75 hp stinger seahorse- cracked lower unit

[OpA28]

I have a 75 hp stinger (not sure the year). The lower unit has a 2" diameter hole where it meets the prop. Im sure its not a gd thing but i was wondering if it would efect the perfomance of the motor. As is i cant get my 18 ft boat any faster than about 10 mph!! I was told that its cavitating n the lower unit is not the problem.

 

[Solittle]

Re: 75 hp stinger seahorse- cracked lower unit

Please, and big please at that, post a picture of this hole. Do you have any idea what rpms you are getting at WOT? Have you checked the oil in the gearcase? Compression? Firing on all cyl? Model number?

Oh and a big WELCOME - You do need to give us a bit more to work with to get any meaningful results.

 

[OpA28]

Re: 75 hp stinger seahorse- cracked lower unit

Ive looked all over the motor and cant find a model number. the only numbers i can find our on a small circular plate directly on top the motor. Not sure how i would figure the rpm's either, sry. The motor was only running on 2 cyl. when i bought the boat n i recently replaced one of the coils. All cylinders seem 2 b firing now. I was planning 2 give it a compression test this comin week. The boat feels like it starts gettin power to speed up then slowly drops back. Ive tried a couple of times 2 throttle up slowly and the motor seems to rev fine but never gets goin. Thanks 4 the quick reply and the welcome.

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[HighTrim]

Re: 75 hp stinger seahorse- cracked lower unit

That small circular plate you found is the frost plug, is it about the size of a quarter? The number on it is in fact your model number, post it and we will be able to get the year for you. You prop may be spun, draw a line across the hub and the prop, or use your cotter pin as a centre mark, run it in the water until you hear it "rev", then pull it out, if the lines are askew, the hub is spun. Pic supplied by FR. And btw, yikes, that is one hole. Check ebay for lower unit shells, should get one for about 100 bucks.

 

[OpA28]

Re: 75 hp stinger seahorse- cracked lower unit

The plate has a M at the top n the numbers r 75ELR78C j4951337. I also brought the prop 2 a marine store n they told me 2 put the motor in gear n c if i can turn the prop. The prop doesnt move on its own but i can turn it which is turning the pistons.

 

[OpA28]

Re: 75 hp stinger seahorse- cracked lower unit

Are the shells interchangable between diff. hp motors? If i was 2 buy 1 i could jst switch the gears between the 2?

 

[moterboat]

Re: 75 hp stinger seahorse- cracked lower unit

My rude 140 had a hole just like that and in the same place,but only half as big,I got a bad lower unit that had a broken skeg and gears and cut a piece to match the hole and had it heliarched on,went to napa auto parts and had paint mixed,they also put it into a spray can and you can't even tell it now..