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Detroit 12V71

Started by LeeB, September 23, 2015, 06:05:33 AM

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snowstorm

i had a 671 do this once. with mine it stuck the piston in the liner. dont know if the liner broke or piston broke and stuck in the liner ports. it broke the rod then it flopped around and poked a hole in the block

LeeB

That one had to of hurt. The boys should have it ready to try out tomorrow but now the boss is backtracking and wants to get someone out to have a look or at least be on hand before we smoke test it.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

Gary_C

Pay particular attention to the fuel delivery system. Now that I think about it more, uneven fuel delivery to the cylinders can cause exactly the problem you had.

You may have had an injection problem disguised as a mechanical problem.
Never take life seriously. Nobody gets out alive anyway.

s grinder

Gray_C is correct have seen it on Detroits a few times where one injector over fuels and burns a hole or melts a piston.I'm surprised when they pulled the head they didn't see the injector tip blown off it or any head damage due to all the shrapel blown around in that cylinder.Not blaming the crane operator because he's way up front,but that motor just didn't blow before making some strange noises like pinging,skipping,ect.

LeeB

Just a little update if anyone wants to know. Got everything back together. Turned it over with the fuel lines disconnected for a little while and aall was smooth. Connected the fuel lines and primed it. Ran it for 5 minutes and shut it down. So far so good. Opened the inspection covers and found the injector on the damaged cylinder to be leaking. Lucky enough we had the tools to set the timing and are now in the process of replacing it. I wonder if this is the root cause after all? Thanks for the heads up on this.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

s grinder

I think that was the problem,bad injector caused over fueling melting piston.When they install injector it is important they overtighten the fuel jumper lines to the injector.I've seen people overtighten they cracking the ferrel in the line causing a internal fuel leak,also call [making oil],i had a special tool and used to torque them.

treeslayer2003

of course Lee, thanks for the update.

on the funny noises or even smoke, i expect a 12 cylinder would sound funny any way compared to a 3 or 4 53 like most of us are used to.and like was said, hard to listen with it way behind ya and watching what your doing.......just like ya should be. i know its some times hard to monitor gauges while loading logs.
i do have a little time with 6 and 8v71s, seen them do crazy things.

LeeB

New update. Ran the engine for a couple of hours last night. changed oil and found it clean, no debris. The injector that was leaking has a very visible washed tip. I believe more and more this was the root cause of the problem. Purchasing has also located another engine. Should be here in about 3-4 weeks. Hope this one holds out that long or longer. We will bring the new one on board when it gets here so it won't add a couple more days getting it from our warehouse to the rig. Logistics is a nightmare here.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

Gary_C

Thanks for the update.

Sounds like you've got that engine ready for another 20,000 hrs. Let that replacement engine sit and collect salt spray for a long time.
Never take life seriously. Nobody gets out alive anyway.

LeeB

I didn't do anything. The maint team gets the credit along with the good tips from you guys. Thanks for all the help. All I did was get them the info they needed to get the job done. Now, knock on wood, let's hope she holds together.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

LeeB

One more (maybe only one) question for you guys. I see some carbon buildup on the sides of the injector tip. Is this common or would it be a symptom of over fueling and unburnt fuel?
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

Gary_C

There is always some carbon around the tiny holes in that tip but be very careful about removing it. Wire brushing is a definite no-no.

I think the main reason for the residual carbon is those injectors are never perfect in how they deliver fuel. They may leak just slightly before and after the main fuel is delivered. In order to meet the specs set by the manufacturer, the leakage must fall within a certain range and they must have a good spray pattern from all holes. That "allowable leakage" is most likely what causes the carbon deposits.

Other causes could be excessive idling and heavy loads at low RPM's.
Never take life seriously. Nobody gets out alive anyway.

treeslayer2003

think i read some where that the N injector atomizes fuel better than the old C

tantoy

So am i correct in figuring that the engine belongs in a crane that is on a oil rig in Saudi?
1968 Garrett 20 Skidder
1991 Ford 1920 Tractor/Loader
2000 Takeuchi tb135 Excavator
Stihl 020, 041 Super, 084
Husqvarna 61, 181SE, 357XP

LeeB

You sir, are 100% correct.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

treeslayer2003

Lee i read your sig line..........dodge guy lol. i have 15 or 20 of them lol. no cummins.

dgdrls

Amazing motors those Detroit blue smoking two-strokes.

Dan


LeeB

The engine is hanging in there so far. It has about 15 hours on it since the repairs. We are only using it when we can't reach stuff with the port side crane.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

LeeB

Just an update on the engine if anyone is interested. The two pistons and liners we put in are still going fine but it cratered another piston and liner in the same bank while I was at home this time. They replaced it with an old one saved from the overhaul done in Nov last year and we are limping it along. They bought a reman from some outfit in Houston for $49k total cost w/ shipping, customs, etc. Actually they bought two. The place in Houston bought from someone in Baton Rouge. I think it's the same one I told them could be had for $12k. Some people just don't listen.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

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