first issue
This is first issue on these transmissions, approximately 4000 on trans, 2500 on engine replaced in 2004, using gauges on dash. I was heading out of marina both gears in forward and when I accelerated both engines from idle (I usually increase RPM’S gradually, never hard), the Starboard side starting whining, I pulled back throttles and gears and noticed trans oil pressure had dropped on starboard transmission to the first number ( I think it is 40). I checked oil level immediately at drift and oil was at the low line of fill, used port motor to return to dock and shut everything down. Came back last weekend and checked oil level on starboard trans and level was at full line. started starboard motor, trans pressure was only halfway on gauge, put in gear forward pressure dropped to 0, pulled back to neutral and it went to half, same with reverse. checked shifters, all checked fine, disconnected shifter and shifted manual to same results. Revved engine and pressure rose to 2/3-3/4 pressure, tried to put in gear, no pressure. whining sound progressed to neutral at this point. It is a high pitched whine, sounds like its at back of transmission, there is less resistance to rotate shaft when in gear. Much harder in neutral.
Cleaned screen and replaced, still same issue. The oil is slightly darker than normal, I usually change at 300 hours, there is 150 hours since last change which was in May of this year. Took oil that I drained into cup from bolt hole where screen access is to a local mechanic and he said it looked fine, there was some minor debris that came from screen area drainage. He said it all looked normal. Mechanic suspects that the issue is the coupler, because the ZF pump never goes bad. I struggle with the coupler since there was no noise other than the whine and no burning smells of rubber. there is also no burning smell in oil of transmission. I have not observed any bubbles in transmission oil while engine running (mechanic asked if oil was bubbly). I drained approx 6-8 ounces of oil from screen clean, which I did not refill and now there is lower oil pressure at idle (first number on gauge) and goes to 0 if I try to shift. The mechanic I spoke to said it should still pressure up even with that much oil out at idle.
Unfortunately, with the 3126 caterpillar, the access hole to inspect is too small for finger to feel for rubber debris if coupler is bad.
The transmissions have only had SAE 30 Oil in them, URSA brand since 2004 (was Texaco now Chevron) when engines were installed by previous owner.
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