Weird Hydraulic Issue cat 315CL

funwithfuel · Feb 16, 2019

If you're dead set on reading negative control tap in at illustrated points.
None of this means squat til we establish baseline. Servo, followed by standby and working pressure. You can and should avoid full throttle for the time being. You have a piston pump, it'll compensate

funwithfuel · Feb 16, 2019

Go to post 15 & 16 on your computer. Download both. Study the description. That is where I've been lifting nearly everything from. It tells where and what as well as why.

TVA · Feb 16, 2019

funwithfuel said:
Please don't interpret my statements. I meant servo. The oil that acts on the end of the spool to actuate a function. We are trying to establish whether the MCV is the problem or is one of the other 3 parts of the boom down circuit suffering a loss. If we can verify pressure changes as I have described in both directions, we can move on. Otherwise we'll have to pursue where the oil is going.
I'm a simple guy. I started learning this reading Case manuals back in the 80s. One thing stuck out. This manual is written in CASE, clear and simple english. I have always tried to explain things in that same way.

I had same idea as you: check the pilot pressure that moves the spool, the only difference is I called it actuator and you called it servo! It still activates by pilot pressure! I would do it right at servo/ actuator.

Problems at this point is two: main one - NC pressure for one of the pumps too high! The instructions that Mobiletech posted provide incremental change of flow with changing of shim thickness at 340 psi. Although it is not direct statement but it only makes sense that what that pressure is supposed to be.
Second this boom down NC drop, and I totally agree with you that we should ask OP to tee one gauge in to servo line right at the servo for boom down age leave one teed to corresponding pumps NC line and check if any correlation between two exists!

TVA · Feb 16, 2019

funwithfuel said:
If you're dead set on reading negative control tap in at illustrated points.
None of this means squat til we establish baseline. Servo, followed by standby and working pressure. You can and should avoid full throttle for the time being. You have a piston pump, it'll compensate

That’s interesting, OP traced his NC hoses to different locations from one on that illustration!

funwithfuel · Feb 16, 2019

If you have the means , cap all hoses to boom cylinders. This will help us determine if you have a problem.

Measure both a & b of boom 1 spool cap, exercise in both directions write down results. Perform the same test at boom 2. After you establish servo . 1 thing at a time.
At idle. No need to shock the new pump. We want to fix the original problem before making another big problem.

Now that I think about it, boom 2 must not be opening properly. If the boom is dropping with the speed to cause shoe lift, it is not allowing the barrel side oil to fill in the rod side with gravity pulling her down. Is this when dropping the boom or lowering at a reasonable speed? Just trying to get as much info as possible.

TVA · Feb 16, 2019

Funwithfuel, do you have Illustration to share with OP where he can find NC relieve valves? But probably not the MCV illustration of which you posted - OP has different port locations from that.
I saw that this model has many different prefixes, may be different prefix uses different MCVs.
At this point I think it is more important to get the NC pressure to normal value!

funwithfuel · Feb 16, 2019

I do not. Nige made that available. I dont have SIS

TVA · Feb 16, 2019

funwithfuel said:
If you have the means , cap all hoses to boom cylinders. This will help us determine if you have a problem.

Measure both a & b of boom 1 spool cap, exercise in both directions write down results. Perform the same test at boom 2. After you establish servo . 1 thing at a time.
At idle. No need to shock the new pump. We want to fix the original problem before making another big problem.

Now that I think about it, boom 2 must not be opening properly. If the boom is dropping with the speed to cause shoe lift, it is not allowing the barrel side oil to fill in the rod side with gravity pulling her down. Is this when dropping the boom or lowering at a reasonable speed? Just trying to get as much info as possible.

He has power to boom down, so maybe you right and that’s the normal operation and system drops the pilot pressure to not to slam boom to the ground ( although I know lots of people who likes to do that, specially in the rocky soil, or to break rocks). It’s something that CAT people should respond on.

funwithfuel · Feb 16, 2019

According to the front page, that is for his machine. I don't know why Cat would deviate from published materials. They are very picky about stuff like that. On top of that, Nige is very particular about posting incorrect or inaccurate information.

TVA · Feb 16, 2019

funwithfuel said:
According to the front page, that is for his machine. I don't know why Cat would deviate from published materials. They are very picky about stuff like that. On top of that, Nige is very particular about posting incorrect or inaccurate information.

You’ve seen the picture of his hoses and ports, and his set up is functioning. I guess gonna have to do “reverse engineering”, start at return port and look for them!

Vetech63 · Feb 16, 2019

Has this gotten anywhere yet?

TVA · Feb 16, 2019

I think I found one, it’s the bolt looking thing on top from ports in the OPs picture of Gauges.

TVA · Feb 16, 2019

And there’s another on the bottom of MCV.

funwithfuel · Feb 16, 2019

Fugetabotit. Focus on what matters.

Vetech63 said:
Has this gotten anywhere yet?

No, I don't think it has.

John C. · Feb 16, 2019

Floridamechanic says the machine is better now that with the other pump. He says the only issue is that the travel on one side is slightly more powerful than the other. He is better off than when he started. Put the machine to work and earn some money back for all costs that have been accrued to this point.

floridamechanic · Feb 17, 2019

MCV tag

floridamechanic · Feb 17, 2019

may help---is that the relief by the tag?

Nige · Feb 17, 2019

funwithfuel said:
According to the front page, that is for his machine. I don't know why Cat would deviate from published materials. They are very picky about stuff like that. On top of that, Nige is very particular about posting incorrect or inaccurate information.

Just to confirm, the testing & adjusting material in the post to which FWF refers was lifted straight from the online information system using the full machine Serial Number given by the OP in his first post on Page 1. Like FWF I'm pretty sure it is correct, because it's been out there for so long. I would have thought it would have been updated long ago if there had been an issue with it not being correct.

floridamechanic · Feb 17, 2019

Well happy to report have boom down zero NC pressure, thank you one and all for all that you did, will be a full time member and try to help someone like ya'all helped me. Thanks to.....
Nige---John C--CMARK--MOBILTECH--FUNWITHFUEL--TVA---VTECH 63---Delmer--UFFEX---Jonno634--CATKC--BlueOx---Kobelco Ireland----
Is truly appreciated that you would take time to help.

jonno634 · Feb 17, 2019

Summary of final answer?

Weird Hydraulic Issue cat 315CL

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