Re: [Amel Yacht Owners] ZF25 Transmission Failure [3 Attachments]


Mohammad Shirloo
 

It would appear that some kind of transmission pressure loss alarm would
be appropriate since the results of a simple error of not tightening the
filter cap (or other source of loss) would be catastrophic.



Mohammad and Aty

B&B Kokomo

Amel 54 #099



________________________________

From: amelyachtowners@yahoogroups.com
[mailto:amelyachtowners@yahoogroups.com]
Sent: Tuesday, July 24, 2018 8:02 AM
To: amelyachtowners@yahoogroups.com
Subject: Re: [Amel Yacht Owners] ZF25 Transmission Failure [3
Attachments]





[Attachment(s) from Porter McRoberts included below]

Dean this was nearly precisely our story of failure on the way to
virgins from USA.

New tranny is an easy fix. Out and in a day. I helped the guy in st
Thomas and learned a lot.

Once a new one, bulletproof.



But exactly the same symptoms. The pump looses pressure and the brake
calipers close and then it's clattering of gears and smoke dust from the
pads. Luckily I (or my crew with 12 and 15year old hearing) could catch
it in about 3-5seconds. I remember sitting on anchor in the middle of
the intercostal for a day in Fort Lauderdale then getting my neighbors
to pull us back home with their dinghies. Talk about demoralizing, all
while moving onto the boat and selling the house etc.



Interestingly it started after an oil filter change, (after an oil
cooler change)The mechanic in Fort Lauderdale did not tighten the filter
lid enough. Then the pump (suction) on the filter and dipstick side
would fail and the pressure would drop and then the problem would arrive
(loss of pump pressure, calipers failing and closing and then gear
chattering etc). Lots of help from Bill Rouse on getting focused on
where the problem was. It was fixed (temporarily) by an astute old
greyhaired navy transmission mechanic who immediately called the
problem. He measured the pressure at the caliper hydraulic outlet. Upon
engine start ok., but then would drop 30 seconds later, this indicated
to him a seal failure. He tightened the oil filter cap and presto
problem solved. Until... 4 days of motoring out to the 65 from Fort
Lauderdale and then failure. Despite tightening, and retightening and
o-ring changes etc.



We limped into st Thomas hoping for a few minutes of power ( as I
tightened with great force on the oil filter cover) to get into a slip.
Luckily we had 35 kts of wind to get us there almost too fast, but
getting in a slip with that amount of wind and tranny as it was was a
sphincter workout. But all ok.



Interesting talking to the ZF dealer who had sent the "greyhair." (Now
I don't trust non-greyhairs) They, the dealer (historically) would take
all ZF25s and mill out another 1/100th of an inch on the body of the
tranny where then oil filter cover would fit, to allow the filter cover
to seat correctly. ZF finally recognized this and then changed it. My
new tranny oil filter cover sits lower. Looking at the old and new side
by side. Now: No suction. No problems.

Not sure if that helps. We had about 1600 hours on the engine at tranny
failure.



The ZF trannies are common.. I bought one from Fort Lauderdale and had
it shipped from the ZF dealer. It turned out to be very inexpensive by
st Thomas standards. I think around 2k for tranny and shipping. If my
memory serves.



I hope this helps. I, like your admiral had lost much faith, but I've
regained it!

Tell me if you want the ZF contact



Porter, (Helen and Grace and Lilly, what amazing crew)

IBIS.

54-152 vista mar marina panama.
Begin forwarded message:



From: "trifin@soundthinking.com.au [amelyachtowners]"
<amelyachtowners@yahoogroups.com>

Date: July 24, 2018 at 5:08:54 AM EST

To: <amelyachtowners@yahoogroups.com>

Subject: [Amel Yacht Owners] ZF25 Transmission Failure

Reply-To: amelyachtowners@yahoogroups.com





Hi All,

After load testing this morning I am 99% sure my ZF25 transmission has
failed.

I know the root cause of the failure, and I will publish separately on
that issue later.



I'm told by the ZF representatives that a new transmission will take at
least 3 months to supply.

I don't want to entertain re-conditioning of this box because I know the
root cause of the problem.



Our sailing season is over before it started, the admiral is devastated
and has lost all confidence in the boat. We will most likely winterise
the boat and go home soon.



However, before I do that I'd like to convert that 99% to 100%, to be
absolutely certain that the problem is the gearbox. I'm finding it
difficult to get the required level of professional support here in
Kalamata, so I'm hoping for some sage guidance from the group.



So, the symptoms...



Two weeks ago we started motoring due to no wind. Flat sea, running
about 1700-1800rpm.

I started hearing some "modulation" of the engine tone, like wandering
RPM.



I also noticed the disappearance of a "rattle/chatter" sound which has
always come from our Morse Control. It's not a loud rattle, but is
clearly transmitted from the gearbox up the gearshift cable and
resonates from the hand control unit. (Is that a standard thing - or an
early symptom of a gearbox problem?)



I thought we had something stuck on the propeller, so we stopped and I
checked it. Nothing.

We started again and the boat would not run up to normal speeds for the
RPM we were using.



We stopped again, and I checked the engine room once more. Fluids ok, no
leaks, nothing looked out of the ordinary. So we continued and I
increased the RPM to about 2000-2100, and continued on making only about
4 knots.



After 10 minutes or so, I opened the engine room again to check, and was
met with an outburst of smoke, burning smell and everything was very
hot. After stopping and investigating further I found the cause of the
overheat was that the shaft brake was stuck closed. The ZF 25 gearbox
was also very hot, and when I opened it to check the fluid again the
lower part of the dipstick was melted into an elongated blob of plastic.


There was no fluid leakage, so I assumed that the fluid level was still
ok.



I found out how to undo the shaft brake, and wedged a spanner in it to
make sure it stayed open. By then everything was cooled down and we
proceeded to motor slowly to shore at about 1200rpm. Interestingly the
"rattle" mentioned above was back.



We flushed and changed fluids and ran the boat gently for a day or two
until we got to a marina.



On testing the boat, we find that all is well until we exceed 2000rpm.
Quite quickly after running at 2100rpm our little rattle stops, then the
engine noise starts to waver and sounds like it it reducing in rpm,
although the digital readout of rpm does not change from 2100rpm. The
boat then starts to slow down from the 8.3 knots it was travelling at
with 2000rpm. It drops a couple of knots. On checking the shaft brake
at this point it is still open so that is not the reason for slowing.
If I increase the engine power, we get no more thrust from the
propeller.



After this happens, I struggle to generate thrust even at lower rpm.
Leaving everything to cool down completely appears to reset the problem.
The rattle comes back, low RPM operation is ok, but when loaded up the
gearbox seems to be failing.



The one thing which is niggling in my head is that the engine rpm sounds
like it momentarily drops down when this problem occurs, although the
rpm readout does not change. However, I can easily increase the engine
RPM by pushing the lever, it just does not transfer to the prop, which
seems to me like gearbox trouble.



All comments/suggestions appreciated. We don't really want to give up
on our summer cruising, and apart from that its cold back in Sydney!



Thanks all.

Dean

SY Stella

Amel 54#154

On Jul 24, 2018, at 5:08 AM, trifin@soundthinking.com.au
[amelyachtowners] <amelyachtowners@yahoogroups.com> wrote:



Hi All,

After load testing this morning I am 99% sure my ZF25
transmission has failed.

I know the root cause of the failure, and I will publish
separately on that issue later.



I'm told by the ZF representatives that a new transmission will
take at least 3 months to supply.

I don't want to entertain re-conditioning of this box because I
know the root cause of the problem.



Our sailing season is over before it started, the admiral is
devastated and has lost all confidence in the boat. We will most likely
winterise the boat and go home soon.



However, before I do that I'd like to convert that 99% to 100%,
to be absolutely certain that the problem is the gearbox. I'm finding
it difficult to get the required level of professional support here in
Kalamata, so I'm hoping for some sage guidance from the group.



So, the symptoms...



Two weeks ago we started motoring due to no wind. Flat sea,
running about 1700-1800rpm.

I started hearing some "modulation" of the engine tone, like
wandering RPM.



I also noticed the disappearance of a "rattle/chatter" sound
which has always come from our Morse Control. It's not a loud rattle,
but is clearly transmitted from the gearbox up the gearshift cable and
resonates from the hand control unit. (Is that a standard thing - or an
early symptom of a gearbox problem?)



I thought we had something stuck on the propeller, so we stopped
and I checked it. Nothing.

We started again and the boat would not run up to normal speeds
for the RPM we were using.



We stopped again, and I checked the engine room once more.
Fluids ok, no leaks, nothing looked out of the ordinary. So we
continued and I increased the RPM to about 2000-2100, and continued on
making only about 4 knots.



After 10 minutes or so, I opened the engine room again to check,
and was met with an outburst of smoke, burning smell and everything was
very hot. After stopping and investigating further I found the cause of
the overheat was that the shaft brake was stuck closed. The ZF 25
gearbox was also very hot, and when I opened it to check the fluid again
the lower part of the dipstick was melted into an elongated blob of
plastic.

There was no fluid leakage, so I assumed that the fluid level
was still ok.





I found out how to undo the shaft brake, and wedged a spanner in
it to make sure it stayed open. By then everything was cooled down and
we proceeded to motor slowly to shore at about 1200rpm. Interestingly
the "rattle" mentioned above was back.





We flushed and changed fluids and ran the boat gently for a day
or two until we got to a marina.



On testing the boat, we find that all is well until we exceed
2000rpm. Quite quickly after running at 2100rpm our little rattle stops,
then the engine noise starts to waver and sounds like it it reducing in
rpm, although the digital readout of rpm does not change from 2100rpm.
The boat then starts to slow down from the 8.3 knots it was travelling
at with 2000rpm. It drops a couple of knots. On checking the shaft
brake at this point it is still open so that is not the reason for
slowing. If I increase the engine power, we get no more thrust from the
propeller.



After this happens, I struggle to generate thrust even at lower
rpm. Leaving everything to cool down completely appears to reset the
problem. The rattle comes back, low RPM operation is ok, but when loaded
up the gearbox seems to be failing.



The one thing which is niggling in my head is that the engine
rpm sounds like it momentarily drops down when this problem occurs,
although the rpm readout does not change. However, I can easily increase
the engine RPM by pushing the lever, it just does not transfer to the
prop, which seems to me like gearbox trouble.



All comments/suggestions appreciated. We don't really want to
give up on our summer cruising, and apart from that its cold back in
Sydney!



Thanks all.

Dean

SY Stella

Amel 54#154

Join main@AmelYachtOwners.groups.io to automatically receive all group messages.