Common Rail Issue

[z28jimi]

Just a heads-up...I had a fuel leak the other day on my starboard QSC 500. Turned out the fuel line from the pump to the common rail had developed an almost microscopic crack under the nut holding the line to the common rail. Found it after losing quite a bit of fuel, but before it could catch fire. Something else to give a quick look at when you do engine checks.

 

[TNT8808]

If I remember correctly this may be similar to the fuel line issue that Frank Webster was referring to with the QSC's when a clamp/support is not installed on some of the earlier models. I found out about it when Zach from Minnisocold was asking what to look for during his survey on his 2008 48DA. I had mine checked, and my engines have the updated fuel lines and I believe Zach's had the clamps already.

Hopefully Frank will chime in, and fill us all in on whether your issue could have potentially been caused by the missing clamps.

-Tom

 

[techmitch]

If I remember correctly this may be similar to fuel line issue that Frank Webster was referring to with the QSC's when a clamp/support is not installed on some of the earlier models. I found out about it when Zach from Minnisocold was asking what to look for during his survey on his 2008 48DA. I had mine checked, and I my engines have the updated fuel lines and I believe Zach had the clamps.

Hopefully Frank will chime in, and fill us all in on whether your issue could have potentially been caused by missing clamps.

-Tom

Rings a bell for me also. Possible service bulletin.

 

[FootballFan]

Frank had identified the issue when I first got qsc600’s.

One of those things that Cummins didn’t seem to broadcast, but if you knew to ask about (thank you again frank), an easy fix.

 

[fwebster]

This isn't a new issue, but one that will potentially pop up on older Cummins QSC engines. In my opinion it is a significant safety issue since the high pressure line to the common rail is under constant high pressure.....±3500 psi......and when the line fractures, it can turn your fuel line into a flame thrower if the crack sprays fuel on something hot or electrical.

The issue is the fact that the fuel line is unsupported and is long enough that it will shake from engine vibration enough for metal fatigue to eventually cause the line to break. The break or crack is usually near the attachment point on one end or the other. The fix is, obviously a new fuel line, and a $2.50 clamp to stop the excess vibration.

When this was first noticed it was by a new 44DB owner who is a member here on CSR. Knowing the potential danger I alerted Sea Ray Customer Service who immediately called the Cummins rep who sells the engines to Brunswick. Their answer was "We don't think this is a serious issue and don't feel the need to alert owners or issue a TSB." What this really says is "we know this is a problem, but we aren't going to voluntarily do the right thing and alert owners since it will cost Cummins less to wait and let those affected initiate the repair and pay for the parts when their fuel lines break". I've been on 2 boats here in Fla with broken high pressure lines and the mess a crack spewing raw diesel @ 3500psi makes is astounding, not to mention the lingering stink of raw fuel for weeks. To my knowledge, no engine fires have occurred yet, but the potential is certainly there.

TO the OP, the fix is a new fuel line.....don't let anyone try to weld or braze the one that is leaking. And make Cummins give you the clamps to secure both fuel lines.

 

[FootballFan]

Don't know for sure - but I suspect the clean up costs from a fracture is more than the actual cost of the line.

I ran into a similar but different issue this past year on my engines. This was related to the high pressure oil lines to and from the oil filter.

Pulled into Charleston, saw that I had oil leaking from one of the engines. Probably lost 1-1.5 quarts - which in a clean engine room looks horrible. In reality each engine holds 14-15 gallons.

The problem was evident, an oil line was leaking near the connection point. Authorized tech immediately provided me with the service bulletin from the manufacturer. They had issued an engineering change, new lines have a flex point built in which eliminates the vibration effect on the flange. The lines are massive in size. Replaced both lines on both engines.

I can dig out pictures of the lines with the new engineering change if anyone is interested.

 

[Robski97]

Don't know for sure - but I suspect the clean up costs from a fracture is more than the actual cost of the line.

I ran into a similar but different issue this past year on my engines. This was related to the high pressure oil lines to and from the oil filter.

Pulled into Charleston, saw that I had oil leaking from one of the engines. Probably lost 1-1.5 quarts - which in a clean engine room looks horrible. In reality each engine holds 14-15 gallons.

The problem was evident, an oil line was leaking near the connection point. Authorized tech immediately provided me with the service bulletin from the manufacturer. They had issued an engineering change, new lines have a flex point built in which eliminates the vibration effect on the flange. The lines are massive in size. Replaced both lines on both engines.

I can dig out pictures of the lines with the new engineering change if anyone is interested.

That would be very helpful...so we can see if were fixed or not ..

TY

Rob

 

[villain style]

I like pics too if anyone can post them!

 

[fwebster]

As a point of clarification, Mark's issue was with an oil line. His pictures may show the mess oil or fuel can make in a bilge, but it won't show anything about the unsupported QSC fuel line problem since he has MTU's in his new boat.

Follow your QSC high pressure fuel line from the pump up to the common rail...it is almost vertical on the front of the engine. The Cummins fix for controlling the excessive vibration if a simple 2 pc metal clamping the middle of the vertical run-on the high pressure line. If your fuel lines have that clam, then your engines have the "fix"; if. there is no clamp on the line, then you probably want to get the clamps and install them.

 

[FootballFan]

Frank is correct. I don't have pictures of the fuel line replacement. When I was surveying the boat with the Cummins engines, Frank had identified this issue to check for.

I was using a Cummins authorized firm - when I asked them about the issue - they knew of the issue and the fix. They confirmed during survey that in fact the new style had been installed on the boat.

My pictures are of the unrelated - but similar - issue I experienced with oil lines on MTU. Will throw a picture up of how MTU fixed their issue with oil lines.

 

[FootballFan]

As promised. Replacement oil lines pictures. If you look where my hand is, this is the change. A flexible section which is on each end of the line. Line is approx. 4 foot - longer if all the bends were straightened out.

The flexible section is to accommodate vibrations while running. 2 lines on each engine for a total of 4. If you were ever looking at MTU's, this is something you would want to check for.