Yanmar YSE8 "slippage"

[seaweavermarine]

Hi all.
I don't know what else to call it...but it is almost like a spun hub on an outboard.
I have good trust at low rpm but as I spool it up I loose thrust. The Keys do not appear sheared in the shaft ends both Prop and couple. I was checking this as we drifted in the ICW so inspections where of the basic variety...hand turning the prop in gear w/ the boys watching the main pulley. They said it turned... and visually inspecting the couple end for new metal.
This kinda surprises me as I did not think i could do that even w/ a ?? 2:1 gear.
This engine is new to me and I just found out what it is.
My pal who is a diesel mech said the trans it mechanical so there is no hydraulic slippage. I spoke to him before discovering the increased thrust at low RPM (will call again!).
If anyone know where I should start I would appreciate it. I'm to return to the boat in Charleston this Thursday and do an offshore race back to Savannah. Tides for departure and return are favorable thank goodness.

27 Pearson Renegade
Vamp

Chris

[pedcab]

Originally Posted by seaweavermarine

Hi all.
I don't know what else to call it...but it is almost like a spun hub on an outboard.
I have good trust at low rpm but as I spool it up I loose thrust. The Keys do not appear sheared in the shaft ends both Prop and couple. I was checking this as we drifted in the ICW so inspections where of the basic variety...hand turning the prop in gear w/ the boys watching the main pulley. They said it turned... and visually inspecting the couple end for new metal.
This kinda surprises me as I did not think i could do that even w/ a ?? 2:1 gear.
This engine is new to me and I just found out what it is.
My pal who is a diesel mech said the trans it mechanical so there is no hydraulic slippage. I spoke to him before discovering the increased thrust at low RPM (will call again!).
If anyone know where I should start I would appreciate it. I'm to return to the boat in Charleston this Thursday and do an offshore race back to Savannah. Tides for departure and return are favorable thank goodness.

27 Pearson Renegade
Vamp

Chris

Well, if you say there are no sheared keys, that the coupling is mechanic and that everything seems otherwise OK my guess would be propeller cavitation or aeration.

Does you boat feature some sort of retrofitted propeller? Maybe there's an engine vs. propeller mismatch...

[seaweavermarine]

Hey Pedcab,
These were the same thoughts my Mech pal was thinking..till he got to his shop and found a manual. He found there are two clutch plates (we guess F/R) but seemingly no "source" for pressure like an auto pressure plate or hydraulic trans.My pal says he would not be surprised if the clutch surfacing is bronze.

I now have the manual and I'm going to copy it...it's a whopping 40 pages.
We could find that the clutch is oil immersed but nothing to tell fill level or fill itself. We could not determine if the tran. lube is the same as the engine.
We did find the oil very low about 6hrs into our trip and used the oil we found(previous owner) on the boat these were all 10-30w. My pal says he would not be surprised if the clutch surfacing is bronze.

I'm hoping that when I get it home to pull it down and learn more. I'm thinking that if I cannot get the plates resurfaced/replaced.. I exchange one disc for the other.
I'm afraid I have been completely negligent in learning and maintenance of this engine.
Chris

[JimsCAL]

Sounds like you fried the clutch. A transmission rebuild may be in order. Not sure about the oil in your transmission, but my 3GM30F uses the same oil as the engine. Check the manual.

[seaweavermarine]

I think so too Jim. The Manual is not clear at all about Tranny lube. It does say replace every 100hrs, but not w/ what or where.
I'm also not able to determine which engine I have either the YSE 8 or 12.
I am progressing well on learning...!
cw

[RichH]

Originally Posted by seaweavermarine

I think so too Jim. The Manual is not clear at all about Tranny lube. It does say replace every 100hrs, but not w/ what or where.
I'm also not able to determine which engine I have either the YSE 8 or 12.
I am progressing well on learning...!
cw

The cover plate on Yanmar transmissions will have the type/grade/weight of 'lube oil' or ATF needed. The dipstick is NOT screwed in to measure the correct amount of 'fill' ... just resting on top of the 'threads'

The trans. most in Yanmars are Kanzaki or variants... once a clutch friction disc 'goes' it has to be replaced .... no adjustment. These friction clutch discs 'wear out real fast' if the trans. fluid isnt changed often or the fluid level is below 'spec'.

[seaweavermarine]

Thanks Rich.
The only place I have not looked for any ID marks of any kind is on the Trans.
It's going to be one of those tight fits in a locker to get it out much less find an ID. I'm working my recovering Knee so it will be able to tolerate the bending required.
Are you of the thought that the plates a bronze?
cw

[paytman]

Hi, mine is having the same problem (again); a Yanmar 3HM35F with the Kanzaki manual transmission (model KBW10 2.14:1). It is only the forward that this happens, as it is used more than the reverse obviously. Mine is a cone clutch, and the 'cone' goes or wears, thereby not gripping the other cone/plate.
You must scour the Yanmar manual as to what oil or ATF to use in your tranny; my manual covers 4 different engines, and 3 of the 4 use engine oil in the tranny, but mine specifically says to use ATF-A (now Dexron III).
And a previous poster is correct about the right amount (also stated in the engine manual) and to NOT screw in the dipstick but measure with it sitting on top of the threads.
I am probably looking at a rebuilt install w/ a core charge to expedite; am hoping to remove and install my self w/ some help of a knowledgable friend.
It becomes all about the alignment afterwards too.
You can look on ebay for rebuilts, or local marine tranny shops.
Robert
LUNA P36-2

[seaweavermarine]

Hey Robert,
As soon as I can I'm pulling mine. The is a funny tube on the portside aft that has what appears to be a fill or perhaps dip stick...but there is no stick, just a cap w/a line attached so as not to be lost...and the tube does a slow 90 forward to terminate in a abrupt 90 fitting into the engine.
I'm going to fashion a catch pan and go at it. The Manual is of no real help.

We did the offshore from Charleston to Savannah. It was pretty funny leaving the city marina in reverse only. We sailed around the peninsula as we had almost zero forward. When we got to the start area the tide was slack and the front that had just passed left little air but we were able to start and made it offshore in good fashion after a bit. We sailed into the back of the front near 1am and fought downpours and periods of no wind. Near 9 am we were still 16 miles from the finish and the last boats powered up and motored past so we did the same...barley. Thank god the tide was with us up the Savannah River as with our low rpm to spin the shaft and sailing speed, we increased from 4 kts over ground to 7.5.
I brought the boat home the last 12 miles under tow w/ my 13 whaler.
I was longing for an outboard bracket and my Yam.9.9 sail drive!

cw

[ffiill]

Just a quick comment to say that if it uses cone clutches its not a true mechanical gearbox only that it is using physical force instead of hydraulic force to engage cone clutches.
A true mechanical engaged gearbox either works like a manual automobile gearbox or more commonly as in case of small Hurth/Zf and PRM where flat clutch plates actuate a physical torque generated lock between input and output shafts in a similar way to manually engaged locking diffs on 4x4s.
Recently dismantled and rebuilt one of these.