My case 446 has some decent carbon build im pretty sure. So I was wondering what would be the best way to clean it out effectively? seafoam? Is it hard to clean the heads manually? or maybe another additive?
The only way to know for sure that the engine has been properly decarbonized is to remove the heads and perform the work. Now, if you are a gamblin' man, then you can try some alternatives that I'm pretty sure will be suggested in this thread. However, suppose for a second that those methods don't work? Suppose that the carbon is still thick enough to close the gap between the top of the piston and the underside of the head and now the piston is banging into the head 3600 times per minute while you are mowing the lawn?
Suppose for a moment that the connecting rod fatigues, snaps in half and gouges the cylinder so deep that it can't be bored to a clean state? Suppose for another moment that you then have to spend $1500.00 plus for another engine? If I told you that this does happen quite often, would that be enough of an incentive for you to either pull the heads yourself or to send the tractor to someone who will perform the decarb for you?
You misunderstand sir. I'm not suggesting that Seafoam will bring harm to your engine. It is a very good product. What I'm saying is this. Short of removing the heads, you cannot tell how good a job Seafoam or any other product does when it comes to removing carbon deposits. If you wish to place your trust in Seafoam to remove 100 percent off the carbon in your engine, than that would be your choice to do so.
This is not something that I would choose to gamble with because of the high cost of Onan parts and all the machine shop work that is needed to -properly rebuild one.
Mr Castoff is not saying Seafoam will hurt your engine. He is merely stating that it is not a miracle cure. It works well there is no doubt, but if you want to decarbonize your engine you need to get your hands dirty.
You probably just scared him out of it Kc. The trouble shooting service manual says "Carbon in the combustion chamber. - Remove cylinder head and clean carbon from head and piston." It's an easy job and with the opposed cylinder engine you can do it setting down. Then you'll be positive it is clean.
Breaking bolts is your only concern. As others have indicated it is an easy job otherwise. I speak from experience, as 6 bolts snapped on me when removing them. All have been successfully removed since then (usng varioius methods), but be prepared. If you feel one start to bind, back it up, then loosen, back it up, loosen, etc. If all goes well, no worries.
The concern on bolt breakage is due to dissimilar metal reaction, head bolt holes that are "open-ended" (allowing an additonal path for corrosion) and a further hardening of the bolts over time (per Bob Mac). Hope for the best, but be prepared (not surprised) for the worst.
Even after going through all this, removal of the heads was still the right move for me. I need to know what I'm dealing with, so seeing is believing for me.
I think my experience is likely the exception, not the rule, as many, many people on this forum have removed the heads with no problems.
Yes, you will need two new head gaskets for sure. Nothing else parts-wise is required. Use tools that don't leave gouges in the aluminum piston. Take your time and work with care. It isn't a fun job but it is a necessary one if you want your engine to have a long life. Check the underside of both valves and into those valve chambers as well. This is also an excellent time to conduct a valve lash adjustment.
And this is why Brian's advice to obtain an Onan service manual on-line is an excellent move. It will provide you with a wealth of information about your engine.
Ok i think im only going to get 1 gasket because the right side gasket looks pretty good to me. But if you think i should replace it say so, because this is my first time ever taking heads off. Also dont these pistons look really clean? I did seafoam it about a week ago but i didnt let it sit i just ran it through.If you notice in the first piston the one valve is completely white? why is this? Here are some pics of the pistons and heads. The first couple pics are the right head and the third and fourth picture are of the left head.
Replace BOTH head gaskets. Don't try to save $12 here ...
Yes, overall that looks to be pretty good and cleaning it now will make it great for quite a period to come. With modern unleaded fuels the recommended interval is 400 hours, but I bias toward more maintenance than less and recommend 200-300 hours to then service it again.
I have used brake parts cleaner to help loosen the carbon. A brass brush on the piston helps, but plastic scraper generally works, also. The screwdriver tip ... gently ... don't gouge the aluminum ... to loosen larger chunks.
i did not see that you listed the year or model of your onan.
i think BF/MS, because of the STUDS. ( use a little anti-sieze on them)
i prefer to use the Graphoil head gaskets 110-2987.
as others have stated this is the time to adjust the valves.
one last comment, i would remove all tin and press. wash everything with HOT water,
also check your motor mount bolts, and rubber washers. ( yearly )
good luck. boomer