Help! How to remove lower unit?

[kawiski]

2004 EFI 115hp 4-storke 4-cyl.

I need to change the water pump impeller but can't separate the lower unit from the upper part even after removing 5 nuts - 2 on each side under the cavitation plate and 1 in the rear by the sacrificial anode. I have the service manual but the "Water Pump" section doesn't say anything about disconnecting the dirve shaft or shift shaft at the upper unit. It just says "remove the 5 nuts", and "remove the lower unit".

The shift shaf is a 2-piece assembly with spline ends, as on many newer Mercury O/B. The bottom piece pulls out with the lower unit, and the top piece remains with the head unit. So it does not require disconnecting at the head unit.

Can someone please tell me what I am missing here? Could it be just corrosion holding the lower unit?
Thank you in advance.

 

[kawiski]

Re: Help! How to remove lower unit?

Even afer some hammering with a rubber mallett, I could only barely insert the tip of a screwdriver and that was it. What else to do?

 

[dkonrai]

Re: Help! How to remove lower unit?

i have a 93 15hp, on that motor, there is a small latch and pin assembly down by the power head. this holds the shift lever to the pivot hinge. look at the bottom of the powerhead. its worth the try.
dk

 

[kawiski]

Re: Help! How to remove lower unit?

The service manual shows that shift-shaft is a two part assembly with spline end joint, as on many later model Mercury O/B. I was told that only on older units, the single pat shift-shaft should be disconnected at the top. On newer units, the lower shift shaft is supposed to just slide out when removing the lower unit without having to do anything to it, and the upper shift-shaft is remaining with the engine head unit.

Any other advise what to do?

 

[JaffeJoffer]

Re: Help! How to remove lower unit?

I am having this exact same issue on my 2003 115hp EFI. What are we both missing?

 

[TONY MAC]

Re: Help! How to remove lower unit?

Sounds like the last person to do the impeller didn't grease the splines on the drive shaft. Keep beating on the lower unit with the rubber mallet while pulling down, it should come off. Good Luck!

 

[Pontuned]

Re: Help! How to remove lower unit?

Sounds like the last person to do the impeller didn't grease the splines on the drive shaft. Keep beating on the lower unit with the rubber mallet while pulling down, it should come off. Good Luck!

I had same issue. I used a block of wood and tapped with a hammer, it came off.

 

[kawiski]

Re: Help! How to remove lower unit?

Sounds like the last person to do the impeller didn't grease the splines on the drive shaft. Keep beating on the lower unit with the rubber mallet while pulling down, it should come off. Good Luck!

The lower unit was never separated before (I know it's overdue...). Maybe Mercury guys didn't put (enough) grease on the drivie shaft splines. So, I called Mercury Customer Tech Support in WI (if you would ever call them, have your engine S/N ready). I told them about my situation and they said I am doing exactly right - removing 5 nuts and hammering. They said "keep hammering" and sometimes I have to wait a day or two until it separates itself (so don't completely remove the nuts). Mercury also admitted that most likely corrosion on the drive shaft spline is causing this stuck problem. I wonder if something like this would be covered by the warranty - assuming that factory didn't put enough grease. I will call them again and ask.

 

[JaffeJoffer]

Re: Help! How to remove lower unit?

Where did they say to hammer? I don't want to crack the aluminum fins. Is there a technique?

 

[BR]

Re: Help! How to remove lower unit?

Having had the same problem on my motor, I used wooden wedge shims in the gap and drove them in perpendicular to the midsection. Seemed a lot safer than pounding on a thin aluminum casting and it worked...eventually. I was amazed at the persistent holding power of corroded splined shafts!

Good luck!

 

[kawiski]

Re: Help! How to remove lower unit?

Where did they say to hammer? I don't want to crack the aluminum fins. Is there a technique?

No, Mercury rep did not say where to hammer on nor any technique, but I was mainly hammering on the bolt head (just below the screwdriver handle) which you see on the photo I posted above - that's for the rear. For the front of the lower unit, I tried to hit on the anti-cavitation plate (fin) near the main body, far from the edge. And I couldn't hit as hard because of limited space I have there.

Using a wooden wedge is an excellent idea as long as there is a gap to insert. I used a screwdriver tip and I think I chipped the edge of the lower unit a bit.

Would you believe what Mercury told me, the lower unit would eventually drop by itself a day or two later if left alone with the nuts loosened?

 

[JaffeJoffer]

Re: Help! How to remove lower unit?

Haha, I don't believe it, mine has been hanging there since last Saturday. I left the four nuts on a couple turns just in case it does decide to drop.

I will try again when I get home from work. Did you get yours off?

 

[Jimmy310]

Re: Help! How to remove lower unit?

I am a visual person so check this link on Youtube this helped me out on my impeller replacement.

http://www.youtube.com/watch?v=E-uzQi7IgwU

When I replaced my impeller the nuts on the side (where your arrows are on your picture) actually separated the lower and upper units. I guess I was lucky.
Also try moving the flywheel by hand or cord. The drive shaft might be stuck and this will help release it.

Hope this helps.
Jimmy310

 

[Toxarch]

Re: Help! How to remove lower unit?

My question after seeing that video is, How do you get those wires back up when reinstalling? Mine doesn't look like there is enough slack in the wires to drop the lower out.

 

[Jimmy310]

Re: Help! How to remove lower unit?

My question after seeing that video is, How do you get those wires back up when reinstalling? Mine doesn't look like there is enough slack in the wires to drop the lower out.

My engine has no wires in the lower unit.

Do yo have a picture of your engines lower unit?

 

[JaffeJoffer]

Re: Help! How to remove lower unit?

Great success! Scewdrivers, a three pound sledge, some PB Blaster, several hours was all it took.

 

[JaffeJoffer]

Re: Help! How to remove lower unit?

Anybody have any tips for getting the lower unit back on? I have the main shaft in but I am hanging up on the small directional spline. How do I position the splined shaft on the lower unit? Does it have to be in the middle? I know I am still in neutral b/c if you turn the prop shaft, the main shaft doesn't turn.

Any tips?

 

[Fuzzytbay]

Re: Help! How to remove lower unit?

Some times it helps to have a second person, who can just wiggle the flywheel slightly while the lower end is inserted to help line up splines.

 

[JaffeJoffer]

Re: Help! How to remove lower unit?

Some times it helps to have a second person, who can just wiggle the flywheel slightly while the lower end is inserted to help line up splines.

Any tips for the directional (fwd/reverse) splined shaft? Wiggle the throttle?

 

[Toxarch]

Re: Help! How to remove lower unit?

My engine has no wires in the lower unit.

Do yo have a picture of your engines lower unit?

There's a gear cable and something else in the front of it.