Seeking root cause of my engine failure

[hsi111]

This thread is a sequel to my (motor rebuild questions) thread. I have a 2003 90 elpto that melted/fused the rings on #2. I have no history on the motor because I bought it knowing it was bad. At my first look, I have been concerned with the stuck/burnt rings on #2. The other rings were fine. Today I took the block to my machine shop and he pointed out minor marring on the other two cylinders. I went home and sure enough there is early signs of a problem on the remaining two pistons. I was leaning towards a root cause of #2 running lean but now I am wondering since the other two cylinders appear to be in early stages of also failing. There seems to me an excessive amount of carbon build up on all cylinders. Of course, I am going to rebuild all 3 carbs and make sure oil pump is working. I am looking for ideas on what else to check. I am now for sure buying 3 pistons and possibly paying to bore 3 cylinders (shop is going to try to hone first) so with all the money spent, I really need to do my best to figure out the root cause. Kinna tough with no history.. Some pics are attached. Any ideas are greatly appreciated….. Rick

This is the carbon build up on all 3 cylinders.



This is the marring on all 3 cylinders.



This is crud found around cylinders. It is not corrosion. It falls off with nylon brush...But it is there from something



This is what started it all. It has been very hot and melted the rings.





Thanks again, Rick

 

[MH Hawker]

Re: Seeking root cause of my engine failure

I would say plugged cooling system and total over heated.

 

[hsi111]

Re: Seeking root cause of my engine failure

I am thinking the same. I definitely need to check water pump and LU for that crud. What about carbon on pistons? Is that considered bad?

 

[Faztbullet]

Re: Seeking root cause of my engine failure

Crud in block and running to cold as its scuffed on the exhaust side. Check poppet and t-stat.......

 

[MH Hawker]

Re: Seeking root cause of my engine failure

2 stroke will have carbon and it looks about normal.

 

[racerone]

Re: Seeking root cause of my engine failure

Carbon on the pistons is very normal and nothing to worry about.-----Post picture of water pump / impeller.

 

[hsi111]

Re: Seeking root cause of my engine failure

OMG, Didn't notice this when I took motor apart. I was too busy just trying to get to damaged piston. I have never seen a thermostat corroded in half.

 

[hsi111]

Re: Seeking root cause of my engine failure

Racerone..... It will be a few days before I can check water pump. Too cold down south right now. I am for sure going to replace impeller and do a good inspection / cleaning of all water passages.

 

[bilge rat jim]

Re: Seeking root cause of my engine failure

OMG, Didn't notice this when I took motor apart. I was too busy just trying to get to damaged piston. I have never seen a thermostat corroded in half.

View attachment 222301

I think you have found the root cause- no water flow. Looks to me like a salt water outboard that hasn't been flushed. Here's an idea you may want to try before assembling the block: put the stat cover back on, turn the block upside down and load it up with CLR. It will probably take the best part of a gallon. Let it sit overnight, and then blow all the CLR out with fresh water. This should remove most of the calcium build-up. You probably should remove the exhaust cover and inspect the baffle as these are also prone to corrosion.

 

[wired247]

Re: Seeking root cause of my engine failure

OMG, Didn't notice this when I took motor apart. I was too busy just trying to get to damaged piston. I have never seen a thermostat corroded in half.

View attachment 222301

I have. Ive seen thermostats that were 2/3 way gone and poppets that were choked up solid. Bad stuff salt.