TOPIC: removing head from mark 55 mercury

Well, no luck freeing up engine - soaking for 2 days tried impact gun on flywheel, levering etc not budging - my brother in law suggested removing head and tapping the piston heads with block of wood and mallet....might help jar it loose - the bolts to remove the head are pretty accessable - should this come off ok and how easy is it to get a new head gasket for this motor?

Thanks

Lee

The reason I am persevering with this is that when I picked up the boat/motor the pull cord was all the way extended - this indicated to me that at some time someone was able to pull the starter cord and the engine turned over, the recoil was extremely stiff and it probably just came all the way out and did not retract - all it needed was a soak in pb blaster and it is as good as new now - my theory is that if someone was able to pull that out at some point the engine was free - its probably just got the rings rusted to the cylinder walls? at least if I take the head off I can look to see if there is any bad scoring on the cylinder walls?

Even if you get her to turn I think it might be worth it to remove the head just to see what the cylnders look like. I was toying around with a very stuck Evinrude, trying to unstick it, and when I finally took it apart, here is what I found.....

JUST a FYI I do have a good long block for a Mark 55

www.marineengine.com/parts/mercury-mark-outboard-parts/mark-55-55e/all

Is that from mud wasps? might have the same problem on mine as they got in everywhere down below.
Lee

Merc's DO NOT HAVE A REMOVABLE HEAD. what you think is a hed is just a water jacket cover.

Before you turn another screw on that engine, pick up a service manual and read the powerhead section from front to back. You can do a lot of damage if you try to disassemble that engine incorrectly so please do not go in there blindly, it is a nice piece when built correctly but a nightmare if it is not.

If you remove the pistons and do not have the right special tool (or know one of the few ways around having one) for compressing the rings you will wish you never seen a Merc

It was apparently lying on the ground for some time and water/mud was able to flow into and pool in the cylinder through one of the cylinder ports. That's my guess anyway. She wasn’t savable, or at least worth trying to save, so said the machine shop. I still have all the parts and replacement power head that probably needs a rebuild as the commpression feels week. I'll not likey ever do anything with it all

Don't junk it....... part it out. There are many parts still usable on it.

As I wrote earlier I have a good block with the crank and pistons all there.

Shipping from TX most likely would be the KILLER

Like Tall Texan said, replacement powerheads are available. Before you go much farther you should separate the powerhead from the mid section, 6 bolts/nuts. Like George said you are going to need a service manual for that block. You will have to dismantle the block, remove the crankshaft and deal with the stuck pistons one at a time. When you do this you will get a better idea if it is worth pursuing. Pics will be helpful. When you pull off the intake cover you should be able to tell if has been submerged, there will be a lot of rust. Intake covers can be removed to see the intake side of the rings. Once again, rust may be an obvious issue.

OK so once the 6 nuts/bolts removed from the bottom the whole thing should come up and off as one unit? I don't think it has been submerged just left for a very long time outside.
Looking for a manual for the motor now.
Lee

Yes the entire top will come off now, but the shift shaft will come with it so you will have to lift it a long way up to clear the leg. Get some help with the lifting!

Thanks, with the help of my son was able to put a bit more leverage on the motor - I used a bar on the flywheel whilst he levered on the flywheel nut with a breaker bar - it moved about 1 inch but then I got nervous that the movement was something other than the pistons moving!!!!!!! I am going to get a wood dowel and insert that into the spark plug holes and give it a few good taps see if that will break something loose.
I have an old 8n tractor which sat behind a barn for years - had the same problem - took about a week of whacking on a 2x4 and levering and then one day it just came loose.

Lee