Blown V Drives 1991 Sea Ray 420

Hey guys first post here but not my first Sea Ray. Little back story. Boat is a 1991 420 DA. I purchased this one about 3 years ago got it for a pretty good price knowing that I would need to do some work to it. Purchased it in Pensacola and brought it across the gulf to the Tampa area.

Boat had 375 HP Cat 3208 Motors ZF trans and MPM ZF 160 V drives. Motors had seen better days and the decision was made that we needed to rebuild them. During breakdown it was discovered that previous owners did very little in the way of maintenance and the cost to rebuild was going to be upwards of 80k. I decided for that amount of money i would just go ahead and replace them with upgraded rebuilt 435 HP 3208's.

The boat came out of the factory weighing 20,000 lbs after 33 years and the addition of a Marlin tower the boat now tops 30,000 lbs. So hence the decision to move up in HP.

So now on with the story. The mechanic was paid to remove the old motors, prep the new ones and get them installed. All was good until the first run of the boat. 15 minutes out of the marina after being on plane for about 10 minutes i felt the starboard motor start to feel like it was struggling to keep up, speed dropping off and it was coming off plane. I pulled the throttles back to idle and the starboard motor immediately stalled out. Both motors put into neutral, restart starboard put into gear and again immediately shut down. Of course decision was made to limp back to marina on port motor. Got about half way back and port motor did the same thing. Dropped anchor called sea tow called the mechanic and then cracked a beer. Not much else to do at that point.

Got towed back in, mechanic came out to the boat, said the v drives needed a fluid change and bearing greased. Paid to have that done. Did sea trial with mechanic boat ran there was some noise from the v drives but it seemed to quiet down. Mechanic suggested to run the boat for a few hours not pushing it hard. We did that with the family seemed to go ok. Noise was still there. Went out a second time and started to get the same feeling in the starboard motor. Said F it limped back to the marina and pulled the port V drive out. Was not easy by myself. Why you might ask did i pull the port and not the starboard. Well i will tell you. The 435 hp Cat 3208 was the largest motor that was put into this boat and the clearance on the aftercooler is less than 1/2 inch. So to get the V drive out i would of had to remove the intake to be able to lift the back of the motor up high enough to remove the bolts holding the V drive to its mount. So V drive out on port side, called mechanic and told him i was bringing it to his shop so that we could break it down with me standing there.

At this point i just assumed that the bearings were fubar so i had gone ahead and ordered new ones. In case you are wondering all 8 of them cost right around 740.00. i have the numbers if anybody needs them. Moving along. Upon breakdown it was discovered that the bearing were fine but the gears not so much. Inside the case it was discovered there was rubbing where one of the gears was what i can only assume was rubbing on the housing. This indicated to me that motors were not lined up correct. Also of note and did intentionally leave this to the end was that i discovered while pulling the V Drive out that none of the motor mounts on the outbound side of motor were tightened down. All 3 motor mounts, not the studs that actually connect to the motor but the bolts that attach the motor mount to the stringers. So i can only assume that the with them being loose and the big ol motor moving around that it threw the shaft even further out of alignment and it just chewed those gears up.

The mechanic is coming out on Thursday to pull the intake on the starboard motor and the V drive, i expect that we will find that one in much worse shape. I have already checked and that motor is in the same position of not having the outbound motor mounts tightened down.

Now comes the big question. These gears are not available anywhere that i can find. There is one set available on ebay the guy wants 3500 per gear. I have heard of a few people replacing with new ZF all in one trans v drives. The drive shaft would have to be shortened and the motor would need to be adjusted to account for the 14 degree down as opposed to the 12 degree down. Has anybody made this swap or something similar. I would prefer to not have my boat on the hard for the rest of the year.

TY

3 years no issues, multiple long distance trips but only after the motors are replaced do both of the V drives fail and they failed within 15 minutes of each other. Both engines had the outside motor mounts loose. If there was loose metal in the gearboxes it would have shown itself a long time ago i would think.

Capt Ralph

Thank you for your insights. I will try to touch on all your points
The HP Rating specs on the old drive line is the same as the new from factory both hp values used the same drive specs only difference was the pitch of the prop. I went with the upgrade in HP only not engine change to keep it all on track with what Sea Ray did on the original models. The inside of the housing is worn which leads me to believe that the alignment was way off.
I have reached out to a ZF shop out in VA but will reach to Travis in the morning. I have no problem putting the new trans V drive in the boat. And have been quoted on both the ZF 260 IV and the ZF 268 IV. Both can handle the HP of the motors in the application that i would use them. The biggest change is that i will be going from 12 degree to 14 degree down so motor adjustment will have to be made. I will speak to Travis and see what he advises.

Engines were pulled and replaced on the hard. I was onsite for the on hard install and alignment but unknown on the water alignment.

the bearing on the port side appears fine but the inside of the case of worn. The starboard v drive is coming out tomorrow so we will see what it looks like as soon as it comes apart.

I have reached out to ZF and will reach out to the contact that the Captain suggested. The cost to cut new gears is far more expensive than the cost of new trans v drives

Update:

Got the Starboard side pulled out on Thursday. It is just as bad if not worse. Spoke to ZF they said the combination of not being aligned correctly once the boat was back in the water for 24 hours and the outbound motor mounts not being tightened down was the undoing of the V Drives, As noted above by @boatpoor once the gears started to each other is was just a matter of time. So by the end of next week i should know which direction this is going either new/used gears or the drives have to be replaced. Don't have much faith in the new/used as they have not been made for over 24 years and being that the gear ratio for the trans works hand in hand with the gear ratio from the V Drive the chances of finding the perfect match is pretty slim. Time will tell. Will update when i know more.

RER
The fact that the mechanic is thus far standing behind his mistake knowing that his helpers caused the problem, but understanding that the buck stops with him. I do still have faith in him. I have know him 3 years and others have know him much longer than that and all say that he is a stand up guy. I know a few that would have just run away or tried to blame this on any number of things but he has not done that. Will this feeling change? I hope not.

Yes