View Full Version : 966f performance question
komatsukid
10-29-2007, 06:50 PM
Hi Guys,
I have been running a 966f series 2 loader for almost two years. When I got put in the machine they just got it back from Michigan Cat the engine got week so they rebuilt it. The first thing I noticed when I started running it was it was weak on power it would only hold about 2000 rpm through a simulated torque stall. Cat came out and turned the fuel and air pressure up after that it seemed to be better until now, when i put a load on the engine, like digging in a hard bank or climbing a steep grade the engine missfires, and blows black smoke and soot like crazy and the turbo doesnt seem to spool up. Any ideas what might be causing this?
Could be a number of things really.
Check the air-filter. (Run without it in for 5 mins)
Pull the intake rubber off and check the turbo is OK :cool:
How does the machine perform under no load? Does it start, stop and tick over ok?
If not then get CAT back on the job.
Ross
jperfect
10-29-2007, 08:39 PM
off the the subject for sec. what part of michigan and who are you working for?
Squizzy246B
10-30-2007, 05:09 AM
IIRC I had a similar problem on a 950F, it was the rubber air inlet piping collapsing when the air filter got slightly restricted and the machine was hot. It would not do it when the machine was cold. I also believe we had to do the turbo up shortly after that.
Sounds like an exhaust manifold leaking.It is pretty common on Cat engines.Ron G
komatsukid
10-30-2007, 05:54 PM
I start the machine and let it warm for about 30 min before running it. It makes the noise all day. I noticed something else not right today, the idel rpm is at 950 revs per min. we have another identical loader, and it idels at about 600 rpm. Anyway I looked at the turbo today the impellar shaft is tight and the compressor "fins" are not damaged. Turbochargers run on exhaust pressure, if the engine is not firing on all six pistons could this cause turbo lag?
surfer-joe
10-30-2007, 11:09 PM
I'd venture to say that the timing is not correct. Ross is right, get Michigan Cat back out and tell them you want a competent hand to go thru the fuel system.
Good Luck!
komatsukid
11-02-2007, 07:23 PM
Cat was here today to look at my loader. The field mechanic and I worked on it for almost the entire day. The first thing we did was check boost and fuel pressures. Both these checked out above normal. Then we moved to the torque converter, this checked out perfect. Next we checked the timming this also was fine. We then decided to adjust the valves, three out of the six cylinders were so far out of adjustment we could nearly slide a pencil between the valve and the rockerarm. Belive it or not adjusting the valves cured 50% of the problem. We then jerked out the injection nozzels and replaced all six of those. After that it was about 75% cured. Finally we "lapped" the injection pump check-valves that shoot fuel to each nozzel. That did it! The ol girl runs like a bat out of hell now!!!
anyway just thought you guys might like to know what we did to fix it.
Well defo not a quick fix job.
We then decided to adjust the valves, three out of the six cylinders were so far out of adjustment we could nearly slide a pencil between the valve and the rockerarm. Should have sounded like a Bag of hammers in a washing machine :eek:
We then jerked out the injection nozzels and replaced all six of those.Woo well that would have broke the bank i recon? :rolleyes:
Finally we "lapped" the injection pump check-valves that shoot fuel to each nozzel.Didnt think you could lap the delivery valves in on them pumps? Well learn summit everyday.
anyway just thought you guys might like to know what we did to fix itYeah thanks for sharing. Glad the machine back up to speed. Any pics wink wink.
Ross
How many hours on the rebuild KK... also what model of engine is used in your 966F?
The need to replace all 6 injectors and mess with the fuel pump check/delivery valves (I'm with Ross on never hearing of this before :confused: ) would indicate low fuel quality or contamination.
Why were the valve clearances so far out? I would be very concerned that the overheads or camshaft lobes were wearing:eek:
komatsukid
11-03-2007, 09:01 AM
There is about 3 thousand hours on the rebuild. The mechanic said the valves should have been inspected/adjusted at the first oil change. I never thought to ask him if the camshaft could have sustained damage due to the rocker arms being so loose. The engine model is 3306. The reason we went into the pump was to eliminate the posibilty of the delivery valves leaking. I have never done this, But he explained to me that if the valves get a "scaling" formed on them fuel will leak down from the injection line. Every time the pump shoots fuel to a nozzel it has to prime the injection line.
Never really had much bother with 3306 engines apart from a few piston ring epidemics and total loss on high hour machine (Graders)
The mechanic said the valves should have been inspected/adjusted at the first oil change. This is careless on CAT's behalf as they should have insisted on this service as part of the warranty and charged handsomely for it including a PDI rebuild report.
I never thought to ask him if the camshaft could have sustained damage due to the rocker arms being so loose.Quite possible but the problem wont rear its ugly head for a while. A clock work tick will spell trouble.
The reason we went into the pump was to eliminate the posibilty of the delivery valves leaking.I have encountered pump delivery problems with 3406 engines but not the 3306. Mainly the metering sleeves (When worn) which can reduce the injector pressure to the injectors. This problem can only be cured by sending the whole pump off to a specialist.
Ross
There is about 3 thousand hours on the rebuild. The mechanic said the valves should have been inspected/adjusted at the first oil change. I never thought to ask him if the camshaft could have sustained damage due to the rocker arms being so loose. The engine model is 3306. The reason we went into the pump was to eliminate the posibilty of the delivery valves leaking. I have never done this, But he explained to me that if the valves get a "scaling" formed on them fuel will leak down from the injection line. Every time the pump shoots fuel to a nozzel it has to prime the injection line.
:( I guess its out of warranty then?
Based on my experiences with reman engines the valves should have been adjusted at the rebuild shop when the engine came off the dyno as part of quality control process. Clearances can tighten up initially, if the valves recede slightly but after initial set everything should be good for a very long time.
If the valves were so loose at just 3000 hrs something must be wearing prematurely such as cam bearings, lobes rockers or something?:beatsme
CatYelloBlooded
05-06-2008, 11:18 AM
A pencil in there? Wow- I'd say that had a little to do with it. When you say they checked the timing, You mean they pinned her at the flywheel and on the pump? Does that engine have a timing advance? In mossville engine plant the engines aren't timed with pins, but flow timed. An instructor showed me this and i'll never pin time it again. What i'm referring to is locking the pump and adjusting the engine relation to it. In the factory they advance the engines slightly to get the power they need at the dyno. If you find a mechanic locally who can do this for you she'll still be in spec and your fuel economy will stay the same; but it'll run like a striped a** ape. Brings an old DITA to life.
komatsukid
05-06-2008, 06:17 PM
i have heard of cat advancing the timing but i dont recall the degrees. last year when cat was working on that 966 we checked the timing using the pins. it was spec.
w2bstoned
06-11-2008, 07:20 PM
How many hours did they get on the motor before a rebuild? I have 14000hrs and still original, It only uses three quaters of gallon of oil per tank of fuel
komatsukid
06-11-2008, 09:22 PM
i dont know how many hours were on the engine prior to rebuild. as of today the loader has 21004 hours on it.
John C.
06-11-2008, 09:56 PM
I don't remember if that engine has hardened rocker arm tips but I thought it did. Anyway the only engine I've found sensitive about needing rocker adjustments is the Cummins B and C engines. The rockers are soft and the valve stems actually wear divots into the ends.
I put a few 3306 engines together and went multiple thousands of hours before readjusting. I would say if they were that bad there was something done wrong at rebuild.
w2bstoned
06-15-2008, 12:11 PM
Komatsukid yours burning much oil? How is the loader holding up after all those hours?
Ray Welsh
06-15-2008, 05:48 PM
How many hours did they get on the motor before a rebuild? I have 14000hrs and still original, It only uses three quaters of gallon of oil per tank of fuel
That oil consumption seems kinda high for a 3306. I have had a few and when they started to drink oil like that, I'd change the oil. Then they would use none for a couple of weeks. 14000hrs is a good indicator for a rebuild, although many will go longer. Hard work is the key to long life of 3306 and remember not to idle them for too long.
I always used straight 30 oil which had a wider working range than multigrades..........C ya........Ray
komatsukid
06-15-2008, 08:09 PM
the machine is good contition having 21000 hours on it. we use a vary high grade grease and stick to a religous maintance schedule. last winter my loader was sent to cat where the bucket and boom control valves were rebuilt. and a small oil leak was repaired at the bell-housing.
komatsukid
06-15-2008, 08:15 PM
another thing i have never seen a 3306 blow as much soot as this one does.
w2bstoned
06-15-2008, 08:30 PM
I tried a new grease thursday, Almost a graphlite like type, It was no good. I change the oil at 250hrs, how about you? I need a new seat now, but cat prices are crazy...
komatsukid
06-16-2008, 08:05 PM
we use TRC grease, seems to hold up well. we set our oil changes at 200 hours to give us a 50 hour leway.
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