Rust color in exhust water at start up

"I have a 1990 Wellcraft 3300

"I have a 1990 Wellcraft 3300 Costal with a pair of 454's w/ Qjets. After sitting for about a month I fired up the starboard engine on the fresh water flush system. A big cloud of rust colored crap flushed out at start up .... wtf. I always flush the salt out with fresh water and salt a way after use and the entire cooling system including manifolds was replaced/rebuilt 4 years ago. The port engine does not ever do this and the starboard started, or I should say I noticed this, several monts ago. After sitting it looks like I'm flushing a bunch of rusty water out of the exhust.

I'm very worried because I fear water in the heads... any advise or tests or past experiences are very welcome.

Other than this "issue" the engines and boat runs great and have never given me a problem.

Rich Swendsen"

"If they changed the exhaust e

"If they changed the exhaust elbows with the 'entire cooling system", they may be the most likely candidate. Flushing will slow down the corrosion, not eliminate it.

If you have FWC, and its "full", the manifolds will last much longer; won't do much for the elbows.

You can always substitute the dock hose for the cooling water on your next visit....if your cloud appears when the hose gets turned on, may be time to pull the elbows and at least check them"

""Flushing will slow down

""Flushing will slow down the corrosion, not eliminate it."

In an attempt to give my risers/elbows more life, I started to flush out my cooling system after each use. I boat in salt water with a FWC system. There was no apparent increase in life of the cast iron risers. That is, I still need to change the risers every 4 years, and they are a rusty mess, internally at that point. I still flush, hoping my plan reduces scaling in the Heat exchanger. Since I haven't had to boil them out in 10 years, maybe that works."

Thanks for the replies.

I d

Thanks for the replies.

I do have the FWC system with the heat exchangers and manifolds cooled with salt water.

So I guess at the end of the season I should pull the risers/elbows and inspect/exchange as necessary.

Thanks ... Rich

"Rich - are you sure the manif

"Rich - are you sure the manifolds are raw water cooled? They are FWC'ed if there's a 'doughnut' between the manifold and the elbow with a fitting, each side going to the HX. Yes, on your plan, unless they 'rot thru' beforehand.

Dave - your findings echo mine - no delta in elbow life with flushing. FWIW, the lack of flushing hasn't impacted my HX yet..."

"Mark- there was a curious dev

"Mark- there was a curious development of the log style BB exhaust manifolds. The early versions (~ early '70's) did not contain a 1" NPT port for the water exit near the exhaust exit. THese manifolds required the donut to allow a hose connection. The newer (80's on) changed in a few ways. No longer 4 drain plugs (only 1), added the 1" rear water hole, a new forward hose connection design also. Bottom line, you now don't need the donut with the extra gasketing, and points of failure/leakage in a FWC system. If you do this change, the riser moves forward a couple inches or so, and the exhaust hose needs to reach that extra distance as well. But, it works well."

"Neat info - but my configurat

"Neat info - but my configuration redefines your timeline. My "1986" BBC had the doughnut water adapters on them so i guess the switch was later (my luck the following year).

I swapped them out for merc style center riser manifolds and got the SS elbows before they went NLA. Kind of curious as a few years later, i saw a 'new' brochure and they had switched to that style (no more rear exit logs).

Had the same 'forward migration issue' with my swap. No big deal as we went from 3" to 4" hose and planned to put the reducers in until the piggybank fattened up a bit."

"I get the exact same thing bu

"I get the exact same thing but happens anytime let boat sit for more than a week. After much investigation, my 1988 Tiara has cast iron elbows in the exhaust before the mufflers. The exhaust is a wet exhaust and when sits wind and waves push some water up into exhaust and sits in elbow. Have checked elbows and seem fine but will eventually replace with fiberglass. In the fall can also see leaves come out when start."

"RM - you must have the good e

"RM - you must have the good elbows. mine were 'uphill' from the mufflers and I don't think they lasted 5 years...just flaked off big chunks until they leaked. The fiberglas one are much more durable and save a few pounds, too."

"Not trying to appear stupid t

"Not trying to appear stupid though some times it comes naturaly, when you say you are replacing with fiberglass are you talking about the muffler or the elboes?

Paul in Maine"

"Sorry - AFUI on my end - its

"Sorry - AFUI on my end - its more accurate to describe the cast iron rust generators as Y pipes, where each exhaust hose, from the elbows, get combined and flow into the muffler and flow out the transom."