How to: Merc 9.9 Bigfoot Hotsink (with pics)

[baitsauce]

There's been a thread on a hotsink for a T-8 running around here lately. Did me a helluva lotta good since I have a 9.9 Bigfoot. So I asked (on that thread) about how to hook one up on a Merc Bigfoot. Road Rage came through. Thanks.

So for you guys with a Bigfoot 9.9 or 15 here is how I did mine:

I went to the friendly neighborhood NAPA store and got a fitting and tap.

http://www.ifish.net/gallery/data/500/hotsink1.jpg



I already had some gorilla snot on the shelf from one of my earlier projects.


http://www.ifish.net/gallery/data/500/gorillasnot.jpg



Remove the thermostadt cover and carefully drill (in this case with an 11/32" drill bit) then tap it for the fitting. A little gorilla snot on both the fitting and the newly cut threads in the thermostadt cover, then simply thread the fitting into the cover. Be careful NOT to overtighten or you'll be spending a whopping $3.95 on a new cover. (Yes, I priced new covers before I started in case I screwed things up.) Then install the cover over the thermostadt again using a little gorilla snot.

As you can see I routed the new line from the thermostadt cover fastening it with a ziptie to a boss for the starter.


http://www.ifish.net/gallery/data/500/hotsink2.jpg





An old piece of heater hose split then ziptied over the new line holds it securely through the linkage port to prevent chaffing. The line then runs to a valve ziptied on the tilt/trim clamp bracket in such a way so the hot water falls directly into the sink.

http://www.ifish.net/gallery/data/500/hotsink3.jpg


http://www.ifish.net/gallery/data/500/hotsink4.jpg


The finished product:


http://www.ifish.net/gallery/data/500/hotsink5.jpg



It is a very good idea to fasten the hose to prevent chaffing and wear, as it will be subjected to quite a bit of vibration. Since installing there have been no problems in the MANY hours trolling for the elusive springers. There is no doubt when the thermostadt opens and closes.

My most humble apologies if the colors of the circles don't match up. (Yes, I have a hard time choosing the right color spinners too.)

[GreshamFisher]

Thanks for the post and pictures. My old Merc 15 2-stroke was plumbed, but I didn't do it with my new 9.9 bigfoot. The guys at Steven's Marine told me there was a bit of risk of over heating if I did that to the newer models. Anyone else have any real-world experience with the possibility of overheating a 9.9 bigfoot?

[mic4fish]

Thanks for the post and pictures. My old Merc 15 2-stroke was plumbed, but I didn't do it with my new 9.9 bigfoot. The guys at Steven's Marine told me there was a bit of risk of over heating if I did that to the newer models. Anyone else have any real-world experience with the possibility of overheating a 9.9 bigfoot?

They told me the same thing I am a little Leary as well, I do value what Stevens says. Thanks so much for the demonstration as I will probably do it I think that as long as you have a shut off valve so you you can shut off the water when your sink is full instead of letting it run alll the time then your going to be fine.

[tallswedeone]

You will not overheat your 9.9, actually by plumbing the line in prior to the thermostat in order to have hot water you will be over cooling the engine causing it to run at a lower heat temp. Running the engine at this lower temperature can then have the issue of causing the fuel to condense with the oil know as "making oil". That is why valves are now being installed with these applications. Be sure to wait until the engine reachs temperature, then crack the valve a little filling your basin and then shut the value off - do not let it run all the time.

[baitsauce]

You will not overheat your 9.9, actually by plumbing the line in prior to the thermostat in order to have hot water you will be over cooling the engine causing it to run at a lower heat temp. Running the engine at this lower temperature can then have the issue of causing the fuel to condense with the oil know as "making oil". That is why valves are now being installed with these applications. Be sure to wait until the engine reachs temperature, then crack the valve a little filling your basin and then shut the value off - do not let it run all the time.


The way this is plumbed it takes the hot water AFTER it passes through the thermostadt, and only then, when its open. That's how its possible to tell when the thermostadt is open. Leaving the valve open, which is how I usually run it, water comes through the hose and into the sink only intermittently (ie, when the thermostadt is open). And its not luke-warm or cold. It is HOT.

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[Orca]

So this would be waste water headed to the exhaust anyway?

[baitsauce]

So this would be waste water headed to the exhaust anyway?


Yup. Don't know why I didn't put it that way in the first place.

[mic4fish]

Very good I feel much better about doing this and am looking forward to having hot water in my sink I have a killer custom sink on the top of my gunnel right by my kicker now if I can just stop fishing and clamming and take the time to do it:D!

[oregonrafter]

I've decided to do this modification to my '03 Mercury 9.9 four-stroke.

The pictures in this thread have disappeared, and I haven't been able to locate any other pictures showing the drill/tap of a Mercury thermostat cover.

If you've done this, or have removed the annode bolt and done it at that location, I'd really appreciate seeing some pictures. I don't want to get this install wrong. I have the new sink and hoses installed...

If I get this finished, I'll post pictures of what I've done.