Go Back  Offshoreonly.com > General Discussion > General Boating Discussion
Changing coolant/antifreeze closed loop >

Changing coolant/antifreeze closed loop


Changing coolant/antifreeze closed loop

Old 03-12-2023, 09:04 AM
Thread Starter
Join Date: Mar 2023
Posts: 1
Likes: 0
Received 0 Likes on 0 Posts
Default Changing coolant/antifreeze closed loop

What is the easiest way to change and flush the coolant/antifreeze on closed loop system?
. Boat on trailer
. carbed 540 BBC
. stainless marine Dry to the tip exhaust


Last edited by Stabbin Cabin; 03-12-2023 at 11:02 AM.
Stabbin Cabin is offline  
Old 03-12-2023, 10:32 AM
Join Date: Nov 2009
Location: KY
Posts: 4,134
Received 476 Likes on 371 Posts

Would help to know what motor
Don't know of a "easy way" but not dramatically hard either. Biggest issue is if the boat is in the water or trailer.

Pull block, exhaust manifold, and heat exchanger plugs. Re-Install plugs and fill with water to flush and pull plugs again to drain water.

Plugs back in and add 50/50 mix of AF
AllDodge is offline  
The following users liked this post:
Bondo (03-12-2023)
Old 03-12-2023, 07:58 PM
Gold Member
Gold Member
seafordguy's Avatar
Join Date: Jun 2006
Location: Seaford, VA
Posts: 4,936
Received 800 Likes on 369 Posts

There are plugs on the blocks that will need to be drained that should get most of it, but most heat exchangers will have plugs as well. Overflow tank?

Assuming it's a half system you wouldn't have to drain the exhaust/headers.

Be sure to use distilled water and AF. After you fill it back up you will probably have to run it and top it off.
seafordguy is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.