Transmission Temperature

What kind of temperature range should there be on a 2.57 - 1 reduction velvet drive transmission? Its connected to a 135hp Perkins in a 45ft trawler. I had an issue with some slippage my last trip out and a mechanic friend of mine said to check the oil and it was black instead of red and also smelled like it was burnt. Auto-Matic Transmission Fluid. Only had the boat for a year and don't know if or when the oil was changed last. My Perkins guy told me to pump out the oil and replace it with SAE 30 or heavier, which I did and it seems to have solved the problem with the slipping has she hasn't done it since. Just wondering what the temp should be. I have a laser thermometer and after running the boat for a couple hours its showing around 190F. Is that normal or is something going on that I need to address asap?

Borg Warner pretty much says "don't let it get over 190* F and if it does, change the fluid ASAP". For fluid, they normally take ATF, but SAE 30 is fine provided the engine doesn't spin faster than some RPM limit (can't remember it off hand).

So yours is running hotter than it should be, and that's likely chewing up the oil (and once the oil is sufficiently shot, then it'll slip).

How old is unit in both years and hours? Suggest you check transmission cooler and oil flow to it. But, 190 is really hot so maybe check with a top flight transmission shop since oil burned. My raw water cooled Hurths get checked for temperature routinely, running around 115F in 55F seawater.

Getting stranded due to a bad transmission can be dangerous. Me, I'd check it out with a pro shop yesterday.

Check the engine temperature on the block the tranny is fixed to. Should be xcose.

FF said:

Check the engine temperature on the block the tranny is fixed to. Should be xcose.

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Only if transmission coolant cooled.

Yes, it depends if the transmission cooler is part of the raw water system or part of the freshwater system (typical in a keel cooled boat). Also, it's important to remember that transmission heat has a direct correlation to horsepower output (fuel burn). If you're cruising at slower speed generating 38 HP at around 2 GPH, the heat generated by the transmission will be fairly minimal. If you're going faster generating 95 HP at 5 GPH, the heat generation will be at least 150% more.

As previously mentioned, some blocked tubes in the transmission cooler may allow enough raw water through to maintain proper engine temperature, but not adequately cool the transmission. If it's a very old cooler, oil sludge may keep the oil from contacting the lowest tubes in the cooler also.

Ted

190 deg F will not discolor or burn the oil in the transmission. On my 45' bus the transmission temp is routinely around 195-205 deg F. The Allison transmission is coolant cooled. Limits are 240 deg F for regular oil and 260-270 deg F for synthetic. Some of the newer transmissions have built-in retarders (instead of Jakes). They will go up to 250 deg F on a long downhill. I think you have something else going on. Slipping clutches will discolor the fluid.

Don't know on the BW, but on a Twin Disc it is important to use a single weight oil, i.e., 30w not 10-30w. The engineer at TD explained to me that the long chain thickeners used to make it multi-vis shear down quickly under the gears and you end up with a 10w before very long.

190 should not burn the oil by itself. In my pickup the oil is made to run at 200 all the time and up to 235 under heavy load by design. But there may be something going on that transmission to make it run that hot.

Most likely your clutch discs are still slipping and need replacement. Check crank and shaft speeds with a phototach under varying load conditions. Don't go on long trips and keep your SeaTow membership current.

My Velvet Drive runs at 130F, connected to A Ford Lehman.
It does have a transmission cooler.

I think something is causing an unnatural rise in your trans temp. It certainly could be slipping clutches. On a warm day after hours of fast cruise my VD transmissions will be about 145 degrees. According to my VD service manual 190 is the max allowed.

Ken

That is unusually hot. Check the coolers

I have the same experience with my Chevy diesel with an Allison 1000 transmission. At 50 degrees ambient temp, the tranny runs at about 150 degrees. At 95 degrees ambient, the tranny runs 240 - 250 with a redline of 300 degrees. The fluid remains red. Last oil change was 90,000 miles ago. So, your tranny oil is dark for a reason other than heat.

gsholz said:

190 deg F will not discolor or burn the oil in the transmission. On my 45' bus the transmission temp is routinely around 195-205 deg F. The Allison transmission is coolant cooled. Limits are 240 deg F for regular oil and 260-270 deg F for synthetic. Some of the newer transmissions have built-in retarders (instead of Jakes). They will go up to 250 deg F on a long downhill. I think you have something else going on. Slipping clutches will discolor the fluid.

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