cat 312 BL hyd problem

[dirtdobber1]

I need help from the experts. Cat 312BL serial no 8JR01214. The hydraulics seem to be overloading the engine. Swing and bucket curl is fine. Boom up and down is ok. Dipper function is slow and reallly loads the engine to the point of blowing black smoke. It tracks fine as long as you are going straight, but twist the machine with the tracks and the engine loads up. It won't stall the engine, but it gets loaded.

I have had rodent problems (chewing wires) so this may be a hint. Any thoughts?

Thanks in advance.

 

[Ace K]

Swapping filters fixed this symptom on one of my machines. Fuel(2) Air Hydraulic(3)

 

[Scrapper]

Lack of power and really bad black smoke when loading the engine could be caused by a bad turbo, leak in the intake tubing between the turbo and cylinder head (possibly a rubber boot chewed throw by your rodents) or a plugged air filter (possible rodent nest built around the filter).

I think I would check the air filter first.

 

[dirtdobber1]

Thank you for the input. I will be going out today to take a look.

 

[dirtdobber1]

Air filter is fine. Turbo is fine. No nests or holes in intake system. Engine operates fine except for becoming loaded when certain functions are activated.

I have read in other forums that fault codes may exist. Is there a way on this machine to display the codes on the dash, or do you have to have some type of scan tool to read the codes? If it can be done from the dash, please tell me how.

 

[06Pete]

The way to access codes is described it the thead 320B throtle problems it just involves pushing a few buttons then you get the codes but you need the book to tell you what they are. Good luck!

 

[kbeen]

dirtdobber if you have a email address i can scan and email you the procedure to get the fault codes out of it if you would like.

 

[dirtdobber1]

Thanks kbeen. I sent it via private message.

 

[dirtdobber1]

I pulled the codes today and there seem to be only two codes - 4208 and 4209. Anybody know what these mean, and whether or not they would relate to my problem?

Thanks

 

[cjplanthire]

first check the turbo is ok look for black or oil anywhere round the seal and make sure the turbo is spinning

then check your hydraulics firstly checking your pressure and flow settings

then change your hydraulic filters

then blow out your hyd oil cooler with a compressor from the engine side (its located beside the radiator)

i had a similar problem with a 312bl similar serial number and all of this solved the problem however 3 months after doing all of this i had to replace the hyd oil cooler my machine was a 2001model 312bl

 

[kbeen]

dirtdobber that info i emailed you should have those codes definitions on them, if not let me know and i can send them to you. also tell me your systems again. you are only having a problem with the stick circuit , ( stick in and out ? ) and the travel circuit. all the other circuits do no load up the emgine ? is this correct.

 

[dirtdobber1]

kbeen,

The info you emailed me was four pages of how to use the service mode. It does contain a tabe of the service codes, but not error codes. You are corrrect that the only functions causing a problem are the stick in and out and travel - only when I twist the machine with the tracks. Straight travel is not a problem.

Regarding cjp's steps, I haven't checked any pressures or changed any filters yet. Turbo and oil cooler are fine best I can tell. The engine functions normally and the problem I'm having ocurrs regardless of oil temp. I haven't changed the filters yet because if it was a flow restriction, I would have problems with all hyd functions, right?

Thanks for your interesting in helping.

 

[kbeen]

i would says yes as far as your last question on having a problem with all the functions if it was a flow problem. i am scanning and emailing you the error codes now. did this problem just develop all ot once ? there is not anything to tie the travel circuit and the stick circuits together other than i think they are both double pump functions but i believe boom up may be as well. you may have too seperate problems. can you check the pressures on each of these circuits and the rpms that it pulls the engine down to. you can get the rpm read out on your monitor.

 

[kbeen]

dirtdobber1 you might check your monitor and see if it could be in the fine control mode. in this mode it does limit the engine to only 70 percent and does have an effect on the stick circuit as well. just an ideal.

 

[JeremiahSr]

320B Engine Choking Repair

This is for the machines that you have already eliminated the turbo charger and checked all fuel problems consistent with this machine. Usually though...black smoke is lack of air or too much fuel. Rarely is heavy black smoke due to fuel restriction though it can happen:

Your PRV is not destroking hydraulic pumps my good sir. Black smoke is because engine is over working and being choked down. The number 2 solenoid in drawing below i think is the solenoid. Sometimes it is the #3 but if you follow hose from the one i have an arrow on it should lead to the top/center of pump. The half a round piece is a cut out of the full round accumulator on valve block. Some machines the block is directly under pump and some are standing up and in front as soon as you open pump door compartment. After comfirming it is correct by following hose remove small nut on top of solenoid and screw the little adjustment screw all the way down. Install nut and secure. Test machine. If it is better then you have to find out if you are getting voltage and a good ground to connection. Do not use machine frame as ground. This solenoid uses ground from computer. This is just to test...if it is bad ground...you can add a jump wire to frame and correct problem. If it is not getting voltage (any where from 5 to 15v i think?) then this gets alot more difficult. But if your wires are good then you need that solenoid. It is called the Pressure Reducing Solenoid. I can look up part number for you tomorrow if you find that is what it is. Purty expensive if i remember though. If it is not this i can coach you real easy on how to turn down the Constant Horsepower of pump output. There are 3 or 4 adjustments on each of the pump actuator valves. Adjusting 1 will keep good pressure but slow amount of oil and machine will still be fast but not so fast the pump is over working engine. There are 2 styles of pumps and yours is a little harder to adjust the front pump than the 2nd style that is for a different serial numbers of same machines. If this is needed i can do that tomorrow...i am tired and heading home. If your PRV needs to be put back in stock location because everything seems correct...remove nut...back out adjust screw till you no longer feel spring pressure then install nut and secure.

Now this info might already be in this forum some where or on the net some where....i never really looked. But i know i never hear mechanics or equipment owners knowing this so.....
These solenoids control different things on machine. The PRV valve is Proportional and will put out different pressures with low to high voltages sent from computer. The adjustment is merely a way to manually put hydraulics into a slower limp mode to keep from choking engine down so bad until proper repairs can be done.

That is a lot of info that a lot of mechanics old and young does not know and me putting this up here will help them and several equipment owners. The mechanics...like me...that guard this info....like i used to...might be upset with me on putting it on the net like this but these machines are getting older and there is plenty of newer machines with much bigger field repair secrets out now and it is time i let this 1 go. If i get too much hate comments or messages then i will delete it.

Good luck!

 

[kbeen]

JeremiahSr i believe he is only having a problem with his travel and stick circuit, if the PRV valve was malfunctioning it should effect all the circuits the same from my experience with bad PRV valves, have you seen other wise on some machines. and thank you for your advice on helping figure this out.

 

[dirtdobber1]

i would says yes as far as your last question on having a problem with all the functions if it was a flow problem. i am scanning and emailing you the error codes now. did this problem just develop all ot once ? there is not anything to tie the travel circuit and the stick circuits together other than i think they are both double pump functions but i believe boom up may be as well. you may have too seperate problems. can you check the pressures on each of these circuits and the rpms that it pulls the engine down to. you can get the rpm read out on your monitor.

Thanks for the codes. The problem did develop at once. This machine is not used very often, but between uses this problem developed. I don't have the equipment to check pressures, but later this week I can check the rpm's. I'm going to replace the hyd filters later this week also.

 

[dirtdobber1]

JeremiahSr thanks for the input. Let me ask a diagnostic question. If the PRV is the problem, would it cause the pump to pull the engine down while the function was in motion? For instance, if I have the stick fully extended and then bring it in, it will pull the engine down on the way in. It does this with no load against the bucket.

I will give your suggestions a try later this week.

 

[kbeen]

dirtdober1 have you tried it with the controls in manual mode ? you can flip the toggle switch there in the cab and put the machine in manual mode instead of aut. mode which is controlled by the computer. put it in man. mode and see if you still have the same symptoms. 1 switch puts in in man. mode and the other switch is to throttle up the engine.

 

[JeremiahSr]

sounds like prv to me. stick, boom and travel will be the circuits pulling engine down the most.