Preventing carbon build-up?

[gw204]

When I winterized my '02 carbed. Merc. 150 last Dec. after it's fisrt season (92 hours run time), I noticed a fair amount of carbon built up on the spark plugs and piston tops. Actually, the top plug on each head was worse (more of an oily film) than the other four (looked pretty normal other than the carbon) but my dealer told me this is due to the bleed system dumping more unburnt fuel into those top two cyls. Is that necessarily true? But that's not the main point of my post....<br /><br />I used only Merc.'s Premium Plus oil and 89 octane fuel all year. I have not yet given her the decarb shock treatment. Honestly, that whole process scares me somewhat. I noticed that there are various products on the market that claim to fight combusting chamber deposits and help prevent sticking rings. The three main ones that come to mind are Yamaha's Ring Free, Merc. Quickleen and ValvTec's Carbon Guard (or something like that). The Quickleen bottle actually only says it helps fight comb. chamber deposits and makes no mention of preventing sticking rings.<br /><br />My two questions:<br /><br />1. Is there really a difference between these three products?<br />2. Would you guys recommend this type of additive? I want to give this motor the best care and maintenance I can.<br /><br />I am planning to switch to Pennzoil 100% synthetic oil now that my warranty has expired.<br /><br />Thanks for any help or advice you can provide.<br /><br />Brian

 

[LubeDude]

Re: Preventing carbon build-up?

You are on the right track by changing to the 100% synthetic oil, you will not have the Carbon problems you are now experiencing any more! However you need to de a decarb, and I would recomend Seafoam as others here on the forum do, do a search on Decarb an or Seafoam and you will get all the help you need. Its a proven product and seems to do a great job.<br /><br />While you are at it, change the lower unit oil to synthetic also.

 

[dashaway]

Re: Preventing carbon build-up?

There ya go.... Seafoam is da stuff!

 

[BillP]

Re: Preventing carbon build-up?

A slight "dusting" of carbon is normal on the pistons. If you have it as thick as a cheap business card at 92 hrs (or 292 hrs)there is something wrong no matter what oil you use. It's running too rich, too cold or wrong plugs, etc. You should be able to go 100s of hrs before any appreciable buildup is visible on the crowns. Check the plugs when cruising...shut the motor down at speed and see what they look like. Don't idle in to the dock and pull the plugs.

 

[Dhadley]

Re: Preventing carbon build-up?

One of the biggest things that we've found to help prevent coking (carbon build up that sticks the rings) is proper set up. Motors that are capeable of top rpm in the low 5000 range coke up way sooner than those set up at 5800-6000. Its not unusual that those in the 5800-6000 range never coke up.

 

[Clams Canino]

Re: Preventing carbon build-up?

Riddle me this Mr. Hadley? <br /><br />If an engine is set up to run in the high 5's, but spends most of it's time at cruise of about 4200, how will it do? I assume better than one that was set up too low?<br /><br />-W