ZF350A Transmission small leak

Usually they'll leak out of either the front or rear seal. Clean the transmission well with a degreaser and the bilge underneath it, and lay diapers underneath it, then keep an eye on where the diaper is getting soiled or before cleaning it use a mirror and your hand and try to feel or see where there is residue. How much oil is leaking?

Hi,

Can you see any oil in the bilge or does it just vanish from the dipstick?

The rear lip seal can usually be done with the transmission in place and just dropping the shaft. However the front one, requires splitting the transmission from the motor in most all cases. a 1/4 pint is actually becoming a good size leak for a tranny. Does the transmission have an external filter that could be leaking?

Something to check, my ZF 220, run straight 30w, make sure your's is OK with 5-xxw.

Hi,

You will hopefully be lucky, I was involved in a vesel once with ZF BW 755 Gearboxes that were supposed to run straight 30 but had for the preceding 3 yrs been run on a steady diet of Shell Omala 150 which is a heavy gear oil.

It was caused some amazement to the bridge team when the correct grade of oil had been flushed through the system a couple of times that the low clutch oil pressure alarms that had dogged the boat since new when manoeuvring vanished by themselves.

From memory there was about 1100 hrs on the engines when the mistake was noticed. Up to that stage all Oil Samples had come back as being fit for further use. As the Lab had been unable to notice the wrong oil was used I was not sure if this was an honest interpretation or not so the vessel changed analysis services and chief engineers at about the same time.

It is possible that the wrong oil is causing the leak.

If it is the ZF style I am thinking of with the scraper, and the scraper handle looks almost like a battery terminal. The entire drum comes out with 3 or 4 bolts (scraper handle and all), you then take it off the boat and clean it with brake fluid, and you need a new paper gasket to put it back ($5 gasket). Be careful not to damage this as the filter assembly is $1600 from ZF. There is also a bolt near the scraper handle that you take out and after scraping it, you can drain out the scrapings. CALL ZF in Miami, they are VERY good about giving advice on how to maintain their transmissions and will walk you through every single step.