1972 JD 450B Dozer Not moving in forward grears

[JsB1]

I have read several posts that are similar to the issue with my dozer, but not exactly - Hopefully someone will be able to shed some light.
As stated I have a 1972 JD 450B dozer. A few months back I had the steering clutches and brakes replaces - all works well.
Just recently the 450B started not wanting to shift into any gear (R/H/L) upon first start up. After it warmed up for quite some time it would go into gear forward and reverse. Then it got where the transmission would not shift into Forward until operating it in Reverse for a bit. Then a few days ago I was pushing some dirt and it quit going into Reverse or Forward. It acted like it wanted to shift but wouldn't move. Finally I go it to go into Reverse after letting it sit for quite some time and got it back to the shop. It would not shift into High or Low Forward.
I read in my Service manual about adjusting the free play on the clutch and made the adjustment to 3.75". I also checked the transmission pressure which is supposed to be 170-180 psi. The pressure I recorded was less than 100 psi. I did not check the pressure when trying to shift to high or high to low.
I hope I have provided enough info explaining the situation. If you need more just let me know. Thank you.

 

[Jim.ME]

Have you checked/cleaned the screen in the transmission?

You say you have the service manual, follow the diagnostic process in it. I would suggest checking all the linkages, transmission as well as clutch, and making all the adjustments as laid out in the service manual, then run all the diagnostic checks with pressure gauges, per the manual to get as complete picture of what is going on.

 

[jon corbett]

screen/filter blocked

 

[JsB1]

(quoted from post at 03:42:54 04/30/19) screen/filter blocked

Guys, sorry about being slow to get back with you. We have had lots of rain (still getting it) and a tornado came through our place on Friday. Mainly destroyed trees and fencing. Came close to the house, but thankfully no damage.
Anyway, I changed the transmission filter/screen in the tranny today. There was very little in the screen, but installed a new one. I don't know really what the issue is as yesterday during no rain I tried the dozer and it operated normally. I pushed a good deal of brush and trees. After operating it for a couple of hours I did notice that it was getting sluggish about going from forward to reverse, but it did not stop moving as it had previously.
After changing the filter and adding another 5 gallons of fluid it moved fine, but I did not get the opportunity to operate it much as it started raining heavily again. I need to check the fluid level first to make sure it is full. As soon as I get the chance I'll check the levels and the operation more in depth and let you know how it goes.
I thank all of you for your replies.

 

[JsB1]

It has been a bit since I changed the transmission filter screen. I have used the dozer a few of time since, today being the last. It operated as it should until everything gets "heated up" then it quits wanting to go in reverse and is very sluggish about going into a forward gear. I did notice to day that there was a definite burnt clutch smell.
Being all considered and since changing the transmission screen, is it reasonable to suspect that the clutch is the culprit?
Any thoughts are appreciated.

 

[Jim.ME]

Burnt clutch smell is often an indicator of a slipping clutch. Does it feel different than after your previous adjustment? Check all the adjustments again to be sure nothing changed. It might have oil on it. If you can see the bottom of the clutch housing there is a cotter pin in a weep hole. The pin should be free and wiggle, it keeps the hole open. If there is oil dripping from the hole it indicates oil getting into the clutch area. A couple possible sources of oil there could be the engine rear main seal or leaking from the reverser input shaft. You might be able to see in there though the plug you remove to adjust the clutch valve, the area should be dry.

Did you check the pressures, after you changed the screen and transmission filter, to see if they improved from the first set of readings you mentioned in your first post? You might have a couple things going on with it.

 

[JsB1]

(quoted from post at 03:37:46 05/23/19) Burnt clutch smell is often an indicator of a slipping clutch. Does it feel different than after your previous adjustment? Check all the adjustments again to be sure nothing changed. It might have oil on it. If you can see the bottom of the clutch housing there is a cotter pin in a weep hole. The pin should be free and wiggle, it keeps the hole open. If there is oil dripping from the hole it indicates oil getting into the clutch area. A couple possible sources of oil there could be the engine rear main seal or leaking from the reverser input shaft. You might be able to see in there though the plug you remove to adjust the clutch valve, the area should be dry.

Did you check the pressures, after you changed the screen and transmission filter, to see if they improved from the first set of readings you mentioned in your first post? You might have a couple things going on with it.

Sorry about getting back...Rain and other things going on. I do have a question. When checking the transmission pressure through the bung fitting should fluid be shooting out through that hole? I have my pressure gauge installed correctly but fluid pumps out through the bung hole opening. Wondering if this may indicate a problem.

 

[Roy Suomi]

Verify the transmission pressures again. Should be 170- 180 psi to operate with any authority at all. If you can get the pressure up there with a gauge in the top center bung port , operate the machine and watch pressures while under a heavy push . If it shows pressure loss and ground speed reduction at the same time , the engine clutch is probably slipping..

 

[JsB1]

(quoted from post at 14:11:06 08/27/19) Verify the transmission pressures again. Should be 170- 180 psi to operate with any authority at all. If you can get the pressure up there with a gauge in the top center bung port , operate the machine and watch pressures while under a heavy push . If it shows pressure loss and ground speed reduction at the same time , the engine clutch is probably slipping..

Roy I appreciate the reply. But can address the issue with fluid shooting out of the bung hole? I have the pressure gauge screwed into the fitting with no leaks around that fitting, but fluid shoots out of the bung hole in a stream. This may be the problem that I have some sore of internal leak. Your suggestions are appreciated.

 

[Jim.ME]

If we are talking the same place; the bung hole where you check the HLR clutch pressure is in the top of the transmission, so anything turning in there could throw some oil out, if you don't do something to seal it around the gauge line.

To Roy's point. If you remove the plug on the left side of the clutch housing, where you can adjust the HLR clutch, is that compartment dry or oily. If oily your engine clutch could be contaminated and slipping. You mentioned a burnt clutch smell at one time.

A bad engine clutch can work some cold, and lose it when it warms from slipping.

 

[JsB1]

(quoted from post at 04:22:17 08/28/19) If we are talking the same place; the bung hole where you check the HLR clutch pressure is in the top of the transmission, so anything turning in there could throw some oil out, if you don't do something to seal it around the gauge line.

To Roy's point. If you remove the plug on the left side of the clutch housing, where you can adjust the HLR clutch, is that compartment dry or oily. If oily your engine clutch could be contaminated and slipping. You mentioned a burnt clutch smell at one time.

A bad engine clutch can work some cold, and lose it when it warms from slipping.

The compartment on the left side does have some oil in it. Where would the oil be coming from? I am not losing engine oil.
To explain further on how the tractor is operating...Everything works well until it gets heated up, then it starts getting sluggish about changing from forward to reverse and visa versa.
Then it will not go into reverse at all. You can feel it trying. If you leave it in forward it will continue to move, but does not have the power it should.
I do appreciate all the advise. One of these days I really need to get the thing fixed, but I would like to possibly narrow down what the root cause(s) are so I would know where to start,

 

[Jim.ME]

If the compartment, under the plug shown in this photo, has any oil in it, you are going to start by pulling the engine to replace the engine clutch. That is supposed to be a dry compartment. If you are not loosing any engine oil, it pretty much has to be coming from the HLR. So while the engine is out you will be re-sealing the front of the HLR, which is in that compartment as well. And working on that could lead to re-sealing the HLR clutches. Your service manual should have sections on removing the motor, changing the clutch, and repairs to the HLR you can study.

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[JsB1]

(quoted from post at 11:09:58 08/28/19)
If the compartment, under the plug shown in this photo, has any oil in it, you are going to start by pulling the engine to replace the engine clutch. That is supposed to be a dry compartment. If you are not loosing any engine oil, it pretty much has to be coming from the HLR. So while the engine is out you will be re-sealing the front of the HLR, which is in that compartment as well. And working on that could lead to re-sealing the HLR clutches. Your service manual should have sections on removing the motor, changing the clutch, and repairs to the HLR you can study.

[/img]

I appreciate your reply. I figured the clutches were bad due to the oil, the smell, and not moving properly. I was afraid it was something wrong with the transmission as well.

 

[Jim.ME]

You may have trouble with the HLR clutches, as well as the engine clutch. As Roy posted you need to verify the HLR clutch pressures and if they are low you will need to decide if you go into that and re-seal them and check for other wear when you do the engine clutch.

 

[Roy Suomi]

There is no seal in that compartment to keep oil from being pushed out BUT, it shouldn't be pressure oil. I've seen a little spatter come out but not pressurized. There are a couple of steel lines on the inside right side of the HLR case. One is lube oil and the other is operating pressure. I have seen the pressure line split before, but not common. These lines are serviceable from the top without serious disassembly. The rotating shaft assembly runs in oil plus lube oil being expelled from lube leakage. If you mess with the oil tubes , remember which one goes where. They cross inside the case. If you install them top to top and bottom to bottom it will not work as you're trying to operate the clutches on lube oil pressure. There are o-rings to seal these oil tubes both front and rear. There is a roll pin that operates the clutch valve , very common to break it and not push down on the clutch valve to make enough pressure. Also serviceable from the top.. very common problem..

 

[JsB1]

Thank you for the information. I have not started working on the 450 yet. I am waiting for the weather to cool down a bit!