3rd blown lower unit in 6 months...

[FishnFritz]

So I am on my 4th lower unit on my now Mairiner 200 in 6 months.  Don't know why they keep letting go. I have a SS 26p 3 blade laser II prop. The one that currently let go made a pop/bang noise and got stuck in forward gear. We were on the Potomac just past Quantico. It made for a long idle back to Leesylvainia.  I've gotten to the point to where as soon as I get a new lower I start looking for a back up.  I always change the gear oil when I put a new one on, and install a new water pump.  Dont know what to do to fix this problem.  And I can't really afford to keep replacing lowers like this.   The motor is pushing a Ranger 391V.  So if anyone would like to take a shot in the dark on this or throw in their 2¢. I would love to hear it. Thanks  

[BrianinMD]

Where you getting the replacements? Reman or OEM?

[Tim Kelly]

Is your prop bent and causing damage to the LU? Have you had the top of the motor checked to make sure the drive shaft to the LU is OK? Unlikely to be a bad run of LUs, check the constants.

[WIGuide]

If these are remanufactured lowers they should come with some sort of warranty. Like mentioned before, you might want to have your motor checked over just to make sure the problem is just with the lowers and not something with your motor causing it. 

[WRB]

Common denominator is the prop.

Tom

[fishnkamp]

Actually the common denominator is the prop and the engines' drive shaft.  Both need to be checked

[Clinton john]

Prop is bent or severely out of balance weight wise and or the drive shaft is bent.

 

Question do you tend to hit things often with your prop and or lower unit?

 

 

[FishnFritz]

Had the prop rehubbed last summer, I try to be as careful as I can about hurting it. I do run the river so it is like dodging land mines out there sometimes with floating debris. But other than that I run lakes with it. I have never hit the bottom with my prop. (Yet)  I've never felt any vibrations while out. I'm poor,  I can't afford a big money remanned lower. And I'm sure that is part of the problem. They have all been Craigslist specials or just kinda fell in my lap because some one knew someone. I try to be as easy as I can on them. I don't shoot for hard holeshots or max speed.  I do put new gear oil in them. And a new waterpump. But short of that I can't afford much more. I am saving for a new prop. Just wondering if I should change the pitch when I get a new one as well. 

[TheRodFather]

What about the other 2, what type of failures did they have?

[FishnFritz]

They both  made just about the same kind pop noise, when they went bad. But the damage was different. 1st , was still able to shift in and out of gear.  But made noise in gear at idle. Like the gears were over running each other. 2nd one had pretty much the same issue. 3rd one made the pop noise during a run from Smallwood park to Potomac creek, and got stuck in forward gear.  But I was able to idle back in gear to the marina.  Let me ask this. So I was told that lowers from a 150-200 would fit. But the gear ratio for the 200 lower was different than the 150/175. Is that a possibility for these lowers to keep letting go? I know that the first 2 were from Xr4's and the 3rd was from a Xr6.  The one that I just put on is from another Xr4.  I'm pretty much expecting this one not to last more than a few weeks.  

I'm also guessing that using the same prop on all these lowers if the gear ratio is different in them that I should probably be using a different pitch prop as well? 

[FishnFritz]

One more stupid question. This latest lower I got came with a 19p prop. I'm tempted to try it. But once again, it's in the same realm as "what's this gonna do"? Is it enough prop?  My other prop is a 26p.  Do I need to find something in the middle? And what's the effects of being over/under propped? What are the effects to the lower? 

[WIGuide]

Running a prop that's too small will give you blistering hole shot with no top end speed. You can run it that way, just keep an eye on your rpm's and don't over rev. I wouldn't spend money on new props or anything until you're sure you're lower will last longer than a few weeks and you won't be swapping again for a while. Then you can get your rpm numbers and find out what you need to do to prop it correctly. 

[WRB]

You shouldn't be over pitched with a 200 hp turning a 26P, 3 blade SST prop. Simple answer is what is the top rpm's, shouldn't be over 5,800. 1 pitch change is a lot, 25-27.

Start the engine with water ears and watch the prop spin, the gap between the prop and lower unit housing shouldn't change....no movement! If the prop has a bad blade you can't see that, needs to be inspected at a prop shop. I would try out another prop from the prop shop who repaired the hub.

Bent engine drive shaft makes a lot of noise and vibrations, you will hear it and feel that.

Tom

[FishnFritz]

top Rpm's with the old lower were 5600. But that was also a 187:1 gear case. This is a 2:1 gear case. Gonna try and get on the water tomorrow morning and see what this one is going to do. Went out yesterday for a little bit to get everything adjusted. I Didn't go over 40mph which is around 3500-4000rpms with the 26p. If I remember correctly. Didn't have any vibrations that i noticed.  It was rough with lots of boat traffic and stupid people on the lake. So really just had time to make sure this one wasn't making noise or having any other issues. And it didn't. Im going to try and take it easy with this one as much as I can. I changed the gear oil before I went out and changed it again when I got back. I just wanted to make sure there was no water intrusion. And there wasn't. So that was good.