Catalina 350 International Association

Hello all...simple question (I think), but I need to change my transmission fluid and am wondering how people are doing it? I've read that if you drain from the bottom there are one-time use, crushable washers that need to be replaced and are hard to locate (so, unless that is wrong, would rather not go that route). I tried siphoning from the top but no luck with that. Any other ideas/methods appreciated! Thanks!

Pete,

I just use a gear oil/fluid transfer pump. Same one I use to change the engine oil, just a different hose. Like any oil change better if the oil is warm, any contaminants up in the fluid, not in the bottom of the transmission.

Run the hose as far down in the box as you can. Suck out all you can, over fill with new fluid and suck out again. Then carefully fill to proper level.

Brett

Pete,

I changed ours when I had the transmission our replacing the damper plate (Wow, what a difference that made!!), so it was pretty easy. One thing I noted was that the drain plug is a 17mm hex. There is not room below the transmission to use a socket and ratchet, and a 17mm open/box end wrench is too long to be able to turn it once on the drain plug. So I bought another 17mm wrench with the intention of cutting it off to about 4" long so that I can remove the plug in the future if desired.

I would prefer to drain from the bottom if possible as you are more likely to remove any particles that have settled that way. Although Brett's suction up - then fill and suction - and fill again process would be a good alternative and seems pretty simple. Although I would be sure to measure the amount originally sucked out just to be sure you were getting all the old oil out.

I haven't done it, but I would assume the crushable washers would be readily available at any auto parts store if you took them the plug so they knew what size was needed.

Good Luck

I've changed my transmission oil twice now, the first time a bit messy, the second time around I cut one side slightly off a shallow-type plastic Tupperware container to hold most of the oil. Personally, I can't help but think you're doing a better job by draining from the bottom; pumping from the top isn't something I would even bother with, but it's up to you. I drove to two auto parts stores and no one had a washer like that. I have re-used the same washer both times with no ill effects. I might source out the proper washer next time though, just so I sleep better at night.

Fat Cat
#258

Couple of thoughts.
1. I change the fluid every 100 hours ( same schedule as the engine oil) . After having to replace the gear box at 500 hours and hearing/learning about how badly the gearbox is designed, I changed my practice. Knock on wood, so far so good.

2. I change from the top with a warm transmission. I picked up a high temperature plastic tube, and have inserted it into the engine oil manual drain system hose with brass connections. This way I get a hard tube that does go all the was to the bottom of the gear box.

3. After draining the system by way of the bottom drain plug the first few times with bloody knuckles I decided to get smart. Did some measurements and collected the bits to allow me to open the drain "from above" with a crowsfoot OE wrench end driven by a 3/8" drive. This has worked very well and about every fifth drain, I do it from the bottom and replace the oh-so-hard-to-find compression washers.

Information on the crushable washer for the drain plug:

For the Hurth ZF 15 MA transmission, the sealing ring for the drain plug is the same sealing ring as on the fill plug/dip stick, so it would be easy to take the fill plug ring and get dimensions for a new ring from a auto parts store or on-line through someone like Fastenal http://www.fastenal.com/web/products?se ... Gaskets"|~.

The Hurth part number for the sealing ring is 3306 301 016. A quick on-line search of that part number (without the spaces) will find numerous suppliers that have them for $4/$5.

Resurrecting an old thread.
Has anyone measured the difference in the amount of transmission fluid recovered via the lower drain plug vs through the dipstick opening? My research indicates that the fluid capacity is .47 l (15.9oz).

Ken, is the capacity of the transmission close to 16 fl oz or is it the difference? I am about to change the transmission oil and I dont know how much oil it takes.

Supposedly our boats have a Hurth HWB150 transmission. The label on mine is ZF15MA. I'm pretty sure they are the same or nearly identical. The Universal service manual lists the transmission fluid capacity for the HWB150 as .58 qts (18.5 oz) whereas the ZF15MA is .50 qts.

When I drained my transmission via the dipstick hole I put the fluid in a 16 oz clear plastic water bottle and would estimate that I removed about 7-8 oz. When refilling with new fluid it's important to avoid overfilling and only add to the full line on the dipstick when it NOT screwed in.