Lower Unit Help!!

[StarznBarrz]

Ive got a Merc 7.5hp and im trying to get to the impeller, ive been told and have come to realize there cant be any other place for it except in the lower unit. So i took the nut and plain washer off the propeller but cannont get the splined washer off? and took the nut right above the propeller beside the water suction whatever you wanna call it off and also i loosened the nut (wont come off) on the opposite side of the propeller and this bottom portion is not budging...is there any insite anyone can give me? I believe i have to take the propeller off to seperate the lower portion from the lower unit, Correct? Please Help!

 

[jbjennings]

Re: Lower Unit Help!!

If it's between late 60's and 80's, you don't have to take the propeller off to take off the lower unit. You need to say what year it is, but there should be just a nut beside the pickup screen just above the propeller and a 9/16? nut on the front of the lower unit just above the cavitation plate. Remove those and the lower unit will come off. Then there's 2 nuts holding on the impeller cover. There's probably an exploded view of your lower unit if you go to Crowleymarine.com and go to the parts catalog. That should help you quite a bit with the diagram. I found a diagram at this address -- "crowleymarine.com/mercury_parts/444/18.cfm"
I couldn't figure out how to save the pic for 'ya.
Good luck,
JBJ

 

[8075mercury]

Re: Lower Unit Help!!

These are great little motors.
I can give you a brief explaination, but a factory or Seloc service manual is valuable as it is full of pictures of how to do everything. Check ebay or local store. You do not have to remove the prop to swap out the water pump impeller. You have a thrust washer in front of the prop that you can get off with some liquid wrench or pb blaster? and a puller or by rocking with a pair of channel locks.

To swap the impeller:
*pull the plug wires and take out the spark plugs for safety
*shift into forward
*remove the nut under the anticavatation plate by the water intake
*loosen the nut on the leading edge of the lower unit where it meets up with the mid section. You can not completely remove this nut until you partially slide the lower unit off some. Sometimes the lower unit is stuck in the mid section. Banging on the anticativation plate is an excellent way to break off a fin. Prying at the seam with a screwdriver is also a good way to break something too. I usually get a rubber mallet and tap on the sides of the bullet or the middle of the housing and tap straight back on the leading edge. Still this can take a while.
*Once you get the lower unit off, the impeller is in the plastic housing around the drive shaft. Getting the new impeller in the hole can be tricky. Try sticking the impeller key on the flat with some grease and grease the impeller too. The impeller turns clockwise viewed from above. Give it a 1/8 running start and screw it into the housing while lining up with the impeller key.

Good luck.

 

[StarznBarrz]

Re: Lower Unit Help!!

Its a 1969 Kiekhaefer Mercury if that helps now....8075mercury....i did take the nuts your speaking of off and actually did pry on it with a screwdriver a little (didnt break anything) but i will deffinatly try the rubber malet idea! If theres anything you 2 or whoever can add knowing what exactly we're working with now Please Do

 

[StarznBarrz]

Re: Lower Unit Help!!

By the way......Thanks for the links jbjennings they're awesome!

 

[jbjennings]

Re: Lower Unit Help!!

Hey S &B,
Your prop shaft splines are probably a little rusty because they weren't greased, as is the splined washer. A little PB blaster soak and if that doesn't work, a LITTLE heat with a propane torch might help, remembering not to blow anything up with gas around. I'd try to get it off just to check for fishing line, etc. and just to have it where it's easier to fool with. Also, I've had to put a rubber mallet on the bullet too, that was excellent advice, but be patient and be gentle! That pewter is some finicky stuff and easily broken/cracked/chipped, etc. When you do finally get it off and follow the advice on the grease on the impeller, etc., you may want to be very careful to get a good seal on your water pickup tube going to the bottom of the water pump housing. And don't overtighten your pump housing nuts and warp the plastic. Those things are easy to get leaks on and they won't pump good enough because of exhaust leaks etc. By the way, those red-band 69's are good looking motors..I like the blue-bands, too.
Later,
JBJ

 

[jbjennings]

Re: Lower Unit Help!!

I almost forgot, have you checked the l.u. oil lately? I was thinking that if your prop was frozen on the splines, it's probably been a while since it was checked. If your l.u. oil doesn't look good, you don't want to pull the water pump housing and look at your driveshaft, you may not like what you see (it's probably pitted in the seal area. Just change the oil and keep it changed regularly, especially before winter starts the last time you use it before you put it up for winter. And if you come across a used l.u. off a 1976 or newer motor that's cheap, you may want to jump on it because they have stainless steel driveshafts. Of course, even stainless wears out.
JBJ

 

[StarznBarrz]

Re: Lower Unit Help!!

i finally got the splined washer off (broke in 2) so nows just the prop. nothings on there anymore to hold it on there but yet the prop. wont come off? i beat on it with a rubber mallet, used pliers to see if i could wiggle on it and it isnt sliding off? i appreciate the Awesome help jb but lets keep in mind lol, this is the first time ive ever done anything like this, in other words im an amature lol so about the l.u. oil, i dont even know what kind to but let alone what it would look like bad so can you give me a little detail on that and im still having a little trouble getting the lower portion off the l.u. to get to the water pump and impeller in the link tells you what things look like and as you can read (on the attachment) ive pretty much done everything i can to try and get it off, i used a rubber mallet and tapped on the sides of the bullet and the middle of the housing and tapped straight back on the leading edge as told to do so by 8075mercury and it still isnt letting up....what should i try now, i really liked how it ran when it did, but now its turned into a real pain in the butt lol