Negative aspects of decarb process?

[halfmoa]

Has anyone experienced problems created by the decarb process aside of the smoke screen? I'm wanting to decarb my 1972 Johnson 65hp and I've read one experience where the carbon removed was more or less sealing a head gasket and the engine subsequently failed. I'm aware that if the carbon was plugging the head gasket it would've failed sooner or later but here's my deal:

My wife's grandfather owned the boat for the last 35 or so years and gave it to her. He was in the USMC and performed preventative maintainence on jet engines so it's very mechanically sound. I'm performing routine maintainence, repairs, and a general rejuventation of worn out aspects and decarbing the engine is next on the list. The wife has been paranoid every time I make an adjustment or repair that something will go wrong and she'll never hear the end of it from her family. (she's right about that) I asked gramps if he ever decarbed the engine and got a puzzled response in return so I'm sure it's never been done. The lake they frequented is a pretty slow paced putt-around-and-look-at-the-pretty-houses lake so I'm sure there's plenty of carbon in there. If I decarb the engine in an effort to improve performance and fuel consumption and something goes wrong guess who'll never live it down? ME!

So, anyone experienced problems created by the decarb process?

Thanks everyone!
halfmoa

 

[robert graham]

Re: Negative aspects of decarb process?

If it's running fine now, maybe skip the de-carb? You could add some Seafoam in your gas tank at each fill-up to maybe slowly clean/remove any carbon/carb deposits as you run the motor around the lake. Maybe let the old dog alone and continue running just fine... if you screw it up, you'll be dog-meat in the family!

 

[halfmoa]

Re: Negative aspects of decarb process?

If it's running fine now, maybe skip the de-carb? You could add some Seafoam in your gas tank at each fill-up to maybe slowly clean/remove any carbon/carb deposits as you run the motor around the lake. Maybe let the old dog alone and continue running just fine... if you screw it up, you'll be dog-meat in the family!

That's what I'm leaning towards but the potential drastically decreasing my fuel consumption is very compelling...especially at 4 bucks a gallon!

 

[ziemann]

Re: Negative aspects of decarb process?

I would tend to agree- if it is running good, then I wouldn't do anything but add some SeaFoam to the fuel mix to slowly decarb it.

If it ain't broke, don't fix it.

I seriously doubt that a decarb will hurt anything and would probably help. But down the road, if ANYTHING goes wrong with it, you could be blamed regardless if you were the cause or not.

 

[Frank Acampora]

Re: Negative aspects of decarb process?

Decarbing will not "drastically improve your gas mileage--in fact, you may not be able to notice anything at all.

I regard decarbing as a "Hail Mary" move, reserved as a last resort when a cylinder has low compression, before a rebuild.

I do not ever decarb any of my engines. Personally, I consider it "snake-oil."

There are those who swear by it and those who swear at it. I have, however, heard of and seen (old) engines that were damaged to the point of needing a rebuild by decarbing.

Modern TCW-3 oils have carbon reducing and preventing properties which should make decarbing a moot point .It is not like in the old days when we used straight 30 or 40 weight auto oil.

Especially in your case: If it aint broke, don't fix it! If mama's happy, the whole house is happy. If mama is P-Oed, the whole neighborhood knows. You have more to lose than an engine.

 

[JimS123]

Re: Negative aspects of decarb process?

In the 1960's I used to decarb religiously every year. As I got older I got lazy. Right now I have 2 motors that I've owned since new and are used every year, but haven't been decarbed in 30 or 40 years. One is a kicker that hardly ever runs past idle. Like others have said, if it ain't broke....

 

[halfmoa]

Re: Negative aspects of decarb process?

Modern TCW-3 oils have carbon reducing and preventing properties which should make decarbing a moot point .It is not like in the old days when we used straight 30 or 40 weight auto oil.

That's just the thing...gramps STILL used 30 weight up until we got the boat a few months ago....for 35 years....and never over about 1/2 throttle unless pulling skiers.

Looking inside the plug holes the pistons look caked and I mean CAKED as in can be scraped off with a pick.

 

[RogersJetboat454]

Re: Negative aspects of decarb process?

That's just the thing...gramps STILL used 30 weight up until we got the boat a few months ago....for 35 years....and never over about 1/2 throttle unless pulling skiers.

Looking inside the plug holes the pistons look caked and I mean CAKED as in can be scraped off with a pick.

"I don't want anything to do with that new fangled TC.... what ever oil" :facepalm:
If it's really that caked, may be worth pulling the head, and manually cleaning the carbon out. Breaking up that much carbon with a liquid decarb could be bad news. A plastic putty knife, shop vac, and finish off with a can of carb clean. Clean the pistons at TDC, then rotate by hand and clean the bits and pieces left behind with a clean rag. Decarb the head, and check the exhaust ports, as they may be plugged up too and need additional cleaning through the exhaust chamber. All said and done, oil the bores down with TCW-3 and re-assemble.

Do this under the cover of darkness after the wifes gone to bed. If anything bad happens, I won't rat you out.

I'm no outboard expert, but this is what I'd do.

Just my 2?

 

[lncoop]

Re: Negative aspects of decarb process?

Just don't boil the carbs in your wife's favorite pasta pot like that other guy did. Anyone remember that conversation?

 

[Silvertip]

Re: Negative aspects of decarb process?

"I don't want anything to do with that new fangled TC.... what ever oil" :facepalm:
If it's really that caked, may be worth pulling the head, and manually cleaning the carbon out. Breaking up that much carbon with a liquid decarb could be bad news. A plastic putty knife, shop vac, and finish off with a can of carb clean. Clean the pistons at TDC, then rotate by hand and clean the bits and pieces left behind with a clean rag. Decarb the head, and check the exhaust ports, as they may be plugged up too and need additional cleaning through the exhaust chamber. All said and done, oil the bores down with TCW-3 and re-assemble.

Do this under the cover of darkness after the wifes gone to bed. If anything bad happens, I won't rat you out.

I'm no outboard expert, but this is what I'd do.

Just my 2?

The problem is that scraping carbon from the crown of the pistons is only half the process. Ports get clogged with the stuff as well. Your only choice is to decarb. Done properly it will not harm the engine.

 

[Silvertip]

Re: Negative aspects of decarb process?

Has anyone experienced problems created by the decarb process aside of the smoke screen? I'm wanting to decarb my 1972 Johnson 65hp and I've read one experience where the carbon removed was more or less sealing a head gasket and the engine subsequently failed. I'm aware that if the carbon was plugging the head gasket it would've failed sooner or later but here's my deal:

My wife's grandfather owned the boat for the last 35 or so years and gave it to her. He was in the USMC and performed preventative maintainence on jet engines so it's very mechanically sound. I'm performing routine maintainence, repairs, and a general rejuventation of worn out aspects and decarbing the engine is next on the list. The wife has been paranoid every time I make an adjustment or repair that something will go wrong and she'll never hear the end of it from her family. (she's right about that) I asked gramps if he ever decarbed the engine and got a puzzled response in return so I'm sure it's never been done. The lake they frequented is a pretty slow paced putt-around-and-look-at-the-pretty-houses lake so I'm sure there's plenty of carbon in there. If I decarb the engine in an effort to improve performance and fuel consumption and something goes wrong guess who'll never live it down? ME!

So, anyone experienced problems created by the decarb process?

Thanks everyone!
halfmoa

Somebody gave you a very "ify" story. You cannot "clog" a head gasket. The only way to do that is if the head gasket was leaking to start with and if that leak was then clogged that would have been a good thing. Remove the plugs. Look in the plug holes with a pen light. See serious carbon build-up? Decarb. If not, simply run it in the fuel. It is good for the fuel, the fuel system will stay clean, and whatever carbon is in the engine will gradually go away.

 

[nwcove]

Re: Negative aspects of decarb process?

Just don't boil the carbs in your wife's favorite pasta pot like that other guy did. Anyone remember that conversation?

i cant see why she would be upset about that! pasta is high in carbs!!!

 

[halfmoa]

Re: Negative aspects of decarb process?

The only way to do that is if the head gasket was leaking to start with and if that leak was then clogged that would have been a good thing.

That's what I meant through and through. The decarb process presumably removed a bit of carbon that was benifically plugging a leaking head gasket. And, for what it's worth, I got the story from these forums...no one has ever streched the truth on here, have they?

So, again....any personal experience with a decarb gone wrong? I promised the wife I'd do some searching on the negative aspects of this operation before I'd try it.

Thanks,
halfmoa

 

[halfmoa]

Re: Negative aspects of decarb process?

i cant see why she would be upset about that! pasta is high in carbs!!!

Now THAT'S funny!!!

 

[nwcove]

Re: Negative aspects of decarb process?

i have been using seafoam in my fuel for a short time, started using it in a 1957 johnson, that ran ok, but not great, a couple of tanks with seafoam added, and the motor now works like a top, maybe it would have cleaned itself up with out the additive, but i will continue to use it, 90% of my boating is just idling around.

 

[ohioriverat]

Re: Negative aspects of decarb process?

I had a piece of carbon take out a cylinder in my old chevy truck, it scarred the cylinder wall and dropped from 175psi to 65psi compression. only safe way to do it i think would be manually and alot of work,my op.

 

[nwcove]

Re: Negative aspects of decarb process?

its a triple edged sword......leave it alone, and hope no big chunks of carbon dislodge, or slowly decarb it with additives, or pull the head, and exhaust cover and clean it up, hoping that nothing goes amiss that could cause divorce! lol

 

[5150abf]

Re: Negative aspects of decarb process?

I have decarbbed mine once a year for quite awhile and never had any problems at all, I did it the right way the first time and now I just run to my first fishing hole and then spray some Deep Creep (Sea Foam in a can) into the carbs with the engine running and let it sit while I fish, smokes like mad on start up but has never hurt the engine.

I have an '81 Evinrude 50 that runs perfectly, compression is 135/132 and it will idle all day long.

As to the head gasket story, it was bad to begin with decarbbing had nothing to do with the failure itself .

Considering it is so baldy carboned I would run a heavy mix of Sea Foam through a tank gas to slowly get out alot of then do a regular decarb, it will not hurt the engine, that one story is the only thing I have ever heard bad about doing this and that engine had already failed he just didn't know it yet and decarbbing didn't cause the failure.

 

[Sea Rider]

Re: Negative aspects of decarb process?

Being such an oldie and as a maintenance issue you could disassemble cylinder head, clean all water paths on head & cranck case, check thermostat condition, could apply power tuner to cylinder head & head piston let soak, squirt more PT, with old toothbrush, or used 3M old scotchbrite green pad remove in circular motion coated carbon buildups on both. Place a new head gasket, torke to specs and change all spark plugs We've been doing same for years on many engines and none of them suffered from light decarbon issues. After that could run power tuner through carb to remove carbon buildups on piston rings.

Happy Boating

 

[robert graham]

Re: Negative aspects of decarb process?

I still vote for just leave the good running motor alone. The carbon on the piston crowns apparently aren't hurting anything, and any attempt to remove the head for mechanical decarb could result in broken bolts that are corroded in place. Probably a steady treatment with Seafoam will slowly remove some carbon and probably prevent building any more deposits. Remember if you screw up that old motor you're gonna be sleeping on the dock for a long time!