case 450 charge pump or bad torque converter?

[jrobe44]

After running about an hr I lose torque converter pressure, everything does fine until then, transmission pressure stays strong i can let the dozer sit and cool off and after another hr of running it acts like something is slipping again. So does that sound like the charge pump? Maybe a pressure relief valve? Or just a bad torque converter. Ive already changed all fluids and filters also. Any opinions?

[mickd]

I had an old 450 years ago- had a similar prob. I had to prime the charging pump , hurry and put hose back on then start.
the gears in the charging pump looked fine but I guess they were worn enough to matter. I replaced them and had pressure
instantly upon start up. Just a thought,you may still have other probs. Those gears are much cheaper than a torque
converter.

[crazyal]

When my charge pump died it just wouldn't suck oil when I first started it. If I parked with the front facing downhill it would get enough oil in it. But it was like a light switch, either it would get oil or it would not and it was always starting. I think at this point in time you may want to get a manual (maybe off ebay).

I think you need to find the pressure valve in the transmission and see if the gauge is reading pressure before or after it. My guess is after it, that's why you either have good pressure or nothing. It could be that valve is faulty and is shutting off fluid to your torque converter. How quick does it happen? I would think a bad torque converter would show up more as a slipping feeling, something that would either start off slipping and just continually get worse as the oil heats up and thins out.

[Gordon Gould]

It is hard to guess from here and it would only be a guess. Your best bet is to get a service manual like Al says and run the specified tests. ( Or hire some one else to do it. ) Then you will know.

[jrobe44]

It takes about an hr to get that slipping feeling and eventually it pretty much jus wont go. When it does this i cant let it sit and idle in neutral and pressure will come back up but as soon as i put it in gear it starts slipping again and loses pressure i can let the dozer sit a couple hrs and cool off and then it runs fine for about another hr and does the same thing again

[jrobe44]

The pressure valve is located on the bottom of the torque converter housing and the line for the guage is on the top of the torque converter housing