Caterpillar 9590 b 1981. Having power problems. Go into dirt and wheels will spin in 1st gear only, but when move bucket the wheels stop you hear the engine rev back when you release bucket movement but won't move hardly. When I say move bucket I mean add pressure to the wheels to dig. 4th gear going down road loses power on little incline. Its like something stealing the engine power. Any help would be much appreciated
sounds like a torque convertor problem check convertor in and out pressures
Checking main pump pressure tomorrow, have adapter waiting for Guage to come in. I have book ordered to see how to check these pressure on torque converter. Could it be internal leak. Oil is clean and nothing in filter, haven't check pickup screen would that be next? Thanks for you reply, will update as I do tests.
I did a transmission pump pressure test and it runs 300 to 500 lbs. While I was running it checking pressure, I recently put a boost Guage and it was about 12lbs at it's high. Sounds low to me.
That's a big variation. Can you elaborate a bit on when you saw 300psi and when you saw 500.? Did you check the converter inlet/outlet pressures.? What does the transmission oil look like.? Clear, dark, smell burned.? Have you taken a look in the filters yet.? Post a Serial Number and I can probably find some test procedures and specs for both transmission, converter, and engine. Has your problem appeared suddenly or has it slowly got worse over time.?
I bought this machine 3 years ago. Changed all fluids when I got it. They still look like the day I poured them in. Filter cut apart and nothing in it. Serial number is 31r01031. Engine is a marine engine transplanted c7z04604 new turbo, exhaust manifold and turbo riser. Spools right up to 11 psi and everything stalls when you dig in hard in first gear. It slowly started losing power especially last 6 months. I checked the pressure at the filter housing with a Guage that read 3000 psi so 300 to 500 was hard to read, have new Guage coming today, but don't think it dipped below 300 in any gear. Didn't really feel any different through the operation of moving dirt. Will retest asap. Any other tests you come up with i will do. I did change both pumps on the hydraulic side a year ago, but they only take the power away when operating bucket and seem to release when let off.
That explains it. You really need a gauge that reads a max of 5-600psi to get accurate readings. Attached the T&A for both the converter and the transmission. Your engine S/N was originally rated for 455BHP. The 950B engine was rated at 155 BHP. Have you got the fuel turned down or something....? That would be normal as far as I'm concerned. In standard form there is insufficient power to run the hydraulics and push the bucket into a pile at the same time. Otherwise once out of the pile you should be able to raise a loaded bucket while moving without it having an adverse effect on the engine.
I haven't or know how to turn fuel pressure up on this machine. Hydraulics work fine just dumping and loading. They where sluggish until new pump. It's hard to tell if it's transmission or engine losing power. I just put boost Guage on. Transmission doesn't seem to slip just at certain point stalls and motor won't give anymore either. Don't know rpm but it's still at 11 psi boost and probably 1000-1200 rpm at stall guessing on rpm. Got new Guage where do I hook up for converter test?
See the attachment I posted above. It has testing for both converter and transmission.
Do I have to pull transmission cover to do the output on converter, can I do without pulling seat? or should I do both? I'm very appreciative of your help thank you
pretty sure you have to pull cover there is a access plate that will get you to p1 and p2 but not the others
A simple stall test will tell you which is the problem.
I would first confirm that you actually have a problem. All that you describe sounds normal. Confirm your issues before risking opening things up and making problems that you didn't have before. Check cycle time on boom up and down, then do steering stop to stop. There will be specs for that somewhere. If you think you are losing power, check the air filter and the fuel supply. There is a brass strainer on the side of the fuel pump on that machine. Maybe it's plugging up. Most of the time when I run into impressions like this, I have to explain to the operator that he is just getting used to everything.
Ok finally got loader in and did tests. P1 was 310 at idle and 380 high idle. P2 was 50 at idle and 60 at high idle. P3 was 50 cold oil in or out of gear, rev made little difference.
That makes no sense. In your OP you said you could spin the wheels in 1st gear. With that value of P2 the loader shouldn't even move. Direction clutch pressure P2 should be within 55+/-5psi (50-60 in other words) of whatever P1 is. So at low idle with a measured P1 of 310 then P2 should be 250-260. At High Idle with a measured P1 of 380 then P2 should be 320-330.
Ok so I went back out this morning and hooked it up to P2. And fired it up and 300 psi shift to forward dropped down and came back to 300. Could I have hooked it to the load maybe. They are stamped plain as day on the housing. Should I put the cover back on and check P1 and P2 while operating.
To measure P1 & P2 you first need the machine up to normal operating temperature. Then put the transmission in 3rd speed with the brakes applied. Take measurements at low & high idle RPM. When you shift the transmission P2 should briefly fall to zero then return to 50-60 less than P1. the guage might flicker for P1 during shifts but nothing more.
Ok I'm going to put cover back on and just go through the port for P2 and P1. I'm trying to understand this transmission. What does pump pressure do compared to torque converter pressure?
Pumps supply flow, not pressure. Resistance to flow is what creates pressure. See attachment which explains how all pressures are generated.
Thank you. I have another Guage coming tomorrow. I have plate back on and 2 hoses hooked up will test asap. That's going to be the easiest.
p1 and p2 is clutch pressure if they are ok then your clutches are nut slipping have you done a stall test
No I haven't. How is this performed? I didn't think transmission was slipping but something is holding it back or just not the power it requires.
Assuming that the machine has no tachometer the first thing you are going to need is a phototach to measure crankshaft RPM. Get all systems to normal operating temperature. Measure engine RPM at High Idle in neutral. Apply the service brake, select 3rd speed and give the engine full throttle against the brakes. Measure the RPM. That is converter stall. Post both numbers because with a non-standard engine there is no knowing what HINL RPM might be on your particular engine. Also please take a look at the engine data plate and post the Arrangement Number that is stamped on it. it should appear on the line directly below the C7Z04604 Serial Number.
Ok got a photo rpm guage and 3rd gear stall was 2045 rpm. Had both gauges hooked up P1 was 380 and P2 was 345.
Had 11lbs of boost
And what was High Idle in neutral.?
I didn't check but idle was 660. I never really has a high idle. Even cold cold. It doesn't fluctuate much on pressure. What idle you want it checked at. Everything is still hooked up?
At max engine RPM with the transmission in neutral. That is what High Idle RPM is. Low Idle RPM could be described as tickover. Did you get the engine Arrangement Number from the plate.?
Ok hi idle rpm is 2334. P1 is 390 and P2 is 335 and just idling P1 is 370and P2 is 315. I did this in real time so no memory on this test. This is all in neutral warmed up
6n6878 arrangement number
Thanks for the RPM info. I don't have access to the fuel setting information so can't comment on whether HINL and TC stall RPM they are within spec or not. Hopefully someone else can chime in. EDIT: Found a HINL specification of 2380 RPM and Low Idle of 775 RPM, so you are not far off at the top end. I can't find a TC stall RPM specification anywhere.
That is the original Arrangement for your machine S/N 31R01031. The Serial Number is actually 7Z04604. 3304 model engines of 07Z-prefix engines were all fitted to machines, it is listed as a vehicular engine. Production began in 1980. I have no idea where the "marine engine transplant" comment came from but the numbers seem to contradict it.
Caterpillar told me it was a marine engine. Went in for parts with the serial number.
Ah-ha, the penny drops............ You posted the engine Serial Number as C 7Z04604, not 07Z04604. Maybe the plate is difficult to read, a "C" and a "0" could easily be confused. C7Z-prefix engines are a C7 model marine engine. So that's where it all came from. Mystery solved. I hope you didn't buy any super-critical parts on the back of that incorrect engine S/N.
That's it. Thanks for clarifying, that makes it easier to look up parts.