1997 GMC Yukon 5.7 4L60E. All stock.
Transmission has been solid as a rock except for P1870 trouble code. I monitored that and sure enough the code would set when the converter couldn’t hold lockup. Narrowed that problem down to either the converter itself, or the small o-ring on the end of the input shaft. But the bullet, pulled the trans back enough to access converter, found a hard and flat o-ring that was likely the cause for not holding lockup. But I thought, I’m going back together with a new converter, just in case. Bought a stock replacement torque converter from Oreilly. Installed that.
Drove the truck and the trans felt weak, like not enough pressure. I did get up to speed enough to feel the TC lockup and hold, quite a few times. Super, that’s fixed, but the rest of the shifting and holding was not solid, though that part had been fine before. I put a pressure gauge on and sure enough the line pressure does not ever rise. In any position it stays about 60 psi. Shift into reverse, no rise. I pulled the trans electrical connector. Pressure goes up to almost 200 psi briefly, then starts falling back down to 50ish psi.
I’m about to drop the pan and check/replace the filter. But can anyone think of anything that could be damaged during the TC swap? Or can the replacement TC have a problem that affects pressure? I’m puzzled. The TC and o-ring are the only things that were changed.
Transmission has been solid as a rock except for P1870 trouble code. I monitored that and sure enough the code would set when the converter couldn’t hold lockup. Narrowed that problem down to either the converter itself, or the small o-ring on the end of the input shaft. But the bullet, pulled the trans back enough to access converter, found a hard and flat o-ring that was likely the cause for not holding lockup. But I thought, I’m going back together with a new converter, just in case. Bought a stock replacement torque converter from Oreilly. Installed that.
Drove the truck and the trans felt weak, like not enough pressure. I did get up to speed enough to feel the TC lockup and hold, quite a few times. Super, that’s fixed, but the rest of the shifting and holding was not solid, though that part had been fine before. I put a pressure gauge on and sure enough the line pressure does not ever rise. In any position it stays about 60 psi. Shift into reverse, no rise. I pulled the trans electrical connector. Pressure goes up to almost 200 psi briefly, then starts falling back down to 50ish psi.
I’m about to drop the pan and check/replace the filter. But can anyone think of anything that could be damaged during the TC swap? Or can the replacement TC have a problem that affects pressure? I’m puzzled. The TC and o-ring are the only things that were changed.
