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Dax DeCelle

606 hydraulic pump mounting flange mystery

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This one is gonna take some time to explain. Grab a beer. 

I am working on the 606 diesel. I am trying to track down a steering issue. When the engine is running, there is noise from the pump and the steering occasionally becomes difficult momentarily. The noise sounds like air in the system to me. I bought the Blue Ribbon Service manual GSS-1337-C, which covers Hydrostatic Power Steering for the 606. On the last page, the Trouble Shooting Chart has two causes of "momentary spots of hard steering..." The causes are:

1. Air in the fluid circuit

2. Sticky valve spool. 

A cause of air in the circuit is listed on page 30 as "A leaky engine driven pump shaft seal..."

I wanted to start with that because it seems logical that could be the source of my air infiltration because the noise comes from the pump area and increases with rpms. So I pulled the flange and pump off. I found a Cesna pump that had been rebuilt by Case IH in what appears to be the mid 80s, judging by the tag on the pump. I took the front cover off the pump and pulled the shaft seal. It is a bit stiff but not obviously worn out. It does happen to be hard to find locally so I will have to order from Case IH. I hope that this seal will prove to have been problematic. The tractor still had good steering 95% of the time, but that 5% was bothering me enough that I won't take the tractor very far from the shed. 

Now, the part where I get really perplexed. Behind the flange was only the remains of a very thin gasket and some silicone gasket from a tube. I pulled up the Case IH parts site to look at everything. They offer several choices. I have flange 381719R1. 

The listing offers two gaskets:

370892R2---.011-.019

370893R2---.016-.024

they also list a spacer that should be used with flange 381719R11, it is 371043R1. My tractor has flange 381719R1 and no spacer. 

It says use this spacer when gear 382902R1 is used. There is absolutely no part number on my pump gear. 

I am wondering which gasket I need and if this spacer should be there and was left out. I assume all of these options are to compensate for gear lash. I also wonder if the lack of the spacer and proper gasket has caused improper gear lash and has the pump shaft in a bind which helps introduce air into the circuit. 

Now, get another beer and tell me what you think. 

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I went to get a Sam Adams I will research the problem, drink the beer and maybe another one ,and then get back to you. I own a 606gas and a2606 gas  and a 2606 diesel which is painted blue of all things.

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On the different gasket thickness of the two available it's to shim the correct gear clearance for your pump. Reuse the correct thickness gasket as was previously used . 

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First beer 1/3 gone how many teeth are on the pump gear 15 or 17? as far as the gasket goes when at the service school in the late 60s instructor said when in doubt use the thick one  to tell you must reassemble pump and flange to housing then go in from the bottom and kind of guesstimate the back lash of the pump gear if it seams really loose use the thin one  I generally use the thick one and don't worry about it.

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20 minutes ago, bitty said:

On the different gasket thickness of the two available it's to shim the correct gear clearance for your pump. Reuse the correct thickness gasket as was previously used . 

Correct. That's called gear lash. Almost nothing remained of the original gasket. What was there is paper thin and brittle. That's why I'm asking all of this. 

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I'll go count the teeth shortly. Thanks to both of you for your input so far. I truly appreciate it. Unfortuneately I am out of beer so I can only ponder these mysteries so much before I have to take a break. 

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Might want to start counting teeth on the driving gear also.   I am not up on a 606 but can tell you that a 656 went through a series of changes on  hydraulic pump drive gears.  What they did was go to a larger capacity pump, then used a gear to slow it down to get same gals as smaller pump which was 12 gal per minute.  They did this to reduce hydraulic noise.  You may have same thing going on with that tractor so be sure to match pump gear and driving gear according to parts book.

I would drop the lower cover and check back lash when pump is installed.  Loose ok, tight with no or very little back lash is no good.

On sucking air, the biggest culprit is always that seal on the suction tube. Has to have a nice crisp lip that fits bore nice and is at proper depth on tube when pump is installed.   Usually replaced them but they are spendy now days. 

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You have gear 373711r1  you should have a 81 tooth drive gear which is the same in all but the first 2 606s. The spacer is used with the early flange and the 18 tooth gear . I agree with pete23 that the suction tube is more than likely the problem. one thing when the steering gets hard do you still have hydraulics? If you move the hydraulic lever does it come out of it? That would point to a flow divider issue. I still got beer left. 

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As far as I could tell, I still had hydraulic pressure when the steering wheel would "freeze up." I was too busy grabbing the wheel with both hands to "free it up" to think about pulling on the lift lever. It may be the "sticky valve spool," but because of the pump area noise in conjunction with momentary stiff steering, and when I would throttle up, the noise would increase and the steering would become difficult, I decided to try the pump first. I need to get the pump reassembled and reinstalled with new seals and gaskets on the flanges before I can move on, so I guess I'll order the thicker gasket, the pump shaft seal, the suction tube seal, and a new belly cover gasket and put everything back together and see if these things were the problem. I was going to make gaskets for the flange and belly cover until I came across this choice of gaskets. I have to order the seals now, so I may as well order the gaskets too. 

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I'm looking at the parts pages again. It appears that the intake tube and seal are sold as a kit for $29. 395335r92. Is this what was meant by "spendy now days?"

Mine isn't looking so bad now. Maybe I'll just go through the bottom like I was told and make sure it is seated properly. 

 

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I would like to order my parts tomorrow and am hoping for a bit more information. 

Does the suction tube come with the seal installed on it? Is that the "kit" that is available for $29?

I am willing to spend the $29 for a new one if you guys think that seal may be the culprit. Mine looks good and seats well, but I don't want to go through this again if it turns out my seal isn't quite right. 

I really appreciate the input. 

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Seal comes on the tube.      You will need to move seal on tube to proper depth.  I usually do some measuring to get it close and then when I install the pump, let the pump push seal to it's final position when tightening the pump mounting flange.  May come with a chart showing proper depth for your application, may not. 

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Great. Thanks for the info. I'll order a new one tomorrow. 

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Finally got the new parts. The new suction tube is shorter than the one that was in it. The seal is close to where the original was. Why is the tube shorter?

image.jpg

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Probably shorter to prevent interference in some applications on the end that goes into the tractor.  However, then again it may be too short for some as it seems to me that the original on some old tractors had the seal fairly close to the end of tube. Might be wrong on that though. At any rate, do as little rough measuring to be sure that when the tube is installed in pump, the seal will be fully seated in the bore in the tractor housing. If it is close to being where it belongs you can just install in pump and carefully install pump, observing from the filter side that tube is indeed entering the bore in housing and when you draw down pump mounting bolts, it will move seal on tube to correct spot.  Lube the seal before installation so it can slide easily if necessary.  Just be darn sure the seal is far enough toward inner end that it will indeed be fully in bore in  housing. 

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I finally got the pump put back in and fired it up. 

At idle, everything seems fine. As I throttle up, the hose from the flange to the steering valve spool gets really noisy and if I grab it, I can feel big bubbles going through it. This hose runs from the "rear" pump to the valve spool. The "front" pump goes to the 3 point lift. That hose feels fine---no bubbles. 

It steers fine while sitting still, but I haven't taken it out yet. 

What now?

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Could your problem be in steering control valving loading and unloading?  Giving a pulsing sensation in the hose.  Just a thought.

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