Yanmar 3GM30 elbow cleaning ?'s

[WindDancer]

Can carbon/rust buildup be cleaned from elbow with diluted pool acid? (50/50)
Should the manifold be cleaned also?(with acid bath) or just the elbow?

TIA
Forrest

[scotte]

FWIW, here's what I did recently.

I replaced (not cleaned) my elbows - they are expensive parts, but considered a wear item. Yours may be cleanable, but if they are more than a few years old, you'll have to make a call on that.

For the manifolds, I took them along with the heat exchangers to a radiator shop. They cleaned them using a fairly mild acid (I don't remember what, but they said it was much less than muriatic), and rodded out the exchangers. Came out very clean. I also took the manifolds to a machine shop and had them resurface where elbows mount, as mine had some rust build up.

I replaced all the gaskets as well (elbow, filler, manifold, and bottom bracket), and then primed+painted everything using high-temp engine paint (I chose "New Ford Gray" as a relatively cheap close-enough paint).

[Badsanta]

I tried to clean mine, but found too much corrosion to make it smooth. Replacement is the only option and then every few years. I think it has a 500 hour life.

[WindDancer]

Thanks for responding, I never thought of taking it to a radiator shop. My Yanmar has a little over 600 hrs total and the elbow has less than 100 hrs, but I had a overheating issue late last year, and cleared the problem by cleaning the water input to the elbow. I only use the engine to/from the slip to open water with a 5 knot speed limit. I know, I need to run it at near full throttle sometimes to reduce carbon buildup, but I hate to listen to that noisy thing.

I will contact some local radiator shops to see if they will do the cleaning.

Thanks again
Forrest

[MitchM]

when you are taking the thing off, just detach the 4 bolts holding the exhaust manifold on and take off the assembly including the elbow. don't try taking just the elbow off . yanmar cleverly 'reverse threaded' the elbow itself and i spent untold energy trying to just take off the elbow, finally called mack boring who told me about the reverse thread. once you have the elbow/manifold assembly off you can undo it as long as you figure out the threads. on mine the el was so badly corroded and carboned up i just bought a new one as all efforts to clean that el were unsuccessful. ( acid, wire brush, etc what a mess.) by the way the symptom of gradual massive carbon buildup was a gradual loss of high end rpms and power as the clogging up of the diameter of the exhaust manifold made it harder for the exhaust gases to escape from the cylinders. the engine ran right on the power curve with a new exhaust el....

[HorizonMarine]

It is possible to do a partial cleanup job on the yanmar elbows. muriatic acid is not effective against that carbon. It takes hours of pounding with a hammer and chisel type tool to get it partially cleared. We have nevr been succesful at getting one to the point where I thought it was acceptable. My advise is to buy a new one. If you are a distance cruiser, chisel out the old one and carry it as an emergency spare.

Gary Horizon Marine Service, San Diego. (curently south of Puerto Vallarta, enjoying life!)

[Artful Dodger]

I notice you are talking of a 3GM30 series engine, any one have experience with the 3YM30 series do they have the same problem

[MitchM]

i think all yanmars wheterh teh GM or the Y series will carbon up their exhaust elbows as will all other diesels. don't know whether the Y series has the reverse thread issue on the elbow, you could call and ask mack boring. I spent a fruitless 3 weeks trying to clean the carbon out of old exhaust el, soaked it in Pb Blaster, tried wire brushes, drills, chisels etc then finally gave up and bought a new one.

[Captain Bill]

I made a discovery that might save you a little money. Torresen marine occasionally has "Take off" mixing elbows at about 1/4 the price of new ones. These are stock elbows taken off new engines because someone had an installation done with the optional mixing elbows. I came across these when looking for replacement elbows for my Yanmars. I got 4 for the same price as a new one. They're not always available so you have to watch their web page.