Carbon build up

"Had the intake off of my port

"Had the intake off of my port engine, model 350-454. Looked inside and noted a significant amount of build up on the back of the intake valves. Suspect combustion chamber and top of the pistons will look the same.

I have long suspected loss of power and increased fuel comsumption on the starbord engine was due to this but forgot to look for it when I had that intake off.

I have tried in the past to run SeaFoam down the carburator and also tried ATF. Appears it did not do much good.

Aside from pulling the heads is there any solution?"

"That sounds like the crap tha

"That sounds like the crap that builds up thanks to "evil-nol". You COULD try the old mechanic's fix--heat 'er up, rev 'er up, and spray water in the carb--but you got it partly apart already, so...

What the heck. You'll KNOW it's good to go then.

Jeff"

"Dont have ethanol,this stuff

"Dont have ethanol,this stuff has built up over the years, prior owner related. I dont feel like pulling the heads and spending any more money that I have to , thing runs strong. We are going to sell her, these days cant justify the expense of boating anymore.

I pulled the intake when I did Valve stem seal job. Wanted to inspect lifters etc since I was working in the area. Also took intake home and sandblaseted it and the valve covers and did #1 paint job on them.

Anyhow to do heads on both engines with gaskets will cost 1k and just cant do that anymore."

"I agree with Jeff, the fuel w

"I agree with Jeff, the fuel we buy today is expensive and not very good for our engines. For the first 15 years I didn't experience any buildup in my intake manifold. Then at year 20 I pulled the carbs to have them rebuild and found buildup inside the manifold under the carb on both engines. This stuff has to be from the gasoline.

I plan to continue boating as long as my health and money hold out. I am 67 and feel the same as I did when I was 50. I hope I last a little longer. I spend about $10,000 per year on boating. When I started 21 years ago I spent about $5,000. Slip fees account for most of the increase and I burn a little less gasoline today since I am no longer on the Mississippi River. Insurance is about the same. Although fuel has doubled in price, it only represents 10 - 20 percent of the boating cost.

I saw a bumper sticker a while back that read "you might as well go first class, if you don't your heirs will." Whereas I don't go first class, I do plan to spend it while I can.

Chuck Hanson"

"I've had good luck with B

"I've had good luck with BG44, a fuel additive. I used to use it in my BMW when I used mobil gas. It worked great. btw, since i am using shell gas, no more bmw missing issue. The boat has negligable carbon build up, at least with MTBE fuel, but I do run it fairly hard, with little trolling/idling. You might just try to run the snot out of it for an hour, assuming it is not missing. I'm on my first big load of E10, not sure what to expect.. "

"try quicksilver's "po

"try quicksilver's "power tune" when its back together. it was made for doing just that job. the build up is usually a byproduct of spending a lot of time at idle, with a rich mixture. after the spring flounder run (most of the day drifting, at idle) I used it. sometimes it takes two or three cycles. Just follow the directions on the can.

BTW - the last step is, as Dave said, "run the snot" of them. you can go longer than the can says but not less."

I may break down and tear this

I may break down and tear this one down the rest of the way. Will decide tomorrow when I am there. I dont like doing a half job but cost may dictate.

"too bad already started to br

"too bad already started to break it down, the old school (i love old school) was is to slowly trickle water straight down the carb, while the engine is running, one barrel at a time. Do this on a 70's caddy and you can see the carbon being spit out the tailpipe."

"A hose with a fine spray of w

"A hose with a fine spray of water works even better, but.... Too late.

Jeff"

"I'm a bit lost here. I t

"I'm a bit lost here. I take it the heads are mounted but the intake is off. You did a seal job with the heads mounted, or that was some time ago?? In any case, if all you need to do now is take carbon off of the intake valves, I don't think I'd be scraping or shooting chemicals into the mounted head intake ports. All that carbon and/or strong chemical will sink to the piston crowns, and maybe lodge in the rings and cause maybe more trouble. I'd button it up and start running some fuel conditioner. It may take awhile to clear out, but it is the safer, cheaper approach."

"I still belive in the more co

"I still belive in the more costly Valv-Tech gas. I get it at a marina a little further away (always a great boat ride) but no build up, and easy start ups."

"Yes I did valve stem seals wi

"Yes I did valve stem seals with heads in place.

I was there on saturday to reinstall and get it running. Stuck probe down the hole and noted the black goo was not hard. Most likely oil residu from the valve guides. All but 3 of the 16 seals were torn. Anyhow I sprayed some spray lube on the 8 intake valves and close it up. Got it running and all seem fine. I did not take the boat for a run as I want to change the oil a second time. First change got the antifreeze and cleaners out.

I will keep using MMO in the gas and try some more SeaFoam in the carburator. May also try the water trick to de-carbon the combustion chambers. Will use Distilled water in a squeez bottle with tiny opening or use Bottle Water typy of container.

Both engines run strong, Compression is very good and only a few pounds between any of the cyliners on either engine. No oil use and no smoke. Fact is they never miss a beat. I however always want stuff perfect and if I was keeping her and had the money, I would do so.

Anyhow I sandblasted the intake and Valve covers and repainted them. Man they look nice, just like glass. Fact Guy at the dock wanted to know if I painted with Imron. No just primer and Duplicolor GM blue paint bomb. Used 2 cans of paint and baked them in the oven."

Good work!

Jeff

Good work!

Jeff

"The water down the carb while

"The water down the carb while running is to clean carbon off the top of pistons, it will not do anything for build up on intake valves. The carbon on the pistons is porous, the water is forced into the carbon during compression then explodes into steam during combustion, shattering the carbon."

"Will try the water to at leas

"Will try the water to at least clean combustion chambers. Backs of valve may have success with continued use of MMO in the gas and Seafoam in the carburators. As mentioned it seems gooey, most likely oil residue from leaking valve guide seals, now corrected, and possibly some carbon."

James is correct: The water m

James is correct: The water mist method is for combustion chamber cleaning only.

Let's hope hte seals cured the gunk problem.

Jeff

"Did the water bit on port eng

"Did the water bit on port engine, did not see much comming out of exhaust. Did it on the Onan and i believe i blew a head gasket. Well hope it is a head gasket and not a ring but will see. Balked on doing any more water on the starboard engine. INstead we took her out and ran up to about 1400 and dumped a qt of AFT down the carb on both engines then ran her up. You know the flow scans were dead even at 3000. When I ran up to 3200 the starboard ran up 2gph higher than port. Seems Like I am on to something.

Well first things first, need to fix gen. Pulled heads and bead blasted them and ordered new gaskets. By the way very little carbon was found in the combustion chamber and the chamber side of the gen valves. Been wanting to pull the heads anyhow. Cylinders also were smooth with no lip."

"As opposed to water, how abou

"As opposed to water, how about sea foam directly into the carb?? I do this once a year or so and it always surprises me how much that mother smokes during the process.

I always figured that it was loosening crud in the carb, intake path, intake valve stem, top of piston and to a much lesser extent, the crud on the combustion side of both valves and then even less, the exhaust stem.

Is this not correct? Whatever it is, there's a ton of smoke and the old gal seems to run better afterward. It seems like pretty good preventative maint and only about 8 bucks to boot.

I also sump my racor regularly through a brass ball valve which I screwed into the bottom of the racors sump bowl. Learned that trick the hard way after ruining a carbostrator. I just sump it every 5 hours of running or so."

"I'm not sure if carbon bu

"I'm not sure if carbon build up on the pistons or valves is really that much of a problem. Sometimes trying to remove the carbon can can also flush it into places where it might cause more damage than if it had been left alone. Carbon on a valve could eventually stop it from closing but by that time the rest of the engine is probably ready for a rebuild. Year ago,I tried the water injection method after reading about it in a popular mechanics magazine from the 1940's...Alot of carbon did come out, alot of moisture got by the rings and into the crankcase, It didn't bend any connecting rods(fortunately) but I'm not sure if it did good or harm. On todays modern engines, this is probably not a particularly good idea. The use of automatic transmission fluid anywhere in the motor is also a strange technique left over from years past. Over 30 years ago I changed a well rounded camshaft that failed very prematurely. The cars owner told me he always added a quart of ATF to the crankcase at every oil change to "clean the lifters". The use of "oil Flushing" chemicals is another way of damaging a motor. Sometimes the old adage, "If it ain't broke, don't fix it" is close to the truth. Just my 2 cents!"

"Update. I did the water thin

"Update. I did the water thing on one engine and did not see anything come out. I tried it on the Onan and blew a head gasket. Though I junked the Gen. Long and short I pulled the heads, bead blasted them , brushed pistons and valves and re assembled. then found that the points were burned which is why the thing started to run bad when the water was added. Guessing the water shorted the spark plugs and caused extra drain across the points. Anyhow now the gen runs better than it ever has. I have always wanted to pull the heads on this unit but never felt like it. This forced me to do so. Found a couple of head bolts rather loose and am guessing this is why the gasket went.

Moral of the story, no more water down the carburator. ATF does a fine job cleaning deposits but guessing SeaFoam is a better choice."