2004 Mercury 225 FourStroke Corrosion

[whalerron]

I have a 2004 Dauntless 220 with a 2004 Mercury 225 FourStroke on it. The 2004 Mercury 225 FourStroke has 230-hours, and it has substantial corrosion in the dry exhaust stack.

Q1: does the cost of repair of substantial corrosion in the dry stack of a 2004 Mercury 225 FourStroke engine exceed the benefit of the repair?

The repair involves replacing the exhaust stack, oil pan and seals If that fix will give a 2004 Mercury 225 FourStroke engine another 1,500-hours of life, I would do the repair. On the other hand, if the repair only gives me another 300-hours before corrosion in the water jacket attacks the lower cylinders, it wouldn't be worth the money to do the repairs.

To anyone who done this repair [to a 2004 Mercury 225 FourStroke]:

Q2: what was your experience after the repair?

Q3: how much more life did you get out of the Mercury 225 FourStroke engine?

Thanks.

[Jefecinco]

I don't believe it's possible to accurately predict how many more hours of use those repairs will provide. If the dry exhaust stack corrosion requires replacement after only 230 operating hours over 12-years of use the prognosis is not good. However, if the replacement parts have been significantly improved compared to the originals that will change the probable outcome.

Is the oil pan also corroded beyond repair?

You didn't say what the estimated cost is for the repairs. Compared to the cost of a re-power the repairs would, I assume, be relatively inexpensive.

Is the engine operated in saltwater?

Is the engine flushed with fresh water after every use in salt water?

How is water getting into the crankcase?

Perhaps there are some preventive maintenance efforts you can take to reduce the likelihood of future corrosion if you replace the stack.

[brill]

I believe that your engine may have been manufactured by Yamaha. Yamaha had a problem with 2000-2005 F225 engines and dry exhaust stack corrosion. You may want to check with your dealer. This concern is very well known for Yamaha branded F225 engines and may carry over to Mercury engines as well.

http://www.boatus.com/magazine/2012/oct ... laints.asp

[whalerron]

The motor is a rebranded Yamaha 225 four-stroke and I was wrong about the hours. It has about 300 hours on it. For the first 10 years of its life, the motor was used in bay behind Ocean City, MD. The dry exhaust problem is not due to salt water corrosion or lack of flushing with fresh water after use. The dry exhaust stack carries exhaust out of the motor. Unlike the 2 strokes, the exhaust in this motor is not mixed with water on the way out. It is assumed that the corrosion is due to chemicals in the engine exhaust and those chemicals eat the untreated aluminum stack. Yamaha recognized the problem and the replacement parts do not have the corrosion problem.

The underside of the oil pan is exposed to these same gasses and it, too, is untreated for corrosion. The oil pans on many of these motors have had holes eaten in them by corrosion.

[Jefecinco]

In that case I recommend the engine be repaired. Hopefully the oil pan has also been improved to prevent early corrosion.

[cspaldi]

We just went through this with same boat, motor and general location. Our corrosion was worse than yours, into the block. We are re-powering with a new engine rather than doing a power head replacement. I have a recent thread on [the re-power] in the performance section here. Looking forward to worry free time on the water but a re-power is certainly expensive.

[whalerron]

cspaldi, where did your Mercury outboard engine get most of its use? Was it in the ocean or in one of the bays? Thanks.

[cspaldi]

Our boat has spent its entire life from new in the Miles River area and into the Bay around there. Kept in St Michaels harbor. Typical light seasonal recreational use only. Kept in the water during the summer and hauled and winterized every year.

[Commok]

I have [a 2004 Mercury 225-HP FOURSTROKE engine] on my 220 Dauntless. The engine has 243 hours.

A technician checked for corrosion [in the exhaust dry stack] during a water pump change. The technician used bore scope. In my case there was no corrosion.

The cost of parts to fix corrosion is about $750. The repair is an easy job--compared to the initial poster's account of his repairs.