Manifold/Risers in the northeast

Strecker25

Strecker25

Well-Known Member
SILVER Sponsor
Nov 20, 2014
4,917
Rochester, NY
Boat Info
2002 410DA
Engines
Caterpillar 350HP 3126
Hi guys, going through a search for our next boat and have a question regarding the exhaust schedules on boats used in the NE. There are many good looking examples in the CT, NY, NJ area.

I know in the southern brine people replace manifolds/risers every 3-5 years. Does that schedule hold up in the NE even when the boat is pulled for the winters? I can't find a definitive answer as to whether the colder water and shorter season have much of an affect.

Obviously this will vary boat to boat, just looking for a general idea so I can factor the parts into the cost before getting serious about anything.
 
If you're in the salt, I would replace every 5-7 years or so, depending upon use. Fresh water, every 10-12.
 
I replaced mine after 7 seasons in salt water year round (Newport Harbor RI) and they looked excellent - could Hardley justify replacing/scrapping them - they were dry joint and that eliminates the most troublesome area.....
 
300 hours or so for salt water users seems typical, which works out to 6-7 years in most areas of the country where year round boat weather does not exist. Being a fresh water boat user for 30 years now, I have never heard of anyone in my area ever replace manifolds.
 
Thanks guys, We’re looking are 1999-2002 340s with a preference to the 8.1s so they would have the SS elbows. My concern with that motor would be that the aluminum manifold has been swapped for cast, and how long ago.

The earlier boats have the 7.4 or early 8.1 with cast exhaust. Many of the cleaner boats have had the exhaust done within the last 3-4 years.

We would be bringing it up to Lake Ontario so I’ll try to find one with a relatively recent exhaust job and they should last a while in the fresh water.
 
5 years on OEM stuff here on Long Island. Less for aftermarket parts.
 
In addition to the exhaust on the 8.1 you may also have to replace the transmission cooler and some 8.1's also have fuel coolers. These coolers have salt water running through them and they corrode just like the exhaust.
You should also know that in addition to salt water corrosion on the fuel coolers Mercury has had problems with ethanol and the fuel coolers. The coolers are painted by Mercury on the inside and the ethanol in the gasoline eats off the paint which in turn works it way down the fuel system towards the injectors. This can cause big problems. Ethanol issues are not unique to Mercury but one could argue that the fuel coolers should not be painted internally.
 
Thanks, I've read about the fuel cooler woes but the tranny cooler never crossed my mind.
 
Gary B said:
In addition to the exhaust on the 8.1 you may also have to replace the transmission cooler and some 8.1's also have fuel coolers. These coolers have salt water running through them and they corrode just like the exhaust.
You should also know that in addition to salt water corrosion on the fuel coolers Mercury has had problems with ethanol and the fuel coolers. The coolers are painted by Mercury on the inside and the ethanol in the gasoline eats off the paint which in turn works it way down the fuel system towards the injectors. This can cause big problems. Ethanol issues are not unique to Mercury but one could argue that the fuel coolers should not be painted internally.
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He's looking at earlier boats - that problem did not start until '05 with the into of cool fuel III
 
Don't forget the heat exchanger and the crankcase oil cooler. All these things have finite lifespans in salt water since they all have raw water running through them. They all need to be included in the "routine maintenance" regimen.
 
rondds said:
Don't forget the heat exchanger and the crankcase oil cooler. All these things have finite lifespans in salt water since they all have raw water running through them. They all need to be included in the "routine maintenance" regimen.
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I'd need a second job to boat where you guys do ;) Thanks for the info, I'll keep all of this in mind while we browse boats
 
Heat exchangers and coolers with the exception of the CF3 are made of brass and have a considerably longer life span than iron or aluminum
 
Cheaper to change early than after you scuttled a motor. Start checking seasonally after 3 years with a hard replace at 5 regardless.
 
SteveRuss said:
Cheaper to change early than after you scuttled a motor. Start checking seasonally after 3 years with a hard replace at 5 regardless.
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I did not know about trans coolers until one failed. Fortunately caught it in time before trans damage. Replaced both trans coolers, oil coolers, risers and spacers. Ouch!
 
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