Kobelco SK300LC Series 4 Engine Bog???

[trip]

Hey Guys, could really use some help with this one please!

Just purchased SK300LC 8.3 Cummings with a bad CYL head and rumor of pump issue. After replacing the engine with a used one, I found that the engine bogs to a stall very quickly when engaging the safety bar by operators left leg. When the bar is lowered, engine goes into a hard stall, and if you pull up quick enough, engine sometimes recovers. I was able to work the safety lever gently while holding back on the bucket lever in order to raise the bucket about 10 inches, and thats all I have gotten out of it (I was not able to get anything from turn or walk). I am more of a wheel loader man and not familiar with plumming/valves on excevators. Neighbor/Friend feels that its going into full wash? (whatever that termonology means). Any help would be greatly appreciated!!

 

[sultan]

Hey Guys, could really use some help with this one please!

Just purchased SK300LC 8.3 Cummings with a bad CYL head and rumor of pump issue. After replacing the engine with a used one, I found that the engine bogs to a stall very quickly when engaging the safety bar by operators left leg. When the bar is lowered, engine goes into a hard stall, and if you pull up quick enough, engine sometimes recovers. I was able to work the safety lever gently while holding back on the bucket lever in order to raise the bucket about 10 inches, and thats all I have gotten out of it (I was not able to get anything from turn or walk). I am more of a wheel loader man and not familiar with plumming/valves on excevators. Neighbor/Friend feels that its going into full wash? (whatever that termonology means). Any help would be greatly appreciated!!

Hmm... assuming that the engine is fine, the variable displacement pump is probably stuck at full flow for some reason and the oil cannot get anywhere. This is rather weird as the hydraulic oil should be free to flow through the valve block unless there is a load. My [uneducated] guess is that a computer on your machine has failed in some way the has put the pump in full displacement and closed all the control valves. A real mechanic should be much more useful than me though :beatsme

P.S. Do you understand how variable displacement axial piston pumps work? When a pump is at 'full wash' as you friend says, that means that the swash-plate that moves the pistons is fully tilted, moving the pistons to their full range and getting max flow. This requires a lot of torque from the engine, especially if there is a tough load, and even more if the hydraulic oil can't get anywhere.

 

[trip]

Sultan, thank you for your reply. So do you feel that I should start looking at the pump or the valve block(behind the cab)? and can I figure these things out for myself or do I NEED to call the dealer. My friend also said that I may be able to ove rride the swash plate near the pump? Thanks Trip.

 

[machine]

Hey Guys, could really use some help with this one please!

Just purchased SK300LC 8.3 Cummings with a bad CYL head and rumor of pump issue. After replacing the engine with a used one, I found that the engine bogs to a stall very quickly when engaging the safety bar by operators left leg. When the bar is lowered, engine goes into a hard stall, and if you pull up quick enough, engine sometimes recovers. I was able to work the safety lever gently while holding back on the bucket lever in order to raise the bucket about 10 inches, and thats all I have gotten out of it (I was not able to get anything from turn or walk). I am more of a wheel loader man and not familiar with plumming/valves on excevators. Neighbor/Friend feels that its going into full wash? (whatever that termonology means). Any help would be greatly appreciated!!

Do you know if it operated ok before the engine swap?
I have found with engine swaps that sometimes the engine installed came out of a truck. Trucks use a different governors than excavators.

 

[trip]

Funny you say that. The machine was a repo. when the company went belly up the engine was already apart and some parts cyl head, intake and turbo are lost for good to a machine shop. i had a 8.3 out of a garbage truck so i installed knowing that i would need to swap AT LEAST the fuel distrubitor. I bought the machine a 1/2 mile in the suger sand and woods and that tow bill (80,000 1/2 mile out = big money) I figured that i could atleast walk it out onto a lowboy. 238hp replaced with a 250hp. I do understand a turbo curve but thought it would get it out. Was I wrong?

 

[sultan]

Funny you say that. The machine was a repo. when the company went belly up the engine was already apart and some parts cyl head, intake and turbo are lost for good to a machine shop. i had a 8.3 out of a garbage truck so i installed knowing that i would need to swap AT LEAST the fuel distrubitor. I bought the machine a 1/2 mile in the suger sand and woods and that tow bill (80,000 1/2 mile out = big money) I figured that i could atleast walk it out onto a lowboy. 238hp replaced with a 250hp. I do understand a turbo curve but thought it would get it out. Was I wrong?

I'm assuming you added a governor...

To the best of my knowledge, truck engines have direct throttle control though the accelerator pedal rather than a governor. If the engine has a GOVERNOR installed (and not just a direct throttle as the accelerator pedal is in a truck), a governor's a governor, they all do the same thing - dynamically adjust the throttle depending on load to maintain a constant engine speed. Yes, there are small differences in the power curves etc. but that shouldn't cause a hard stall like that.

 

[trip]

yes, i did put the old governor on (round and mounted on the block under the fuel distibuter) but have been adjusting it by hand.

 

[sultan]

yes, i did put the old governor on (round and mounted on the block under the fuel distibuter) but have been adjusting it by hand.

OK... I doubted the possibility of forgetting the governor :tong.

Does the governor adjust the throttle appropriately on load?

Hmm... how would anyone test that... does the engine put out a small plume of black smoke before stalling when you turn on the pilot controls?

If the power curves of the new engine are different from the original, the engine can behave a bit wonkily (engine rpm moves all over the place under load due to over/under-correction by the governor) but it should still keep on chugging on well enough to move the machine a bit (provided that the engine is the same ballpark).

 

[dirthog]

you can not adjust the govenor (stepping motor) by hand you need to do what is called A adjustment on machine. also if you moved the stepping motor by hand with the key on it is more than likely junk now! Even with out it adjusted it should not kill the engine when the lever lock is down it sounds like you have some lines crossed on the pumps at least that is where I would start

 

[machine]

Trucks use a variable speed governor that allows the driver to adjust the amount of fuel being delivered to the nozzles. A variable speed only governs fuel at idle and cuts back on fuel when the RPM reaches the set maximum for that engine. It will add more fuel to maintain max RPM if the throttle is held at full speed. A limiting speed governor allows the operator to chose the speed he wants and the governor will adjust fuel volume to maintain that speed. A truck governor would only work in your application if it were held at full throttle or pedal to the metal.

 

[machine]

Disconnect the throttle linkage that Koby is using and wire the fuel lever to full and give it a try. If that won't work then look at hydraulic pump control.

 

[Jam]

Just my two cents but at idle that engine should run away happy out with the pilot controls engaged, even if the pump is at full swash, the flow wouldnt come near to overwelming the valve chest to that extent. Start looking at plumbing maybe something got mixed up

 

[Yellow]

i would say yes quiet true

 

[dirthog]

even at a idle any Kobelco you can counter rotate the tracks and not stall the engine if it is working the way it should

 

[trip]

Thanks guys, after I dug into it more I do feel that it is a pump issue and will start on that this week. At high idle and putting the safty bar down the engine goes into a hard stall where would you guys start 1. the main pump 2.controll valve 3. ?wires that might be unplugged in the left arm rest that controll the safty bar or 4. ???

 

[sultan]

Thanks guys, after I dug into it more I do feel that it is a pump issue and will start on that this week. At high idle and putting the safty bar down the engine goes into a hard stall where would you guys start 1. the main pump 2.controll valve 3. ?wires that might be unplugged in the left arm rest that controll the safty bar or 4. ???

I'd check the control valves first. The engine shouldn't stall, even with the pump at full flow if the control valves are working properly and letting the flow through them. Also, the control valves are partially computer controlled, so check if it's a computer issue rather than an issue with the valve itself. I hope it's just a computer issue because fixing/replacing the control valves is usually very expensive.

 

[PD Mech Steve]

SK300 issues

Trip:

I am not real familiar with the 300 series but I do have a fairly extensive knowledge of hydraulics systems used. I can tell you that I beleive the system is what is called a closed loop system (correct me anyone if I am wrong) With this type of system the oil does not pass through the valves continuously when operating correctly. When demand for oil diminishes the pump flow is shut down. If your pump is at full stroke all the time it will create a load. The relief valves in the system will crack and allow oil to dump into the tank. What I don't know is if this is enough to cause the engine to stall. I would guess that pilot oil is is being applied to the main pump as soon as the saftey lever is lowered. I don't think the pump is stuck. If it were the saftey lever would have no effect on it. If in doubt, disconnect pilot oil from main pump and test with gauge, lever up & lever down.

 

[beckco909]

yes it is a closed system meaning the pump has to be stroked to be activated so there could be as simple a foot control piston stuck not returning witch would stroke the pump but i would start by checking all the relief valves make sure none are stuck if the pressure cant be relived it will dead head the pump ether dragging down the engine and stopping it.

 

[MR. KOBELCO]

hi,
1 - you need a " A " adjustment procedure to properly set up engine rpm with the computer control.
do NOT force stepper motor for fuel throttle when power is on for you will fry the computer!
2 - if the engine loads with putting the lever lock engaged (down) your pilot controls, pedals, joysticks and such are shifting a valve to block the neutral circuit turning on the pumps or...
your lines at the hydraulic pump could be crossed.
call me
i'll get you to gauge in on the pumps to figure this out.
can troubleshoot over the phone.
need ser#
YCU-####
cheers!