Heat Exchanger = Missing on 4.3L Closed Cooling System

[zul]

Boat is in a heated garage and it rarely gets below 32 deg around here ... but I am not wanting to rely on that. It's my first year with this boat and just found that the closed cooling system was removed by the previous owner. I'm using the Owners Manual and Merc Service Manual #18. Steps for Raw and Closed cooling systems are both covered. Do I simply follow the raw cooled instructions?

I've drained and wired the engine block (2 plugs).
I've also disconnected the in-line hose for the power steering cooler.
Now I am wrestling with the hose from the circ pump, and it's NOT gonna budge without additional tools or advice -- Dish Soap?

I've got thumb tabs (one black/one blue) at the bottom of each exhaust manifold, so I"ve got to disconnect those yet.

With the closed cooling system removed, are there any extra steps I need to look out for? I don't think there's any difference in performance? I'm a fresh water guy so I don't think I really 'need' the closed cooling system? I've done 2 days of internet reading over this and learned a lot.

Once I get the circ pump hose off and manifold tabs disconnected, is that it?!! I've got the outdrive removed and gear lube drained.

Another Questionable Story:

About a month after getting the boat, I realized that the engine serial # was scratched out. I've been trying not to freak out about that over the summer... but ... I'm guessing it means a previous owner blew up the engine and had a mechanic rebuild it. Does a reputable mechanic scratch out the serial number as proper procedure? Will it affect my insurance (as in - can the boat be insured?)

Thanks All !!

 

[Bondo]

Ayuh,..... What makes ya think it ever had closed coolin',..??

Many, many motors out there don't have the original serial number on 'em, as it more so covers the accessories on the GM long block,.....
Insurance Co.'s shouldn't care,...

Now I am wrestling with the hose from the circ pump, and it's NOT gonna budge without additional tools or advice

Slip a hose pic or screwdriver 'tween the rubber, 'n the pump housin' to free 'em from each other, then twist 'em apart,....

 

[zul]

The black cover over the carb states "Closed Cooling Applications Only".

This same cover has all the serial numbers but the one next the 'Engine Serial Number' has been purposefully rubber out by a screwdriver.

This boat was originally purchased in Minn and I bought it from a guy in Phx, AZ. The engine hour gauge had 190 hours when I bought it ... and now it's at 290 hrs. I doubt that the boat has spent any time in salt water but it's possible. I'm reading that if people run boats in salt water with closed cooling and don't flush em' it'll lead to bad problems. Especially when the (half) closed cooling system comes off. Just one more thing to worry about?

 

[Bondo]

Ayuh,.... That cover means absolutely nothin',.....

For a long time I had a 5.7 cover on my 4.3l,....
Or my ole 135hp outboard with 80hp badges,....

If the motor is original, there'll be an aluminum tag riveted to the block down by the starter with the serial number on it,....

 

[Scott Danforth]

make sure you drain the manifolds

as Bondo stated, the cover means nothing. I have an AQ271C (small block V8) cover that will probably go on my built-up big block. I may change the decal to AQ471C