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Crusader 454 XL Cooling issue

390Express

Regular Contributor
454 Crusader, complete closed cooling system (only the risers and exchanger are raw water cooled). I did a valve job on the starboard engine this year. All back together, running well, but overheats after about 5 minutes.

When I was disassembling the engine for the valve job, I drained an astonishing 5 gallons (and that did not include the block). I filtered the drained coolant while putting it back in, and likely spilled a gallon in the process of draining and filling it.

I'm trying to figure out if I just need to "burp" air out of the system to get it to run cool, or if I have a bigger issue. I noticed that upon cool down, most of the heater hoses collapsed hard, not sure why. While the engine was running and getting hot, the heat exchanger remained cool. I pulled the top vent bolt on the exchanger while it was running, and only air came out... Then I shut the damn thing off as it was heating up, left the vent bolt out, and lost about 1/2 gallon of coolant out of the vent. (OOPS!) Seems like coolant is circulating through the heat exchanger, just have to figure out if anything is malfunctioning, and if not, the best way to get air out of that enormous system.

The risers always remained cool, the raw water side seems to be doing its job.
 
being as they hold over 8 gallons, the 5 you got shouldn't have been a surprise.

normally, you will need two or three 'bleed cycles' to get all of the air out, especially if it doesn't have a degas bottle. some still have the vent plug in the top of the tstat housing...loosening that helps for the initial fill.

Anyhow, start it up until the temp gauge gets close the the t-stat setting and then shut it off...let it cool enough to open the HX and recheck the level, fill if needed and then repeat until the coolant level stops falling (with the cool down phase)...

you can also use a vacuum to purge the air but it requires more work...
 
Thanks Mako, great advice, as always. Just wanted to make sure that I’m on the right track, and not overlooking some larger issue.
 
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