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New boat with a hot Tranny...borg warner velvet drive Q

Posted: Fri Jun 05, 2015 7:21 pm
by Dave Koester
Friends,
We are running our new-to-us Troller from Bellingham to South East and having to back off the power to keep the gear under 190 degrees which is the max indicated in the manual for it that I downloaded. The result is that we hover around a 5 knot cruise…lots of time to think!

I have a Borg Warner 71c (2.91-1) attached to a 60hp Isuzu c-240 on a 30’ fiberglass Monterey Clipper (Monterey Boat Works). The motor is cooled with a keel cooler. The transmission is cooled using a heat exchanger (about the size of a pepsi can). Because the heat exchanger is running engine coolant through it, it is clear that the gear is not going to be less than the engine (170 degrees) giving me only a 20 degree difference between engine operating temp (170 degrees) and max gear temp (190 degrees).

I have spoken to a pro trucker that I know and he says that gear over temp for them is about 220 degrees…But the Borg manual clearly states 190 …argh..
I have read on the internets that synthetic oil makes the Borg Warner slip so switching does not seem to a slipperier oil does not seem like an option. The manual indicates ATF of 30 weight are both fine…The fishermen I have spoken to all seem to prefer 30 wt.
My first thought for remedy is to try a larger cooler (heat exchanger)…they can’t come much smaller than the one that I have…but I would be very interested to hear from those with better thoughts and more experience.
Thanks for your consideration

Dave
F/V Addie L

Re: New boat with a hot Tranny...borg warner velvet drive Q

Posted: Fri Jun 05, 2015 7:37 pm
by Cfood
Depending how patient you are, you may want to remove the existing cooler and get it boiled out, clean and pressure tested first. I'm assuming at the system in place was adequate some time ago and a larger cooler not required. check for good water flow and that all is ok with your plumbing. Double check the thru hull and what whatever valve you have for good water flow. Would probly stick with recommended oil for now

Re: New boat with a hot Tranny...borg warner velvet drive Q

Posted: Sat Jun 06, 2015 12:20 am
by Dave Koester
seems like the more I roll this one around I keep landing on taking the trans cooler out of the coolant loop and going with sea water. I understand that there is a company in Bellingham that makes heat exchangers that are sold world wide under different names and they will make whatever size you want with any connection size you indicate. seems like a smallish electric pump (Jabsco?) that was wired into the ignition would be enough keep sea water flowing through it...I wonder what the ideal operating temp is for a gear box...some folks I talked with said they can put their hands on the ones cooled with raw water...which seems cool to me given that is is attached to a 150 degree engine...

Re: New boat with a hot Tranny...borg warner velvet drive Q

Posted: Sat Jun 06, 2015 12:22 am
by Dave Koester
seems like the more I roll this one around I keep landing on taking the trans cooler out of the coolant loop and going with sea water. I understand that there is a company in Bellingham that makes heat exchangers that are sold world wide under different names and they will make whatever size you want with any connection size you indicate. seems like a smallish electric pump (Jabsco?) that was wired into the ignition would be enough keep sea water flowing through it...I wonder what the ideal operating temp is for a gear box...some folks I talked with said they can put their hands on the ones cooled with raw water...which seems cool to me given that is is attached to a 150 degree engine...

Re: New boat with a hot Tranny...borg warner velvet drive Q

Posted: Sat Jun 06, 2015 4:10 am
by paul
Make sure that your coolant goes to the gear cooler before going to the engine.

Re: New boat with a hot Tranny...borg warner velvet drive Q

Posted: Sat Jun 06, 2015 5:31 am
by Dave Koester
Thanks Paul...I just confirmed your point...yup it is on the cools side of the system already. This AM I will remove the trans hoses and blow through it to confirm flow .

Re: New boat with a hot Tranny...borg warner velvet drive Q

Posted: Sat Jun 06, 2015 6:48 am
by Dave Koester
no constriction in the cooler...blew right though it...I love the taste of 30wt in the morining

Re: New boat with a hot Tranny...borg warner velvet drive Q

Posted: Sat Jun 06, 2015 1:56 pm
by paul
It sounds like your heat exchanger is to small. You could call a heat exchanger company and have them size one for you. Going with saltwater brings a lot of other problems and maintenance. I don't think that the salt water temperature is much different than the keel cooler coolant temperature.

Re: New boat with a hot Tranny...borg warner velvet drive Q

Posted: Sat Jun 06, 2015 6:34 pm
by lone eagle
i ran saltwater through the gearbox heat exchanger and used a belt driven jabsco pump. I suggest you monitor gearbox oil pressure too.

Re: New boat with a hot Tranny...borg warner velvet drive Q

Posted: Tue Jun 09, 2015 2:06 pm
by thediverdude
Just a thought, might want to check accuracy of temp gage

Re: New boat with a hot Tranny...borg warner velvet drive Q

Posted: Tue Jun 09, 2015 7:47 pm
by MonkeyFish
I have a similar size boat with the same gearbox attached to a 90 horse john deere. The gear is cooled by an exchanger that measures 4"x24"on the outside. It is plumbed between keelcooler and engine. Always measures 165 degrees, when running, verified by my little infrared gun. 150 at trollingspeed.
Maybe your exchanger is too small, or plates warped, or a blocked passage?
I would definitely check the gauge, sometimes they lie.
Good luck, hope ya work it out.

Re: New boat with a hot Tranny...borg warner velvet drive Q

Posted: Wed Jun 10, 2015 4:53 pm
by Dave Koester
We are just rolling into Ketchikan after 10 days at 5 knots + or - through BC..nice trip. I will order a bigger cooler in the morning. thanks for the feedback