Gunk piled up on spark plug J150

[kenmyfam]

Re: Gunk piled up on spark plug J150

When was the last time you did a really good decarb ???
Seen similar on 2 stroke motorcycles back in the 70's that were all carboned up. Found it was caused by the exhaust port being full of carbon and the exhaust gas not getting away quick enough. The remaining unburnt oil that did not make it out of the exhaust just burned out and eventually became lumps of carbon. This scenario showed more on multi cylinder motors as the other cylinders "took it for the team" On single or twin cylinders the motor just started to run horribly and were stripped down for a "scrape it out" decarb. The longer it went on the worse it got.
I would whip the head off and check out the top of the piston and have a good look inside to begin with. It will cost you a gasket but I think that is a small price to pay.
Just mt 2 cents though as I have never seen this personally on an outboard. However I have seen a lot of 2 stroke motorcycles and the principle is the same. Your plug photos look just the same as what I found.

 

[backyard mechanic]

Re: Gunk piled up on spark plug J150

I'd have to ask what oil are you running and at what mix. Either way there has to be a reason for the high carbon fouling you are showing.

Hotter plugs are great if you need them but carboned up plugs may lead to "glowing" plugs and then pre-ignition which will cause piston melt. Don't band aid this issue... find the cause and fix it or you may be buying a new one at 10x the cost of the repair.

 

[jonesg]

Re: Gunk piled up on spark plug J150

Wow thats extreme looking, it looks like water intrusion ,

emulsified oil and water look like mayonaise.

Its in serious need of an overnite soak with seafoam to dissolve the carbon.
I would pop the head too.
Test reciculation valves and hoses for that cyl.
Somethin is clogged somewhere.

 

[ezeke]

Re: Gunk piled up on spark plug J150

Looks like aluminum throw-off from pre-ignition to me. Whatever the reason, you should correct it before you run the motor again.

 

[jwellcraft]

Re: Gunk piled up on spark plug J150

The last de-carbon treatment was just a week ago with the johnson / evinrude engine tuner (1 can). And for the oil I am using it is the johnson / evinrude XD50 2 stroke oil and I add 16oz of oil to every 6 gals of fuel. So yesterday I put 46 gals of fuel in so I added 3 & 3/4 quarts of oil.

 

[kenmyfam]

Re: Gunk piled up on spark plug J150

The last de-carbon treatment was just a week ago with the johnson / evinrude engine tuner (1 can). And for the oil I am using it is the johnson / evinrude XD50 2 stroke oil and I add 16oz of oil to every 6 gals of fuel. So yesterday I put 46 gals of fuel in so I added 3 & 3/4 quarts of oil.

Looks like it's time to whip the head off then. See what you find.

 

[jwellcraft]

Re: Gunk piled up on spark plug J150

Yes guess I will have to do this now..I spotted a light in this #1 cylinder last night and the piston looks very clean so maybe there is water intrusion and it was getting steam cleaned. Hopefully its just a gasket and not a rotten block.

 

[kenmyfam]

Re: Gunk piled up on spark plug J150

Yes guess I will have to do this now..I spotted a light in this #1 cylinder last night and the piston looks very clean so maybe there is water intrusion and it was getting steam cleaned. Hopefully its just a gasket and not a rotten block.

Look forward to seeing what you find.

 

[jwellcraft]

Re: Gunk piled up on spark plug J150

Pulled the head off and so far the piston is good (no play), the cylinder sleeve is good (no scores) but there is alot of carbon built up in the exhaust port and no build up in the others. They are really clean so I guess the can of engine tuner did the job. I will spray some carbon cleaner in there and try and get this broke up and don't think I had any water in there because I run this boat in salt water and I have noticed this build up once last year when I first got the boat and so far there is no signs of corrosion or rust so I think its just a bad case of carbon build up. When I first got the boat I had it a couple of months before I checked the plugs and did some servicing and realised it ddn't have in any thermostats so wouldn't this cause a carbon build up? I will include the pics.

 

[kenmyfam]

Re: Gunk piled up on spark plug J150

Running cool could well be a cause of carbon build up. But just one cylinder ??
Hopefully you get the carbon out and things improve.

 

[jwellcraft]

Re: Gunk piled up on spark plug J150

I thought of that as well yes but can't think of anything else except the carburetor setting then because it does burn alot of fuel but it runs very strong for the age. I will try my best and get this carbon removed and do a compression test and see how things go from there. The o-rings were also good, (no cracks). Don't you think if it were water intrusion I would find water in the cylinder and would it just affect that one cylinder? There was a bit of black silicone around some water jackets as well but don't think any were blocked.

 

[kenmyfam]

Re: Gunk piled up on spark plug J150

I thought of that as well yes but can't think of anything else except the carburetor setting then because it does burn alot of fuel but it runs very strong for the age. I will try my best and get this carbon removed and do a compression test and see how things go from there. The o-rings were also good, (no cracks). Don't you think if it were water intrusion I would find water in the cylinder and would it just affect that one cylinder? There was a bit of black silicone around some water jackets as well but don't think any were blocked.

I would give it a major decarb and go from there.
Water will only get in where it can so it may well only get into one cylinder.

 

[jwellcraft]

Re: Gunk piled up on spark plug J150

What would you suggest to use for a good de-carb?

 

[jwellcraft]

Re: Gunk piled up on spark plug J150

Here are some closer pics of the exhaust chambers and the pics of the other pistons on the same side (starboard). Tell me what you think..

 

[kenmyfam]

Re: Gunk piled up on spark plug J150

Well the more gunk obstructing the port, the less easily the exhaust gas gets out. Needs to be cleaned right out to begin with and go from there.

 

[kenmyfam]

Re: Gunk piled up on spark plug J150

OK so that is one bank. Wondering if the other bank looks the same ???

 

[jonesg]

Re: Gunk piled up on spark plug J150

Pulled the head off and so far the piston is good (no play), the cylinder sleeve is good (no scores) but there is alot of carbon built up in the exhaust port and no build up in the others. They are really clean so I guess the can of engine tuner did the job. I will spray some carbon cleaner in there and try and get this broke up and don't think I had any water in there because I run this boat in salt water and I have noticed this build up once last year when I first got the boat and so far there is no signs of corrosion or rust so I think its just a bad case of carbon build up. When I first got the boat I had it a couple of months before I checked the plugs and did some servicing and realised it ddn't have in any thermostats so wouldn't this cause a carbon build up? I will include the pics.

Those pics look like a steam cleaned piston.
Or have you cleaned the pistons with carbon cleaner already?

 

[kenmyfam]

Re: Gunk piled up on spark plug J150

Those pics look like a steam cleaned piston.
Or have you cleaned the pistons with carbon cleaner already?

It does look really "clean" in there. They all look similar except that one exhaust port ???. That's why i asked the "what the other side looks like" question.

 

[jwellcraft]

Re: Gunk piled up on spark plug J150

Yes I have started cleaning this out.

 

[jwellcraft]

Re: Gunk piled up on spark plug J150

The top one just wiped off clean but the rest took a little more than wipes to get that clean. And yes it did look like it was steam cleaned compared to the others although I just did a can of engine tuner a week ago.