Hurth Transmission engagement issue

[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.

 

[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.

 

[ttmott]

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.

Not necessarily "shifting" issues but clutch engagement issues. It's that hydraulic pressure that compresses the clutch packs together and rotates the prop shaft. Air leaking through the filter cover is the primary culprit in these issues as that is the suction side of the hydraulic pump.
This goes back to clutch slippage issues and disc heating / warpage eventually causing the transmission to stick in either forward or reverse and killing the engine when placed in gear.
I'm not implying this issue might not be the valve body as @dtfeld has experienced but rather doing the testing and forensics before throwing money at it.

 

[dtfeld]

Pressure is more related to pressing/holding the disks together, not enough pressure and the disks will slip, and produce heat and quite a bit at full load. One reason I added temp sensors to mine...I think a huge oversight on the Part of Sea Ray. The amount of pressure to hold the disk it directly proportional to the amount of torque the gear is transmitting to the shaft/prop.

The control block is nothing more than a hydraulic valve. Moved one way, sends pressure to one side of the plates through passages in the shaft, or opposite for the other direction. Basically the same thing as you would find on a log splitter (huge over simplification). These things are so simple it kills me that there not a better diagnosis.

Bottom line, try to eliminate the cheap and easy things like shift lever travel/engagement, fluid levels/ filters air leaks etc, but if you follow the manual diagnostics...the pump/control block becomes a binary choice. It either works, or it doesn't.

I spent a lot of time researching this on Boatdiesel.com, and this is a fairly common issue. Boat starts having issues getting into one gear or the other until it takes a long time to shift, or not shift at all. Losing engagement at cruising speed was the other complaint. There was never any resolution or details to it other than "replace the pump/control block". Grrr.

I spent a year sweating this issue (hoping I didn't trash the gear), working through all these issues.

 

[Capt.Will]

ISSUE UPDATE:

I ordered a brand new Control Power Block from Transmission Marine. Two days later they called and said they thought they had one on the shelf, but were mistaken so he sold me a remanufactured Power Block for about $650.

I received and just installed it and so far at the dock the transmission engages immediately as it should. Like I stated before it would not engage until I shifted back and forth several times.

I feel really good about this so far but the real test will be this weekend when I take it out on the lake. Will update then after a few runs.

 

[dtfeld]

I’d like to know what remanufactured means. But regardless, replacing seems to fix the issue. Curious if it was the old style or new style solenoids?

Keep us posted!

 

[Capt.Will]

I’d like to know what remanufactured means. But regardless, replacing seems to fix the issue. Curious if it was the old style or new style solenoids?

The representative stated that it is rebuilt (remanufactured) and tested. It was painted a grey colored paint and seemed to be in a newer condition. It also came with a new Neutral Safety Switch installed. I had to transfer the temp sensor (I believe it is anyway) where a plug was on the new one.

 

[dtfeld]

Any idea who rebuilt it? Curious what they did because I've had the old ones apart. Not much to them...

If there is a procedure, i wish they would publish it

 

[Capt.Will]

ISSUE UPDATE:

Took the boat out twice this past weekend and each time the boat performed flawlessly. Into gear no problem. Response at any RPM was excellent. I will always keep in mind this issue that happened and expect the unexpected but just wanted to let everyone know that so far so good on this problem solved.