96 Mercury 40hp locks up when hot

mtalolor

Recruit
Joined
Jun 17, 2011
Messages
3
I have a 96 mercury 40hp I ran low on oil and it locks up when it warms up. It seems to run ok and the water pump works, I took off the lower unit suspecting a bearing problem but saw nothing obvious and now am thinking it's a bearing in the powerhead and am getting ready to remove and disassemble that. Have been looking on-line in different forums but haven't run across a similar problem. Any input would be appreciated. Thanks.

Mike
 

Jake_MN

Petty Officer 2nd Class
Joined
Jun 1, 2010
Messages
106
Re: 96 Mercury 40hp locks up when hot

What do you mean by "locks up". Does the engine shutoff? Have you checked compression since you ran it low on oil?
 

mtalolor

Recruit
Joined
Jun 17, 2011
Messages
3
Re: 96 Mercury 40hp locks up when hot

The engine will stall out as it warms up and it will restart until it gets warm enough to a point where it's siezed up and will not turn over until it cools. No I did not check the compression.
 

Jake_MN

Petty Officer 2nd Class
Joined
Jun 1, 2010
Messages
106
Re: 96 Mercury 40hp locks up when hot

You should check the compression, and not run the engine until you're diagnosed the problem. You risk melting your powerhead if you haven't already done so.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: 96 Mercury 40hp locks up when hot

Is the oil injection system working? Continue to run the engine until it seizes and you will be looking for a new power head.
 
Top