Why does it take 15 minutes for CAT 988B controls to start working after engine start? Once they start working, it's 100%, but it seems that this interval of inop controls after startup (in 90degF temps too!) seems to be getting longer each time I run it.
When you say "controls" I assume you mean the bucket raise/tilt controls..? Or are you referring to the transmission control..? Your post isn't clear. if the hydraulic system - an air leak on the suction side of the implement pump and thus the pump losing prime when it sits for a long time..? What grade of oil do you have in the hydraulic system.?
[New member, read dozens of your posts, will be printing and framing this reply to hang on the wall] Yes, all hydraulics and trans also. It just sits there at idle. Can rev up engine fine. After 10-15 minutes, all works fine and continues to work fine for hours of running. AW46 fluid, but it is only about 65% full in tank, as I can only get so much fluid at one time.
hi,you need to determine if the pilot system is at fault or the main implement system. I would check the pilot system pressure first
Jeff, please post a Serial Number just to narrow it down as to exactly what vintage of a 988B you have. Both transmission AND hydraulics no go when you first start up..? They're two completely separate systems.......... Also suggest you get a sufficient quantity of oil to top off your implement hydraulic tank (I assume your reply above refers to the implement tank) to the correct level. What type of oil are you using the in transmission..?
Yes sir, roger on the hyd fluid. 50W09448. Correct, no lift, tilt, steer, and shift lever will not stay in fwd or reverse position, for 10-15 minutes. My intent in posting this question was under suspicion that perhaps the machine keeps all these functions disabled until a certain specified temp or pressure, or some other condition was reached, and then allowed those functions to engage thereafter. Sounds like maybe that's not the case. I do not know what trans fluid is in it, but it is full (bought it a few months ago).
So to me it sounds as though you have two completely separate problems. They may or may not be related but at first glance I don't think so. What's your thoughts Mark..?
A machine that's 30+ years old (it left the factory Feb 1989) - they weren't designed to be that smart back in those days.
Much obliged to you both for the suggestions, and quick replies! I will proceed accordingly, and report the outcome back to this thread.
Regarding the transmission, if you don't know what oil is in it because it was never changed in your ownerhsip then now may be the time to treat the old girl to some new SAE30 TO-4 oil and some new filters. Also when you have the transmission drained you could remove the magnetic screen from the drop box and check it out/clean it. Compare the condition to the photos from the other thread. Check out this thread - post #43 onwards on page 3. HeavyEquipmentForums
Yes sir, trying to get just a bit of initial dirtwork done first, then that's at the top of the agenda!
Hi,as I see it everything is related. The main lift and tilt control valve has its own supply pump. The main control valve is controlled by pilot oil from the pilot/ brake pump which is in tandem with the steering pump i.e. back to back. This pump group has common pump intake The transmission controls are connected to the transmission control lock group which senses low brake pressure and will return the lever to the neutral position if the brake pressure is low So the common area to look at is the steering /pilot / brake group pump intake system
That makes sense. The transmission direction control cable has the famous "claw" on it that only opens when brake pressure rises far enough. If you remove the six small screws, open the cover, and look inside I'd guarantee that the fingers remain closed for your "10-15 minutes" and as soon as they open (as shown in the illustration) everything will work, including the implements.
I just did a project like this on a Komatsu WA600 of the same vintage. Old machine likely means old pump suction hoses from the transmission and the hydraulic reservoir. Same thing for the oil and filters in both systems. On the machine I worked on all the pumps were worn out but not broken. In that era nearly all those machines mounted the pumps on the back of the engine which was at least a couple of feet above the oil levels in their respective reservoirs. It is my experience that the pumps will all make noise when the engine is started and keep making that noise until fluid has reached the pumps and purged all the air out of the systems. I suspect your is doing the same. I had to change the pumps on the machine I was working on along with both oils and all the filters on the machine. The project cost nearly $20,000 total and I obtained aftermarket pumps instead of factory ones. Big machines mean big costs. I hope your machine is not in the same condition. Good Luck!
I was late getting to work here so I missed saying that if the transmission would not stay in gear it could be lack of brake pressure. First thing I would want to do would be to have the hydraulic tank full, don't want to cause any more work for the pumps to get their prime on start-up! And yes on checking to be sure there are no loose hose clamps on the suction lines. Low oil level and loose or hard hoses on suction lines could be some if not all the cause! then there is the possibility of weak pumps!
I feel like I owe you guys money. God bless every one of you. It was the low hyd fluid.
I do Paypal if you need an address to send the funds to! I'll be sure to share it with the others
Well at least it apparently proves one thing. The manufacturers don't put sight glasses, dipsticks, plugs, etc, for measuring oil levels on machines just for decoration ...........