Hi guys. Quick question we have a cat 740 (b1p) dump truck here. In the mornings start up and put it in drive moves off fine but when you brake it slows down through the gears fine but when it gets to first gear it will not sit still. It will stall the engine instead of just sitting on the torque converter. Its as if the torque converter is locked from the word go. After maybe 30 mins working it starts working right and you can sit stationary with your foot on the brake ,transmission in drive no issues. Its like when the oil heats up she comes good. Anybody any experience with these machines?
What viscosity of oil does it have in it..? Has anyone taken a look at the electronic controls using Cat ET to check if there are any Active or Logged Diagnostic Codes in the Powertrain ECM..?
V interesting... I've been looking after (amongst other things) a fleet of B1Ps and AXMs for about the last eight years and I've never come across this. It seems fairly obvious that a good first guess is that the TQ lockup clutch isn't disengaging. I'd say nige is on the right track. Get ET connected and see what is going on in the run screen. Keep us posted.
Does that converter have a freewheel stator ..? Just checked - yes it does. So if the ratchet mechanism on the freewheel is worn/damaged maybe it's slipping when it shouldn't..? An oil that's too heavy might also cause that sort of phenomenon when cold which kinda fits with the symptoms. It also has a lockup clutch and maybe if the shaft seals are dodgy the lockup clutch might be getting pressure that's partially engaging it...a quick pressure check of the circuit would confirm that. Of the two my money's on the freewheel stator.
Cheers for the fast replys guys. We have 1 man that does all the servicing here and no repairs so oil is generally changed exactly when due. I tink they are running 430 in the tranny. I wil speak to him today and see. Our next step wil probably be check with the ET and go from there. It doesnt seem to be a common fault anyway!!
When a Stator breaks loose of either it's Ground Shaft Splines or it's Spragg Clutch if equipped it will Kill the Engine and machine will hardly move. This may not sound logical to you but Been There Done That. I go with Lock Up clutch not Unlocking. Later Bob
Find out as many details as you can about the oil (brand, type, viscosity rating, etc) and post them back here please. Bob, I've been there done that too with completely foobarbed stator clutches on 994's (***king bar steward things) and I agree that the symptom is like it's trying to stall the engine and is often mis-diagnosed as the engine having no power by a large majority of mechanics/technicians. However a ratchet mechanism that's jumping the occasional tooth is a different thing. I saw something similar to this 740 on a 773D once.
Hi guys got it sorted easily anyway thank got. There is 3 solenoids on top of the transmission 1 for upshift 1 for downshift and the lock up clutch 1. Took it out and it was stuck freed it up and it came back good so just ordered a new solenoid and away we go
I have 6 740EJ trucks 2005 models, I'm curious to see if you have had any trouble with the tranny coolers. Since I bought these units nothing byt failures antifreeze leaking into trannynce clutchesget contaminated tanny failure. Appreiciate a reply on these units
What brand & viscosity of oil are you using in the tranny, and what brand/type of coolant..? Do you carry out an oil analysis programme..? I've seen rashes of cooler failures attributable directly to the oil or coolant being used.
We are running CAT oil and recomended anti freeze. Seems the issue isthe rubbers sealing the two fluids are failing, with no way of knowing failure has occured tranny is generally lost first time it slips. Cat is not reconizing what I call a product defect unless others come forward probably nothiing will happen