So i picked up a project truck last year thinking it had a bad motor, weird clacking noise when idling. I went through the entire motor looking for the usual suspects, ie cam phasers, oil pump/timing set, valve lifters, checked bottom end bearings. The phasers had been locked out so they're not a problem (plus it means the ECU was flashed for the upgrade), changed what looked like a brand new timing set, added a high flow oil pump, changed the valve lifters, even took thw heads off to make sure nothing on the top end was the problem. I then dropped the oil pan and checked all if the bearings, still nothing wrong. It did seem like the noise was coming from the back if the motor near the oil pan, so i tried driving it a bit to test out everything else, found that the transmission would shift fine when cold but would start to shift hard when it warmed up. Here's the weird part about the noise, at warm idle it clacks, at 1000 rpm it sounds perfect and doesn't lack any power, above 1200 rpm it clacks and seems to follow the rpm for speed. I knew i needed to rebuild the transmission, and so far nothing looks too bad, just worn clutches, could the noise be coming from the torque converter? Fluid looked good and at the right level. Any thoughts would be appreciated. I am planning on replacing the torque converter when i re-install Sent from my SM-G975U using Tapatalk
The 4R75 is known to loose either the reverse band or the overdrive band. Loosing the OD could cause some of the symptoms your experiencing. What does the fluid look like?
So i rebuilt the transmission this last weekend, found most of the clutch packs looked good, reverse band was good, the overdrive band was worn and the nusheings looked perfect. Flyid was black a a bit gritty. I think it was ran hard before i got it, had the typical worn out items in the valve body so i ordered a zip kit and a thicker stiffening plate. Feom what i saw i think it might have been the torque converter that was the issue. Hopefully I'll get it installed here shortly and can verify that it's nothing else. Sent from my SM-G975U using Tapatalk
Update on the truck. Got the transmission installed, ended up not getting the torque converter seated correctly so i destroyed the trans pump and torque converter. Replaced both, pulled the motor and did a full rebuild. Got that installed and got it to run, but it ran like crap, throwing a ton of codes. Ended up being a blown fuse (#32) that controls the EVAP solenoid, O2 sensors, MAF, Throttle, blah, blah, blah. Got that sorted out and when it was running i noticed i hadn't plugged in the A/C plug. As i touched the harness to plug it in the truck died immediately. Fogured it was a bad plug for the crank position sensor because that was the next thing in line on the harness. Replaced the plugs for the crank and cam sensors and now i can't get it to fire up again. I tested the sensors and all three tested good (.311 ohms on the crank). I get 2.5 volts at the crank sensor plug with my meter, and about 5 volts at the cam sensor plugs. I see 35 psi on fuel. It did sputter a couple of times, but not enough to even sustain it (like it was one random cylinder that caught for a second). Any suggestions as what to check now? Sent from my SM-G975U using Tapatalk
