Hey guys I have been trying to search the site for some information on a Cat 312 excavator I just purchased. The one post that I think has the information "cat 312 BL hyd problem " it is not showing up, not sure if thats from the update to the site. From reading some partial posts it sounds like the PVR valve or seliniod. I'm trying to find out where the PRV is located (schematic) or the part number for it. Also is it a pressure relief valve or a proportional reduction valve? Just wanted to make sure I have the proper term for it. If I purchase a new PRV will that need to be calibrated? If so, does anyone have the info on how to calibrate it? Also does anyone know where to get a new or rebuilt ECM ? The dash moniter is not currently working and having to use the switches behind the right arm rest. Pin #7DK01488 Serial# 6LK01675 Thanks guys for your help.
Good day Your diagnostics are difficult to follow, if you have a schematic post it here and I will try to help out. Good if you can explain what issue you have with the machine. Kind regards Uffex
That’s is a straight 312. The prv is in the pilot block. Follow the line coming from top of the pump it will lead you straight to it. You do have to calibrate it through the monitor. You also need to do a sweep test will monitoring Hyd. Pressure and amp draw from solenoid. Before diving into Hyd problems you need to make sure you are making horsepower. Clean fuel system and boost pressure. If it blows black some when it’s stalling out you are getting plenty of fuel so don’t go down that rabbit hole. If your monitor is not work and you’re failed this will more than likely be your whole problem. You can do a google search for a controller but good luck. Cat is always my safest bet.
Thanks for getting back to me. The machine runs and seems to be working fine when there isn’t a big load. When digging or curling the bucket all the way. The machine bogs down and can even stall out. It will blow some black smoke as it’s blogging down but not a terrible amount. When idling I don’t see blow by from the engine.
Good day Tyler I would suggest giving the engine a top to tail, if the machine has made a few hours it could be real worthwhile. Kind regards Uffex
Are you still looking for a hydraulic schematic.?
Thanks Nige From the post I guess this is more to do with the engine, if it should change I will get back to you. Keep smiling Uffex
If it is bogging down I would say prv is rite on track. But ensuring horsepower of a unknown machine is always first
Yes if you have a hydraulic schematic that would be great. I found one that has 4 seliniods I think is for a 320 but my machine has 3 seliniods. I don’t know which one is the prv. I looked up how to test the seliniod, do you by any chance know how many ohms or the range that it should be when I test it? Thanks again for everyone’s help.
I suggest that you should take the advice of the posters #7 & 8 above and eliminate the engine first before moving on to the hydraulic system.
I don't know if you are aware but your excavator was originally built for the Japan-only market and was never originally intended for sale anywhere else. Some documentation exists but it is all in Japanese. There is an Operation & Maintenance Manual XJBU2088 and a Parts Manual XJBP7177. With a machine Serial Number of 7DK01488 the nearest 312 model marketed in the US would be a 6GK-prefix machine of Serial Number lower than 6GK00392. Even then, the documentation applicable to the 6GK machine would not be guaranteed to be 100% applicable to the 7DK.
Good day Nige Would that have the same engine as the NAFTA - European machine ? KR Uffex
Nige Thanks for the info. I was made aware before I purchased the machine it was grey market. It came with two parts manuals the Japanese one and also a the 6gk one. I’m trying to track down a service manual as well. Im mainly planning on using the machine for personal use on my projects. So it shouldn’t be used too heavy. Just want to get it back in good working condition. A big thanks to all that are helping me through the process. It’s great to have all this knowledge in one place to be able to ask questions and get help.
The 7DK has a 3064 engine. From what I understand the principal differences between the ISJ machines and the rest is the bodywork and especially the cab. However that's not to say that the hydraulics and power train are exactly identical to the 6GK. I can't find either a hydraulic or an electrical schematic for a 7DK machine anywhere.
I work on several 7dk machines for customers and resort back to the 6gk prefix for parts and Service. The prv is easy to find if you follow the power shift line from the pump to it. It is it’s on solenoid and block. You can do a sweep test and see if the needle is jerky. Obtaining a manual would be a great idea.
Been searching around for a service and maintenance manual and haven't been able to find any with 6gk prefix. I found plenty of places that want to sell the download, but many of them seem shady. Have any of you downloaded ones before or have a trusted site to download. Thanks
The fault you described needs to be operated on the display screen of the instrument to adjust the output of the PRV. This process requires the display of the rotational speed and meets the requirements of the parameters before it can be carried out. You need to provide a picture of the instrument, and I will guide you..
Are you meaning a hydraulic test pressure gauge or a special electronic instrument for taking the measurements? If it is a hydraulic test kit, I have one of those.
Search for Cat Publication SENR6130. I have just done that but came up empty apart from a download that is obviously a scan of multiple pages taken from an old version of the Cat Service Information System (SIS) that IIRC was decommissioned at least 2 years ago. This is NOT a genuine manual. https://issuu.com/lebo847386526453/docs/caterpillar_cat_312_excavator__prefix_6gk__service A large number (maybe all) of the downloads that are offered online are this type of knock-off sold from Eastern Europe for maybe $60. To give you an idea the genuine article costs $950 in paper form or $670 on a CD. At the risk of repeating myself and based on what Uffex & MBar mentioned above I think that you would be well-advised to sort the engine out first to eliminate any possibility, however small, that you have an engine problem before proceeding into the hydraulic system. To attempt adjustments of the hydraulic system to compensate for an engine issue would be an exercise in futility.