Lower unit is gone but what about Upper?

[nckellys]

Hello, I have a 1986 Wellcraft Elan XL 19.5 ft. It has a 4.3L Merc 205HP(4 barrel) With Alpha I.
I bought this project boat last year. I've rebuilt engine, replaced coupler and replaced some upholstery. We've finally been able to use the boat on a regular basis but last weekend I hit a rock and tore up the lower unit on the Alpha I Gen I out drive. The Stainless steel prop has a large dent, most of the skeg was broken off, the prop shaft is bent and the top of the drive shaft is twisted off.

Even though is sounds like this boat has seen allot of use the hour meter reads 210 hrs. The engine was rebuilt because the water pump failed and the engine was run hot. A hole was found in the top of one of the pistons. Going through engine we saw little wear so I tend to believe the hour meter.

Any way, I need to replace the lower unit and was wondering if I should replace the upper as well. I hate to spend the money if I don't need to but I don't know how to evaluate the condition of the upper unit. I Know that when the drive was trimmed all the way up (trailering) and engine is run (like in the driveway with garden hose and muffs) I would hear some noise.

Any suggestions, Thanks, Brian

[Tech Support]

You should not run your engine when the drive is in the trailering position. This puts extra strain on the u-joints and can cause them to fail. You can remove the top cap on your upper drive and visually inspect the gears for any signs of chipping or cracks. Also, since your lower had the drive shaft shear off you need to make sure the broken piece is not stuck in the upper. With the drive off and the halves separated you can turn the upper input shaft and see if it feels smooth. When the lower unit takes a hit like you describe it is hard to be sure about the condition of the upper.

Tech Support

[nckellys]

Thanks for the info. Sorry for all the questions.

I pulled the cap off the upper and the gears show no sign of wear. The corners are there and edges of teeth look sharp. I have not taken upper drive off yet so I couldn't rotate shaft to see how it feels. To tell the truth I was hoping to avoid that if possible. It is difficult to get it back on because there is a swim platform over it. Maybe I should pull the platform off to aid in installation of out drive.

I'm beginning to think that I may just replace lower for now. This boat only has a few hundred hours on it. Upper drive looks great cosmetically. It a Model 205MR V6 1986 Wellcraft Elan XL 4.3L 205HP.

Is It easier (or better) to put both halves together first and then install to gimble housing? Or would it be better to just bolt lower half to upper with upper already installed?

The top part of drive shaft is still up in the bottom of the upper unit. All that holds it in is the friction of the new seal I put in this spring when I replaced the water pump. I could pull the seal out (destroy it) and it would fall out but I was trying to come up with a clever way to get it out with out wrecking the seal. I tried a strong magnet but no go.

How do I size the prop? I would like to buy one of your aluminum props and then see if I could have my stainless one fixed. The one that was on it was a Michigan SSM-249 C, 14 X 19 RH. Would it make sense to buy the same size. I could pull a tube pretty good but top end was only around 43 MPH (w/o tube). The prop was pretty well beat up with a lot of small dings. It was what was on the boat last year when I bought it. Merc manual states I should be at 39 - 48 mph at W.O.T. 4400-4800 rpm. I think this rpm was about what I saw at top end speed (43mph).

Thanks for your help,

Brian

[Tech Support]

Since your upper is already installed you can just bolt the lower up to it. It sounds like the prop you had works good for your boat so I would just stay with the same.

Tech Support

[crouchleyke]

I was in the same position.

Brian,
I was in the same position that your in about 4 years ago.
Low hours on a drive that had been hit. I dont think mine was as bad as yours as my lower shaft was just twisted not sheared off. I had a local rebuilder take a look at it. He sold me a used lower unit and "rebuilt" the upper based on the fact that the gears "looked" ok. Well it lasted about 4 1/2 seasons and then went blam a week ago. Apparently there was a crack in the upper box tooth set and it took this long to break. So you have a judgement call to make. I myself, travel far enough in my boat that going down can be a very very bad thing. If that is not an issue with you, you might want to try it and see how long it lasts. Another posible problem is destroying the engine coupling from a shaftline lockup. For that reward you get to remove the engine and install a new coupling. Thats my say in the matter. Check my thread as I progress with a complete unit that I just got from SDE. Cheers!