On Fri, 17 Jul 2020 23:12:46 -0700 (PDT), Mike
wrote:

On Saturday, 18 July 2020 16:02:53 UTC+10, wrote:
On Fri, 17 Jul 2020 22:36:51 -0700 (PDT), Mike
wrote:

On Saturday, 18 July 2020 15:23:30 UTC+10, Mike wrote:
On Friday, 17 July 2020 15:12:21 UTC+10, wrote:
On Thu, 16 Jul 2020 17:04:13 -0700 (PDT), Mike
wrote:

On Thursday, 16 July 2020 16:20:13 UTC+10, wrote:
On Wed, 15 Jul 2020 18:10:37 -0700 (PDT),
wrote:

Hi, I have a 40hp Mercury outboard that sounds an overheating alarm when revs, get over around 4500 rpm, this outboard is a US made 4 cyl 2 stroke 1996 mod,
first of all this outboard does not have a thermostat by design, so i replaced the impeller but the impeller blades were bent only and not realy damaged in any way so i am concerned that i have not fixed the problem, the engine is in very good condition for its age so i am wondering if any one else out there has had a similar problem with this engine and if so was it resolved and how.
regards Mike.

Are you sure about the thermostat? What is the serial number?
If you haven't checked the water pressure, that is a place to start.
If it isn't around 15 PSI or more at cruise RPMs you still have a
water supply problem. Next might be corrosion in the water jacket.
There are a number of schemes to flush with salt away or just vinegar.

Hi, Thank you for your response, the S/N is OB095842, yes i'm sure about the thermostat. I have had the boat out since but due to another problem i couldn't get it over 3000 rpm so not a good test for the alarm problem, I've since had the problem fixed with a new float and needle, so when i go out in the next day or two i'll see if the alarm problem is still there.
The Mechanic said the alarm problem should be fixed now but i'm not that confident so iv'e been checking around just in case its not, so i know what to tackle next.
Regards.Mike

I am not having much look looking up that motor by S/N or finding a
60HP 4 cylinder. It must be an Australian thing.

Hi! its a 40HP 4 Cylinder 1996 Vintage.
Mike


Hi Again, sorry i got the s/n wrong it should have been 0D095842 1996 40HP 2 stroke.
Mike

OK I still had no success finding that S/N but I also don't see a 4
cyl 60, only the 65. Maybe it is the same motor tho.
At any rate I think go back to the basics. Look at the water pressure.
That will eliminate a lot. You can tee off the pee stream line to get
it.


Its a US made 1996 40Hp 4cylinder 2 stroke S/N 0D095842

Dunno

https://www.boats.net/catalog/mercur...ard-by-hp/60hp

I don't see any 4 cyl.

You might want to try
https://www.thehulltruth.com/boating-forum-14/

There are a few dealer mechanics who hang out there.