Cat 312 Grey hydraulics slow

[rudeag]

Slow response time on all functions, noisy pump. Pump rattles and groans. Hyd filter is new, old one was cut apart for metal flakes but found none. Do not have
high pressure test equipment readily available but were nominal on tested circuits. Everything seems to indicate bad pump but want to make relatively sure as it will not be easy nor cheap to replace.

 

[Coaldust]

Rule out any engine low-power issues, next. Maybe check the case drain volume on the pump.

 

[rudeag]

Rule out any engine low-power issues, next. Maybe check the case drain volume on the pump.

Rule out any engine low-power issues, next. Maybe check the case drain volume on the pump.

Case drain volume? Help me here, please. Engine does not bog down.

 

[Coaldust]

A hydraulic pump always has a bit of leakage past the pistons and slippers in the rotating assembly and that is used for lubrication. That oil is routed back to the reservoir and we call that case drain. As the pump wears, the volume of that fluid increases. We measure the case drain volume to determine how much wear the pump has.

I don’t have access to SIS at the moment. Maybe someone can post the procedure and specs.

 

[John C.]

A Cat excavator will have a case drain filter that you should cut open before condemning the pump. Rattles and groans can come from drive coupler or other places as well. I assume it is an "A" model machine from the title of the thread. You might provide the full model number, serial number and amount of hours on the machine to help things out a bit.

 

[BigWrench55]

Is it possible that you are hearing the noise from the pump drive coupler and not the pump itself? Slow hydraulics is a indicator of low flow. You definitely need to run some pressure reading for pump output.

 

[rudeag]

A Cat excavator will have a case drain filter that you should cut open before condemning the pump. Rattles and groans can come from drive coupler or other places as well. I assume it is an "A" model machine from the title of the thread. You might provide the full model number, serial number and amount of hours on the machine to help things out a bit.

Are u talking about the main hyd filter that I have changed and cut the old filter and no metal flakes present? An A model is what? Model # is 312 and it is grey.
Hours on are 11412hrs. s/n is 7DK02085 Thanks for your help!

 

[rudeag]

Is it possible that you are hearing the noise from the pump drive coupler and not the pump itself? Slow hydraulics is a indicator of low flow. You definitely need to run some pressure reading for pump output.

Pressures were run and nominal but response time is slow indicating to me that the flow is not up to par. And not able to tell if pump or couple is the culprit

 

[John C.]

There is a main hydraulic return filter in the hydraulic tank plus a small spin on filter between the hydraulic pump and the hydraulic tank. That is the case drain filter.
Cat put series designations on their models of excavators. It started at 312, 312B, 312C and so on. By your serial number, your machine isn't gray market, it is an A model and the year of manufacture is 1993. If the pump is original, I'd say there is a strong possibility it needs some work done. There are some electronic things you can look into before removing the pump. The link below is to a video showing how to access the diagnostics. I don't recall which number in the menu gives you the faults but someone should be along to give you that info.

Good Luck

 

[Vetech63]

Check your hydraulic oil for air bubbles in the tank after you run it. You could have air intrusion through a suction leak which will also create alot of noise and weak hydraulics.

 

[rudeag]

There is a main hydraulic return filter in the hydraulic tank plus a small spin on filter between the hydraulic pump and the hydraulic tank. That is the case drain filter.
Cat put series designations on their models of excavators. It started at 312, 312B, 312C and so on. By your serial number, your machine isn't gray market, it is an A model and the year of manufacture is 1993. If the pump is original, I'd say there is a strong possibility it needs some work done. There are some electronic things you can look into before removing the pump. The link below is to a video showing how to access the diagnostics. I don't recall which number in the menu gives you the faults but someone should be along to give you that info.

Good Luck

 

[rudeag]

Thank you I have been told this machine is grey and I have Chinese/Japanese markings in several places most notably
in the electronic "brain" box left rear door. Yes it is a 1993 model as far as I know. My monitor panel is somewhat different than in the video. Have changed the hyd filter but where do u access the filter in the hyd tank?

 

[John C.]

Been a bit since I’ve been on 312, but there should be a cover with four bolts on top of the tank. Filter should be under that.

 

[Nige]

Cat put series designations on their models of excavators. It started at 312, 312B, 312C and so on. By your serial number, your machine isn't gray market, it is an A model and the year of manufacture is 1993.

I would agree with the 312A designation but I think it is grey market. It was built in Japan only for the local market and there is no info in SIS regarding the 7DK-prefix other than a few Service Magazine articles that link it to the 6GK-prefix machine (also Japanese-built but for the World market) for which complete info exists in the online resource. There is a Serial Number break in the 6GK-prefix range at 6GK00392, and it appears as though the 7DK-prefix machine has similar technical & performance characteristics to a 6GK-prefix machine machine of S/N 6GK00393-Up.

Based on your Serial Number you can get a Parts Manual to suit your machine from Cat Publications. Although all the text is in Japanese the Part Numbers are not, so linking stuff to the illustrations would not be too difficult.
Reference is XJBP7177. Cost was $89 for a pdf download the last time I looked. At the same time a paper version from a dealer was $110.

 

[rudeag]

I have acquired a parts manual and it shows an element in one portion of hyd tank. It doesn't appear to have any direct flow to it as it is suspended in the tank.The other portion of the tank has a screen on top of the main hyd pump inlet. My question is how is it attached as tank is 32" tall and the access plate has an 8" opening. Also are there any good downloadable manuals for the 312A?

 

[rudeag]

Sorry I am looking for a downloadable service manual for Cat312A. Thanks.

 

[James Sorochan]

The first pic shows the inlet screen and the second pic ( DD detail ) shows the Flange above that you remove then pull up on the rod that's attached to the screen.

 

[Nige]

Also are there any good downloadable manuals for the 312A?

You need to search for Cat publication reference SENR6130. That is a service manual for a 6GK-prefix 312 excavator. It may not cross over 100% but it's the best that you are likely to get because publications for the 7DK-prefix machines were only ever produced in Japanese.

 

[rudeag]

James S. Thank you for the diagrams, I do have the parts book but my question is what holds the screen in place on the pump inlet and better yet after removal of screen how do I re-install the screen as it is at the bottom of the tank. NIGE thank you for the service manual number, do know if anyone offers it as downloadable?

 

[James Sorochan]

rudeag, If the pictures are correct the screen has the rod going threw it which extends upward to top off tank. After you open up the round flange above it you should see the top of the rod above the hydraulic level of oil. You can grab it and wiggle it and pull up until it releases. There should be a o-ring on the bottom of screen that keeps a seal around the inlet pipe. This is what the Deere/ Hitachi machines were using so I would suspect others also have used it. Not sure though.