4 cyl re assembly without ring compressor?

[Yachtzee]

It it possible to re assmble a 650 merc 4 cyl without the fancy mercury ring compressors?
Any tricks to do it without the tool?
Thanks

 

[2Smokinya]

Re: 4 cyl re assembly without ring compressor?

If it is 2-stroke, then I believe you do not even need a ring compressor.

 

[p15camborne]

Re: 4 cyl re assembly without ring compressor?

When I was young in the 60's, my buddy and I compressed 35 and 40 hp Johnson/Evinrude rings one at a time with a coil of piano wire. So had to do each piston in two steps a ring at a time.

 

[Chinewalker]

Re: 4 cyl re assembly without ring compressor?

I've done them with an extra set of hands. Also done them with ring compressors made from hose clamps. Also done them with the pistons in first, THEN installing the crankshaft. Had to get a smaller torue wrench for that one, though...
- Scott

 

[Chris1956]

Re: 4 cyl re assembly without ring compressor?

Yacht - I always installed the pistons individually using my fingers and a screwdriver to compress the rings. This requires that the rods be removed from the crank. it is an easy procedure , but tedious, especially on a 6 cylinder motor.

 

[fishinjack]

Re: 4 cyl re assembly without ring compressor?

I have used large "zip strips" Snugged them with pliars and slowly tapped down the piston.

 

[Yachtzee]

Re: 4 cyl re assembly without ring compressor?

Thanks to all who responded! I have done the hoseclamp trick on VWs and motorcycles. I bet it is pretty tedious to put all four sets of rod bearings in with the pistons in the in the bores! But based on all your feedback I have begun a teardown of this old 1967 merc model 65O. The bottom crank bearing is bad as is the seal. I believe this is why it was running kind of wierd Not sure how much play should be in the rod bearings, but I want to replace them. I have a book for this motor but is is not very detailed. I have a couple of other questions about how to get the crank out I will post under seperate cover, Thanks!

 

[rolmops]

Re: 4 cyl re assembly without ring compressor?

Here is the special tool:
Take a water bottle (the smallish type) and cut the bottom out of it,now make a lengthwise slit up a ways.Place bottle around the piston and squeeze around the rings with one hand while pushing the piston down with the help of a stick or screw driver through the bottle neck.
This tool is made to fit many sizes of pistons.

 

[Yachtzee]

Re: 4 cyl re assembly without ring compressor?

Cool, Thanks for the tip!

 

[Chris1956]

Re: 4 cyl re assembly without ring compressor?

Yacht, There shouldn't be any detectable play in the rod bearings.

 

[Yachtzee]

Re: 4 cyl re assembly without ring compressor?

I am not sure there is any play at all except with the pistons out of the bore they will rock back and forth a bit. if you pull them straight in and out with them in the bores I do not detect play. If I had to guess that one was a bit looser it would be cyl #1 only.
The crank journal looks alright.
Are there tables available with dimensional tolernaces for crank etc?
There do not seem to be any in the lame book I have

While I am asking, is any daylight at all acceptable under the reeds?
I have acouple that are not dead flat against the carrier. I have seen bikes run fine like that but I do not know about an outboard
Thanks

 

[Chris1956]

Re: 4 cyl re assembly without ring compressor?

Yacht, Some space under the reeds is OK. Side to side play of the rods is OK, as long as no in-out play on the rod bearings, which seems to be your case.

 

[jebeebe]

Re: 4 cyl re assembly without ring compressor?

I made a dummy cylinder that was tapered on the outside to fit in the tapered cylinder sleeve and rest on top of the sleeve. (this squared it up with the bore). I used an automotive ring compressor (cheep) and slipped them into the dummy, then set the dummy on the bore sleeve and tapped them in with a hammer handle. They never knew when they left the dummy and entered the bore. I have a machine shop and made this one so it was free to me. I realize not everyone has that option, but I just thought I would pass that idea along to anyone who might do a lot of this kind of work. Also, this only works with "cracked rods" where you can put the pistons in one at a time.

 

[Yachtzee]

Re: Thanks to all!

Re: Thanks to all!

This Forum is great!
Thanks to all who have chimed in with a TIP