Transmission Overheat

[Little Princess]

Hi,

I’m new to the forum and recently experienced an overheating situation with my starboard transmission. I have a 2006 40 Sundancer w/CMD QSB-380s and ZF80IV gears. I received an alarm via the Smartcraft System View that indicated 205 degrees in the starboard transmission vs 150 degrees in the port transmission. I was running at about 2700 rpm and when I slowed to about 1500 rpm the temperature dropped and the alarm cleared, but it was still consistently 50 degrees higher than the port side.

There doesn’t appear to be anything fouled in the props and the engines were both showing similar, stable temperatures so I don’t think there is anything blocking the raw water intake. The gear pressures, while bouncing around a lot, seemed to be similar on both transmissions while cruising, although at lower rpm’s the starboard gear pressure was a bit lower. The fluid was a little less than a quart down, but no evidence whatsoever of any leak. After bringing the fluid level up, the starboard gear is still heating up 5-7 degrees higher than the port while idling at the dock (I haven’t had the opportunity to leave the dock since the original episode because of a combination of schedule and weather).

My dealer had a mechanic take a look, but they are going to refer it to the Cummins service tech, so I need to wait some more. In the meantime, any ideas would be greatly appreciated. Is there a way to tell whether the transmission cooler is blocked?

Thanks.

 

[fwebster]

A blocked transmission oil cooler is a pretty common issue where the local waters contain what we call eel grass in Fla. It is a very fine grass than can easily pass thru the holes in your strainer but is too long to pass the heat exchanger in the transmission cooler. One end of the grass goes in one tube the other end in another tube and, over time, enough grass is trapped to cause problems.

If the design of your cooling system will allow it, try pulling the hose off the inlet end of the transmission oil cooler and see if you can see and pick put any grass with some tweezers or forceps.

Good luck.............

 

[Hampton]

Or, take the hose off of the other end and flush it out backwards with a hose.

Just under a quart low sounds like an awful lot to me. That may be part of your problem. That fluid flows through the cooler (obviously). If the pump was sucking air bubbles due to low fluid, you'd get a lot less cooling. As you slow down, less fluid is splashed up and away from the sump allowing full cooling capability again - just a thought. I wouldn't spend too much on a mechanic before testing it again - after flushing the cooler and filling the fluid.

 

[Little Princess]

Thanks for the advice guys. I will check the cooler. Once I can get out for a test run this weekend I will know for sure whether the oil was the issue.

Thanks again.