I first posted a couple of weeks ago and said that my engine was binding up. I was able to move the flywheel back and forth but it keeps binding in the same spot, Based on the suggestions I received I have done the following: pulled the flywheel and checked the magnets; pulled the lower unit; pulled the upper bearing on the crankshaft; and today I pulled the cylinder heads. I am pretty much a greenhorn when it comes to engine mechanics but I can read and follow directions. All 4 pistons are moving which I believe eliminates a broken connecting rod as the problem. Visually I can't tell if there is a problem or not as they are all intact and a pile of metal shavings didnt fall out. But again, this is new territory for me. Just before the problem occured, I started to hear a noise that sounded like a bad bearing which is why I removed the upper bearing. I am really at the limit of my comfort zone but I need to decide if its worth pushing ahead to diagnose and possibly repair or is this a sinking ship that I should give up on.
Any and all opinions or advice are welcome..thanks
You've done a lot of hard work trying to diagnose the problem. All steps are good ones to determine the problem. I'd probably take the exhaust covers and side covers off and look to see if a ring has cracked and is binding on a port opening. Usually, if a ring cracks, it can wedge between the head and piston top and will cause that binding. Do you see any pitting on the piston top or matching head surfaces? About the only thing you have not done is to pull the engine apart. Doing so would let you check the lower bearing and the rod(s) and main bearing inside the block. Did the engine still have good compression when you started your disassembly?
Right now I am only able to turn the crankshaft maybe 20 to 30 degrees so it is hard for me to answer the compression question. As far as the pistons go however, I do have one that has what I guess would be called "worm tracks" on the non contacting face. It also differs from the other three in that for the 3 others, they have more of a sticky black carbon residue on the faces while this one has more of a slimy grey residue. For all the pistons, I can grab hold of the faces and wiggle them in place so none of them are currently wedged in place. When I moved the flywheel to the sticking point I was still able to wiggle all the pistons which has me thinking that it is an internal bearing but thats only a guess
The "wiggle" is normal for pistons. When the crossflows carbon up, the carbon gets around the rings and causes them to stick in the ring groove. The pistons loose some of the wiggle as carbon fills the normal clearance between piston and the cylinder liner. The carbon buildup can get so great that it prevents the oil in the fuel from getting to the rings. The rings get hot and break. The broken ring edges can catch on the intake or exhaust ports. The grey substance in the one hole could be water. You may have a leaky exhaust cover, or head gasket which is letting water into that cylinder.
I finally got the name of a person from a friend who I trust in these matters and he is going to take a look at the situation tomorrow. I think I have gone about as far as I am confident in going for now. I needed to find someone willing to take a look rather than the " how old??..ya just get a new powerhead/motor"
Thanks to all who have provided advice to me along the way and I will let you know what I find out
Your choices are,another eng,rebuild your powerhead ,or buy a replacemrnt rebuilt powerhead.This website has all the parts and the replacement rebuild if you go that way.My guess,is,between you and your friend,you can do the job.OH Yes,a manual too.You can start be disassembling your powerhead.All the electrical components can be removed while connected together,allowing the reinstallation to basically drape over the new powerhead an then be screwd in place.I would suggest you dissesemble and throughly clean the carbs.A lean run engine can blow up.Your block(the eng.without the pistons,etc)will likely need machine work.That may consist of boring the cyl.walls oversize to the next piston size.Usually ,010 oversize is the next size up.Depends on whether you have severe damage.If damage is too bad,you then may need a new cyl.sleeve installed.To rebuild,you need 4 piston kits,new rod bearings,new bottom crank bering,(center and top are lkely ok)a rebuild gasket kit.You can look up the parts on this website.Figure 300 - 500 for machine work.Then,compare what a complete short block(rebuild ready for your carbs,wiring,flywheel,starter)would cost.If your engine,less the powerhead is nice and clean,no other major probs.going on.Your eng is likely worth the effort.
If you compare your overhaul price vs the cost of a new engine with 90 hp, you are probably $ ahead to overhaul-it just depends how handy you are. Any chance your outboard friend would like to help you with your project? Even though the old crossflow technology is dated, there are still plenty of parts available for them. They are pretty simple technology compared with modern engines. There are many knowledgeable folks on this board that are willing to help with your questions during any overhaul.
1994 Evinrude 88 hp powerhead problem
Linear Mode
