Cat 953b running ruff when under load?

Hey guys,
I just got done helping my mechanic put all the external stuff back on my 953b (fans, belts, air filter box, ect....) yesterday. It cranked an ran fine yesterday but I didn't drive it around, I just ran the bucket and arms a little. Anyways it has a freshly rebuilt motor, built by my mechanic, in it. We had to have cat come out last week because the motor wouldn't stay running long and it was missing and blowing a lot of smoke. Cat found were one push rod had slipped out of place (explained the missing) and said that it was running rather ruff because the check valve was bad on the fuel return. We replaced the check valve and fuel priming pump and it cleared everything up but it still was blowing grey smoke pretty good but my mechanic said that was to be expected until I broke the motor in good and seated the rings good. Cat checked the fuel rail pressure and said it was great and holding fine ant low and high rpms.

Well I whent to put antifreeze in the loader today and get it ready to be moved. Cranked it and let it warm up, everything running great set aside from some the grey white smoke. Throttled it up to 3/4 throttle and the smoke died away pretty much. After letting it run for about 10-15 minutes I decided to drive it around and play on it some. Once I started driving it the motor started acting up when it got put under a load from driving forward or reverse and running the hydraulics. It operated fine for a little bit but then started choking out when driving it around. The motor would bog down and it would start blowing a good bit of black smoke. Once I put all the hydraulics back in neutral, the rpms would build back up but the motor was running ruff. I let it continue to run on low idle and it cleared up and started running smooth again. Tried driving it again and the same thing happens. Let it sit at low idle and smoothed back up. I took the air breather off of the back side of the turbo and checked to make sure it spun freely and didn't have any play in it. Took the air filter out and ran it to make sure it was getting adequate air.

It seems as if I have something going wrong in the fuel system? What is your opinions on why the motor would run ruff when the hydraulics are engaged and then continue to run ruff after the hydraulics were disingauged?

Many thanks for all of yalls advice!

were the injectors removed or replaced?
If so, one or more may not be seated correctly. Were they set up according to specs?

To check if they are seated, put a sight glass on the return fuel line and watch for bubbles. alot under load usually an injector not seated. If it runs really rough, its normally #6 barley noticeable its normally #1 It could be any inbetween.

Hey lee-online,
Many thanks for your opinion! The injections were rebuilt and origanly installed by cat with new cups and a whole new injector controle rail. Then when cat came out and fixed the push rod that slipped, they had to re adjust all of the valves and recalibrate all of the injectors. That is still a possibility though! I might have to check the fuel return with a sight glass!

Running through a sight glass is how we check all 3116's after we do injectors. I have cut the cups so they looked nice and clean, seated the injector and sync'ed it only to have a bad seal. Under load/boost it allows air into the fuel and then it runs rough. The fuel enters at the back of the head, #6 so whatever one is allowing air in effects those down stream from it. At idle it may run fine.
Some bubbles are normal, its a lot of them that rush through under load that indicate a problem. If it runs really rough then it may be like foam.

Connect a sight glass at the check valve, point it uphill and connect the line to the other end and run it.

There could be many other things, I am just guessing based on the work that has just been done.

Thanks a lot lee-online!!!
I will check that tomorrow afternoon if I can find a sight glass available somewhere. Wear do you normaly find a sight glass ready available? Also if I am able to find one then I just hook it to the check valve and other end of fuel return pipe and look for a lot of bubbles comming through at low idle and high idle? Does it need to have the load put on it? So many thanks for your advise!

How much a badly seated injector affects engine performance depends on which cyl it is in. #1 has little affect but #6 will foam the fuel supply all the way down from 5 to 1 starving them all. Once that is corrected you may have a linkage or HPCU adjustment problem causing engine overload. Do linkages first.
Later Bob

Hey bob,
What do you mean by linkage or hpcu adjustment? Many thanks!!!!

When the cab was flipped/ engine removed you had to unpin the linkages. Is the underspeed override valve adjusted correct.

HPCU = Hydraulic Power Control Unit = hystat

jca57jd said:

Hey bob,
What do you mean by linkage or hpcu adjustment? Many thanks!!!!

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All of the linkage to the HPCU, Speed and direction, Rh & Lh steering, Speed and brake and Underspeed override linkage needs to be adjusted from time to time. The Underspeed override is connected to the throttle and allows the machine to move a low engine RPM. This is for moving not working, mach will stall under any load if the link is not connected or out of adjustment.
Later Bob

All of the controls seemed to work great! I'm not sure about the under speed over ride? I do know that the machine did move at low rpm fine. It seemed to have more of a problem at higher rpms. However the motor did bog some when I moved it at low rpms, but I kinda expected it to at low rpms. Should I try moving it tomorrow with the controle lock for the v pattern forward and revers down?

jca57jd said:

All of the controls seemed to work great! I'm not sure about the under speed over ride? I do know that the machine did move at low rpm fine. It seemed to have more of a problem at higher rpms. However the motor did bog some when I moved it at low rpms, but I kinda expected it to at low rpms. Should I try moving it tomorrow with the controle lock for the v pattern forward and revers down?

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To adjust the underspeed override, With the engine off, pull throttle all the way back untill it locks. Then disconnect the short link between the end of the throttle and the back of the HPCU. Lift up on the link untill you feel the resitance on the lever of the valve. Adjust the link untill the linkage pin just fits. The lever can be lifted more but stop when you feel resistance and adjust to that.
Later Bob

Is the engine timed correctly?

If it ran somewhat ok before the rebuild then i would guess it is related to the rebuild or removal of the engine.

Why was the engine rebuilt?

d9gdon said:

Is the engine timed correctly?

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Don, the timing is done with the "Top Set" like a Detroit.
Later Bob

Yeh the timming has been checked twice! The motor dropped a valve on the second cylinder. It sait broke down for a little over a year. The turbo did have a little water in it when I looked at it before I bought it. I talked to a humongous grading companies head mechanic today and he said that he thought it sounded like the turbo was bad. What is all of your opinions on the possibility of the turbo? The mechanic said that even if it felt tight and spun freely, it could still be bad? I also,talked with a turbo repair shop and they said that if it dropped a valve then it could have easily most up the blades in the turbo and still fill tight and spin free? From the symptoms I have described, do you think the turbo is another possibility? It rained all day hear so I did not get a chance to work on it any. Many thanks for all of your support and advice guys!!!
Thanks, John

jca57jd said:

Yeh the timming has been checked twice! The motor dropped a valve on the second cylinder. It sait broke down for a little over a year. The turbo did have a little water in it when I looked at it before I bought it. I talked to a humongous grading companies head mechanic today and he said that he thought it sounded like the turbo was bad. What is all of your opinions on the possibility of the turbo? The mechanic said that even if it felt tight and spun freely, it could still be bad? I also,talked with a turbo repair shop and they said that if it dropped a valve then it could have easily most up the blades in the turbo and still fill tight and spin free? From the symptoms I have described, do you think the turbo is another possibility? It rained all day hear so I did not get a chance to work on it any. Many thanks for all of your support and advice guys!!!
Thanks, John

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It could be very likely that when the engine ate the valve, the pieces being spat out of the exhaust could take out the turbine blades on that side of the turbo. Depending on how bad it is, there may not be enough turbine blades left to drive the turbo with the exhaust gasses... I know nothing about the engine in that machine however so I can't help with any of the other symptoms...

Nah IMO the turbo is fine from what you have said,

Has anyone checked cam timing?

Btw it sounds like you need to fire your lube man and hire a real mechanic.

Pj

I think that when it sat for the year, you have water in the system, i would clear all lines and filter/ tank. good luck, sam

Thanks guys! I took the turbo off today and took it to get reconditioned. I got another mechanic scheduled to come out and look at it on Saturday. That is if the turbo doesn't solve any problems. Y'all have gave me a lot of great advice! Keep it comming.

jca57jd said:

Thanks guys! I took the turbo off today and took it to get reconditioned. I got another mechanic scheduled to come out and look at it on Saturday. That is if the turbo doesn't solve any problems. Y'all have gave me a lot of great advice! Keep it comming.

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JCA, any time you have an engine failure that involves broken parts, do the turbo. They catch any debris from it and it eats the turbine fins. Been there done that.
Later Bob