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StrmChzr 11-21-2013 07:54 AM

Tranny oil leak
After winterizing my boat a couple weeks ago, I noticed oil was leaking out the forward bilge.

I tracked the oil back to the zf hurth tranny.

The oil leak begins here slightly forward of the serial number:

Another view of the tranny and the tranny oil cap is off so I could check tranny oil level. It's low and seemed very thin, but didn't appear milky as if water had intruded:

What gives???

CantRepeat 11-21-2013 09:22 AM

Looks like a breather cap; did you happen to over fill the trans?

StrmChzr 11-24-2013 11:41 PM

Unfortunately, I did not have time to change any fluids prior to winterization. I'm positive the tranny oil wasn't in the bilge after pulling the boat out of the lake the last time this season prior to winterization. However, I did use my 4runner to pull boat/trailer the 15 miles from lake to my house and noticed the front trailer tires looked low, but pressure was 45psi. I figured the 4runner hitch was too low and wasn't distributing weight to tires appropriately.

Could something this "minor" make tranny fluid overflow? I attached pic to demonstrate how the boat was sitting in trailer when I winterized it. To my eye, it doesn't look to bad, but it was definitely bow heavy.

bsloop 11-25-2013 12:13 PM

Still hard to discern much from your pics.

It looks like new oil in bilge yet you comment on your transmission. Most ATF is red but the fluid appears clean yellow which is also counter to you not having changed the oil. I would expect it to be dark.

What are your fluid colors?
Have you checked the level of both?
Any chance you have a spare bottle of oil that has begun to leak?

StrmChzr 11-25-2013 03:01 PM

bsloop - Unfortunately, the pictures aren't much help at all. The ZF Hurth direct drives use ATF, but the manual states 4.5 quarts of 10W40 for V-drives and gear reduction transmissions.

Pretty confident the oil in bilge came from tranny, but hard to demonstrate with the sucky pics. When I checked the tranny oil it was low, however, I didn't check it the proper way. According to the manual, the boat needs to run for at least 5 minutes to get an accurate tranny fluid reading on dipstick and I didn't do this so it may actually be lower than the dipstick reads.

mikeg205 11-25-2013 03:32 PM

Which ZF 63 do you have... this spec calls for ATF...

bsloop 11-25-2013 03:34 PM

Interesting on the 10w40, not familiar with it but I am sure it has been discussed somewhere before. It would explain the "clean" oil.

From your pic of the vin tag and trans lines, I might happen a guess the crimp on a trans cooler line is leaking.

GM Allison trucks have a known issue with their lines leaking at the crimp (poor crimp design). They go fine for a couple years then as it starts to get cold, they begin weeping.
Temps warm and it may stop for a while but then as it gets colder, it leaks again.
Possibly a similar case?

Check the underside of the lines to see if they may be leaking further up and the drip is forming at that location?
Many threads on trans line and cooler replacements.

sand2snow22 11-25-2013 08:26 PM

Supposed to be in between the lines. Hopefully you just over filled it. After sucking, they usually take exact 3.5 quarts. I just overfilled my personal boat barely over the top line, this thread now makes me want to suck a bit out..

93Prostar190 11-25-2013 11:25 PM

I just tracked down a hard to find leak around a bolt that was backing out on my velvet 1:1

mikeg205 11-25-2013 11:31 PM


Originally Posted by 93Prostar190 (Post 993824)
I just tracked down a hard to find leak around a bolt that was backing out on my velvet 1:1

Picture? which one?

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