Gear pressure sender exploded & transmission questions.

[snowranger]

I noticed my transmission pressure gauge (Murphy) reading 0 the other day and (uncharacteristically) figured it was a gauge malfunction. I had some work done to that engine recently and the engine pressure sender was disconnected accidentailly last week so I figured this was probably the same - dumb. When I got around to going back to check the sender, the unit was in two pieces and spewing tranasmission oil. I am not exactly sure how long it was like that but I would guess at least hour or two of running. I know there was some oil lost but the dipstick still shows low but within the normal level. While I learned a lesson regarding trusting my gauges (go figure after many many malfunctions, blown senders, gauges etc.), I am confused at why this happened and also whether I should be concerned with any damage to the transmission.

The sender is securely attached to the engine above the transmission so contact with the engine wouldn´t have caused it. The only thing I can think of is a failure causing the sender to break up. Has this happened to anyone before? Seems lika an unfortunate place for a failure!

Regarding the transmission itself, it never missed a beat or made an unusual sound. I would have thought that 350psi running through the sender would have emptied the transmission pretty quickly, there is still a good amount of oil in there. Do I just need to top off the oil, replace the sender and monitor the transmission or is there something else I should do? Should I have low pressure alarms on my transmissions?

Thanks for any input!

Eric

[Avenger]

Chances are it's only the sender that failed, but.....

I would put a mechanical gauge on it to verifiy that the pressure is in spec., also, it's possible that the regulator hung up and the pressure spiked so I would monitor it carefully, and just to be safe I would drain the fluid and check for any glitter, clean and inspect the screen etc. I know it's a hassle, but a new gearbox is a bigger hassle.

As far as the rate of fluid loss, senders usually have a small orifice to start with, and then there's other things like a diaphragm and such, so it's possible that you didn't lose that much fluid. Low pressure alarms are certainly a good idea. Personally I'd like to see temperature gauges on them too. I believe monitoring pressure AND temp will tell you a lot more about what's going on in there. But, that's just me and it's usually expensive, and there's no room for all the gauges we'd like to have anyway.

[snowranger]

I hear you. That is pretty much what I though but it is good to hear a second opinion. Thanks for the input!

[seapower]

No need in repeating what Avenger said, as in my opinion he already told just about verbatum what I would have replied. The only thing I might add is to "tee" in a manual gauge to your sender for a very good sea trial. Make sure that the pressure stay's up in the "operating" range, after the oil has a chance to get used some and hot. This will also give you a chance to verify your helm gauge. Sender's have flanges that are stamped together. If all is good after the sea trial, you may want to leave the pressure sender in and install a "low oil pressure swich". That way if you loose oil pressure an alarm will sound. By the way you can get Murphy Switches that have a dual function, they act as a gauge, and have an alarm switch built in. You will have to wire it up for dual function. Just a thought.Like was said, it's way cheaper than a new gear. Frank,SeaPower

[snowranger]

Thanks for the tip Frank. I have t's on my engines, might as well put them on the gears.