5.7 mercruiser alpha 1

D

Dcary

Recruit
Joined
Jun 1, 2010
Messages
1
I have a 1990 5.7 mercruiser with alpha 1 outdrive.
When I first took the boat out this summer, it was running hot, up to near 200 degrees but only at idle. I replaced the impeller, housing and all gaskets and O rings and also replaced the Tstat.
Now when I take it out, it runs at around 150 at idle but climbs to 175 at cruising speed.
Can anyone help me with what I should try next?
 
Bondo

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,462
Re: 5.7 mercruiser alpha 1

Now when I take it out, it runs at around 150 at idle but climbs to 175 at cruising speed.
Click to expand...

Ayuh,.... Which T-Stat did you use,..??
Did you find ALL the pieces of the impeller,..??
 
D

dirtyoldman

Petty Officer 1st Class
Joined
Apr 30, 2007
Messages
359
Re: 5.7 mercruiser alpha 1

Dcary said:
I have a 1990 5.7 mercruiser with alpha 1 outdrive.
When I first took the boat out this summer, it was running hot, up to near 200 degrees but only at idle. I replaced the impeller, housing and all gaskets and O rings and also replaced the Tstat.
Now when I take it out, it runs at around 150 at idle but climbs to 175 at cruising speed.
Can anyone help me with what I should try next?
Click to expand...

It's worth finding out whether the gauge is accurate. I was going nuts about mine (the same engine) this year, and the temps were fine. My gauge was 20 degrees off.
 
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