DPS-A wont go into gear

Greetings. I’m new to the forum but did some reading on older posts and figured you guys might be able to help me.

Wife and I just purchased a used 2011 Cobalt 232 with a 5.7Gi and a DPS-A drive. Boat only has 50 fresh water hours on it so it’s about as new as you can get. Last evening, we went out for a cruise. Boat ran flawlessly most of the trip. Then, my wife asked me to stop so she could take a picture of the sunset. When we went to get back underway, the throttle revved up but no forward motion. The drive did not engage. I tried forward and reverse to no avail. I tried messing with the manual warm-up button. No joy. At that point I got a buddy on the phone and arranged for him to come give me a tow back to my boat lift.

Today I set out to do some diagnostics:

I reached up behind the control unit while I moved the throttle lever forward and aft. I was able to discern for sure that both the throttle and gear selector cables were moving. I worked my way aft to the transom. Again, the throttle cable worked fine, as expected, and the gear selector cable seemed to be OK too because it moved slightly when moving the throttle/gear control. Then it was time for me to jump in the water. I lowered the boat so the drive was at eye height, and removed the rear cover. I’d hoped to find the cable disconnected, which would have been an easy fix. No such luck. Cable seemed firmly attached to the bellcrank, and the bellcrank connected to the eccentric. I had my wife move the throttle/gear selector forward and aft as I watched the eccentric rotate from approx. the 1:00 position to the 5:00 position, with neutral at approximately 3:30. Then I lowered the boat some more to fully submerge the lower drive and had my wife start the engine and run through the gears. Again, the linkage assembly worked flawlessly, with no bangs, grinding, or otherwise objectionable sounds, but the props never moved. When shut down the props turn freely in both directions.

Cable is good and control unit is good. Problem seems to be inside the drive.

I’ve gone about as far as I can go with my limited knowledge of these drives. Anybody got any ideas where I go next?

Drain the gear oil into a clean container. If it is clear and is not contaminated, it can safely be reused.

Remove the shift mechanism (at the rear of the transmission) and look at the shift shoe!



This will cost you three O-rings and one fill port gasket only.


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It'll be Wednesday before I can tow the boat back around to the ramp to get it on the trailer. I'll plan to get it back on land and drain the lube to look at the shift shoe this weekend.

Regarding the O-rings, are these pretty standard? Or are they Volvo-Penta parts? Just need to figure out where I need to get them from.

Thanks

The O-rings and gasket will need to be OEM or Sierra.
You will need one O-ring for the shift mechanism, one for the dipstick and one for the drain plug…... and a gasket for the fill plug.

You can find the p/ns here.

https://www.marinepartseurope.com/en/volvo-penta-explodedview-7749307-44-10681.aspx


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OK. Pardon the delay. Took longer than I expected to get the boat back on the trailer where I could work on it.

Removed Props, drained Gear Oil (nice and clean), and pulled the shifter/eccentric to look at the shoe. I'm certainly no expert but it doesn't look worn or damaged to me.

I'm trying to upload pics and can't seem to get them to load.

Trying pics again

Photos are not visible!


With the shift mechanism removed, rotate the propellers.
Does the sliding sleeve (the part that the shift shoe operates up/down) rotate?

I gave up and turned it over to the local Volvo mechanic. I passed on all the diagnostics I did (per your suggestion). I should have a final determination on the cause this week. He thinks it's the shearable coupling between the upper and lower units. Sounds like that's where you were leading me too. Still have no idea why that would shear, but it is what it is. I'll let you know what the final repair is.

Suggestion:

Ask for and be willing to pay for proper diagnostics up front.
Upon receiving proper diagnostics, and ONLY upon receiving a work scope "quote" that refers to the diagnostics, do you sign the work order authorizing the repair.
If the repair does not correct the problem, then ask that they explain the charge to you!


Good luck, and let us know what the problem was!

By the way...... did you try what I suggested in post #8?


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I didn't. I brought it over to the shop before I saw your post, but I did relay the message. They're a pretty reputable shop, but I'll stay on top of em!

OK. Just spoke with my guy at Washburn's Boat Yard in Solomons MD, in case you want to check on their reputation thru Volvo (they are a certified Volvo Penta repair shop). He did say that the shear coupler was sheared. He thought that was that, and we could go replace it and move on, but then his mechanic said there’s another issue…. With the lower unit removed and the drive on the stand (in gear), he said the drive turns at the prop approx. 2 turns before it starts to bind. When they loosened the top bearing cover it turns freely with no bind. Tighten it back up and the bind returns. He’s thinking that suggests perhaps a bent main shaft. That statement made my wallet hurt…. I’m going to stop by tomorrow to have a look and witness this behavior.

I’m having a hard time thinking of how we went from cruising in 60ft of water to having the whole inside of the drive twisted up. I didn’t hit anything. I went from a mid-cruising speed to stop. I didn’t accidentally engage reverse. I don’t even remember putting it to neutral in an obvious aggressive manner.

Does any of this make sense? Any questions I should ask specifically?

In order to shear the vertical shaft spline coupler, you'd need:

....... an impact against a submerged object (props would tell the story)
....... tremendous and excessive torque force against the drive.
....... lower unit gear failure that caused the gears to lock up.
....... just plain ole fatigue failure.


Here's what he is talking about.
This is for the DP-SM..... as I do not see a DP-SA listed.
http://www.marinepartseurope.com/en/volvo-penta-schematics-MarineDrivesTransmissions.aspx

I once had a Volvo drive AQ110 that the P/O had had an OOPS with and hit something necessitating a new prop. I ran that boat for a season and a half before the forward bronze drive cone sheared off. Apparently the P/O had caused a crack in the cone but the tolerances/fit allowed the drive to operate with the cracked pieces of the cone lined up and engaged... sort of a high friction clutch (or a dog clutch with lots of tiny teeth). Then one day ..... :-( Soooo, what you are seeing could be the result of an impact in the past.

sandkicker said:

.................. Soooo, what you are seeing could be the result of an impact in the past.

Click to expand...

That is very possible.
I have removed spline couplers that have been badly twisted, yet they still performed.


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The guy at Washburn's did say the coupler that sheared did indeed look like it was twisted. He said it's possible that the previous owner hit something, or became airborne and the landing caused the damage, but it didn't quite fail....

I get the coupler damage. That at least fits the behavior, but I'm stumped how the upper bearing is now binding.

....... but I'm stumped how the upper bearing is now binding.

Click to expand...

Please elaborate on this “binding“!

Within the upper transmission unit, and as a component of the cone clutch, there is a sliding sleeve.
The sliding sleeve is what pulls itself into one of the two rotating gear cups once initial friction is achieved.
The sliding sleeve is operated (up/down) by the shift shoe.
The shift shoe groove in the sliding sleeve is eccentrically cut, meaning that if you were to rotate the sleeve you would see that the groove changes position.

If a person was to rotate the vertical shaft, it may be possible that this alleged “binding” is a result of the sliding sleeve rotation and the eccentrically cut groove causing intermittent resistance against the shift shoe!


Your mechanic should understand what I just suggested.


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I stopped by the shop yesterday to witness the binding at the mechanic was speaking of. I have to correct my previous statement. He did not have the lower unit off, and was not turning the vertical shaft. The entire unit was assembled and he was turning the input shaft from the engine. In reverse and in neutral the input shaft would turn freely. When in forward, it would turn just over one revolution and bind. He could over come the binding and get the shaft to turn further, and it would bind again in just over 1 revolution. I thought it was curious that it would bind just over one revolution. If there were a problem with the main vertical shaft, on a 1.95 drive, it should bind just under 2 revolutions. The mechanic agreed. When the he loosened the top 4 bolts on the cover over the top bearing, the drive would rotate freely. No binding.

This is when things got interesting. He removed the top cover entirely, exposing the upper bearing and race. With the drive-in forward, he turned the primary input shaft. It was difficult to see at first but the bearing race was very slightly lifting about once per revolution. I wish I had a dial indicator to see how much it was moving, but I'm guessing it was maybe .020"-.030". That is what was causing the binding. The top cover, with the factory installed shims, was a putting pressure on the upper pairing when it was moving up-and-down. When the pressure of the top cover was released, the bearing was free to move.

I don't know if this movement is typical or not. It seems that it probably shouldn't be moving up-and-down, so maybe something is indeed bent. I haven't been able to connect the causal dots between the sheared coupler and this problem in the upper unit. Neither can the mechanic. How did this happen?

My next question is, can I put a smaller shim under the top cover and re install the drive and see what happens?The binding is easily overcome with just hand applied torque. Clearly my 5.7 could handle that without even noticing it, but I assume the binding would eventually eat the bearing.If I put a slightly smaller shim it would relieve the binding in the high position, but would also not support the bearing in the low position. I know that is probably not recommended, but the alternative is a new upper unit. If it MAY die anyway what do I have to lose?

Thoughts?

..............................

painkiller said:

I stopped by the shop yesterday to witness the binding at the mechanic was speaking of. I have to correct my previous statement. He did not have the lower unit off, and was not turning the vertical shaft. The entire unit was assembled and he was turning the input shaft from the engine. In reverse and in neutral the input shaft would turn freely. When in forward, it would turn just over one revolution and bind. He could over come the binding and get the shaft to turn further, and it would bind again in just over 1 revolution. I thought it was curious that it would bind just over one revolution. If there were a problem with the main vertical shaft, on a 1.95 drive, it should bind just under 2 revolutions.
The 1.95:1 is a result of the over-all reduction. In other words, the combined reduction of both the upper unit and the lower unit.


The mechanic agreed. When the he loosened the top 4 bolts on the cover over the top bearing, the drive would rotate freely. No binding.
That allowed the upper driven gear bearing to become free.

This is when things got interesting. He removed the top cover entirely, exposing the upper bearing and race. With the drive-in forward, he turned the primary input shaft. It was difficult to see at first but the bearing race was very slightly lifting about once per revolution. I wish I had a dial indicator to see how much it was moving, but I'm guessing it was maybe .020"-.030". That is what was causing the binding. The top cover, with the factory installed shims, was a putting pressure on the upper bearing when it was moving up-and-down. When the pressure of the top cover was released, the bearing was free to move.
** The shims between the upper bearing and the top cover are there to place a "squeeze" on that outer bearing race as to prevent it from rotating.
We shoot for an approximate .003" squeeze.


I don't know if this movement is typical or not. It seems that it probably shouldn't be moving up-and-down, so maybe something is indeed bent.
Possibilities:
again.... shift shoe with the eccentrically cut groove.
bent upper gear unit's vertical shaft.

I find it interesting that the symptoms do not show up while turning the drive while in REV.

I haven't been able to connect the causal dots between the sheared coupler and this problem in the upper unit. Neither can the mechanic. How did this happen?
Your coupler does indeed show signs of having been twisted prior to shearing.

My next question is, can I put a smaller shim under the top cover and re install the drive and see what happens?
See ** above.

The binding is easily overcome with just hand applied torque. Clearly my 5.7 could handle that without even noticing it, but I assume the binding would eventually eat the bearing.If I put a slightly smaller shim it would relieve the binding in the high position, but would also not support the bearing in the low position.
Yes, and if the outer race was to start spinning (from lack of squeeze), it will eat away at the housing.


I know that is probably not recommended, but the alternative is a new upper unit. If it MAY die anyway what do I have to lose?
Let's say that the upper vertical shaft is bent.
If the mechanic is savvy and is not seeing you as an "open check book", that shaft can be replaced without the need to do any time consuming set-up and/or re-shimming.
However, the top nut controls the Up/Down movement of the vertical shaft, and may require adjustment and/or a different nut value.
See my red arrow in the first image below.

These nuts are available in an array of thicknesses.
The time required to adjust this is minimal.

Click to expand...

Sorry for the long delay. Boat is finally fixed and in the water. We now have 5 drama free hours without dying in the water and needing a tow. I think the worst is over….

So, what happened?

My Volvo guy read this post and agreed that the bent shaft thing being the cause of the binding didn’t seem right. He swapped shift shoes and nothing changed. Then he ordered the whole shift mechanism (the 4-bolt assembly that holds the shoe). That fixed the problem 99%. He said that, in FWD (as before) there was still a perceivable (barely) bind, but before you really needed to push though it to keep it turning. Now he says you probably wouldn’t register the difference on a torque wrench. This was with the old shoe or the new shoe. The issue was in the shift mechanism. Not the shoe. This all still seems weird to me, but the boat is up and running again. Hopefully it stays that way!