I disconnect the line from the tank, will fuel siphon out of the tank? The tank is full. The fitting is at the top of the tank. Obviously I’ll have to catch whatever flows back down the line. What can I expect? Also, when the repair is made, I’ll need direction on priming and purging the air out of the line. Dave A. Said to just start it. Where does all the air go?
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Adam,
The electric priming pump on your Racor primary filter assembly will purge the air from your fuel system (the reason I will not remove it from my coach). If you need assistance, just call me. 713-254-4156 The phone service is spotty here in Alaska, so if I do not answer, just leave a message and I will call you back when I get a phone signal.
Gerald
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Adam, think your are getting ahead of yourself with this problem. Subject adding electric fuel
Pump into your C-12 system in not nessary because the fuel system setup is complete different
than on the HEUI injection systems on Cat C-9 and down. Understand that the fuel transfer pump
gear pump ( has a larger volume and pressure ) on Cat C-10 and up including your C-12 engine.
Diesel fuel is delivered through the secondary fuel filter 1R-0749 and within that secondary fuel
filter base there is two check valves that holds fuel pressure in a fuel manifold on your C-12
engine and maintains 90 psi at all times. Your injectors on the C-12 are a two stage injector
Electrical and mechanical of which a mechanical push rod operates injector and electrical from
engine ECM meters the fuel. ( see Ask Dave picture of C-12 secondary filter base with check
Valves ). As Gerald indicated removing air via: aftermarket add on if condition is not allowing
entry of air. Caterpillar OEM secondary filter has a Hex bleed plug that is little harder to get at
But will pick up diesel fuel almost instant because the fuel manifold is retaining diesel fuel.
Again not to confuse you but we are talking two complete different fuel systems than what your
reading about. Dave Atherton Retired Cat Mechanic
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Thanks Dave. I think Gerald was just referring to the Air Purge pump that is currently part of my Racor primary filter. Believe me, I want to do this fix the simplest way possible and get back on the road! I appreciate all the help and input.
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Update: Turns out the leaking line could not be repaired. Tech said besides there not being enough room, the line just seemed to be weeping fuel. Couldn't identify a pinhole leak. From the forum discussions, this is indicative of a compromised line. So, I will figure out a way to run a new line from the tank to the primary fuel filter. I'll also replace the line from the primary to the fuel transfer pump. I'm wondering if this weepy line can be the reason for the constant diesel smell in my storage bays? I could never detect any evidence, but the smell was constant.
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Hi Adam,
Reasonable sure the fuel line is the culprit, My wife can detect diesel fuel 2 blocks away! Soldier on...…
Fred
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Adam keep up posted I’m interested on how you rough the line
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I posted some info on the types of "fuel line" available in this thread "Semi urgent. Engine serial number". Mentioning now just in case your interested.
If you're replacing cloth/braided fuel "hose" with nylon fuel "tubing", the tubing has a smaller OD (for same size ID as the braided hose) so that will make it easier to run.
Ideally you would run the new tubing through the same route as the existing fuel hose but access to the support clamps along the frame may be difficult. In that case abandoning the old the fuel hose in place is probably the best. I recently ran some four-conductor wire (about the same OD size as 1/2" tubing) from front of coach to rear and it was not too hard (other than getting into some uncomfortable positions). I ran it along the wiring harness routing inside the frame rail - so I'm sure you can get your replacement fuel hose from front to back.
Good luck.
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After countless trips to various hose and tubing specialists, and getting a different opinion from each one, I finally decided to go with the CAT recommendation (picture attached). Both CAT Parts and Maintenance agreed that this was the correct line to use. I really considered the plastic tubing route, but I couldn’t really find anyone to help, including the ParkerStore, that makes the stuff. They looked at me like I was from mars and had never seen the stuff I had printed out for them. And, I couldn’t blindly order parts on line, not knowing exactly what I would need. So, CAT was beyond helpful and it’s their engine, so they ought to know, right? It’s another hydraulic line that is supposed to be diesel stable, and it was cost effective, about 30 cents an inch (much better than the $15/ft Teflon stuff one company recommended. Adds up when you need 45 feet!) I also had them make the line from the primary to the transfer pump from the same stuff. Incidentally, they said this was the same line used from the transfer pump to secondary filter, when the engine was manufactured. I can run the new suction line in a way that it can be removed without too much difficulty, if it ever needs to be replaced. Hopefully that happens long after I’m gone! Thanks for all the help on this.
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Did you have the fittings crimped on? Or what fittings will you use?
Also what is the inside diameter of that hose (1/2", 5/8", etc.)?
Good luck
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Inside diameter is 1/2 inch, like original. JIC fittings will be crimped on, Like original. Bought extra so I could loosely run the line, mark it to the exact length, then I’ll ill take it back to CAT and have them crimp the fittings. Then back home for final installation.
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The long ordeal is over. Fuel line is installed. Everything working as it should. I’m attaching some pics of the fix. Basically I re-routed the line down the side above the generator, over LP tank, then secured it to the LP piping that runs behind the slide. The space ends at the pass through just before the water compartment. At that point I drilled in to the storage bay just below the inverter. Once in, there was just enough space to fit the line back in to the frame rail and snake it over the holding tanks to pop out above the axle on to the engine compartment. I left an extra loop of fuel line in the engine bay so when I eventually need to replace the primary filter set up, I’ll have a little more flexibility. The best part about this route is if I ever have to do this again, it can probably be done in about an hour. Special thanks to all those who contributed, especially Dave, Gerald and Mike. Wouldn’t have even attempted this with out the deep knowledge base of the BAC! I owe you all a drink if we ever meet up!
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Nice job!
I would replace those tiny black cable-ties with the "175 lb or 250 lb-breaking strength" ones - and add a few more, if you get a chance.
This is one product where I've been disappointed buying off Amazon (too much junk for sale in this category).
https://www.cabletiesandmore.com/heavy-duty-zip-ties
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Nice Job Adam, let the Love affair begin! Fred
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Congratulations. I'm in awe how anyone can get in to those places. I'm 6-3 and 215 lbs. No way.
Did you have it up on blocks or jack stands, or was it all done under there?
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Also my congratulations. Did you find any bodies while crawling through those caves?
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Let’s just say muscles are aching that haven’t ached in a long time. I’m 6 foot with long arms, so while my size was a drawback, the reach was helpful. The coach was raised up on the airbags as high as it would go then blocked. It’s always a little nerve racking crawling around under there. Current project is replacing the the under side slide seal. Another fun tight spot!
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Fred, you’re not kidding! Like any love affair, it’s love/hate. Friends ask about the Beaver, and I tell them, “When everything is working like it should, it’s am absolute dream. But when something stops working, it’s a nightmare.” I’m the type that will try to fix just about anything first, before I’ll pay someone. Sometimes it works out. As I said, the friends on the BAC forum have been a valuable asset. I really appreciate you all and your willingness to help out and field my endless questions!
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Adam you are so right, like any ambivalent relationship I've learned to talk sweet to her right before I rip her guts out. Don't get discouraged just soldier on and take lots of breaks! Fred