changing transmission fluid

Manual for our boats says once a year or every 100 hours. I change every three seasons or every 100 hours whatever comes first. Its really easy and quick, so no big whoop. I just pull the dipstick and insert the small plastic tube from my Jabsco PortaQuick. It sucks consistently 4 qts. out of each transmission that way and I refill with fresh Dexron III ATF ... actually I use REDLINE D4 ATF
 
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I do mine every other year. Always looks and smells fresh. Book says every year, but the people I trust say it's overkill. Never had a problem with this frequency.
 
Just checked the ZF marine manual and it says every year or 100 hours. I change mine every fall. I really do think that may be overkill, but that's what the mfr says to do.
 
What about the filters? i do mine at the same time. I agree it's over kill. Also reuse the filter use a can if brake cleaner than air good as new. The filters are $75 each from SR so 1 spare pair is enough$$
 
The filters are just screens, so clean and reinstall. I would not know for what reason anyone would nedd spares??
 
Only reason to have spares is to have a set ready to install instead of getting out of the boat cleaning the existing ones then getting back into the bilge, As we all know contamenation is the concern of ATF and having a set of filters clean and dry just moves the process along. Hope this helps.
 
I have a spare set of filters - so I can thoroughly clean the old set and they are ready to be installed. I change the transmission fluid once a year. Which is always less than 100 hours. Seems excessive - but - I am sure there is a reason why it is recommended. The filter has an allen wrench bolt on top of the transmission with a circular metal disk under it.
 
the filters are in plain view under a round plate with a hex head screw right in the middle of them. The round plate is about 3" accross and has a small tab to help pry it out. Rember that their is o ring gasket that should be replaced.
 
I change mine every other season. It seems fine when I change it, so I haven't considered doing it yearly.

But I do have a problem getting the level correct when refilling. The dipstick is often hard to read, or the level seems to change slightly depending how long you wait before checking after refilling.

Is there a trick to getting it to the right level quickly?
 
The reason the level changes is because some of the fluid has drained out of the oil cooler. The trick, if there is one, is to fill the transmission to the top mark on the dip stick after servicing it. Then start the engines and let them run about a minute. Shut them down and recheck the fluid immediately and top off as needed.

I notice that some of you choose to change the fluid and wash the filters less frequently than ZF recommends. Well, the condition of the fluid is only part of the reason you service the transmissions. When you wash your filters you should wash then separately in different batches of solvent , then examine the wash solvent for residue from the filters that washed out. That way, if you notice metal filings or dark residue you can begin to monitor what is going on and hopefully identify what is happening. Losing a transmission on a trip away from home can never be a good experience. Aside from the inconvenience and cost, you are at the complete mercy of the marine service industry where ever you happen to be and you may even have to leave the boat at some distant location and drive or fly home leaving the boat behind.


I service my filters every year and noticed some junk in the solvent. I watched it a year and the same thing happened the next service, only there was more metal in the solvent. I passed a magnet thru the debris and determined that what I was seeing was ferrous metal.......that means it was not normal clutch wear (fiber and brass), was not something bumping/rubbing the interior of the gear case (alunimum) so it had to be a bearing, a gear or a shaft. The 3rd year it was even worse, but the transmission pulled good, didn't slip and was quiet. I serviced it at mid year and found more metal, then I began hearing a rumble in both forward and reverse.......and knew the cause - a bearing on the output or intermediate shaft. I was out of time so we shopped for and located a new transmission and replaced it.

By servicing the transmission regularly, I was able to rechedule a major repair for after the season, had time to research used vs. rebuilt vs. remanufactured vs. new, was able to shop for a transmission, was able to do the repair at my marina and use the mechanic that has helped me with my boats for 20+ years.........in other words, regular service allowed me to do a major repair on my terms and my schedule.

If you never leave home then it isn't a big deal, but if you depend on your boat to get you to distant places and home again..........well, there is a reason the the transmission manufacturer say service them @ 100 hours or annually.
 
Frank,

What brand and type of transmission fluid do you recommend? I could not find it in the manual. I have the hurth v-drives.
 
I used valvoline ATF-III, but I believe the synthetic spec is now IV. Also purchased my filters half price from MER marine in Seattle. Agree, filter change was a waste.
 
Jim,

Look at the filter cover on the transmission and it will tell you what type lubricant to use. But, believe your boat is going to be a HSW 630 or ZF 63 and it will take a Dexron III ATF. Down load the current manual and look on page 61 ....there are about 100 suitable fluids listed.
 
I use Redline D4 ATF. It is Dexron III and GL-4 spec, just a little thicker than regular Dexron III ATF. Please note NOT to use Dexron IV spec fluids. It is fully synthetic but of significantly thinner viscosity (fuel efficiency reasons for newer cars with auto trans) than the Dexron III spec ATF.
 
I use Castrol's ATF fluid that meets the spec. I clean the filters with mineral spirits and then rinse them. I cleaned my dock neighbors as well. He had substantially more crud in his filters than I did. I change annually. His were 3 years between changes. It was substantially more. Mine barely had anything in the filters.
 
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