Transmission fluid

[jonelli]

I installed new fluid today according to the instructions I've read. I used an electric pump to suck out the old fluid which was about 10oz worth. Then I used a manual fluid pump to put about 300ml or so back in. It's really hard to tell how accurately filled it is. But there's definitely fluid at the the dipstick bolt marking height. How critical is the level? If it's a little more or a little less than the exact mark is it fine?

 

[RoyS]

Stuff is invisible.

 

[svchickadee]

Paint a white strip on the dipstick and the fluid level will be easier to see. Fluid should be red.

 

[Stu Jackson]

Use the dipstick, ROLL it on a paper towel to see the level on the stick.

 

[weekendrken]

What’s “a little” to you? Just fill it correctly but don’t overfill. If you can tell it’s under, then it’s under.

You didn’t state what tranny you have or what engine, or what year, or what MK (facts matter!) so I won’t be specific on the volume. But the specs are in tranny manuals online.
However I haven’t needed to know the volume since 1995.

I fill using a Nalgene squeeze bottle with the pointy top, with a 1/4” vinyl hose zip tied on. I marked it once at the correct fluid volume. I fill to the mark, tip it up, fill the tranny with the precise amount - eazy peazy no muss no fuss no runs no drips no errors. Hazard Fright has squeeze bottles like this but not the same quality.

Alternately you can mark a squeeze-bulb battery filler tube at the same distance as on the dipstick. I used a zip tie because fluid will eventually loosen tape and it will fall off (probably inside). Slightly overfill the tranny, suck it down to the precise level with the filler (use this method in the spring if you’ve filled the tranny for on the hard.) Put a zip tie around the bulb/tube half. The fluid will make the rubber so slippery the two parts won’t stay together.

Or pull the stick, roll it onto a white paper towel, you’ll see where the level falls on the stick.

 

[Ron20324]

Paint a white strip on the dipstick and the fluid level will be easier to see. Fluid should be red.

Not necessarily. It could be 30w oil.

 

[jonelli]

Sorry, it's a Hurth on a M25XP.
I did roll it on a paper towel. But the towel still bleeds and the line isn't accurate. It's in the general vicinity of the mark.
Maybe I'm just being overly cautious but just wanted to know how accurate it needs to be.
I didn't have a small squeezer/sucker for small adjustments.

 

[weekendrken]

Not necessarily. It could be 30w oil.

You use SAE 30 oil in your tranny? Interesting. How’s it run for yah?

 

[Brian D]

Interesting that most responses have been on how to read the level, not how much is too much or too little. You stated that you can see the liquid on the stick. Most dipsticks that I have seen have a MIN/MAX range mark. As long as your are within that range you should be good. If a little over (mm not inches) I wouldn't worry, but if you are worried just suck some out. If you are closer to the MIN then I would recommend adding until you are closer to the MAX.

Better to be slightly over than under. Also, run the motor until the transmission fluid has had a chance to circulate and warm up, then check the levels.

JMHO

 

[weekendrken]

Most dipsticks that I have seen have a MIN/MAX range mark.

Better to be slightly over than under.

JMHO

Here we go down the rabbit hole into left field. A Hurth has no min - max dipstick. AND it should not be overfilled due to the angle that the tranny sits. So it’s better to SLIGHTLY underfill initially, then top off after running. We’re talking a gnat on the head of a pin as to what happens with an over or under fill. But I’m just saying as a rule DONT overfill a boat transmission.

The spec for a Hurth 50 or 100 is 0.3L or 0.33 qt.

 

[smokey73]

You use SAE 30 oil in your tranny? Interesting. How’s it run for yah?

Use the fluid that the manual specifies - period. Some transmissions I assume use Transmission Fluid if it is supposed to be red. Some use regular SAE 30 weight oil. Use what the manufacturer of your tansmission says. Mine says 30 weight oil and that is what I use. The fluid type may even be on the a plate or on the fluid dip stick. The regular oil is very hard to read since it does not get dirty like the diesel oil does after awhile, hence the paper towel trick.

 

[weekendrken]

Mine says 30 weight oil and that is what I use..

What engine/tranny does she have?

 

[LeslieTroyer]

The hurth takes ATF, I use a clear condiment squeeze bottle, full to the shoulder is 300ml. Don’t screw the dipstick down when taking the reading- just straight up and down unscrewed.

There is only a full line on the dipstick no range markers. @Stu Jackson merhod of rolling the stick on a paper towel works

Les

 

[Ron20324]

Use the fluid that the manual specifies ...Some use regular SAE 30 weight oil. Use what the manufacturer of your tansmission says. Mine says 30 weight oil and that is what I use. .

So, yeah, Drkin, it runs pretty well. Thanks for asking. Smokey replied before I could get to the boat. I'm pretty sure the tranny on my 3YM20 says to take out the plug and clean off the stick, put the plug back, but do not screw it in. Pull it out and if the is any drop of oil on the bottom of the stick, it is "full". There is no hi/low marks.

 

[smokey73]

So, yeah, Drkin, it runs pretty well. Thanks for asking. Smokey replied before I could get to the boat. I'm pretty sure the tranny on my 3YM20 says to take out the plug and clean off the stick, put the plug back, but do not screw it in. Pull it out and if the is any drop of oil on the bottom of the stick, it is "full". There is no hi/low makes.

I know mine says not to screw in the tranny dip stick (which is round, not flat like the engine dip stick) but mine has a small "groove" about 1/4 inch up on the shaft of the stick and that is what I use as the "full" mark. I roll the dipstick on a clean papertowl and see if ther is oil (30 weight) below the groove but not above the groove. Just changed the oil about a month ago and the old oil was clean as a whistle with no discoloration or burnt smell but I changed it anyway. Cheap insurance.

 

[jonelli]

First, thanks for all the replies.
I'm pretty sure I'm close the mark on the level from what I can see by rolling it on the paper towel. I was mostly asking how critical that level was. I installed about 300ml or so of ATF fluid so I'm not concerned that it doesn't have fluid. The old fluid was pretty dirty. I've had the boat for 4 years and this was my first tranny fluid change.
Pretty sure the PO didn't do it anytime recently before I got the boat and I was just learning the basics when I got her. So after a couple years of engine service under my belt I wanted to make sure I had this down too.
I have most of the other engine service down I think.
I have a nice electric oil pump to suck everything out of everywhere but now I see that I need a few more dedicated unique tools for some items. I like the squeeze bottle solution.
This time I only had one of those manual hand pumps from harbor frieght to reinstall new fluid. So what I did was to first manual pump clean fluid into a spare bottle so all the lines were full, then I noted the level on the new fluid bottle and pumped in about 300ml or so.
The I used the dipstick to check the level on a paper towel and it was approximately at the full marker. So I feel pretty good about it.
I was just curious how critical or exact that marker was since the paper towel didn't seem very accurate.