Engine winter commissioning taking forever

[mregan]

Was putting the boat away for the winter this weekend.  Raw water seacock was shut.  Pulled the raw water strainer out, started the engine.  Typically I run right back and start pouring a gallon of antifreeze in.  Usually takes only a minute or 2 then I shut off the engine.   This time I run back to the strainer and the water hasn't gone down.  Wait a minute and it starts to slowly go down.  Add a bit of antifreeze and wait.  Nothing happening so increase the rpm to 1800 or so.  Go back to the strainer.  It would slowly go down, stop then rapidly drop, I'd fill it back up and wait.  Kept doing this over and over.  I think it was about 15 min before it took the whole gallon.  Temp was about 185ish when I turned it off.

Earlier in the season I overheated the engine.  Since then it has been running fine, staying about 160-170 when underway.  Not sure what was going on with it yesterday.

[KWKloeber]

Why not simply drain the system?  It's SO EASY to do.  KISS instead of make work.
I have never ever used pink/blue stuff in my M-25 (27 years.)
That's nearly $300 of beer money (in place of -100F antifreeze.)

[Ron Hill]

mre : Why not just take the raw water hose off the thru hull/strainer and put it into the jug of anti freeze??
Sounds like you need a new impeller??

A few thoughts

[Jim Hardesty]

Sounds like you need a new impeller??

Second that.
Jim

[Ted Pounds]

Why not simply drain the system?  It's SO EASY to do.  KISS instead of make work.
I have never ever used pink/blue stuff in my M-25 (27 years.)
That's nearly $300 of beer money (in place of -100F antifreeze.)

Being a "belt and suspenders" guy, I always did both. 😉

[KWKloeber]

Sounds like you need a new impeller??

[/quote]

Or possibly you have something blocking the Hx tubes? 
Which a forced ritual of removing the caps to drain the Hx instead of pinking-it is the reveal, and as well removes any excuse not to quickly rod each tube to keep ahead of (rather than on the tail end of) a buildup/blockage.

[scgunner]

$300 of beer money is money well spent, Cheers!

[Jeff Kaplan]

Does sound like you need a new impeller. On my M25, I installed a 3 way ball valve on to the raw water intake. In the boating season, sea water pulled thru, when winterizing, I close that ball valve, install a hose to the new opening and put into a 5 gal bucket of fresh water and run engine for about 15 minutes, then shut off. Change oil, filter and fuel filter. Start engine again and run maybe 5 minutes, then when bucket almost empty, add 2 gal of engine pink stuff and run till all gone, shut off. This has worked for me for the past 16 seasons, no problems in spring.  Easy.

[mregan]

I'll check the impeller.  After the overheating in July, replaced the impeller, old one had lost some fins in the overheating.  Engine had been running fine for the last 2 months so figured the new impeller was still okay.

[Ron Hill]

mre : Impellers are like light bulbs - some last longer than others!!  Think you need to check it again.
If OK then look at the faceplate that you took off and take some fine (400 grit) wet dry sand paper and refinish the face.  Also check to make sure the hose from the thru hull to the pump is clear.

A few thoughts

[Jim Hardesty]

old one had lost some fins in the overheating.

Hope you found the missing fins.  If not they may be plugging the heat exchanger or some other place causing slow flow.
Jim

[mregan]

Found the fins when I overheated in July. Couple in the housing and 1-2 at the heat x intake.  Since then the engine has been running like a champ, 160* all the time.  Was just when I was winterizing I noticed the problem again.  Will go down next weekend and check the impeller.