ZF slippage after fluid change

I have been following this thread and have a couple of comments.
1. The pick up tube for the pump is in the front of the gear box. If you are under filled, you may be starving the pump when the bow of the boat pops up when starting to go. The oil will go to the back of the gear box.
2. If the pump is starving for oil you can trash the pump quickly. Be carefull here if you are slipping don't keep trying.
3. If you get the oil to the right level and you still have issues get the shift pressure tested.
4. IF the shift pressure is low, get the relief chack valve checked first. These have broken their springs on occasion.
5. What are the odds that both tranny's died at the same time? Lets hope for low oil!
 
fwebster said:
Part of your problem may be that you are referencing the wrong transmission manual.

Your photo shows that you have Hurth HSW-800-V, not ZF-80-IV transmissions. ZF bought Hurth and redesigned the HSW-800 into the ZF-80-IV, fixing some known issues, then redesigned it again into the ZF-85-IV. One major difference is the transmission fill plug and dipstick design was changed. The HSW-800 has an expandable rubber plug that is fully seated in order to check the fluid level. The ZF-80-IV has a threaded plug that isn't seated but only contacts the threads for checking the fluid level.

Also the whole question of fluid volume on these transmissions is confusing because the external lines and oil cooler hold fluid. If you follow the manual procedure, i.e. run the engine before changing the fluid, your lines are full and you will never get all the fluid out, nor will it take 7+quarts to fill the transmission.
Click to expand...

  • My transmissions have a plastic threaded dipstick with a triangular shaped top.
  • Transmissions were serviced the Fall 2010 - ~10hrs run time before I took ownership in August 2011 and had about 270hrs total when I changed fluid this fall 2013.
  • I routinely checked the fluid level and found it to be bright pink and not carrying any particles visible on the dipstick or when wiped on a white rag.
  • I do not recall if I checked transmissions screwing dipstick back into housing, or only by contacting first thread to housing. All I recall is that the transmission fluid levels were consistant side to side and fluid appeared/smelled good at every check.

More info soon. Work schedule keeping me busy and next visit to the boat won't be for a day or three.
 
Gary Hill said:
I have been following this thread and have a couple of comments.
1. The pick up tube for the pump is in the front of the gear box. If you are under filled, you may be starving the pump when the bow of the boat pops up when starting to go. The oil will go to the back of the gear box.
2. If the pump is starving for oil you can trash the pump quickly. Be carefull here if you are slipping don't keep trying.
3. If you get the oil to the right level and you still have issues get the shift pressure tested.
4. IF the shift pressure is low, get the relief chack valve checked first. These have broken their springs on occasion.
5. What are the odds that both tranny's died at the same time? Lets hope for low oil!
Click to expand...

Gary -

All good thoughts, thanks. Interstingly this boat came out of Holland, Michigan. Was named 'Koinonia' at that time, last owner last name was 'Burrink' or something close to that.

From all the information here I am starting to formulate a theory that isn't going to have a happy ending. Will know a bit more in a few days, but what I know now is that two transmissions that are rotating while in neutral and at idle are not a good sign. The port side has always done this, but very slowly. Both port and starboard are rotating now - enough to walk the boat against the mooring lines.

Its clear that the clutches aren't happy. Due to pump starvation? Possible. Due to a difference in fluid, or new fluid 'cleaning up the aged clutch disks'? I may never know. Here are parts of an lengthy email exchange with one of Seattle's ZF repair facilities...I am nearly resolved that regardless of cause, the transmissions will need to come out and minimally, the clutch packs rebuilt. If it turns out that the pumps were starved and bearing/shaft damage has occurred, I may be money ahead to replace the units with a pair of upgraded ZF-85-IV. I like the completeness of this solution - just NOT the price.

...

Its just like a transmission in a car and you NEVER want to change the fluid once you start slipping! That fluid has all the clutch material floating around in it and it actually helps to keep the clutches engaged, now that the fluid has been changed all of that particulate has been removed and causing more slippage and more heat in turn warping the clutches even further. You run the risk of welding the clutch packs together and will lock the transmission in gear, it’s never fun when this happens. I would advise against trying to run it, you may end up causing more damage and making the rebuild even costlier than it would be right now. The heat of the slipping clutches can be the cause of major failure and warping.

...

It sounds as though you need a rebuild or two. When they start doing that it means that the clutch discs are warped from overheating/slippage and causing the clutch pack to actual grab while in neutral. It’s basically taking up the slack between the clutches and causing the shafts to spin. Unfortunately there isn’t a way to increase the horsepower rating out of the transmissions during rebuild, they are prisoners to the factory specs. Just as you said they are right on the line of being rated for that horsepower. The chevron MD-3 is exactly what we would use on those, it is a great all around fluid. ... It is hard to quote a rebuild on one of those until we get it opened up. If is just needs clutch packs you could be looking at $700-1000 if it needs clutches and bearings it could be $1500-2500. If there is any shaft damage you would probably just want to purchase new at that point. ... Let me know what you would like to do.

...


 
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Mark,

I work in the spline and gear world and many of the splines in those transmissions are made on our machines. Anyway, I wanted stay upbeat with my comments but also needed to let you know that you may be doing more harm than good.

It is a fact that changing fluid in a tranny (car or boat) that has been neglected creates issues. Not only do you lose particulate but sometimes the new oil makes the fiber on the clutch plates come apart.

FYI I rebuilt my dock mates 63IV a couple of years ago. We could hear the pump going so when he went on the hard over the winter he pulled the tranny and brought it to my shop. His main issue was wear in the pump. However, there was enough crap in that gear box that required all bearings to be replaced. His clutch plates were OK and we left them alone. The shafts, splines and gears can take quite a bit of abuse. Clutch plates, pistons, bearings and pumps, not so much.

Lucky for him I was walking down our finger dock, his hatch was open, port engine running, I could hear the pump up on the dock. We caught his in time. If you have any questions, feel free to ask.

Good Luck

PS, our current boat has the electric shift models. If you do have to upgrade, look at these very close. They are awsome and there is no cable getting in the way in the ER.
 
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Markrinker- your feedback from the ZF rep is consistent with the symptoms. Fluid level +/- a few mm (the length of the threaded part of the dip stick) is not in it's self the reason for clutch slippage. Slippage causes heat which causes the plates to deform which will tend to cause the output to turn in neutral (you know this). There are three primary reasons for the clutches to slip:
1. Incorrect fluid. If by chance someone put gear lube or engine oil in the cases the critical function that ATF provides for the friction plates is lost and the clutches will not be able to develop enough friction between the plates and discs. Consequently, slippage, heat, and failure. This could have been done in the past then bandaged with fresh fluid.
2. Incorrect hydraulic pressure. Low fluid level (really low) or an air leak on the suction side of the fluid supply will cause low pressure and insufficient clamping force for the clutch packs and the consequential slippage, heat and failure. A second cause of low pressure can be lack of full articulation of the shift linkage which again will not provide full clutch clamping pressure. The last is the mechanical elements like the hydraulic pump and pressure regulating elements.

Can you rotate with relative ease the propshafts by hand? You should be able to and they should turn with equal force all the way around. If not- it's the clutches.
if you are having the same problem with both gears I suspect item 1 above. Get the hydraulic pressure checked first then move to evaluating the clutch packs.

my starboard is a Hurth 800 and port is a ZF 85 - I have quite a bit if experience with these gears (actually education).

oh, and if you are going to have to pull one or both , the port gear should as a minimum have the bearings replaced on the counter shaft.
 
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The Hurth HSW 800 (what you show is in your boat) and ZF 85(in the above link) are not the same gears however the ZF is in all aspects an improved HSW 800. The ZF has a stronger case and improved gear train which corrects the comparatively weak counter shaft bearing assembly in the HSW 800.
 
Sure would like to find two USED or REBUILT ZF85s, rather than rebuild my HSW800s to have them fail again in the lifetime of the boat. I would like to make this an improvement, not a Band-Aid repair.

Anyone have any idea where I could find these? Internet searchs have not been productive so far...
 
Having been thru a failed port HSW 800-IV, I would urge you caution in any rebuilt ZF in this model group. When we got my transmission out, there was no way I would attempt to rebuild it in any way other than complete new internal hydraulics, new hydraulic lines and cooler, all new bearings, complete disassembly, and vatting the case. The counter shaft assembly is the weak link and when it fails it fills the case/fluid with metal particles from the bearings, races and shafting. There is no way to remove all that debris from the hydraulic system short of replacing it. By the time you buy all those parts from ZF, you will spend the cost of a new transmission.

No rebuilder I talked to could or would tell me what they replaced. It is, therefore, a fair assumption that the rebuilder only replaces the failed parts.

I wouldn't be fooled by warranties offered by anyone on a transmission…..even ZF. When you go thru a transmission replacement, you quickly find that most of the cost is in the labor to remove and replace the marine gear which wouldn't be covered by a transmission warranty. ZF's reputation is that they are difficult on warranty claims, usually pointing the finger at others in the repair process.

The difference between new (negotiated) and rebuild (parts and labor) isn't that much, so it was an added bit of assurance and an easy decision for me to choose new. My replacement came in the middle of the summer so a delay for a rebuild would have been difficult…..boat yards and mechanics are very busy here. By having the new transmission here, I was able to have it and the transmission cooler painted and ready. We hauled the boat out Wed nite, pulled the transmission Thurs morning, cleaned up and repainted the starter while the boat yard did something else Thursday aft, then put the new gear in Friday morning and were back in the slip by Friday noon. Finally, this was an easy replacement. I was able to separate the transmission by jacking up the front of the engine in the boat….i.e. there was enough room to move the gear forward and separate the coupler splines, then lift the gear up and out….but this is a 450DA. I don't know if there is room to do that on the 410DA, however, your larger deck access may make it easier to lift the transmission.

Good luck with your project………….
 
Thanks, Frank - all good points. The more I dig for info in preparation of this repair, the more I am leaning towards new. Its a more certain and likely to last approach, and keeps the repair window shorter, as you pointed out. Also, getting the transmissions 'split' and up and out does not appear to be impeded by overhead, side, or forward clearances.

I spent some time at the boat yesterday and re-verified fluid levels on both sides were in the operating zone, even removing a pint or so from the port side which was slightly overfilled.

Performed a test that had not occurred to me before, that was from a dead stop to engage one transmission at a time, and accelerate. Both sides 'let go' as the turbos spool up and the engines start making big torque. Port is more loose, but the starboard lets go as predictably. They are both in need of repair or replacement. Reverse works fine. The boat moves fine at hull speeds.
 
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Here is a quote from ZF for a rebuild vs. new for my ZF 280. I chose rebuilt.


Rebuild ZF 280 transmission. New materials to include oil cooler, oil lines, pump support and new coupler.

Labor $5075.00
Freight $716.00 <inbound and outbound>

New ZF 280 gear
ZF 280 $9214.00 includes oil cooler, lines, pump support and coupler.
Labor $400.00 <tear down and diagnose old transmission>
Freight $716.00 <inbound and outbound>

 
Jerry - that's quite a spread. I'd be likely to rebuild in your case if advised it was a reliable and common practice for that model transmission.


In my case, the best case scenario for rebuild (clutches only) is about $2000 each. With all bearings and seals? $3K each. Bad shaft and/or gears? More than new...all that for an HSW 800 V2 that are viewed as outdated gear by most I've talked to.

I can get brand new ZF 85 IVs for about $5500 each. Labor/storage/lift fees will be about $1000 less if the repair is done in one session vs. two haulouts 3 weeks apart.


  • Estimated total cost involved, rebuild assuming bearing and seals: ~$10K.
  • Estimated total cost involved, new with warranty: ~$14K.

I may even be able to sell the takeout gear for rebuild worthy cores. Anyone interested?

Say what you want about warranty, but if the boat is sold or traded in year #2 (...which was our plan before this fiasco) the boat will sell better and I will ask $10K more for it with the upgraded gear and remaining warranty. It actually becomes a valid selling point for the reliability potential for a soon to be 15yr old boat in otherwise great shape.
 
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How many hours were on your gear, when to had to have it rebuilt?? I just put a 2000, Sea Ray 460 with ZF drives 280 gears,(approx. 1500 hrs.) through survey, and the oil sample for the Stb. Drive cam up with Severe Copper levels, not sure if I want to continue with this purchase??
 
My gear was replaced at 800 hours. In my case, I believe my gear was compromised by user error. The "user" in this case, is a very good friend who, after a few beers, decided to pull one engine out of gear (to be funny!) while we were running at speed. I felt the difference immediately, looked down and pushed the tranny back in gear.
Obviously, my friend shouldn't have done that and I should have brought the engines down to idle and put it back in gear. I reacted quickly when I saw that the boat was out of gear.
problems started many hours later with slippage at higher rpm's and eventually it was every time I ran at cruise. I then tried to see what would happen if I came out of the hole aggressively and it slipped in a big way.
i will never know if that was the reason or not in that it took another 50 hours from the original incident to failure, but I had it rebuilt and it is running well.
My wallet is lighter but my friendship is intact.
 
Thanks, Very Good information, I think that same sort of thing might have happened with this drive, a shift into gear under high power load, at least I know what to expect in the future. A lighter wallet for me too!!
 
I'm not completely buying that the gear will fail if it is brought to neutral at speed then re-engaged; that doesn't mean operendus normalus. The prop is still spinning, albeit at a lesser rate and re-engaging will spool it back up in short order; there will be some slippage in the clutches but that is normal until fully engaged. If on the other hand at zero speed and one would drop in gear at high engine rpm's certain clutch slippage and reduced life at a minimum would result let alone the shock to the gear train. Dropping the gear from forward to reverse at speed, well, that's another pickup the parts story. The primary key to clutch engagement load, and frictional capability is the hydraulic pressure and that is what I see as the principal issue with these ZF/Hurth gears; we have no instrumentation for hydraulic pressure and temperature. If the hydraulic pressure is less than spec or the oil is aeriated the clutch pack piston will not compress the clutches and plates together with enough load to eliminate slip. Slipping at speed will put a lot of heat into the clutch packs and cause warpage in the discs and plate; I believe this is more the issue with the bulk of clutch failure. Warpage is indicated by the prop turning when in neutral or in extreme cases the gear is locked up and engagement into gear kills the engine. We simply don't have enough data to establish the forensics and ZF does not have a routine to check pressure.
As a side note a trolling valve intentionally drops hydraulic pressure and allows the clutches to slip for very low idle speeds; critical to these arrangements is a solid heat exchanger as the oil takes the brunt.
 
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ttmott said:
I'm not completely buying that the gear will fail if it is brought to neutral at speed then re-engaged;
Click to expand...

I too can testify that going to neutral at speed and re-engaging a transmission can cause damage. A number of years ago in a previous boat running Cummins 450C's with ZF transmissions, I was bringing the boat on its last trip of the season to the wintering-over yard. I was running along the coast at high cruise speed and overtaking a sailboat (under power) that decided to do a Crazy Ivan right in front of me (shame on me for not making a wider approach). Anyway, I panicked, grabbed a shifter instead of the throttle and took an engine in and out of gear. I missed the sailboat then proceeded to the harbor with nothing appearing to be amiss. When I started to make my approach I learned the engine was stuck in forward. I then had the pleasure of making the landing in a lot of wind with only one engine. The transmission was toast and had to be re-built over the winter at the cost of several big bills.
 
Progress!!! Picked up my new ZFs yesterday...can't wait to get them installed!!!

Question: I like the look of those grey cases, hate to paint them white. If left bare, would they corrode? Can they be clearcoated, instead?
 

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