I can't find one in my books. I'm having some problems and a retired Cat mechanic says there is a screen on the bottom of the torque converter housing. But I cannot locate it in the books. According to AI says it shares the screen with the transmission. Caterpillar 988A 87a 784 serial number. Thank you I tried to edit the title to say 988A, but I don't know how.
Number 13 is a lubrication line. If that is stuck open will that cause the machine not to engage the transmission? It's not a pump pressure line.
13 is the torque outlet relief. It's job is to keep the convertor full of oil a empty torque would not transfer power to the transmission very well This is pretty old stuff I seem to remember just a tube going to drop box the big screen and magnets in bottom of dropbox is all i remember If it was me I would get a reading on p1 and p2
You are correct. We have check that screen and magnets. Nothing of concern. We have also checked the torque sequence valve, pressure relief valve and some others. The only one we haven't pulled off so far that we just found in our book is that torque converter relief valve. We have also pulled the pump apart and resealed it. It is a good shape internally. I'm just wondering number 13 would cause the tranny not to engage. 2 years ago this machine never missed a beat. It was loading trucks. It dumped a bucket in, backed up and it never went forward again. We've done everything we can think of. So if 13 is stuck open could that do this?
I don't think it would stop it completely here is a wild thought your left pedal isn't stuck a little? I still would check p1 and p2
Nope, that actually was the first thing we checked for, I understand that disengages the transmission. Always look at the simple things first. Which we have been doing. We've been working on this on and off for I think 3 years now. And it happened in the blink of an eye. The machine never missed a beat. Never gave if you want hesitation or issue. Just backed up from dumping a scoop and never went forward again. And the guys did take some pressure tests, but it was a couple years ago now and I don't really remember what the results were. But it must have been within the parameters or we would have dug deeper in that area. Of course also tested the pressure at the filter housing and it was also within specs I do believe. It's a real head scratcher
I realize what I am about to say is apples to oranges but we had a Deere 544H that did something somewhat the same except we had no movement in either direction out of nowhere. The machine had around 7K on it at that time as I recall and everyone was scratching their heads. It was narrowed down to something internal in the transmission itself. The transmission was removed and torn down to find there was a steel pressure line inside the transmission that had split where the tube was welded along its length. Again I realize we are not talking even the same brand or anything close other than it was also a wheel loader but it was just something that makes one go 'hmmm'.
With that length of time having passed it would probably be better to start all over again by checking pressures and post them all up for those with access to specs to comment. IMO at this point you shouldn't be assuming by depending on peoples' memories.
I certainly wasn't asking for advice based on people's memories of my old machine. I was actually hoping you would find this thread. I'm simply asking if number 13 if stuck open would cause the transmission not to engage. I figured you would know. It's not like we've been working on this since steady. We have other loaders. Just as we get the time we are tinkering with it. I appreciate any advice from everybody. Thank you
What I was saying is that having worked on the machine on & off for 3 years maybe it's time not to trust the memories of those who have been working on it during that time ( "And the guys did take some pressure tests, but it was a couple years ago now and I don't really remember what the results were" ) and start from scratch again. Anyone who wants to give you advice really needs to have some numbers to chew on. IMHO a stuck converter outlet relief valve #13 should not stop the transmission from working. Time to put gauges on the machine again and get pressures from everything in the powertrain starting from the pump and moving downstream.
Okay. That's the answer I was looking for. Thank you. Back to pressure tests