450 straight HLR problems (long)

[oljoe]

I have had the motor, clutch housing and front cover out three times since my last post and the top cover off at this time. The first time I removed everything I found a piece of gasket material under the oil cooler bypass valve. I put it back together and it wouldn’t move and the clutch didn’t feel right. I removed everything again and discovered that the set screw for the throw-out bearing lever wasn’t indexed in the hole that is in the clutch shaft. I packed the transmission pump full of petroleum jelly this time and reassembled it again. When I started it the machine shifted and moved like it should. One of the steering clutches was frozen and I spent about 5 minutes trying to break it loose. During one of the shifts from forward to reverse it quit pulling again and I shut it off. After about an hour I started it and was able to move back to the work area. I shifted from forward to reverse a couple of times before it quit pulling again. It has been sitting in that spot for about 6 months.
Last weekend I decided to give it a go again. First off I checked the transmission pump pressure. When I first started it the pressure came up to about 80 psi then started bouncing between 80 and 160 sometimes pegging the gauge. This was a rapid bounce not a slow rise in pressure. There was a buzzing noise that seemed to correspond with the rise in pressure. I shifted the reverser into forward high and the pressure dropped to 0. The bussing noise stopped. I shifted back to neutral and the pressure slowly rose to about 70 and bounced, but not as drastically as before. I pressed the clutch pedal and the pressure went back to 0 and didn’t return when the pedal was released. I shut off the engine and waited about 5 minutes and started the engine. The pressure came up to 60 and held for 30 seconds until I shifted the reverser, then it dropped to 0. I shifted to neutral and the pressure rose slowly to 40 after about 15 seconds.
I decided to remove the top cover and check for internal leaks. I made the mistake of starting the machine with everything exposed. That was a bad idea. I then made a cardboard “shield” to direct the oil back into the case and started it again. The pressures made the same fluctuations as the previous test and I saw something interesting on top of the accumulator housing. There are 3 holes (orifices) on top of the housing that had foaming oil coming out??? This made me think that the pump may be sucking air.
I pulled the engine, clutch housing, front cover and transmission pump again. I could tell that all of the gaskets and the pump cover o-ring were good. The gaskets were compressed where they should be and the pump cover o-ring stuck up above the mating surface of the cover. I pulled the screen, in the bottom of the transmission and it was not plugged. There was a little dirt and paint chips in the screen but it wasn’t plugged. I did find that the filter housing, which is a steel tube that fits inside the transmission case to hold the filter, was a little loose. There is one 5/16” bolt that holds it in place and it was backed out about 2 turns. I don’t think that this would have caused any problems because the outside filter cover presses the housing back and the filter has a spring that holds it tight to the back of the housing. If anyone else has a different opinion on this I would welcome it.
I couldn’t find anywhere that air could get into the suction side of the pump. I turned my attention to the pump itself. The pump doesn’t have any unsightly scratches or marks other than the area where the inside rotor meets the bushing sleeve. The book shows that there is supposed to be .030” of clearance between the sleeve and the inner rotor. This is not the case as it has been rubbing. I put a straight edge on the rotor and could not see any indication of wear in that area, just some scuffing. Next I checked the clearance between the inner and outer rotor. I used a feeler gauge between the point of the inner rotor and it’s mating surface on the outer rotor. I was able to get a .012 gauge between the two making sure to have the mating surfaces at the closest point. I have scoured the tech manual and can’t find a spec. for this clearance. Is there one??? Would excessive clearance in the pump cause the symptoms that I currently have? I have checked the internet and found that gerotor pumps, which is the style of this pump, should have .004” to .007” when new. I’m getting much better at disassembling and reassembling this thing but would rather only do it once more.
Sorry this is so long. I’m trying to let you have all of the information that I have available. I really hope someone can help.

BTW a new pump is $601 and some change so I don’t want to replace it if that’s not going to make it work.

The previous posts are here
http://www.jdcrawlers.com/messageboard/ ... php?t=7602
and
http://www.jdcrawlers.com/messageboard/ ... php?t=9285

[oljoe]

I’m back to square one with a new pump installed. I talked with a mechanic that works on most all brands of older track machines. He didn’t think that the pump was the problem, but I crossed my fingers, forked out $600 and replaced it anyway. It turned out to be a $600 mistake although I have ruled that part out. Back to the drawing board. Right now I’m looking for ANY suggestions. Please someone throw something out that I can try.

[oljoe]

I removed the accumulator housing to check it and the shift valve. I disassembled to check for scoring or binding in the valves. Everything was smooth and free. There is a small screen that fits in the housing that was damaged with one end of it partially plugging one of the passages. I bought a new screen, replaced all of the o-rings and re assembled. I still have the same problem with the pressure going away after a few seconds of running. I did figure out that the buzzing noise was the pressure line, the one that connects to the accumulator housing, would vibrate when the pressure rose and would stop vibrating when the pressure would drop to nothing. I saw mention of a clamp in the tech manual.