Decarb-yes or no?

[lakelover]

This is a quote from the Johnson/Evinrude discussions above:<br /><br />

The Decarb probably washed away the carbon build-up that was helping seal the rings and that's where you lost more compression. Just a theory..

I've been thinking of decarbing a 1969 Johnson 9.5 that probably hasn't been decarbed in over 10 years, if ever. As for performance, it's kind of tired.<br /><br />I've wondered about this very concern, whether decarbing would be helpful or would it cause further performance deterioration because of the reason in the quote above. <br /><br />Any thoughts? Thanks.

 

[phatmanmike]

Re: Decarb-yes or no?

its always been told as helpfull to me. im not really sure if that quote above is really even possible<br /><br />but what do i know<br /><br />mike

 

[rickdb1boat]

Re: Decarb-yes or no?

The reason I said that was because that engine has serious compression problems. If enough carbon built up in the ring seats and piston dome, I can only assume that it would affect the intial compression readings and account for the loss of compression after the decarb. A healthy engine, with good compression now, will certainly benefit from a decarb. Also, as I said, this was just a theory on my part about his motor. If anyone can explain why he lost compression after a decarb, I'd sure like to know what they think. For all I know, he may have read the tester wrong and needs to do it again. I'm not there. But after all, the only thing he did was a decarb on a known bad cylinder...

 

[Dhadley]

Re: Decarb-yes or no?

We have seen a couple of cases where there was an engine problem after a de-carb job. In both cases the de-carb was fogged into the motor as per instructions BUT it was left in the motor over a week. (One case was a week the other was much longer) The de-carb instructions say to let it sit for a specified time (usually a few hours)and then run it out.<br /><br />The de-carb eventualy dried out the sleeves of the oil. On any given motor when the motor stops its likely an exhaust port is open which then exposes that cylinder to air. With no oil in the pores of the sleeve surface rust started. When these motors were eventually restarted, damage ocurred.<br /><br />Obviously we have no way of knowing what happened to this persons motor but these two cases we do know what happened.

 

[roscoe]

Re: Decarb-yes or no?

Seafoam Deep Creep also says it can be used as a fogging oil for long term storage. <br /><br />Maybe they used a decarb potion that didn't have the requesite oil for metal protection.<br /><br />Also, a broken ring can happen at any time, even during a decarb, as the engine is running.<br /><br />??

 

[lakelover]

Re: Decarb-yes or no?

Well, I don't know what the compression is, but the motor runs well for its age, I'd say, just a little tired, and temperamental at starting sometimes.<br /><br />Sounds like de-carb is a good idea. <br /><br />rick,<br />Your theory sounded pretty logical to me, that's why I wanted to check it out. I've never really heard a recommendation against de-carbing.<br /><br />Thanks.

 

[oregonducker]

Re: Decarb-yes or no?

lakelover,<br />I say decarb it. I'm not a pro and hadn't heard of decarbing until I found this site. Once I learned I promptly decarbed my 72 johnson 25 horse which always started and ran fine but it just didn't have all the power I thought it should. It does now. Seafoam made a definate and immediate difference in that motor.

 

[Solittle]

Re: Decarb-yes or no?

I know there is no direct transfer of knowledge between a 2 cycle OB and an automotive engine and I do believe in decarbing an OB - Having said that years back I was poor as the proverbial church mouse and needed a car. Bought a tired 57 6 cylinder stick shift Ford for $150.00. In trying to "make it better" I decided to clean the internal oil crud and sludge buildup by draining the oil and refilling with kerosene - running it just a short bit and following with a regular oil change - sorta like decarbing an OB.<br /><br />Well it worked in that it cleaned the goo - motor blew up a short time later. Seems it needed the goo to keep running fairly well. So I think there is something to be said for leaving a motor that is running OK alone.

 

[quantumleap]

Re: Decarb-yes or no?

So little - I've heard of doing the same but with diesel fuel. I don't think kerosene has the ability to adequately lubricate under the rpm's of a car engine at idle. I bet you ruined the bearings right of the bat. The cleaning probably would have beeen successful had you used the right type of cleaning product. Cleaning a moor isn't a bad thing if it's done correctly. It didn't need the "goo" to run, it just didn't have any lubricant while you ran it on kerosene.

 

[rwise]

Re: Decarb-yes or no?

I decarbed my 1958 50 hp evinrude, 80 - 87 lbs comp, went up to 93 - 97 lbs comp. starts better runs better! I run a carbon preventitive every tank now.<br />Richard