2004 Carver 466 MY Transmission Problem

[wkeith]

Hello All!
I have the Volvo 480 hp diesels with ZF model 280-1A transmissions. While under power at 1900 RPM my starboard transmission went to neutral. Tried unsuccessfully to get it into forward, but would go into reverse no problem. I have checked the coils, solenoid valves and valve body with no luck. Verified electronic shifter operational. This is a new boat to me and certainly was not counting on a major repair.
Suggestions please! Qualified mechanics in my area that might be able to fix.
Thanks,
Walter

[Viper]

Could be a few things; faulty distributor/control valve, solenoid, oil pressure, and worst case the clutch pack. Check wiring and plugs for corrosion. I assume you checked the condition of the fluid and the fluid level? Look for fine metal particles. Are you getting any rotation at all in fwd gear? You may have a trolling valve that should also be checked. Is this a Volvo EVC application? If so, when was the last software update done?

[wkeith]

Thank you Viper!
Less than 60 hours ago oil analysis done for survey, all clear. Trans oil new and full. No rotation except when under way with engine running and in neutral and other engine moving boat. Yes, EVC system. Surveyor had Volvo hand held device and said all items up to date.

[Viper]

So tied to the dock, if you turn on that engine and put it in forward idle, you have no rotation correct?

How have you determined that the solenoids are actually functioning? Are you able to swap the solenoid plugs at on the control valve to see if the problem switches to the other side?

[wkeith]

No rotation when put in forward. Swapped solenoids still no forward gear. Swapped coils and shifter when put in forward trans. went in reverse. So know coils good too.

[Viper]

That tells me that you're getting a command for forward so it seems to be isolated to the tranny. I assume you're getting no fault codes. Doesn't sound good but I'd be getting someone to check pressures before condemning an internal component such as the fwd clutch pack as that means tranny removal. The control valve would be easy to dismantle and check for restrictions. There is also an oil filter screen, and some also have a spin-on though if you're getting rotation one way, those should be okay, doesn't hurt to check though.

I have seen a clutch snap it's shaft which I assume was due to an impact the owner had the previous season. This is why you always advise the insurance company in an impact claim to remove the tranny, dismantle, and inspect in case there is internal damage. This adds a considerable cost to the claim so they usually say NO and hope it'll last a season or two. That's when you advise them that if the tranny fails in a season or two, it must be considered part of the original impact claim...get it in writing!

Fingers crossed it's something external.

[wkeith]

Good advice. Thanks for all your suggestions. Have ZF guy coming this week to do pressure checks, etc. We'll see. Will report back once problem resolved.
Thanks again!
Walter

[wkeith]

Well, the verdict is in. When shifted into forward the pressure drops to almost nothing and then tries to increase slowly. Shifting to reverse the pressure increases rapidly. The suggestion is to exchange for new unit instead of rebuild. Discovered someone has been into this transmission before me so don't know what that was about. Don't have final pricing yet, but he indicated $9 to $10K for complete job. OOUCH!

[Viper]

Shoot. That's too bad. Would be interesting to find out what failed, and whether that unit experienced an impact. Those units are pretty robust so a failure just on its own isn't very common. An eventual failure due to a past impact though is not uncommon.

Don't know why he's suggesting not rebuilding without opening her up first though. Well I kind of do but we won't go there!

I wonder if this would be covered under your insurance policy? Go out and hit something! Oooops, I didn't just say that