1969 G900 Steering getting hot

Joe Pro

Member
Hey guys, while working ground on my 900 with the Vickers pump and external steering cylinder, the power steering pump and reservoir get hot, I mean hot hot!! So hot that I started carrying a fire extinguisher just in case. The line that goes to the steering motor that you can see from the seat, through the opening in the dash, gets so hot you can't touch it. I just had the pump rebuilt and it steers just fine. Is this normal?
 
NO! Better look into it before the pump fails like right now! sounds like the oil is going over the relief valve;. Now you need to determine why. Stick a pressure gauge between the pump and the steering motor and with out turning the wheel see what kind of pressure reading you have.
 
(quoted from post at 18:10:19 05/27/14) NO! Better look into it before the pump fails like right now! sounds like the oil is going over the relief valve;. Now you need to determine why. Stick a pressure gauge between the pump and the steering motor and with out turning the wheel see what kind of pressure reading you have.
I did do that before and after I installed the new pump. But all seemed well. I did notice that I have a leak from under the dash somewhere. What fluid should I run? I put ATF in it, but last night I put hytran in it because it's what I had in the truck and topped it off with that. It steers really good, but what can make it so hot? Too much pressure?
I've also had issues with the hydraulic (closed center) system getting hot, but I finally got it to keep oil in the system until something around the console went "pssshhhtttt bang" around midnight last night so I shut it down and went home I was so mad!!
 
Just an odd thought to add....Is this a "new" tractor to you? I have a 5 Star that the previous pump got hot. One of the steering lines had been broke an brazed, which resulted in about a 1/4" hole to let the oil go through. Is it possible there might be a line under the dash that has been fixed?
 
(quoted from post at 11:22:30 05/28/14) Just an odd thought to add....Is this a "new" tractor to you? I have a 5 Star that the previous pump got hot. One of the steering lines had been broke an brazed, which resulted in about a 1/4" hole to let the oil go through. Is it possible there might be a line under the dash that has been fixed?

Alan I really don't know, what I do know is that @#$% leaks everywhere on this thing. The only fluid that doesn't leak is the coolant and that surprises me. I've been putting a couple gallons of hyd fluid in the resiover each nigh because it leaks and is going somewhere. (not in the crankcase) After what went bang last night and 5 gallon of oil dumped from somewhere I left it. I've not had this tractor long, and this is the first time I've really used it for anything. It does have a leak under the dash, (power steering) but I topped it off and kept going as I could see the lighting in the sky and they're calling for rain.
 
Probably wise to perform some tests as the others have said. The only thing I would add is that you can't hold your hand on 150 degrees, and 150 degrees would not be considered hot. On my 900, I'm sure that the heat from under the steering wheel would nicely heat a cab in winter. Thankfully mine is an open station.
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After reading this I know know what you meant by your text. I
have adopted an old saying for every time stuff is hard, or
breaks. "NOTHING is ever easy!" Usually followed by #%@&$
 
What readings did you get on the gauge when you had it installed, both turning the steering wheel and one with just the engine running?
 
(quoted from post at 12:44:29 05/28/14) Probably wise to perform some tests as the others have said. The only thing I would add is that you can't hold your hand on 150 degrees, and 150 degrees would not be considered hot. On my 900, I'm sure that the heat from under the steering wheel would nicely heat a cab in winter. Thankfully mine is an open station.
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Huh, you really think it gets that hot? I mean I want to say I was running like 700 lbs then with the wheels turned the relief was close to 1500psi maybe 1400? Can't remember. the pump gets hot, the reservoir gets hot, the dash gets hot, I was wearing a white t-shirt and last night I was cooking. But it steers perfectly, well after I topped off the oil it was fine.

Curt, do you have an infrared (laser) thermometer? I'd like you to take some readings for me if you could. Also how hot does your closed center "crap" get, and I mean crap because that's al the hydraulic system is on this! Mine gets hot the reservoir gets hot, the tubes and lines get hot and the pump gets hot, I've had a coat and crap tucked over it and nothing caught fire, but I'll get a thermometer on it maybe tonight.
 
That is a nice G900 Curt. Ive always liked the looks of them. I know on a hot day my M670 Super power steering lines are hot enough that you cant lay your hand on them.
 
I'll secure one from work today. I'll be plowing tonight so I'll get some readings. The 900, in my opinion, is about the finest tractor that MM made, at least of all of them I've operated. You probably know that the hydraulic pressure in that system is adjustable. I keep a screwdriver in the tool box at all times and adjust the pressure just enough to accommodate my needs, that may or may not help, too. I think it would be odd for you to have all of these hydraulic problems at the same time.
CC
 
(quoted from post at 15:41:41 05/28/14) I'll secure one from work today. I'll be plowing tonight so I'll get some readings. The 900, in my opinion, is about the finest tractor that MM made, at least of all of them I've operated. You probably know that the hydraulic pressure in that system is adjustable. I keep a screwdriver in the tool box at all times and adjust the pressure just enough to accommodate my needs, that may or may not help, too. I think it would be odd for you to have all of these hydraulic problems at the same time.
CC

Curt, no I didn't know it was adjustable. How to I adjust it and how do I know how much to adjust it?

I don't know if I'll be able to run it tonight to check the temperatures, solely due to the fact that every last drop of hydraulic oil was pumped out from an unknown leak at midnight last night, but once I fix the leak I'll get my infrared thermometer going. While your plowing please check the power steering pump, reservoir, dash in several places, line under the steering wheel that you can see about 2" of from the seat. Also the closed center pump and lines. That would be ever so helpful! Where are you located at?
 
The adjustment is a slotted big screw vertical in the back of the pump in what looks like a small cylinder about the size of a 12 ga. shotgun shell. I hooked up an implement the other day and hydraulic couldn't pick it up, I turn the screw in until the implement rises. Back it out, decrease pressure, turn it in increase pressure. I'm in Hudsonville, MI.
 
You guys are playing with fire. Do check the temperature, do check the pressure and check how much leakage you have out of the case drain. Can you borrow a flow meter? If you have 700 PSI on your steering pump when not turning the wheels you are kidding yourself. When that pump is not working that pressure should be closer to 100 PSI. You are working that pump and building lots of heat!. Pressure is caused by resistance to flow. In the neutral mode the only pressure is what it takes to circulate the oil! How can I contact you?
 
(quoted from post at 21:50:36 05/28/14) You guys are playing with fire. Do check the temperature, do check the pressure and check how much leakage you have out of the case drain. Can you borrow a flow meter? If you have 700 PSI on your steering pump when not turning the wheels you are kidding yourself. When that pump is not working that pressure should be closer to 100 PSI. You are working that pump and building lots of heat!. Pressure is caused by resistance to flow. In the neutral mode the only pressure is what it takes to circulate the oil! How can I contact you?

You can send me and e-mail at [email protected], and we can go from there. I Don't remember the steering pressure, I can tee a gauge in again and check it maybe it was 400? I found a steel tube that looks like it was rubbing on something then blew out. I'll do some checking thanks!
 
Pro, After plowing last night for about 3 hours, no component of the steering system was over 185 degrees and no hydraulic component was over 175. Any help?
 
(quoted from post at 10:59:52 05/29/14) Pro, After plowing last night for about 3 hours, no component of the steering system was over 185 degrees and no hydraulic component was over 175. Any help?

Huh, that's a lot warmer than I thought it would be. I need to check mine. This is why I couldn't check it last night! You or anyone doesn't have quick access to a G900 parts manual supplement for the closed center lines? I left mine at home and need the part number for this line.
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Can't help with the part number. Even if you had it, I doubt it would help you obtain one. More than one "pipe" on my 900 has been replaced with hydraulic hose.
 
(quoted from post at 17:41:12 05/29/14) Can't help with the part number. Even if you had it, I doubt it would help you obtain one. More than one "pipe" on my 900 has been replaced with hydraulic hose.

Yep, I'm leaving work now with a hose and some elbows! I've had good luck getting NOS parts, and have a bunch myself but I need the line fixed now!
 
I know it is a different system but my M670 super steering lines were 110-120 degrees and the power steering reservoir was 134 degrees. I don't believe I have a supplement manual for the G900s but I do have some service bulletins from the late 1960s. I can see if I run across any info for you.
 
(quoted from post at 21:50:28 05/29/14) I know it is a different system but my M670 super steering lines were 110-120 degrees and the power steering reservoir was 134 degrees. I don't believe I have a supplement manual for the G900s but I do have some service bulletins from the late 1960s. I can see if I run across any info for you.

Last night I got it up and running, I did some investigating with my infrared thermometer.
The power steering reservoir was 165', and the pump was 175. The line under the dash that I was concerned about was around 114'. This is all after several hours of hard work.

Now the closed center pump was 275' when I quit for the night., the filter canister was about the same and the hydraulic reservoir was well over 200'. this is what worries me as to why this is getting so hot?? I've changed the filter and checked the breather, which is not there, but I have one coming in today. I replaced that line that blew out on my and I think it holds, 6 gallons of fluid and put a little over 4 in it before I took off. It was late and dark so I didn't check the fluid level in the hyd system as I took the readings.
 
Here are a few pictures of my "pure junk setup" I thought the disc was the nicest one I've seen so I bought it. 3 acres in the other night, two bolts that hold the front gang on sheared off and the gang just about flattened the tire.

I've been pulling it with the wings up, because it's really hard moldboard plowed ground but it fits up really nice. That 12' disc set deep will work the 900. The 900 looks almost gold, but I assure you in normal light it is Energy Yellow!
 
Do you understand how that closed center system works? Have you checked your compensator setting and your case drain leakage? Those temperatures will cause you major problems!
 
(quoted from post at 23:39:53 05/30/14) Do you understand how that closed center system works? Have you checked your compensator setting and your case drain leakage? Those temperatures will cause you major problems!

No, no and no. I'm a very skilled mechanic, but there is little information on the MM closed center systems, and it's not very similar to the equipment that we repair today. So far all I know is that I can adjust the pressure down. I think I had a case leak, the upper plug in the pump was leaking and I uh, repaired that quite quickly to get in the field.
 
First...are the 900's like the 670's...totally separate systems for
steering and hydraulics?? I think they are??? Never the less,
the closed center systems are great except when you develop
leaks or your pump gets worn. This system depends on
constant pressure. Leaks or wear present real problems in the
form of heat and further wear. First priority is to stop your leaks
and never let it run low on oil. I definitely feel your pain...I own
a 670 from hell, but I think I'm on the down hill side of it.
 
(quoted from post at 11:22:28 06/02/14) I am pretty sure the closed center hydraulics were the same or quite similar on the 900 and 670.

I did find some things out this weekend. I topped it off with oil. I also lowered the hyd relief? pressure by turning the adjustment on the pump out. After these two things were done I had much lower temperatures. The pump case was around 210' while the engine crankcase was close to 200. The reservoir and cylinder were much cooler around 150 I think I recall. I've got three, somewhat large leaks in the system, but after I got it home last night, I washed it good because that line blowing pretty much eliminated every chance of finding any leaks, by putting 5 gallons of fluid all over everything under the seat, then getting covered with 6 inches of dust.
 

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