Please help mercury lower unit

terriblebikermike666 · Mar 27, 2011

please help. im in a sticky situation. i have a 1987 mercury black max 135 V6 engine my lower unit has the skeg broken off and the gear casing is cracked. it came on my boat this way. the rest of the motor is good. it has 125psi on all 6 cylinders and runs good. the lower unit is still functional. has forward nutrel and reverse. I am wondering which lower units are interchangeable, so i can broaden my search for a lower unit. the local mercury shop was not help and tried to charge me for knowledge eventhough ive bought countless numbers of parts from them. they are stiff. any input will be extremely helpful. I am a new member to this iboats forum site and i would like to say hello to all. this seems like a very practical useful site for the average boater!

thanks: mike

terriblebikermike666 · Mar 28, 2011

Re: Please help mercury lower unit

ive found plenty of information on lower units but noting telling me from what year to what year will fit my application. this is frustrerating

carholme · Mar 28, 2011

Re: Please help mercury lower unit

Mike;

What is the s/n of your engine?

Gerry

j_martin · Mar 28, 2011

Re: Please help mercury lower unit

Most V6 Lu's will fit that engine, including the smaller diameter XR/4 and the high performance/racing stuff. Pretty much anything off a 2.0, 2.4, or 2.5L engine from 135 - over 200 hp. The later ones are better. There are aftermarket new ones also.

With S/N these guys will look in their crystal ball (documentation) and tell you exactly what you have, including gear ratio so you can match it up.

If it's been hit that hard, be sure you look over the mid real close, also. It would be a shame to get it working good just to have it break off the clamp and drown.

terriblebikermike666 · Mar 28, 2011

Re: Please help mercury lower unit

yes the serial number on my aluminum frost plus and the motor mount is 0B104308
it doesnt look like its hit THHHHHHHHHAAAAATTTTTTTT hard. it had no gear oil in it. i just filled it up last night and ran it and no leaking. the motor is now off the boat. the mid section doesn't move at all and feels really solid and i don't see any cracks anywhere after inspecting it for like 2 hours. i got a price of 900$ to weld it and rebuild the whole thing. is it worth it. since i paid 700$ for my boat, motor and trailer. i want this motor on my boat because my other mercury 90 tower of power wont push the boat good enough. I am willingly open to all suggestions since its almost boating season.

thanks: mike

carholme · Mar 28, 2011

Re: Please help mercury lower unit

Mike;

The engine comes up as a model number 1135726:

Parts listing:

http://www.crowleymarine.com/mercury-outboard/299.cfm

Service Manual:

P/N 90-976583

If you have run it and it is not leaking, where is the crack? If you know the welder is reputable and it is a repair that you will not have to worry about distortion of the case, why not just strip it down, have it welded and re-build it yourself, especially if you feel the guts are in good shape.

I will PM you the name of a guy local to your area that you may want to talk to who may have an empty housing or may be able to put you onto one.

Gerry

terriblebikermike666 · Mar 28, 2011

Re: Please help mercury lower unit

well i have found a lower unit. its off of a 1990 mercury 200hp V6. the lower unit has visible differences from mine. it has a bullet or nosecone style lower end. it comes with a prop. the guy told me it will fit my application but i want to be somewhat assured that this will fit my application. it seems like a good deal and especially with a prop. he said the unit this came off of, 2 pistons were scored as hell with almost no compression on them. what do you think? is it the correct unit?

Chris1956 · Mar 29, 2011

Re: Please help mercury lower unit

Mike, I think that will work, provided it is the same shaft length. I bought a '93 Merc 135HPV6, and put a gearcase on it from a '86 Merc 150HPV6. I think that nosecone stuff you are seeing is just high performance mods.

j_martin · Mar 29, 2011

Re: Please help mercury lower unit

Lu should fit, with the caveat that the driveshaft is the same length. Prop has to be specified for each particular setup. Motor, mounting, boat, weight, etc all figure in. Final selection is by trial and error.

terriblebikermike666 · Mar 29, 2011

Re: Please help mercury lower unit

i have heard something about a shaft pin on the driveshaft or something that is on a few models from 1985-1995 . i guess i will try my best of luck with the lower unit off of the 200hp. thanks

j_martin · Mar 29, 2011

Re: Please help mercury lower unit

Some LU's preload the driveshaft bearing with a pin in the end of the shaft. Some preload the bearing with the bearing carrier itself. They are interchangeable. Just install each one as it is supposed to go.

hope it helps
John

Please help mercury lower unit

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