How bad is it DOC?? PIC

[boatster]

So today I was running my motor four miles from the docks when it died. A very mechanical sound from the motor was heard. Needless to say after cooling down I returned limping to the docks. I came home and took the powerhead and exhaust gasket off to see this: <br />

<br />I then looked at the oil pump lines and they were dry. The top piston is scored to hell. The second is a little better, and the bottom is worn but not dead. How bad does it look? What are my options? Can I still run the motor and what will be different now that the pistons and walls are scored so badly? I think I was negligent with the oil pump and failed to bleed the oil out from my last mechanical incursion into the motor. How bad is it doc?

 

[rodbolt]

Re: How bad is it DOC?? PIC

bad bad<br /> the motor must be disassembled for inspection. now you must carefully inspect the crank ,rods and wristpin bearings.<br /> good luck and keep posting

 

[JB]

Re: How bad is it DOC?? PIC

We need the engine's identity so we can notify next of kin.

 

[rodbolt]

Re: How bad is it DOC?? PIC

hahahaah yep.

 

[boatster]

Re: How bad is it DOC?? PIC

Rodbolt,<br /><br />what am I risking if I just continued to run it like it is? Assuming just the scored pistons and walls is what I've got. Running with oil of course.

 

[rodbolt]

Re: How bad is it DOC?? PIC

bring paddles<br />it will lock up and finnish off the crankshaft. good luck and keep posting

 

[boatster]

Re: How bad is it DOC?? PIC

Took some 400 emery cloth to the piston walls of #1 (top piston) and put the motor back together today. Started her up and idled for a long time. She started and idled rough but eventually evened out and was able to smoothly turn at 750 rpms. I later took the boat to the ramp this evening to test it out (paddles ready) and slowly worked the speed up to WOT after a good long time. The motor ran smooth and had no loss in top end speed. I am going to do a leak down and compression test tonight to ascertain the extent of damage that I couldn't find in the run today. She may still run afterall.... (to be continued)

 

[jafa]

Re: How bad is it DOC?? PIC

Hi Boatster<br />Something been bugging me , is this the same engine that had the high temp alarm problem ? Please dont tell me the wires for low oil and over temp were crossed.

 

[boatster]

Re: How bad is it DOC?? PIC

Rockhopper, <br />I don't believe the wires were crossed. They are all color coded so I assume red-red blue-blue etc is good. It was a waterflow problem actually. I plugged 1 purge hole under the powerhead to reduce the diversion of cooling. This purge hole sat right next to the pipe from the lower unit. It didn't seem all that important. There were 4 others that I left alone. Since this was a saltwater motor, maybe corrosion made the holes<br />|| <- that much bigger, and thus overheating alarm at idle. At anything above idle it didn't overheat.<br /><br />However I did do a leak down test and the top cylinder leaks a good amount. Middle cylinder is ok. Bottom cylinder almost perfect. My question would be, if its leaking on the leakdown why does the motor still perform the same? And is a leak down as important in 2 strokes as it would be in a 4 stroke? Should I do a compression test?

 

[rodbolt]

Re: How bad is it DOC?? PIC

hello<br /> like I said keep paddles cause when it dies it will be spactacular. its more critical that a two stroke not leak nore than 10% or so. the blowby in a 4 stroke just makes a mess and burns more oil. in a high performance 2 stoke those hot gasses blowing past the rings not only eat the piston but contaminate the incoming air fuel mix resulting in a lean out, resulting in more erosion and finnaly the crank rod bearings give up,, unless the wristpin or piston siezure beats it to the blow up. <br /> 400 grit wont polish enogh to make a difference. its cheap to fix until the crank lets go.<br /> good luck and keep posting

 

[boatster]

Re: How bad is it DOC?? PIC

Hi rodbolt,<br /><br />are you saying it would be cheaper to get the block rebored and move up to oversized pistons and rings? I'm going to have to call my suzuki dealer to see what the rebuild parts will cost. What do you recommend I do? <br /><br />EDIT: OK ok I reread your post above. Anything else I should do or should I just give up on this motor? Would the cost/benefit be too high?

 

[boatster]

Re: How bad is it DOC?? PIC

Ok I did a complete and full leakdown and compression test on the motor this evening. The compression on all three pistons is within a few lbs of each other. I also did a leakdown and they all don't leak much at all according to the gauge on the leakdown tester. Mind you this was all done with a cold motor. I will try a compression test with the motor warmed up to see if theres a bigger difference. My guess is despite the looks in the photo. The engine wasn't that badly damaged possibly. More observations to come.....

 

[Osprey]

Re: How bad is it DOC?? PIC

Although your ingenuity and dogged determination is to be commended, I’m with RodBolt. Keep your paddles handy stay close to home and make sure you have a current fire extinguisher. When she finally lets go it could be glorious.

 

[rodbolt]

Re: How bad is it DOC?? PIC

hello<br /> if the crank is not damaged you could replace all 3 pistons and overhaul the carbs and replace the piston pins and bearings as well as the t-stat and water pump for less than 700 or so. if you wait until the blowby takes out the crank it goes to 1400 or more<br /> your choice<br /> good luck and keep posting

 

[boatster]

Re: How bad is it DOC?? PIC

You're right. Well I'm gonna run it till it dies. $700 on an old engine isn't economical. I will post a full post mortem when/if it dies.

 

[boatster]

Re: How bad is it DOC?? PIC

Hi Rodbolt,<br /><br />would it be possible to rehone and put new rings instead of replacing the pistons? Pistons cost $80 each and the 2 rings per cylinder cost $20. Or Could I just rebore and replace only the top cylinder only? My manual says the compression should be 95 psi. I'm getting 95 psi on the middle and lower pistons and 90 psi on the top piston. Also with the leakdown tester the lower 2 pistons have virtually no leak at TDC. However the top is definitely leaking at TDC. Could I just rebuild to top piston (replace & rebore) and leave the other two alone? Thanks.

 

[Grant S]

Re: How bad is it DOC?? PIC

I know you asked Rodbolt, but he has already told you what is the best thing to do. <br />Reboring and replacing one piston would cause an imbalance in my view.<br /><br />A hone and new (or good seconhand piston) and rings would be the most inexpensive way to find the compromise you are after in my opinion,or even just the rings if you could clean the piston up good enough ,which I doubt, but remember it is not a reconditioned motor.

 

[BugEyes]

Re: How bad is it DOC?? PIC

Originally posted by boatster:<br />would it be possible to rehone and put new rings instead of replacing the pistons?

Don't do that. It has been done in an Evinrude I am currently rebuilding. Gave reasonably good comp but bad noise at low RPM from the piston slop.<br />Either you do the rebuild full out or you might as well just run it until it dies. Looking at the pictures all your pistons are shot. According to my SELOC manual for the Evinrude it's OK to replace only one piston to oversize but on your engine they seem to all be badly scored.

 

[rodbolt]

Re: How bad is it DOC?? PIC

secondary compression is inportant. primary compression is just as important. that piston and rihg set must seal as well going down as going up. just bite the bullet and ask sant to bring parts for christmas. the fact that the exhast cover came off tells me this motor is not badly corroded. why dont you pull the cyl head and give some pics<br /> with new pistons you will need new wristpins and pin bearings and circlips. for 700 or less you should have a reconditioned motor, if the crank/rods are ok. buy a good used motor for that.

 

[boatster]

Re: How bad is it DOC?? PIC

Ok,<br />thanks guys. I hear you loud and clear. A complete rebuild will be the only option if I go back into this motor. Does anyone know if I can get aftermarket pistons for this motor? Or maybe even a source for second hand pistons (as Grant S) has suggested? Just one piston alone is $80 from Suzuki. <br /> The other option of buying another used motor is tempting but I've been down that road before. Theres always a reason why someones selling their motor and it isn't usually good.