Hurth Transmission engagement issue

[ttmott]

Well, I found Marine Parts Source online that I made the purchase of O-Rings and gaskets. I also ordered the filter cap assembly because mine is rusty and may be a problem. $177 FREAKING bucks for it. Outrageous. Even EBAY was pricing it for that amount. I sure hope this solves the problem.

Yea but if that cap doesn't seal and leaks air the trans will not work at all or if it does the clutches will probably slip.

 

[Capt.Will]

Yea but if that cap doesn't seal and leaks air the trans will not work at all or if it does the clutches will probably slip.

Exactly why I am biting the bullet and purchasing it. It sucks, but so does a boat you cannot use with such a short boating season.

 

[dwna1a]

My transmission (straight drive) was very low on fluid like yours. I replaced the fluid and found my problem. Everything was great for a month or so. Then it started again, RPMs stayed up, drive dropped down. I had warped the clutch plate at the first incident.

I could have sent it out for a rebuild but I got lucky and found a rebuilt. The old girl has been fine since.

Also, have you checked the props and shafts? I will post a pic of this shortly. The guy across the way thought his trans was shot. He went through hell to fix it. The photo will show you what he found.

 

[dwna1a]

Photos

 

[dtfeld]

By Orings do you mean piston rings?

They are metal and clip in place. They can wear a grove in the mating surface.

 

[Capt.Will]

By Orings do you mean piston rings?

They are metal and clip in place. They can wear a grove in the mating surface.

I ordered the O-Rings kit for the Fine Filter cap assembly. I believe the piston rings are part of the kit as well.

 

[dtfeld]

I ordered the O-Rings kit for the Fine Filter cap assembly. I believe the piston rings are part of the kit as well.

Im not sure about a kit but Orings for the fine filter will come with the new filter.

The metal piston rings are about $20 each and take about 5 minutes to replace once you have the control block removed (six bolts, so also easy). Transmission Marine as others have mentioned

 

[Capt.Will]

ISSUE UPDATE:

As stated above I removed the Control Block over the winter and replaced the Control Block gasket, Input shaft piston rings, Fine Filter w/O-rings and fine filter cap assy. Also drained and replaced the Transmission fluid.

Launched the boat a couple weeks ago and initially from start up the transmission would not engage again until I repeatedly moved the shifter back and forth from forward to reverse several times. Eventually engaging and I was on my way. Made that trip (7miles) across that lake with no issues with planing and docking.

Second trip out was this past weekend. Same issue. Transmission would not engage after engine start up again until I repeatedly moved the shifter back and forth from forward to reverse several times. Once it finally engaged I had a successful ride across the lake to my destination with no issues on plane or maneuvering at the destination dock.

So simply put, when the engine/transmission is cold the transmission will not engage until I shift several times to open up the fluid and circulate through the system. Note: After running the boat I will check the dip stick and I will hear a poof of pressure when removing, so I know there is pressure.

I am in desperate need of advice here. According to the service manual I am leaning toward a Control Block replacement. But would like to make sure with some advice from experience here. Thanks in advance, William

 

[Capt.Will]

Cheapest price I found for the ZF part is about $1300. I see several on EBAY but they do not appear to be ZF branded. Don't think I want to take a chance on an after market unit.

 

[PlayDate]

Cheapest price I found for the ZF part is about $1300. I see several on EBAY but they do not appear to be ZF branded. Don't think I want to take a chance on an after market unit.

Will,

I believe the lack of response is that you have exhausted the knowledge bank of CSR on the internal workings of ZF transmissions. I know ZF does a decent job of technical support so you may want to send them an email: zf@kgk.se

Most of my work on these things is pulling them out and replacing them. I never got into the rebuilding business because of the amount of time and warranty issues of doing rebuilds. Rebuilds on 25 year old transmissions raises no end of problems including rebuild tolerances and parts.

You get high marks for trying. It definitely is a pressure problem within the transmission. It could be something as simple as a check valve/ball not sealing until it is cycled multiple times. The good news is that once it engages .....it stays engaged. If it slips after it engages or drops out of gear.........that usually means a bigger internal problem.

I like your idea about the control block but dropping $1,300 to test the theory is a leap of faith. Hopefully ZF can at least help narrow it down.

I'm sorry I can't be of more help.

 

[Capt.Will]

Will,

I believe the lack of response is that you have exhausted the knowledge bank of CSR on the internal workings of ZF transmissions. I know ZF does a decent job of technical support so you may want to send them an email: zf@kgk.se

Most of my work on these things is pulling them out and replacing them. I never got into the rebuilding business because of the amount of time and warranty issues of doing rebuilds. Rebuilds on 25 year old transmissions raises no end of problems including rebuild tolerances and parts.

You get high marks for trying. It definitely is a pressure problem within the transmission. It could be something as simple as a check valve/ball not sealing until it is cycled multiple times. The good news is that once it engages .....it stays engaged. If it slips after it engages or drops out of gear.........that usually means a bigger internal problem.

I like your idea about the control block but dropping $1,300 to test the theory is a leap of faith. Hopefully ZF can at least help narrow it down.

I'm sorry I can't be of more help.

It is a leap of faith because I am definitely do not want to pull the boat/engine this season. If I have to I will during the off season while indoor stored.

The gentleman from Transmission Marine (whom I purchased the Control Block) stated that it could be several things. Piston ring wore the inside housing of Control Block, Control Block is failing internally, etc. According to the service manual all fingers point to replacing the Control Block. I feel that I have to try this one last ditch effort to save the season before having to pull the engine. I really, REALLY do not want to do that.

 

[dtfeld]

Cheapest price I found for the ZF part is about $1300. I see several on EBAY but they do not appear to be ZF branded. Don't think I want to take a chance on an after market unit.

I went through this same exact experience with my HSW800-IV and the good news is replacing the control block solved the problem for me. I went ahead and replace the other one preemptively, and they run like tops.

I looked high and low as to a troubleshooting guide for the control block, but unfortunately, all road pointed to replacing the control block. New ZF85's are about $8k each, but the electrical control block was about $800 delivered with a new gasket and 3 new piston rings.

I took the units apart, and found some wear in the pump, that I guess might lower the pumps pressure enough to cause a problem. With the HSW800's mated to the CAT 3126, this transmission is right on the edge of being able to handle all the torque.

 

[Capt.Will]

I went through this same exact experience with my HSW800-IV and the good news is replacing the control block solved the problem for me. I went ahead and replace the other one preemptively, and they run like tops.

I looked high and low as to a troubleshooting guide for the control block, but unfortunately, all road pointed to replacing the control block. New ZF85's are about $8k each, but the electrical control block was about $800 delivered with a new gasket and 3 new piston rings.

I took the units apart, and found some wear in the pump, that I guess might lower the pumps pressure enough to cause a problem. With the HSW800's mated to the CAT 3126, this transmission is right on the edge of being able to handle all the torque.

Reports like yours are definitely encouraging and I really, really hope that this solves the issue. I have had to pull and engine before in a smaller boat and it is an absolute lose sleep at night pain in your gut feeling the whole process. Plus, the cost would just about break me. I am hopeful and will press on with this current momentum forward.

 

[PlayDate]

Reports like yours are definitely encouraging and I really, really hope that this solves the issue. I have had to pull and engine before in a smaller boat and it is an absolute lose sleep at night pain in your gut feeling the whole process. Plus, the cost would just about break me. I am hopeful and will press on with this current momentum forward.

Will,

I'm glad you said it. The 330 Sundancer is the worst SR ever to work on. I'm a big guy 6'2" 220 lbs. and it is impossible to do even simple things on that boat for me. You need a midget mechanic to just do a tune up and don't even get me started on changing the impellers.

I don't know what SR was thinking when they put big blocks in that hull.

I hope the control block solves the problem and it is worth the expense because the alternative of pulling an engine is far worse.

 

[ttmott]

I can't see where you measured the system pressure. I don't believe you really know anything until the hydraulic operating pressure is known.

 

[dtfeld]

I would check the pressure, but there is something in these control valves that is flakey, and there isn’t enough info from ZF to diagnose as detailed as I would like. It really is expensive trial and error. At the root it’s either mechanical linkage, hydraulic (to much/not enough fluid, leaks, bad pump etc or in some cases electrical. I eliminated everything I could before replacing the pump/control valve.

There are a couple pressure relief valves inside (really just a spring loaded piston) that a suspect sticking or not sealing. Your guess is as good as mine.

But at the end of the day, problems solved with a tranny to live another day.

 

[PlayDate]

I can't see where you measured the system pressure. I don't believe you really know anything until the hydraulic operating pressure is known.

I can agree but I didn't think there was a test port for pressure on the ZF63 until I found this:

https://www.sbmar.com/articles/zf-63a-pressure-and-temperature-sender-locations/

Even given that........you would still need to know what the nominal pressure was at that test point to evaluate the whether the pump/valving was working properly.

Certainly would be worth looking into........

 

[dtfeld]

I believe the pressure/rpm curves are in the manual. I'll post up when I get home, but I want to say 325 psi at cruising rpm?

 

[ttmott]

I can agree but I didn't think there was a test port for pressure on the ZF63 until I found this:

https://www.sbmar.com/articles/zf-63a-pressure-and-temperature-sender-locations/

Even given that........you would still need to know what the nominal pressure was at that test point to evaluate the whether the pump/valving was working properly.

Certainly would be worth looking into........

I believe the pressure/rpm curves are in the manual. I'll post up when I get home, but I want to say 325 psi at cruising rpm?

Look at post 11 in this thread. The Hurth pressures are slightly lower than the ZF pressures.

 

[PlayDate]

So….if I read that chart correctly at idle the pump should be pushing 145 psi. Much less and that could cause shifting issues that the OP is experiencing.

As @dtfeld noted….. max pressure is around 325 psi at 2,000 rpm. What is perplexing is that if idle is marginal….it is hard to imagine that 2,000 rpm would be nominal.

I’m curious what the pressures are.