Fitting a cooler to Hurth 100 gearbox

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Iceblink

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has anyone tried fitting a cooler to a Hurth gearbox? After reading up about them it seems they have a bit of a reputation for being unreliable. A US based site recommends fitting an aftermarket cooler which they claim prolongs the gearbox life (along with regular oil changes) I found a UK supplier for a cooler that simply bolts on the side of the Hurth and takes heat from the casing. Has anyone fitted something similar? where would be the best place to plumb it in? Via a T after the strainer and before the raw water pump? http://www.boatpartsandspares.co.uk/zf-hurth-gearbox-oil-cooler-4843-p.asp
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Hi. I have the Hurth HBW50 which appears to be of the same design but of a different size engine. Mine is still going strong after 27 years and my engine is right at the top of its spec. Is your engine power close to the to end spec of the gearbox? Only then would i bother. I do not believe that cooler will have any effect anyway. Coolers need large surface areas between the two mediums with the metal between as thin as possible. That cooler will have neither and as you will be plumbing it into the saltwater circuit i would certainly not have those brass hose tails. It is normal for the gearbox cooler to take the full flow of seawater and not from a t-piece otherwise how will you know what proportion of your seawater will go through the gearbox cooler?

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I have a perkins 4108 with a ZF10 gearbox, which I believe is the same as a Hurth 100. IT comes as standard with a cooler that looks similar to the picture and is essentially just bolted to the side of the gearbox. The cooler is fitted directly in the salt water intake between the filter and the pump. The 4108 (at least when new) develops about 49HP which is at the top end of the power for the ZF10. Cooler has been there for 30 years.....
 
I have the same gearbox on my comercial boat which runs in gear all day. I wanted to fit a cooler but was advised against, the reason being that they are designed to run 'hot'. Change the oil every 100 hrs.
 
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neil1967 said:
I have a perkins 4108 with a ZF10 gearbox, which I believe is the same as a Hurth 100. IT comes as standard with a cooler that looks similar to the picture and is essentially just bolted to the side of the gearbox. The cooler is fitted directly in the salt water intake between the filter and the pump. The 4108 (at least when new) develops about 49HP which is at the top end of the power for the ZF10. Cooler has been there for 30 years.....
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Do you have a picture of how the cooler is connected to the water line?
 
The commercial cooler fitted to my 4-107 / PWM gearbox combo destroyed itself inside ...

I gave it to a pal of mine who is a Metals Master ... he laughed when he saw what they had used .... he was amazed it had lasted so long ...

He took the outer round case and built new tube internals ... larger bore and fewer .. as he said the original had too many and too small a bore ..

15yrs later - that cooler is still doing its job .....

As to connection :

It takes the raw water after the engine block - then through cooler - cooling the gearbox oil and then back to manifold to exhaust as usual .. I have raw water cooled engine.
 
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