135 Mercruiser converting to FWC

[enn858]

Hi from Denmark

We imported 4 Bayliner 175 BR in September this year (brand new imported from USA), 3 of them where for my friend and 1 is my own, mine got FWC etc from day 1

Now my friend with one of the other boats wanted to install FWC on his - he has been runing the boat 5 hours in Saltwater (since september - he dident make a FW flush after use) - he called me to ask if I would help install the FWC system and ofcourse i will so i went down to him to start the instalation

As i opened the termostathousing there was what i would consider quite heavy corrosion in the colingsystem (small rustflakes in many places) so after installing the FWC system we ran the boat for 1 hour with clean fresh water in the closed system and then changed to 50/50 anti freeze - but I am not shure we realy stopped the corrosion process,

Has anyone any knowledge on how to make shure all Salt is out - and what we should do to prevent further corrosion in the block?

Should we change the anti freeze mixture once more after eg. 1 year to make shure the corrosion process stops?

It is scaring to see how fast the block corrodes away in Salt water - I am shure that the block would not last more than a couple of years in the baltic sea salt water.

I will try to post some oics of the block / thermostat housing later today - you will be amaised of the extend of corrosion.

 

[Mystic Dragon]

Re: 135 Mercruiser converting to FWC

I think your friend's problem began when he didn't flush the system after use. As soon as air mixes with the salt water, the corrosion begins. What's done is done. The corrosion that has taken place is probably not going to ruin the engine but I would run some of this 'salt away' stuff through it first before I put the FWC on it.

Aside from replacing the engine, manifolds and risers, flushing the system will at least minimize the damage and then the FWC can do its job.

I am curious to see the pics.

 

[tommays]

Re: 135 Mercruiser converting to FWC

The only real problem you might have WHICH is a BIG one is the scale may clog the exchanger tubes


you still need to flush after every use to make the manifold and riser on the 3.0 last in saltwater

11 years saltwater with nothing but freshwater flushing when we get home

Tommays

 

[Don S]

Re: 135 Mercruiser converting to FWC

The rule of thumb used by the manufacturer is that it's ok to install a FWC system on boats with 125 hours or less. Since they are only a couple of months old you shouldn't have any problems at all converting to FWC.

 

[enn858]

Re: 135 Mercruiser converting to FWC

I think we will change the antifreeze next fall - and flush the closed system then it will probably be OK

I know thare is no full FWC system for the 181 (135 hp) Mercruiser - so the exhaust manifold and riser is still raw water cooled. How often should we take the riser off and inspect for corrosion - just to be on the safe side (i have a "endoscope" one of these instruments where you can look inside a cylinder or water jacket without dismantling anything) så if i take the riser off i can inspect the manifold with the endoscope - and where is the "soft spots" on the exhaust manifold (where is corrosion likely to be worst)


I have taken 6 pictures of the thermostat housing and block - will try to post them

 

[tommays]

Re: 135 Mercruiser converting to FWC

My pictures are at 10 YEARS in saltwater with flushing everyday after use

We may be to brave BUT have gone 28 years on are 1977 ski boat before changeing when a plastic bag caused and overheat and then cracked a manifold when water cooled them to fast

i have done this with the people i ski with on many boats BUT the boats were always flushed as soon as they were back on the trailer



Tommays