89 Mercruiser 3.0L Alpha 1 Gen 1, overheat at idle, fine at higher rpm

toneybrown

Petty Officer 2nd Class
Joined
Jul 1, 2013
Messages
104
Ayuh,.... Back-flushin', all the water should come outa the copper tube,.....

Ok, looks like I have a busted hose that connects right above the bellows to the upper drive. The hose is dry rotted and has a chunk missing. Not alot of water escapes when back flushing, but I'm fairly certain more water would be leaking when water flows the opposite direction under pressure.

Anyone have a name for this hose or a part number? Will I have to remove the upper drive now to replace it?
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,958
Ayuh,.... If that hose is rotten, odds are the bellows are also about to fail too,....

To change any of those parts, the bellhousin' needs to be pulled,....
'n with the amount of work, 'n busted fingers, changin' ALL the rubber parts at once is the only way to do the job,.....
If ya use the trim limit, 'n sender, those should be replaced at the same time as well,.... the wires rot,...

Just look up the transom service kit for yer serial number,....
 

TyeeMan

Master Chief Petty Officer
Joined
Feb 27, 2006
Messages
849
And as previously mentioned, make sure the water supply hose is cut to the correct length or it will kink and you will get hot or overheat at idle.
2 boats ago I had 3.0/Alpha, when I bought it I had the dealership install all bellows and a water supply hose. Picked it up at the dealership and went to the lake, same thing you are experiencing, heated up at idle, cooled down up on plane.
Long story short and thanks to this forum, I learned the water supply hose (Mercruiser part) was too long, , , dealership had no idea. I printed off the thread with the measurements, had the dealership shorten up the hose and I was golden. Everything worked perfectly.
 

toneybrown

Petty Officer 2nd Class
Joined
Jul 1, 2013
Messages
104
Update and hopefully the last issue for a while.

Replaced the Impeller housing and the hose from the outdrive to the transom. Turned on the hose, fired her up and had a steady stream of water from the hose that connects to the T-stat housing.

Reattached the hose to the T-stat housing, cranked the water back up and idled for a good 10min or more. Temp gauge got the 145 and stayed there the entire time the boat was running. I think my water flow issue is fixed. Not sure if it was the Impeller housing or the hose, but either way I'm back in business and ready for a 3rd voyage that will hopefully be more successful then the first 2.

Thanks again to everyone for your expertise and taking the time to help out a newb to this Mercruiser system. I hope I learn as much about it as I did my OMC over the next several years.
 

zellerj

Petty Officer 2nd Class
Joined
Dec 13, 2017
Messages
136
And thanks for completing the circle and reporting back. All too often on this forum the thread just stops, and no one learns when the thread is not carried to a closure.
 
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