Hypothetical situation: what do do when injector lines break?
 

Hi all,

I'm one of probably many who've had their metal fuel injection lines break while driving. For me, the incident cost me three days out of a vacation and some towing fees. I was thinking today about how I could better handle a similar situation in the future.

Does anyone think--or, better yet, know--if crimping, JB-welding, or otherwise blocking off a broken injector line would allow someone to continue driving (minus 1 cylinder) without damaging the IP? Really, the only reason I pulled over and called for a tow was that fuel was spewing everywhere; the car continued to run fine. I could've saved myself some grief if the car would've made it to the dealership on its own power.

So I guess this is just a thought experiment, but if anyone's tried what I proposed, I'd love to hear about the results.

Thanks,

DL

I've never heard of those lines breaking before! How did it break?

Not possible. The injection pump is a hydraulic machine. Since diesel cannot be compressed it would hydrolock the pump and start breaking hard parts inside.

Keep some spare return line hose with you. If the line is broken tie it into the injector return lines by connecting the injection line to an injector return port (also bypass the disabled injector). The volume of fuel pumped is very small so it cannot pressurize the return system.

Yea, loop it to the return lines. Just curious, where did it break?



Ive always wondered if you can safely run on less than 5 cylinders if you loop the fuel supplies. id be concerned about cylinder lubrication and the valves. Imagine the fuel economy if you cut off 2 cylinders. Hopefuly forced will get back to us

I've crimped shut the injection line on a Cat 3208 (mechanical injection pump just like the M and MW pumps) and drove on seven cylinders, worked fine and drove from Chicago to Milwaukee that way. Cat guys said it wouldn't hurt anything, they were correct. I don't see why the M and MW pumps couldn't handle it as they're the same design.

One dry hole doesn't hurt the engine either, provided the coolant flow is good to keep the head from doing wierd thermal expansion things. A 2-stroke would have top-end problems (like a DD 71 or 92-series) but not a 4-stroke, just becomes an air pump. I'd keep the RPMs moderate though.

I do prefer the return-line route though, sounds like a good contingency plan.

I'd be curious as to how the pump handled the crimped line. Even if there is some internal relief, just imagine that it's getting exercised quite a bit. :eek:

I'd prefer to just break/cut the line off at the crack and run it to the return circuit via the "plug" on the second fitting on the rear-most injector.

Not a problem apparently. Ran 3000rpm for the next hour and a half. It was a fairly new pump BTW, some performance changes, my bad on the line breaking (stressed) and filling the crankcase with a few gallons of diesel fuel before the crank hit the fuel and went into runaway, ... long story.

Dangerous
 

First, you should be glad that you didn't have a fire with a running diesel engine in the middle of it.....injection pressure diesel can spray a long way....hot exhaust is on the opposite side of the engine for a reason...!!!

All of the larger Marine Engines that I am familiar with, have a means of jacking up the cam follower of each individual injection pump element (lifts the plunger off of the cam)......and this is the only way that I know of to do it. The bigger Bosch pumps have this feature.

The idea of looping the (what I have always called "Injector Leak Lines") rubber hose from the forward most injector into the FI pump end of the broken fuel line.....that hose and piping should have sufficient capacity to carry the fuel back to the tank.....this might be an EMERGENCY, LIMP HOME, ONLY method.

You would still be driving a big time fire hazard..!!! :rolleyes:

SB

I was on a Container Ship with a 18,000 HP M A N main engine, we had a different problem...a 4 ton piece of con rod kinda flew thru the side of the engine.....initially we blocked the piston (also a feature of big engines) and patched the crankcase hole....and went to Norfolk, VA and after making our repair a bit more reliable, we went on to Bremerhaven, Germany minus that cylinder.....a bit slower, but running with 1 cylinder cut out is an accepted procedure with ABS (American Beureau of Shipping)

It's across from the exhaust because of packaging.

Diesel fuel on the exhaust manifold isn't optimum, but not an instant disaster necessarily. It's not as flammable as gasoline fumes, nor as flammable as concentrated ethylene glycol (anti freeze).

I think that the OP was looking for a limp-home solution, and the loop of fuel hose to the return line is an excellent suggestion for that IMO.

Tell it to the USCG
 

If I must, I will find a textbook on large diesel engines, and prove that it is a design factor. I have a nice diesel library.....

Hot atomized diesel fuel is EXTREMELY FLAMMABLE.....any hot diesel fuel is volitile.....

I have seen such a fire on a turbocharger casing......Fuel Oil sprayed onto it......and it ignited.......

SB

It would be interesting, since glycol and engine oil are also flammable, and located near the exhaust.

Also look up C-12 aftercooler fires ;~)

First I would pray that its pretty close to a good dealer that can get a new one quick. Than maybe get some very small hose clamps, and put a bit of hose over the leak and clamp the living hell out of it, with some JBweld. Its ok if it dribbles, but try to stop most of the fuel.

You can run quite a ways down a cylinder.

That is why those 7 little clamps are on the hard lines. they keep the lines from vibrating and cracking.

The only experience I have had with a cracked line, is about 25 yrs ago on a cat engine in a dump truck we had at work. but that one was sucking air and shut us down.

Charlie

now im thinking about cutting off a a cylinder or two to see if gas mileage improves :idea3:





If it works, you'd probably have to rotate the cylinders often to make sure you don't cause uneven wear.

Not on a diesel. The other cylinders will just consume more fuel to take over the load. Thats why you see many gas engines now disable cylinders but none of the electronic diesels do it.