decarb / sticky ring ?s

[bpberry]

if a motor has sticking rings how lquickly can decarb free things up? Is there a way to check if the rings are sticking? Compression ia a little low on teh bottom two cylinders on my 93 225 vindicator e225stle , and a visual inspection of the cylinders through sparkplug hole shows no difference from the rest of the cylinders that are good. Oil in the chamber brings numbers up so prob something to do with rings. Engine sat up for a good while before I bought it. Prob not used for a year or better, then I picked up the boat/ motor? Thanks for taking time to answer my ??

ps: top of my pistons seem to be real crusty looking with carbon also, how clean should they be? Might be time for a deep clean

[bpberry]

would it be a bad idea to change the head gaskets and see what that does? or at least retorque the heads? I did nt say but it was rebuilt 6 months before it got to sit for a while. All holes .030, and other than some low speed loading up with fuel when idling or no wake zones , runs good to me. thanks

[ChampioNman]

Carboned up after 6 months? Rings shouldn't be stuck after 6 months and a fresh rebuild.

[bpberry]

It was rebuilt in mid of 2005, and the guy used it for the rest of the year and it set up on a boat lift for about a year or and I bought from him one year ago. I kind of thought the same thing, but I dont really know how he used it. He was prob in his late 60s early 70s so he probably putted around everywhere. It does not look like a big deal to change head gaskets so I might pull the heads just to have alook at the motor . If I do I will post pics and see what you think. Thanks

[ChampioNman]

Your investigation will cost you $70.00 for gaskets. When you re torque them bring them up to 10 ft lbs and then to the final 18 ft lbs. Pictures will help for sure.

[bpberry]

I took the heads off tonight and think I may have a bigger issue. The lower two cylinders that are low on compression (one was 55 and one 75) seem to have loose pistons. By that I mean I can put my hand on top of them in hole and get a good deal more movement than the other cylinders, I m think between 1/16 and 1/8 inch slop. I could not tell any major differences in the cylinders though compared to the cylinders that have good compression , other than all of the others still have a bit of crosshatch and the lower two dont have any. No big scratches , gouges , discoloration . etc. But I am not an engine rebuilder either. I took pics of the pistons and one of a cylinder showing the cross hatch but I could not get a good pic of the low cylinder. They are basically the same . Why might the piston be moving so much ? Thanks for any advise.

[bpberry]

sorry I dont know what I did to make it so big

[Mr Limpet]

Some movement is normal as the piston alloy is designed to expand as it heats up to operating temperature. By your description of the weak cylinders and their proximity to each other, you might have had a blown head gasket or a loose head bolt. I would check the head surface for warp, mill them down @ 5 thousandths and make sure you install the new gaskets correctly with the proper side facing you (head side). You can always bore the 2 week cylinders and install larger pistons in those cylinders. It will not throw off the balance of the motor. I had a '87 XP 150 with similar issues and did that with no ill effects. While you have it apart you should check the rods for straightness. Used rods are ok to use as long as they check out straight. I replaced the whole set of pistons and the cost was @ 700.00. Mark everything and put the parts in plastic ziploc bags. Lable the bags with a sharpie and take pictures as you tear it down. It is not as hard as it seems and you can pay an expert to assemble the block and rotating assembly if you are not comfortable. There is no magic in this, but there are a few things you should know when matching the rods to the caps. Scribe them before you remove the rod bolts or they will never go back together correctly. Use a sharp pencil to check their fit. Ask and I can tell you how to do it.
From the sounds of things, I would think some rings were put in wrong on those 2 cylinders if the gasket didn't blow.
When you crack open the block halves you'll be amazed how close the rotating assembly pieces are to each other - and to think that those pieces spin so fast, so close together.
Sealing the block, intake and heads is VERY important when reassembling. The motor is a big air pump and it must be air tight to work correctly for a long time. Replace all bearings when you tear it down and you might install Boysen Reeds and recirculation valves while you are at it.
It is not as hard as it looks to rebuild.

[ELGIN]

Those are really big pictures, if those are the cylinders with low compression (55-75) what were the other compression numbers?

[bpberry]

the other 4 are right at 100 each on a 1993 evinrude 225 vindicator e225stl
Does the powerhead need to be completely removed from the motor assembly or can it just sit where it is to go deeper. But im not taking it apart yet, not sure if I want to mess with it, about to start a new job with more workflow , might be better off paying someone to do this and just do what Im good at to pay them for what they are good at

[ELGIN]

If the pictures are of the low compression cylinders I would get two new head gaskets bolt her up and run it.