Someone Rear Ended My Motor Lower Unit

[TSCTSC]

Dear all,

Over the weekend, some guy rear ended my boat trailer with my boat on it while waiting in line for boat launch. It dented his bullguard and apparently, he hit my lower unit or prop. We could not discern any visible damage to the motor or the lower unit except for one mildly dented prop blade. At the point of impact, the motor was trimmed up in anticipation for launch and the transom saver had been removed. From inside my truck, it felt like a small to moderate jolt. I have a cushioned hitch.

Once on the water, the motor was still able to start but would stall after 1 sec. This happened about 4-5 times. Eventually, after prolonged starting and pumping the fuel pump, it was OK. I was able to go from neutral to forward and reverse with no problem. Idling felt a little rougher but was stable. Once under power, at about 2000+ rpm, there were some funny burping sounds which resolved after 5 minutes. I was able to trim the motor up and down with no problem. Now, the motor starts OK and runs OK. It moves from neutral to reverse and forward as usual. Only thing is that I feel that the motor is idling a little rougher. Since the accident, I have not performed a WOT on it.

My questions are :

1. What do you guys think of the accident and the subsequent symptoms?

2. What should I do now? Should I send the boat to a dealer to have it checked out? What could be the potential problems after the lower unit is hit?

3. I guess the prop needs to be changed. Someone told me that in the long run, a dented blade on a prop is not good for the lower unit. Is the prop change something that I can do myself? If so, are there any particular concerns with a Yamaha 90 2 stroke oil injected 2001? It is a 90TLRZ model.

4. Would it be also a good time to ask the dealer to perform preventive maintainence for my motor if no damage is present? I believe that this motor has always been self maintained by the previous owner and has never been to the dealer. What does preventive maintainence involve and how long would the motor be in the shop on the average?

Any help and advice would be greatly appreciated.

[Wishin2BFishin]

The starting and running problems are (most likely) nothing to do with the accident. Could be old gas or something is wrong with the engine. Have the spark plugs been changed recently? If not they are not hard to change. If the prop got hit hard enough to bend it, the shaft that the prop goes on could be bent or damaged as well. If the prop is bent it will cause a vibration that could do some damage if you keep on using it. Most places can send your prop out and have it repaired and balanced for less than a new prop. If you have the money I would buy a new prop and send your old one out to be repaired then you would have a spare prop for an emergency. You can buy a special wrench that takes the big lock nut off the prop too and have them show you how to change it. It's not very hard to change the prop.

Best of luck...

[musky hunter]

If the accident only dented a prop blade I doubt that there is much damage to the lower unit. I concur that the rough running has to do with other factors not related to the accident. You must get the prop fixed, even a small imbalance could cause all kinds of problems: bearing failure, cavitation, vibration, loss of performance. I'd either change the prop or have it repaired immediatly.

[TSCTSC]

Thank you all.

If I change the prop, where can I go to determine the exact specifications of the prop that I should get aside from asking the dealer? Thanks!

[Wishin2BFishin]

The prop should have some numbers stamped on it where the blades are welded on. When everything was working okay before the accident did the boat go fast enough and seem powerfull enough to pull a skier? If not you may want to look into getting a different pitched prop for a replacement?

[blakjack23]

I had my boat rear ended when I was on the way to one of my club events about a month ago. After I felt the hit I thought for sure my lower unit was going to be messed up. I got out and the only thing I could see was a very small dent in one of the prop blades. For all I know it was there before, but I am assuming it was from the hit. I took it to the lake and mine also seemed to not want to idle well right away. I ran it like I normaly do and since the first five minutes I haven't had any problems with it.

[TSCTSC]

Interesting. So you had the same problem after being hit. Wonder what is the cause of that?

As for the prop, is there some place I can go to get information on what pitch prop I should get for the motor and boat. I have a 16 foot Mr Pike Lund and a 90TLRZ Yamaha 2 stroke. And what prop brand is recommended?

Thanks

[Valv]

Check your steering bracket and where tilt + trimm attaches to transom brackets and pivots up and down.

It is a weak spot and it might have cracked or bent. I've had many motors that got rearended and had center section completely gone.

[TSCTSC]

The whole thing looks ok to me. Maybe I dun know how or where to look. Can you tell me exactly which portion to look at and how it looks like? THanks.

BTW, what prop would you recommend for my rig?

Thanks

[JohnMickish]

The starting/idling problem probably comes from a little fuel being splashed into the intake runners after the jolt. I am assuming these motors where carborated?

[TSCTSC]

Yeah...I think they are carburetted.

So you think that could be the case? I mean, why doesn't the fuel splash when I am being jolted on the lake on big waves?

[BIG DS]

The running issue is due to the motor being jolted in the trimmed up position. It dumped the gas out of the float bowls. That is why you had to pump the bulb to get it running decent. You had to refill the float bowls with fuel. If the motor has never been taken to a mechanic to be serviced, chances are the carbs have never been taken apart and serviced. They should be cleaned and a new needle and seat installed usually each spring when it comes out of storage. It should also be properly winterized every fall ie: change lower unit grease, fog the power head, drain gas from carbs. Set an appointment and when it comes in the shop it should not be in the shop for more than a day if they have the parts in stock.

Depending on the prop, it may only have a part number stamped on it. Otherwise, there will be a number like 13x17 which is the prop diameter and the pitch. Either way it will be in the hub of the prop. Either on the outside by one of the blades as mentioned or on by the prop shaft. In which case you will need to remove the prop to get the number. If it seemed to run right at WOT, stay with the same prop as you had.

It would not be bad idea to take the boat to a dealer anyway. As mentioned the pivot point on the transom clamp should be checked. Also the transom should be checked for damage. A hit like that can put an extreme amount of torque on a transom. I hope you got some info from the other driver just in case.

[ChuckN]

Quote:

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They should be cleaned and a new needle and seat installed usually each spring when it comes out of storage.

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Geez, that's a bit much to re-build a carb every spring. Never had to do that to any of my boat motors if properly winterized.

[TSCTSC]

Thanks to all.

I checked the transom and as far as I could tell, there were no warping or cracks. I also could not discern any physical damage to the trim mechanism. In fact, I could not see any damage at all.

In any case, I will bring it to a dealer and have them check it out. I really like your explanation on why I had starting problems when I had the hit. It sounds the most logical.

As for the carbs, I think I will ask the dealer about it and at the same time do some service and checkup.

And yes, I got the guy's information.

[delmuts]

TSC. would you e-mail me at [email protected] thanks! del

[Trouthunter]

BIG DS's response sounds a little like that episode of Seinfeld where Jerry's car gets stolen by the mechanic...

[BIG DS]

That depends mostly on how much you use your boat. If it sits for a couple of weeks or more at a time the fuel will start to break down. Yes, even if you put in a fuel stabilizer it will break down. Once it starts to break down it starts to leave deposits in the carbs, even when properly winterized. The fuel stabilizer only slows down the process a bit. You may not need to clean the carbs each year, but once they start to plug and you start to run your 2 stroke lean and the powerhead burns down, suddenly some preventative maintenance doesn't seem so dumb. Just an observation.