Detroit 71 injectors doing my head in

[sx_turbo]

Good day all,

hope you are all having a good sailing season.

I am new to the forum and have come to ask questions regarding Detroit 71 series injectors.

the background to the story is I work for an engineering company in UK and have recently (around 1 year ago) rebuilt a pair of 16v71n engines and a pair oLd TwinDisc MG521 gearboxes that are fitted on an old Benetti boat.

When we rebuilt the engines we had them tested and passed both our own quality procedures and BV's quality procedures and the vessel owners quality procedures.

Any way 9 month later they finally have the engines installed after sitting dockside for 6 of those months, and we finally get the engines up and running.


We then had 2x injectors fail at the very end of the first 8 hour sea trial, they had seized solid at full chat, luckily quick thinking from our engineer saved the port engine.


then after a further 50 hours of running one of the injectors on the port engine sprung a major fuel leak from the injector control rod,


now at the end of the sailing season, I've just taken another phone call stating that one of the engines has run away again, and the vessel engineer used the emergency shutdown flaps

I am unsure of any other details at present,


anyway sorry for the long winded post, when we rebuilt the engines we used all genuine parts, except for the liners we used FP Diesel as they are a much better quality product than the OEM, and the pistons were Interstate Mcbee for the same reason as the liners, we find the OEM ones always come up under sized.


I digressed again,


we are only using reliabilt injectors yet they seem to be consistently rubbish,

is there anything better we can use than the reliabilt rubbish?

[ranger58sb]

You might get good info on boatdiesel.com...

-Chris

[Woodland Hills]

I have a pair of 12v71s and it is my understanding that you need to test all Reliabuilt injectors since the failure rate is over 50%.

[sx_turbo]

Originally Posted by Woodland Hills

I have a pair of 12v71s and it is my understanding that you need to test all Reliabuilt injectors since the failure rate is over 50%.

yeah, certainly seems to be the case,

thing is they test and go in fine, then fail within 100 hrs of running

[DougR]

Don't know the answer to your questions, but suggest you contact some of the larger DDC distributors in the states such as Stewart & Stevenson, Johnson &Towers, Valley, etc.

DougR

[Cadence]

[QUOTE=sx_turbo;2728563]Good day all,

hope you are all having a good sailing season.

I am new to the forum and have come to ask questions regarding Detroit 71 series injectors.

the background to the story is I work for an engineering company in UK and have recently (around 1 year ago) rebuilt a pair of 16v71n engines and a pair oLd TwinDisc MG521 gearboxes that are fitted on an old Benetti boat.

When we rebuilt the engines we had them tested and passed both our own quality procedures and BV's quality procedures and the vessel owners quality procedures.

Any way 9 month later they finally have the engines installed after sitting dockside for 6 of those months, and we finally get the engines up and running.


We then had 2x injectors fail at the very end of the first 8 hour sea trial, they had seized solid at full chat, luckily quick thinking from our engineer saved the port engine.


then after a further 50 hours of running one of the injectors on the port engine sprung a major fuel leak from the injector control rod,


now at the end of the sailing season, I've just taken another phone call stating that one of the engines has run away again, and the vessel engineer used the emergency shutdown flaps

I am unsure of any other details at present,


anyway sorry for the long winded post, when we rebuilt the engines we used all genuine parts, except for the liners we used FP Diesel as they are a much better quality product than the OEM, and the pistons were Interstate Mcbee for the same reason as the liners, we find the OEM ones always come up under sized.


I digressed again,


we are only using reliabilt injectors yet they seem to be consistently rubbish,

is there anything better we can use than the reliabilt rubbish?[/QUOTE

Are you positive the cam to injector clearances were correctly set? Or the cam shaft bearings are good?

[boat driver]

Originally Posted by sx_turbo

Good day all,

hope you are all having a good sailing season.

I am new to the forum and have come to ask questions regarding Detroit 71 series injectors.

the background to the story is I work for an engineering company in UK and have recently (around 1 year ago) rebuilt a pair of 16v71n engines and a pair oLd TwinDisc MG521 gearboxes that are fitted on an old Benetti boat.

When we rebuilt the engines we had them tested and passed both our own quality procedures and BV's quality procedures and the vessel owners quality procedures.

Any way 9 month later they finally have the engines installed after sitting dockside for 6 of those months, and we finally get the engines up and running.


We then had 2x injectors fail at the very end of the first 8 hour sea trial, they had seized solid at full chat, luckily quick thinking from our engineer saved the port engine.


then after a further 50 hours of running one of the injectors on the port engine sprung a major fuel leak from the injector control rod,


now at the end of the sailing season, I've just taken another phone call stating that one of the engines has run away again, and the vessel engineer used the emergency shutdown flaps

I am unsure of any other details at present,


anyway sorry for the long winded post, when we rebuilt the engines we used all genuine parts, except for the liners we used FP Diesel as they are a much better quality product than the OEM, and the pistons were Interstate Mcbee for the same reason as the liners, we find the OEM ones always come up under sized.


I digressed again,


we are only using reliabilt injectors yet they seem to be consistently rubbish,

is there anything better we can use than the reliabilt rubbish?

Good afternoon-
Sitting on the dock for nine months prior to vessel install is a question, and the seizing of two injectors is a concern-
are we discussing both engines or just the same port engine?
injectors that seize are generally a fuel lubrication issue- and/or during sitting they were without fuel and thereby corroded. For a warranty discussion I would need to know the fuel used, the storage facility climate (or shrink wrapped in the open) specific size injector. and fuel filtering manufacture and specs.
A runaway engine, particularly the same engine , and shutdown via intake air damper is a sign of another source of fuel- or multiple injectors cracked which when fuel is shut off should have had same effect.
Is oil normal>

Personally on a 12v71 a runaway is generally resulting of a bad/broken set of rings and/scavenger ring. getting the fuel from the crankcase.

[sailorboy53]

I was in trucking over 40 years and owned numerous 2 stoke Detroits and will tell you Relibuilt parts are crap especially injectors. A far better choice is Korody-Colyer parts. As an example if you buy a set of Reliabilt 65cc injectors they will flow anywhere from 63 cc to 67 cc so they are not balanced whereas if you buy K-C they will all be flow rated at the exact same cc rate. Same goes for pistons and rods so a rebuilt Detroit using K-C parts is almost a balanced engine increasing power output and longevity as the cylinders are not competing against each other,JMHO

[Techtool]

What Micron is your secondary fuel filter? I worked for years on 53, 71, 92 and 149 engines in the mining sector. Bio sludge can be a problem but more often its particulates of carbon that get in the fuel tank via the injector return lines.