Hello everyone!
Take your seats and buckle up, this is going to be a long one.
So I own a 1993 320 CE, pre-facelift M104 coupe with a 722.3 transmission showing a millage of 184.000 km on the dash. Last year I overhauled it myself (head gasket engine out job, timing, and all the gaskets/rings/sensors, probes, wear items, remanufactured wiring for engine, throttle, dash out evaporator core replacement, tranny out for seals and everything), and it ran well for a while. It`s still getting hot sometimes, around 110 degrees, but never got to the red line over 120. But now let`s talk about the transmission saga.
While on a mountain trip, a little spirited driving, I experienced some noise from the gearbox that got worse on the way back and stayed that way. Also, when the noise emerged, the transmission felt a little erratic with the changes, but everything came back to normal in a couple of days. The noise, like a whine, louder in reverse or 1st gear, was coming from the TC/front pump zone. I`ve driven the car a couple of times, short trips only, until it also developed an oil spill from the TC while reversing. Serious spills, leaving a red line on the asphalt. So I left it parked for a while until I finished my garage with a lift and everything for these kinds of jobs.
Two weeks ago I took the gearbox out and found out that the pump bearing was now a part of the torque converter. I had a spare transmission from a W210 (also a 722.3, but without the rear section with a cable speedo drive), the good part was that the pump and TC were similar to mine. So I swapped the whole pump/reverse piston assembly and the torque converter, changed the filter, new oil, and voila: it worked like a dream... for a while. Because I can hear the problem coming back.
So the gearbox works wonderfully, very smooth changes, but after 1000 km driven last weekend, I noticed a new whine coming back from under the car. More specifically, from the same pump/TC area. Can be heard while in Neutral or in Park, it`s quite loud and with a changing pitch. I bet it`s the same pump bushing about to be ripped again. So why does my car eat those bearings/bushings?
I`ll give you the first theory. So, when I replaced the rear crank seal, I changed the flex plate bolts. Didn't bother to measure the original ones for any stretching, just ordered new ones. But the new ones (original code from Mercedes) came with a different shape, longer threads, and bigger heads (torx instead of M12 star-shaped heads - I`m attaching pictures). I installed them, torqued them, and didn't bother to measure anything. But in the light of my gearbox problem, I started thinking: could be the bolts, with their big heads, pushing the torque converter against the pump and it`s destroying its bearing? How are the tolerances there, can 2-3 mm make a difference?
Take your seats and buckle up, this is going to be a long one.
So I own a 1993 320 CE, pre-facelift M104 coupe with a 722.3 transmission showing a millage of 184.000 km on the dash. Last year I overhauled it myself (head gasket engine out job, timing, and all the gaskets/rings/sensors, probes, wear items, remanufactured wiring for engine, throttle, dash out evaporator core replacement, tranny out for seals and everything), and it ran well for a while. It`s still getting hot sometimes, around 110 degrees, but never got to the red line over 120. But now let`s talk about the transmission saga.
While on a mountain trip, a little spirited driving, I experienced some noise from the gearbox that got worse on the way back and stayed that way. Also, when the noise emerged, the transmission felt a little erratic with the changes, but everything came back to normal in a couple of days. The noise, like a whine, louder in reverse or 1st gear, was coming from the TC/front pump zone. I`ve driven the car a couple of times, short trips only, until it also developed an oil spill from the TC while reversing. Serious spills, leaving a red line on the asphalt. So I left it parked for a while until I finished my garage with a lift and everything for these kinds of jobs.
Two weeks ago I took the gearbox out and found out that the pump bearing was now a part of the torque converter. I had a spare transmission from a W210 (also a 722.3, but without the rear section with a cable speedo drive), the good part was that the pump and TC were similar to mine. So I swapped the whole pump/reverse piston assembly and the torque converter, changed the filter, new oil, and voila: it worked like a dream... for a while. Because I can hear the problem coming back.
So the gearbox works wonderfully, very smooth changes, but after 1000 km driven last weekend, I noticed a new whine coming back from under the car. More specifically, from the same pump/TC area. Can be heard while in Neutral or in Park, it`s quite loud and with a changing pitch. I bet it`s the same pump bushing about to be ripped again. So why does my car eat those bearings/bushings?
I`ll give you the first theory. So, when I replaced the rear crank seal, I changed the flex plate bolts. Didn't bother to measure the original ones for any stretching, just ordered new ones. But the new ones (original code from Mercedes) came with a different shape, longer threads, and bigger heads (torx instead of M12 star-shaped heads - I`m attaching pictures). I installed them, torqued them, and didn't bother to measure anything. But in the light of my gearbox problem, I started thinking: could be the bolts, with their big heads, pushing the torque converter against the pump and it`s destroying its bearing? How are the tolerances there, can 2-3 mm make a difference?
