10-19-2012 11:48 PM
Hopefully this is my last post on this issue. The engine has been online for the past 24 hours and we’ve had no problems!
After my last post we went back at took a better look at the linkage. We disconnected all of the rack control rods and found 3 injector racks were stiff and sticking. They were causing the linkage to bind and not return and I’m speculating that they got worse when the engine was hot. We think that something got in to the fuel system and damaged the plungers causing the racks to stick and probably have some damaged tips as well.
I don’t have an injector tester so we went ahead and swapped out all of the injectors and changed the fuel filters. We didn’t see any type of contamination or grit etc in the filter housing and we marked and saved the injectors to be checked at a later date. FYI these injectors were installed approx 2000 hours ago.
Thanks Again for all the replies, they really helped!
10-16-2012 08:54 AM
Turning the shaft worked out great! Thank You! It made a noticeable difference when we had everything disassembled, we only did the left hand side, the right looks fine and due to limited working area we decided to let it go. Now with the actuator back on we are having problems with it returning on it's own to the no fuel position. I see no binding anywhere on the linkage at all so I believe that it must be reduced spring pressure from the injector control rods. I'm going to get them on order ASAP along with new shafts and bearings....
We ran it under load today for approx 1 hour and had no problems at all. The only thing that we noticed was a significant difference in the Turbine housing temperature from right to left. The left hand side was consistently running 100 Degrees F hotter then the right, then all of a sudden they evened out! This was after approx 20 minutes of running under load.Very strange! I checked other units and they were approx 20-30 Degrees different while under load. It had me thinking that we possibly had a restriction on the left side Turbo turbine outlet. We're going to pull the left side in the morning and have a look.
If I had any hair left I would be pulling it out right now because this thing is really throwing for a loop! We definitely have a linkage issue but I can't wrap my brain around how that could cause the problem. I just can't see mechanically how one side could stick due to the linkage. Both sides are interconnected, and I understand that the linkage is designed to drop down and close to shutdown the engine, but I just can't see it binding while it's being controlled by the actuator and not having an obvious performance problem or over speed condition.
I sat down and figured it out on paper and it seemed to make sense that one side may be over fueling but in practice when I'm running the engine and bumping the actuator I just can't see it happening!
We're going to carry on tomorrow until we get it figured out!!
Thank You Again, I Sincerely Appreciate The Help!
10-15-2012 06:48 PM
10-15-2012 07:50 AM
Thanks for the reply, it's very helpful.
We took a closer look at the linkage and it is definitely worn. We removed the front cover on the left side and actuator linkage and cover on the right side. The left side center control shaft has a flat worn in to the round shaft, and the bushings on both side are worn. The engine has 24000 hours on it, we checked another with 12000 and found the left side shaft was very similar but not quite as bad. The shaft worries me and I'm going to order them and the bushings and replace everything at overhaul later this year but I'm hesitant to deadline it for the linkage because the ball and socket on the cross shaft appear to be OK and I don't really see how it could ever jam or stick causing the engine to over speed or run away....
The only solution that I could come up with as far as the worn linkage causing this problem would be the difference in the rack travel due to wear on the shafts, but we went through and synced the injectors and found that they were all loose but pretty close. We screwed the adjustment rods an average of 20 clicks to sync them up, but that equates to very little movement on the rod itself.
I was hoping that something would jump out as a huge difference but nothing really has. I don't see how the linkage could stick on one side or not engage on the other etc...
I'm really having trouble figuring out how just one side could have this problem! The engine has a common air box, so I would think if it was a plugged after cooler/air filter... then the problem would show up on both sides. We have a common fuel rail, so if the fuel pump or pressure regulator was bad then it should also show up on both sides.. My first thoughts were either over fueling on the right side or the left side wasn't firing at all and causing the right to do all the work!
We've got the valve train off now so we're going to go ahead and pull the injectors and also the right side Turbo.
Thanks for the help and I'm open to any suggestions that you guys have!!
10-14-2012 02:14 PM
Ran into to this many years ago and root cause was worn linkage at the cross over shaft at the front of the engine. For some reason it always seemed the right side fuel control linkage wore more than the left side on the mechanical engines, at least in my experience. Another possiblity is a turbo dragging, is this an older engine with the larger turbos? A quick way to check is to see if the compressor discharge temp is as high or higher than the "good" bank.
Hope that helps, Mike L.
10-14-2012 08:50 AM
Here's a strange one, on my 1 MW 3512 the right side (only) exaust manifold and turbo are glowing red! Abnormally red! Here's the background:
1) The engine was running the previous day and had the same problem so the operator shut it down.
2) We came in the next morning, did basic checks,found no problems and put it online, stepping up the load slowly...
3) The unit ran fine for approx 7 hours at approx 700 KW. We used an infared gun off and on all day and the EGT was farly even on both sides, no unusual smoke from the exaust Etc.
4) After approx 8 Hours we noticed light white smoke from the exaust, had a look and it was indeed glowing! Performance seemed fine, a little vibration but no misfiring.
5) Once it cooled down we checked cam timing , checked injector linkage (We have mechanical injectors), checked valve lash/Injector timing and all are OK. We changed the air filters and ran it at about 800 RPM, for about 30 minutes while monitoring EGT and everything seems fine.
We don't have an injector tester so we plan on swapping them out in the morning. To me it seems very strange that only one side has a problem, I thought for sure it was going to be cam timing but it's not the case.
Anyone have any thoughts?