Hurth 360A Transmission - Oil Cooler or Not?

[Troubadour52993]

I have a new-to-me 1986 Beneteau Idylle 15.5 which has just been repowered with a rebuilt Perkins 4-236. It has a Hurth HBW 360A transmission, which has been working to date. I believe when I first checked the trans fluid level, it was low and I had to add fluid.

Today I went to check the trans fluid level again, and the fluid was milky. After draining the bad fluid I pulled the trans cooler and it is trashed - the inner flange of the body is rotting away, allowing the seal to buckle, hence the water; one of the oil hoses to the transmission is totally blocked with corrosion, no transmission fluid (or water) in the shell side of the cooler.

According to my manual, this transmission does not require a cooler for continuous operation below 55 kW/74hp, which is near max power for the Perkins (85 hp).

I was thinking of "shorting" across the cooler ports with a short length of hose instead of replacing the cooler, but would like to know if anyone runs their transmission without a cooler? Is the 74hp spec ideal, and I would have trouble with overheating at much lower speeds?

Any help appreciated!

[jdoe71]

Don't know about that trans, but the older, smaller Hurth's were famous for failing due to heat. Most reputable rebuilders suggested transcoolers of various types to help with longevity. If your install had a trans cooler then my personal preference would be to stick with it.

[michaelmrc]

a new transmission oil cooler can be obtained from any tranny or auto parts store cheap investement and unless you run continually in arctic temperatures the cooler cant hurt.

[shakey doug]

Hurth 360 boxes have real issues when run hot, would not consider running one in tropical or temperate climate waters with out one.

You can't buy experience but you will pay for it.

Doug.

[Troubadour52993]

Thanks, I have purchased a generic oil cooler and will hook things up when it arrives next week.

I plan to run the engine/transmission with fresh trans fluid, then drain and refill. It looks to me like the oil pump on the back of the Hurth works directly off the input shaft, so it should pump whenever the engine is running. Can anyone confirm this, or does the trans have to be in gear for it to pump?

[Idylles15.5]

I own a 15.5 and I have done a complete four year overhaul on the boat, from Gel planing the hull to new fuel tanks and a complete engine rebuild. My best friends family owns a huge machine shop and do all kinds of custom work, motors, trannys, etc from boats to Ferraris you name it. His father was kind enough to blue print and balance my perkins 4-238. During the rebuild it was dicovered that perkins used four differant forging plants for the rods and other parts. My engine had four differant rods, one from each plant in it. Diesels obviousely don't turn very fast so it was fine for the rpm it turns. Talk about out of balance though. Anyway to get to your point they also rebuilt the whole tranny. I have owned my Idylles for awhile now and you have to remember the keel is ten thousand pounds. The boat does have some weight to it. Even if your not beating on the engine rpm wise, you have to consider the load on the tranny, just like a truck going up a hill with a heavy load on it. If your plowing into a heavy sea right on the nose, the load on your tranny will increase significantly even at a lower RPM. Definitely put the cooler back on, and the right one too. Not some bs generic replaement.

[Ram]

I had the same gear hurth 360 in my trawler and the cooler died and then i lost the gear bx , i had it rebuilt and lost it again a few years later to a bad cooler- buy a good cooler and have it checked every few years - its gonna be hard to get parts for that gear ( I have an extra one if anyone needs it) after losing that gear i put in a new gear HD gear that was rated about twice as much as the 360 was- good luck!