Have had a long term problem with the steering clutches not fully releasing at lower rpm on my D6. I finally put together enough test gauges to check the pressure ports on the trans hydraulic system. Some background: * the steering clutches have had new seals on the release pistons * replaced bevel gear bearings (since I had it apart) * adjusted steering clutch valve linkage * magnetic screen for pump checked/cleaned * Torque converter screen checked/cleaned * No heating problems with engine or torque converter * Visually checked for leakage on steering clutch line where it Tees into top RH rear of trans - No visible oil leaking into trans case * Disassembled trans pump to check condition - no visible wear, .003 side clearance on gears (No spec. given for clearance between top of gear teeth & housing? May have to check that) 1) Took pressure readings and found Pump pressure (Low Idle readings were low) & (High Idle readings a little high) Torque Converter Inlet pressure was a little low (cold oil @ 55°F) 2) Adjusted High Idle pump pressure down to get it in spec. Adjusted Converter Inlet pressure up to spec. 3) Re-checked pressures: Low Idle pressures well below spec.....High Idle pressures OK See marked up pressure chart Looks like either the pump is weak or something has an internal leak...... Would my Cat dealer have equipment to bench test the pump for pressure & flow?....or would it cost as much as replacing the pump? Any Suggestions on how to proceed? Sorry...Don't know why the .pdf is coming in so large. View attachment Chart.pdf
I still don't see where you have checked for excessive leakage in the transmission or for weak or broken valve spool springs in the steering clutch control valve. Tooth to housing clearance in the transmission pump should be about the same as side clearance. Usually 0.004 to 0.005" clearance is considered worn out.
I did a visual check to be sure that the fitting at the top rear of the trans wasn't leaking......Unless it wouldn't show up there. video: https://www.youtube.com/watch?v=8S9VwCYyvsY&feature=youtu.be The steering clutch valve was disassembled when I did the clutch piston seals...no broken springs. With steering clutches engaged there is zero pressure to clutch pistons. Not sure how to tell if steering clutch valves are dumping oil back to sump when they are closed. If there are other ways to check for leaks I'd like to hear about them. Haven't been able to find anything else listed in the manuals. I know it was mentioned that there are a couple of sleeve seals in the lube line where it enters the front of the trans, but I was under the impression that was very low pressure, I may pull that tomorrow and see they're ok. I'll call Cat tomorrow and see if they can bench test the pump....Cat classic pump is about $500.(found a chinese pump on e-bay for $135 but I'd be scared it would be junk)
Doesn't appear to be leaking at the control valve connection in the transmission. There are specifications for checking the springs in the steering clutch control valve. If it's not there then it's back to the pump performance or you still have leakage at the steering clutch pistons.
Exactly how much PSI are you getting at each steering clutch elbow with the lever fully back at low idle. You have full pump pressure available but only need slightly over 100 PSI to release them. Later Bob
Hi Bob, Check his "Chart pdf" Running 160/170 psi where it should be 315 psi to the steering clutches.
I'll see if I can temporarily block off the line at the steering clutch valve. If the pump pressure comes up with it blocked then it should isolate the problem to the valve.
Block the elbows at the top of the steering clutch case. That will tell you if the control valve is losing oil. Might be assembled wrong. Later Bob
Maybe two problems? OK, might have found a problem.... Warmed up the tractor and rechecked the Low Idle pump pressure....270-280 psi as before. High Idle= 350 psi (just right) Blocked off the steering clutch line with a piece of sheet metal and rechecked low idle pressure.....got some improvement. Checked 300 psi (spec is 315 min.) So, I must be losing some oil through the steering clutch valve (without blocked line, the steering clutches have zero pressure with clutches engaged) While I had it warmed up I pulled the trans top cover again to recheck that the trans supply line wasn't leaking. It wasn't, but found quite a bit of oil coming from the relief valve body at Low Idle. video: https://www.youtube.com/watch?v=1ScFPuHgh4U In my first video the engine was cold and it didn't leak nearly as much.....Is this much oil normal? Leaks just as much with steering clutch line blocked or not. So, do I have two problems? (steering clutch valve & trans relief valve )
Looks to me like your transmission relief valve is the problem. Being that both steering clutch circuits are running low pressure the trans leak is robbing the steering clutch control valve. Wait for Bob/Ont opinion, he is the expert here.
That's what it looks like to me too....think I'll pull the relief valve and check it out.....only about 4 bolts since the cover is already loose. Have to be careful....my luck I'll drop a bolt down in the bottom of the trans case. That would be bad.
I saw the video and that is too much oil coming out of the valve. They do normally have oil flowing out of them but much less and you get a big burst when you shift so watch out if you are looking in. Use parts book or manual to get spools assembled right. Later Bob
Put some nice clean lint free cloth around the valve before removing the bolts and valve. maybe some old bed sheets? Work slow and careful, should be no problem. Agree with Bob about that looking like way to much flow of oil. Haven't worked on a D6C trans but that valve body looks similar to say an old 966C and as I recall those only had a gentile flow of oil with maybe a short spurt as you shifted gear to gear. Wild guess would be a broken spring or some kind of crap stopping the spool from moving free.
Bob/Ont, It makes a lot of difference whether the oil is warm or cold......cold was a slow leak, warm was the big leak in video. When you've seen them was that with warm oil? Disassembled the trans valve...no obvious problems. The springs measure about 1/16" shorter than free length spec. The piston/bore fits seem pretty good. No way to tell which valve is releasing the oil as the port is connected to both valves internally. All I can think to do is replace the springs and try it again. It's getting tedious running the tractor out of the shop to warm it up and check pressures....don't have exhaust hose to vent it outside.
What counts is the spring length under the specified load, as given in the specs.
One thing I wonder about, selector spool adjustment???? Have you ever had the valve out of the trans? If you have the pressure control pack back together check the spool ends match up with machined surfaces of the body. Maybe OM has a pic from a manual showing this and what gear to be in to adjust it. Later Bob
I checked & adjusted the speed & direction spools for adjustment a couple of weeks ago. One was off about 1/16" the other was real close. I can see it would be nice to have a spring test tool.....something like this maybe. http://www.ebay.com/itm/Repco-3600-...=BI_Heavy_Equipment_Parts&hash=item4ae208b44d
Would be cheaper to get new springs if you need them, concentrate on assembly of the valve. Something is in the wrong place I think. Later Bob
Bob, the selector and safety valve are all external adjustments on these. Don't think that is an issue. D6c10K, how about just looking in to getting some new springs. I'd think they would still be available from Cat. I'm a little late with response. My internet has been down
Have you had the complete valve assembly out of the transmission right down to the clutch housings? Also do you have a parts book and or service manual? One or the other usually has good pictures that can help you see where parts go and which direction things like spools face. I pay very close attention to any small orifices in spools to be sure one isn't plugged. I had a loader once that would not move at all. They were thinking it was a major failure in transmission. Problem turned out to be a little speck I could hardly see plugging an orifice. Cleaned that out and problem was gone. A couple gaskets and orings instead of a major rebuild. One question I don't recall asking or seeing mentioned. You say this is a long term problem, but has it ever worked right?
I ordered new springs last evening....hopefully they'll show up before the holiday. As far as I can see it was put together correctly. Will follow the diagrams carefully when going back together. With new springs it will be just a guess on what shims to use.
If you need any additional help in the way of an Assembly Manual or Parts diagrams, just send me a PM with your Serial Number and your email address.
Parts book shows standard shim pack to consist of 5M7915 (0.030") Quanity - 4 and 5m7914 (0.010") Quanity - 3
Thanks Nige, I've got a set of manuals so I think I'm covered for diagrams etc. Old Magnet, Wasn't sure if the parts book listing for qty of shims was the std. setup....makes sense that it is, so I'll start there. (It had (2) .030 & (3) .010 shims)
Upon closer inspection of the valve body I found one bore that's not quite right. The outer bore land (about 1" deep) has a rough spot that looks like it didn't clean up when it was made and it's got some taper. One direction the bore very close to 1.000" at the outer end but tapers about .003 bigger as you go in. The other direction is .0065 oversize in the rough spot and about .003 oversize down inside. The valve spools show some surface wear, but it's no more than about .0005" So, is the valve body junk? Doesn't look too good. The valve body doesn't seem to be available by itself. OEM Cat assy - $2535 Classic part - $791 Unless I can find a used one.
Not looking to good. I suppose you could try it with the new springs and see what happens...while looking for a replacement.
HI D6c your post made me sign up to forums instead of being just a reader of posts lol I have a D6D 4x and have experience with replacing this valve I went aftermarket because I was at a point of parts swapping in my troubleshooting and the price was the determining factor. I put a aftermarket valve on and the trouble came back within a few hundred hours so I replaced all springs in the valve with original Cat and the problem has never returned just a bit of information that may help. I am still having a slight bit of steering problems like yours until the machine warms up then steering is normal hope this helps
I had a crane valve body that was bad like the body in the photo. Grove price was 9700.00. Took it to a machine shop they boared it out and pressed in a stainless steel sleeve and reboared to factory specs for 350.00.
I put new springs in the trans valve body, but it didn't have any effect. I went to the Cat dealer and talked with one of the Techs and the components shop foreman. (They were very willing to spend time troubleshooting the problem....Ziegler is good that way) They weren't sure that the amount of oil coming from the valve was bad, although one of the mechanics on the bench thought it was excessive. They made some suggestions of more checks I can make: 1) Adj the high idle up a little (it was just below the min spec) Won't help low pressure readings, but might affect some the the high idle settings. 2) Re-shim the torq inlet pressure to where it was originally even though it checked low. (It's best to adjust them by bench check only because done on the machine you can get it set too high) 3) Set Torq outlet pressure to high end of spec. range 4) Check safety valve operation (start engine with trans in gear) to see if you have to shift to neutral before it will move. 5) Block off steering clutch tubes at gear case (previously suggested by Bob/Ont) to see if pressures rise. 6) Depending on pressure readings may want to tear down steering clutch valve an inspect Also stopped by an independent shop that does quite a be of work on older tractors. He suggested I might also: 1) set low idle up about 100 rpm (650 rpm spec seems pretty low to begin with) 2) In his experience the sequence relief valve is often the culprit and it doesn't always look bad when taken apart. (available aftermarket) 3) Trans pump can sometimes look good and not work right either (He can get an aftermarket pump for $140....cheap enough to try if no other solution is found. 4) He thought he had a used steering clutch valve that I could try if it looks like mine is leaking He looked up the parts I bought when I put new seals in the steering clutches....could of sworn I put in new bearing cages for bevel gear bearings but it didn't show up on the list and I can't find any old parts laying around....might be I'm having a senior moment. jd550g, I think you're right about using genuine cat springs....both shops asked if I used genuine springs or not. I'll get through this list in the next few days and post what I find.
I would have asked what the original bore size and clearances for the transmission control valve are supposed to be. I thought you already did the blank off plate tests for the steering clutches. Seems like a lot if fiddling, none of it going to replace missing metal in the bores and worn valve spools.
3) Trans pump can sometimes look good and not work right either (He can get an aftermarket pump for $140....cheap enough to try if no other solution is found. That's an interesting statement about a gear pump. When it comes to pressure control valves in a trans like this quite often you're better to replace them especially if you can find a good used one for testing. All it takes is a little wear on bores and spools and everything goes for poop.
From measuring some unworn spots on the bore & spool it looks like it originally had a min of .0015 clearance...maybe as much as .002. Don't think they had a spec. for new bore/valve clearance. The Cat mechanics didn't seem too concerned about valve clearance...they were more concerned about any wear that created a step in the valve body which could cause the spool to hand up. That's why they wanted me to check the trans "safety", to see if it was sticking. ( I checked it and the safety valve operates ok...machine doesn't move when started in gear) I had previously blanked off the line just ahead of the steering clutch valve and got about a 20 lb. boost in pressure, but I hadn't tried blocking off the clutch tubes at the top of the bevel gear case. That's what they were recommending that I do to see if I could find a problem with the clutch valve. Part of my problem getting pressures checked has been not having enough gauges to do everything at once. Ordered some more hoses and gauges yesterday to make it easier. The other thing is I have to move the tractor out of the shop (into the cold) because I don't have an exhaust vent hose. Look into getting some but it's pricey. About $15 ft for 4" and I'd need about 35'. Suppose I could buy a short piece for the muffler and then use some other kind of pipe to get outside.
I'd agree, 0.001 or less to no more than 0.002" would be preferred spool clearance. 0.006" at pressure would leak like a sieve and be considered worn out.
I'm guessing I'll end up replacing the trans valve assy. When you add the oversize amount of the bore and undersize amount of the spool, most of the worn area is about .0045/.005 clearance. The one small spot that looks like a manufacturing flaw is about .008 clearance but it doesn't extend the full length of the bore land. Even if I find other problems I think I need to find another trans valve.
As mentioned, bore and sleeve could be an option, along with new spools.
Suppose I could bore & sleeve the outer bore since it seems to be the only bad place. I do have a Bridgeport mill and boring tools. If it's junk as is I guess I can't hurt it.
If you have the tools and skills to do the job I say have at it. And don't forget pictures of the finished job, we all like pictures! We had a hydraulic valve that managed to crack a spool, worked fine until used at higher pressures. As spools are fitted at factory they were not sold separate. Took old spool to a good machine shop and for less than 1/2 the price of a valve the made us a new spool that worked just fine.