4.3l mercusier alpha one gen 1 cooling questions.

apollo5646

Cadet
Joined
Aug 16, 2009
Messages
28
Hello all, well there is still like 3 inches of snow on the ground but I'm thinking of warmer days. At any rate I have two questions. First at the end of last year I was winterizing the boat per the guide on this forum and i was pouring the antifreeze through the hoses and I decided to remove the the thermostat housing and pour some down the block before pulling the the drain plugs. Well of course i jazzed the housing gasket up something good and so i replaced it but while i had the thermostat housing off i was going to remove the thermostat. I couldn't get it to budge to a rapped on it a few times lightly to try and free it up but to no avail. So i just left it in and reassembled and test ran the motor to make sure i had no leaks. Now for my question before i removed the housing the motor would take a long time to warm up on the muffs idling. Now when i had tried it again the on the muffs it warmed up real fast so i shut it down out of precaution. I'm sure that the raw water pump is good since its not more then 6 months old and i was getting water to the thermostat and cooling everything great prior to me removing the housing. Is it possible that the thermostat was just stuck open and when i tapped on it, it was freed up? or is the thermostat now stuck closed? I will probably just replace it this spring but then how does it come out of the housing? There is a brass retainer of some sort that holds it in and i can't for the life of me figure out how to get it out.

2nd question is to replace the raw water impeller is it necessary to pull the whole drive off the the boat and then split the upper and lower halves? I just saw a video on u tube where the guy just removed the lower half and did the work and then reinstalled.
http://www.youtube.com/watch?v=jXq35NOX8kw

thanks for all the help and here to an early spring in the Midwest.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,285
Re: 4.3l mercusier alpha one gen 1 cooling questions.

Ayuh,... My guess is, the T-stat was fine, 'n now it's stuck closed...
It comes out hard, due to the build up of crud...
All ya can do is try to carefully remove it, 'n replace whatever gets trashed doing so....

Only the Lower unit needs to be pulled to replace the impeller,...
But,...
There's other inspections, 'n maintance that needs doing annually, that does require pulling the rest of the drive...
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 4.3l mercusier alpha one gen 1 cooling questions.

Year and SN of your engine would help, there have been many different thermostat housings over the years.

As far as pulling just the lower, YES, it can be done but I don't recommend it.
If you have never done the job before, you will find it's a real PITA to try to line everything up when going back together, and making sure everything works.
You also need to pull the drive yearly, to lube the coupler splines, inspect for water in the bellows, check alignment, lube the ujoints, and check the gimbal bearing. So might as well do it all at once and make everything a lot easier.
 
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