Counter rotating swap for standard

[fsujack21]

I have a 99 mariner 150hp counter rotating 2 stroke on a an old 20' Mako center console. The lower unit is cracked and completely destroyed. I'm having trouble finding a replacement counter rotating lower unit. I have found many standard rotating units in good condition and I was considering converting. I have done a lot of research but I have gotten conflicting results as to what exactly is involved in doing this conversion. So I'm hoping that someone can definitively answer if there is anything more than swapping the counter rotating lower unit and prop to a standard lower unit and prop??

Thanks
Jim

 

[tazrig]

Re: Counter rotating swap for standard

The only difference in a counter rotating drive is in the lower unit. If you change the entire lower unit and the only difference is counter rotating to standard rotation and you change the prop from counter to standard you should be fine. How did the lower unit get trashed? I ask only because if you were going full tilt and all of a sudden you hit something that caused the whole engine to stop you might have damaged the head of the engine as well. You might want to check out the top half to make sure it's ok before you invest anything in another lower half. After you pull the lower half check that the flywheel still turns and then check the head for compression.

 

[fsujack21]

Re: Counter rotating swap for standard

First off thanks for the reply. I have heard that is all it takes from multiple sources but I had one Merc mechanic tell me it was way more involved and I needed different controls and a few other items. I felt like he was full of sh@t but I wanted to be sure.

To answer your question the top half runs like a champ. Compression etc is just fine. Funny story as to the damage. I bought the engine used off eBay last year knowing that the tilt trim motor was bad. I'm pretty mechanically inclined so I figured it would not present a problem. I had my boat stored at a yard about 45min from my home and had the motor shipped there. During the course of mounting the motor and fixing the trim motor I got very frustrated with both the commute to the yard and the constant aggravation of not having a certain tool that would be in my garage or having my engine hoist sink in the grass of the yard, when I have a nice two car concrete pad in my driveway at home. Turned out that the tilt trim motor mounting bolts were so corroded that they were seized and I needed to send the entire housing to a machine shop to have the bolts properly drilled out and retapped. Well in my infinite wisdom I was so frustrated with my working environment that I decided to drive my boat home so that I could expedite the repairs when I got the tilt/trim assembly back from the machine shop. So I manually lifted the engine and engaged the trailerring tab and tied the motor down with several ropes and straps.Well along my journey I hit a big bump and all of my ropes/straps failed and the outboard came crashing down as I was driving 45mph. I pulled over checked it out and aside from a 1" chunk missing from the bottom of the skeg everything seemed fine. Unfortunately after I completed my repairs and after a sea trail I realized that the housing was cracked and the lower had complete water intrusion.
So now due to my frustration/impatience I'm in the market for a replacement lower. Sometimes educations are very expensive! Lol

 

[Chris1956]

Re: Counter rotating swap for standard

Well, SEI will sell a new gearcase (std or counter, your choice), for that motor. They are not a lot more expensive than used units.

Std controls pull the shift lever forward for forward gear. You can check your controls to see if they are std or what. You will likely have more choices of props, with a std gearcase.

 

[fsujack21]

Re: Counter rotating swap for standard

Looked into SEI but they don't sell a counter rotating lower for my engine. On their website they only sell the counter rotating for the 3.0L. In regards to your comment about std controls I'm not clear on what you meant. I didn't know that there was any other option than standard controls. But to verify that they are standard the test is that the shift lever moves fwd in fwd gear? I'll test that out thx.

 

[Chris1956]

Re: Counter rotating swap for standard

yes, shift lever moves forward on std controls to put motor in forward. Do you really want counter rotating or is it just to avoid buying new prop?

 

[fsujack21]

Re: Counter rotating swap for standard

I'm looking to convert to a standard rotating. The availability and price of the std rotation is my motivation. I have a stainless steel prop with less than 30hrs on it as well as an aluminum spare that are counter rotating so that is a factor but even the cost of buying a new prop and selling the ones I have still seems worth it. My only concern is that I don't want to go ahead and do the conversion if there was some unforeseen expensive change that needed to be done also that would make the conversion cost prohibitive.

 

[tazrig]

Re: Counter rotating swap for standard

First off thanks for the reply. I have heard that is all it takes from multiple sources but I had one Merc mechanic tell me it was way more involved and I needed different controls and a few other items. I felt like he was full of sh@t but I wanted to be sure.

To answer your question the top half runs like a champ. Compression etc is just fine. Funny story as to the damage. I bought the engine used off eBay last year knowing that the tilt trim motor was bad. I'm pretty mechanically inclined so I figured it would not present a problem. I had my boat stored at a yard about 45min from my home and had the motor shipped there. During the course of mounting the motor and fixing the trim motor I got very frustrated with both the commute to the yard and the constant aggravation of not having a certain tool that would be in my garage or having my engine hoist sink in the grass of the yard, when I have a nice two car concrete pad in my driveway at home. Turned out that the tilt trim motor mounting bolts were so corroded that they were seized and I needed to send the entire housing to a machine shop to have the bolts properly drilled out and retapped. Well in my infinite wisdom I was so frustrated with my working environment that I decided to drive my boat home so that I could expedite the repairs when I got the tilt/trim assembly back from the machine shop. So I manually lifted the engine and engaged the trailerring tab and tied the motor down with several ropes and straps.Well along my journey I hit a big bump and all of my ropes/straps failed and the outboard came crashing down as I was driving 45mph. I pulled over checked it out and aside from a 1" chunk missing from the bottom of the skeg everything seemed fine. Unfortunately after I completed my repairs and after a sea trail I realized that the housing was cracked and the lower had complete water intrusion.
So now due to my frustration/impatience I'm in the market for a replacement lower. Sometimes educations are very expensive! Lol

Thats too bad, but if it makes you feel any better we've all done stuff like that and for the ones who haven't they will. You might try one of these to help assure that never happens to you again:

transom saver - iboats

Also if you switch both the lower unit and the prop then your shifter should be fine. ie: fwd =fwd and rev = rev

 

[Chris1956]

Re: Counter rotating swap for standard

Gee, if your PTT works, you don't need no stinkin Transom Saver. If your transom breaks from motor bounce on the road, it was bad to begin with.

 

[wired247]

Re: Counter rotating swap for standard

I'd keep it counter rotating. You can get real good deals on counter rotating props sometimes.

 

[fsujack21]

Re: Counter rotating swap for standard

Yep. If the tilt trim assembly was actual on the motor instead of at the machine shop when I transported the boat then we wouldn't be having this conversation. Oh well, like I said costly mistake, but it wasn't my first and it surely won't be my last. Thanks for the help.

 

[fsujack21]

Re: Counter rotating swap for standard

I'd keep it counter rotating. You can get real good deals on counter rotating props sometimes.

I would if I could actually find a decent counter rotating lower to replace it as I have two good props for it already. But finding the lower has been the issue and the few that I have found were significantly more expensive then the standard ones that I've seen.

 

[tazrig]

Re: Counter rotating swap for standard

Gee, if your PTT works, you don't need no stinkin Transom Saver. If your transom breaks from motor bounce on the road, it was bad to begin with.

I suggested a transom saver (don't know why they call them that) to prevent his motor from bouncing off it's lock and hitting the road again. If his transom is that weak he's got bigger problems then I care to think about.

 

[wired247]

Re: Counter rotating swap for standard

20'' LH 1.87 Bobs Nose Cone 2.5L 200 Lower


FWIW I dont use a transom saver. I use 2 qty 6 inch long piece of heavy walled 5/8" ID PVC slipped over the outside lift ram dampeners. Lower the motor on to them and they keep the motor up with no stress on the hydraulics. Thats since I got fancy. I used to just shove a 2x6 piece of lumber in there.

 

[Chris1956]

Re: Counter rotating swap for standard

Do you realize the load and change in load your hydraulics take as you blast across the water in that Checkmate? I cannot imagine the hydraulics would be subjected to anything near that kind of loading, as you bounce down the road.

 

[wired247]

Re: Counter rotating swap for standard

Do you realize the load and change in load your hydraulics take as you blast across the water in that Checkmate? I cannot imagine the hydraulics would be subjected to anything near that kind of loading, as you bounce down the road.

Shock loads from hitting bumps and such will be worse than a constant load from blasting the water out of the river. That and if you are on the water and your seals leak you just make an adjustment. On the road you wont notice your skeg is making furrows in the highway until its too late. Ive known a couple of people over the years that wasted their skegs on the road because their hydraulics drifted down from blown seals or bad check valves.

 

[jbcurt00]

Re: Counter rotating swap for standard

Um, aren't they TRANSOM savers? For the extra leverage a motor in the lifted position imparts to the transom?

Not skeg protectors just in case I get a hydraulic leak......

Although the ram pipes probably help too.

 

[wired247]

Re: Counter rotating swap for standard

If your transom breaks from driving around with a motor on it you have some transom problems you need to address. Ive seen some pretty damaged lower units from the use of transom savers. Ive never seen a damaged transom from not having used a transom saver. Ive never used one in 33 years of boating. If I was using a Johnson I'd use the factory lock levers and did for years to hold the motor up. Mercury V6s don't use those and only have one flimsy lock on one side that is really only good for servicing the hydraulics. The ram props work well for it. I'm a lot more concerned about the hydraulics popping a leak than from my highly reinforced transom getting shredded.

 

[Chris1956]

Re: Counter rotating swap for standard

Gee, the load on my hydraulics when blasting across the water changes from moment to moment, as I cross waves, or skip from ripple to ripple. I cannot imagine the load comes close to that when pulling the boat on a trailer. I usually leave the motor about 2/3 down, and she doesn't even bounce.

 

[wired247]

Re: Counter rotating swap for standard

I dont have to imagine it. Ive seen hydraulics that lowered on their own through leakage and destroyed lower units by dragging them on the ground. You can do whatever you feel comfortable doing. I will chock my hydraulic rams.