'84 Merc 150 - V6 2.0 - can't get powerhead off.

[MAtkins]

I've got 10 9/16" nuts pulled off the powerhead.
The 2 in the front aren't all the way off because I have to nudge the powerhead off the mid section far enough for the nut to slip out.

As far as I can tell all 10 bolts are off (front 2 almost all the way off) but I can't so much as budge the powerhead.
I've tried prying with a big screwdriver & a crowbar but I'm afraid if I put too much pressure on it I'll crack the cast iron.

The book says I should be able to pull the powerhead off now, of course they suggest a 'suitable hoist', 'powerhead removal eye', etc. I've seen posts here that say I should be able to just pull it off by hand with a couple of friends.

So far, we can't budge it.
What's got ahold of it and how can I pry it loose?

 

[Faztbullet]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Put pry bay under rear stud and pry up and should pop loose. If its a salty dog or brackish water motor the lower studs are most likely corroded into the midsection.If this is the case the easiest way to remove is to drill thru adapter plate and stud as this cuts them in half.

 

[AMD Rules]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Don't forget to make sure you also undo the shift linkage.

The two longest studs on each side can be difficult to come free and slide through the adaptor plate. Careful not to bend them, or it gets worse. You're probably fighting the base gaskets, if they have never been off, it is difficult.

If you pry up under the studs as mentioned above, the gasketing should come free.

An engine hoist would be your friend in this instance.

This was a fresh water motor, 1985, never been apart. You can see the longer studs were corroded making removal difficult.

 

[MAtkins]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Thanks very much for the help & the pics.

I learned a trick that worked. Hopefully the pic will explain it.
I did get it to pop loose & had about a 1/4" gap between the powerhead and the midsection.
3 of us tried to pick it up off the boat but it still wouldn't budge.

So, I still can't get the powerhead to come off.
I'm going to find a hoist so can pull the motor straight up off the midsection.

I think the motor has seen salt. I tried to take the exhaust manifold off and snapped 8 of the bolts off.
It didn't take a lot of pressure either. All the bolts for the exhaust manifold are snapped off or out.
The coils are off the manifold.

I still can't get the exhaust manifold off at all. It just won't budge.
Any ideas as to how to get it to come loose?

 

[wired247]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Your motor has seen salt. I can see that from that one bolt. Only saltwater bolts look like that. Rest assured that every boat motor in Florida has been in saltwater.

 

[MAtkins]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Thanks Wired: I figured as much.

The pics AMD Rules posted tell the story.
I've gotta pull the powerhead straight up at least 18".
I've bought a lift eye so I should be able to do that when I get it.

So, how do I get the dang exhaust manifold off?

Also, as I do the rebuild is there anything I can do to protect it from salt corrosion?
I wouldn't mind cruising around the Banana river or the Intracoastal myself if I can get it running dependably.

 

[Iceman66]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Are the lower unit still attached?
Could be corrosion or lack of lubrication on splines where the drive-shaft goes into the crankshaft.
Can sometimes do it difficult to get the lower unit down or in your case, the powerhead up and off.

 

[wired247]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

I had a 125 Merc that wouldnt budge once. I kroiled the studs dropped the lower and shoved a 2 X 4 up the mid section and placed a jack under the powerhead and lifted it off the mid from below. Worked like a champ.

 

[MAtkins]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Yea the lower is still attached and it's still on the boat.
I see 4 bolts it looks like to remove it - the book seems to concur.
Are there any surprises I should expect when I drop the lower?

That 2X4 idea looks like it should work great.
What do you mean by kroiled?

I'm still hoping you guys have some magic to loosen stuck gaskets.
I still can't get the exhaust manifold off.
Bolts are snapped or off and I can't get so much as a butter knife into where the gaskets are.

I tried hammering a screwdriver, then the putty knife into the edge where the gasket is.
I can't pry, hammer or see any way to get either the manifold or the plate beneath it to come loose.

 

[wired247]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Kroil is a brand penetrating oil. It smells bad but works good.

try heating the manifold up around the corners with a torch. I think you may have to hammer and chisel the thing off and buy a new one on ebay. Once you get the powerhead off you should be able to sinsert a crowbar into the motors exhaust cavity and you can pry to plate off from the inside.

 

[Iceman66]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Yea the lower is still attached and it's still on the boat.
I see 4 bolts it looks like to remove it - the book seems to concur.
Are there any surprises I should expect when I drop the lower?


The surprise could be that the lower unit wont come down, because as I wrote in my post:

Could be corrosion or lack of lubrication on splines where the drive-shaft goes into the crankshaft.
Can sometimes do it difficult to get the lower unit down or in your case, the powerhead up and off.

 

[Chris1956]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

The gearcase bolts on with more than 4 bolts. There should be 5 nuts and a hidden bolt under the zinc anode.

 

[MAtkins]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

I found 6 total including the one under the 'zinc anode'?
I'm not positive they all held the lower on.

I got it off with no problem.
So, now the lower is off and the powerhead is loose.

This week-end I'll try to get the powerhead off the mid-section using the lift eye and a come-along.

 

[Chris1956]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Should have one nut in front on top, two nuts behind that on top, and two under antiventilation plate. Then unbolt anode and remove bolt under it.

 

[MAtkins]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Chris: Yea, that's right.

Can I use a 2 ton come along (cable winch puller) to pull the motor up off the mid section (and the boat)?

 

[wired247]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Yes.

 

[MAtkins]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

WHEW! Thanks, I should have it off the boat this weekend then.

I don't know what it'll take to get the exhaust manifold off or the one snapped stud out of the block.
I've got little nibs to work with so I'll heat them, spray them with penetrating oil & bang on 'em a bit.
Maybe I can get lucky with vice grips.

 

[s1120]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Ive been fighting this same thing. I have a 83 150 black max I need to rebuild the powerhead and I cant get her to budge! I didn't thinking of putting a little pry force up on the rear studs. Ill give that a shot. This is a fresh water engine, and I see zero signs of any salt use, so Im guessing its the gasket.... but MAN its stuck!!!!

 

[racerone]

Re: '84 Merc 150 - V6 2.0 - can't get powerhead off.

Lock 2 nuts on the long studs.----See if you can then turn those studs.--------------------If they turn that may loosen up the corrosion products ( white powder ) that is jamming them.-------If you find only a few studs stuck , then you can drill through the stud from the side.----Bin there done that.