Is my Mercruiser 4.3 running hot ??

[HasseEd]

Have bought a Sea ray 190 -87 with an mercruiser 4.3LX Alpha one. I read 180 F on the temp gauge while running at normal speed, under heavy load I can reach 190 F. I have checked the thermostat(160F model) and it starts to open at 158F and is fully opend att 180F. Have a new impeller in sterndrive and it?s raw water cooled.
Is this temperatures readings ok? Have read somewere that 160 F is normal working temp for this engine ?

/H

 

[ENSIGN]

Re: Is my Mercruiser 4.3 running hot ??

The higher readings may just be the gauge.Check the engine with a infared temp gun and compare your readings.

 

[HasseEd]

Re: Is my Mercruiser 4.3 running hot ??

The higher readings may just be the gauge.Check the engine with a infared temp gun and compare your readings.

Thanks !
I did check the engine yesterday with an infrared temp gun and the highest temp I read was 150 F(66 C), while temp gauge showed 180 F.....
So proberly the gauge or the sender is not working. Can I simply change sender and gauge ?
I don?t know if I have any hot water alarm thats connected to the gauge.

/H

 

[ktbarrentine]

Re: Is my Mercruiser 4.3 running hot ??

Are you sure you are supposed to have a 160 T-stat and not a 140 T-stat? Better check the book... sounds like yer running hot.

 

[ENSIGN]

Re: Is my Mercruiser 4.3 running hot ??

Change the sender first,this is most likely the problem.

 

[sharkin95]

Re: Is my Mercruiser 4.3 running hot ??

testing the gauge: turn ign. switch to off..remove wire from S send ..turn ign sw to run, needle on gauge should read O or 120 ..turn ign sw to off. Connect a jumper wire from grnd to send..turn ign sw to run .. needle should read hot or 240 if not replace the gauge.

Testing the sender: ohms meter needed ...ohms readings are 140 deg 121-147 ohms... 194 deg 47-55 ....212 deg 36-41

my suggestion would be take the sender out clean it on a wire brush wheel re-install it with very little red threadlocker on the threads try it.

 

[sharkin95]

Re: Is my Mercruiser 4.3 running hot ??

The t-stat should be 140 deg with raw water cooled.....that I would change.

 

[HasseEd]

Re: Is my Mercruiser 4.3 running hot ??

Thanks!
I will by a 140 deg t-stat and check the sender/gauge.
/H

 

[HasseEd]

Re: Is my Mercruiser 4.3 running hot ??

Why does my temp gauge shows 130 F when ign. switch in position OFF ? When turning ign. switch On the temp gauge drops down(cold engine,not running). When running the engine temp starts to rise and shows running temp of engine.
If I stop the engine and ign. switch in position OFF it still shows 130 F ???
/H

 

[ENSIGN]

Re: Is my Mercruiser 4.3 running hot ??

Alot of gauges won't zero unless the key is on.

 

[HasseEd]

Re: Is my Mercruiser 4.3 running hot ??

Have changed the t-stat (140 F) and now working temperature is about 155-160 F. Is it ok to have 15-20 F over opening temp of t-stat on temp gauge under normal load of engine ?

I noticed that the temp sender is mounted on waterpump ! shouldn?t it be placed on the t-stat housing ??

/H

 

[Don S]

Re: Is my Mercruiser 4.3 running hot ??

With your IR temp gun, check the temp right next to the sender. It should closely match the gauge reading.

If sitting in the water or on the muffs and you are seeing 155 to 160, something isn't right in the cooling system.


EDIT
Just looked at your picture, there is why you are seeing high temps, put it up on the intake or the thermostat housing where it belongs.

 

[HasseEd]

Re: Is my Mercruiser 4.3 running hot ??

With your IR temp gun, check the temp right next to the sender. It should closely match the gauge reading.

If sitting in the water or on the muffs and you are seeing 155 to 160, something isn't right in the cooling system.


EDIT
Just looked at your picture, there is why you are seeing high temps, put it up on the intake or the thermostat housing where it belongs.

Thanks Don S !
I will put it up to the intake or T-stat housing, wonder if it`s fits right in or do I need an adapter ?
/H

 

[HasseEd]

Re: Is my Mercruiser 4.3 running hot ??

Already have the tempersender on the right place on the intake, it has a braun wire.
What does the sender do on the waterpump ? It has white/blue wire connected to it.
/H

 

[Oshkosh1]

Re: Is my Mercruiser 4.3 running hot ??

One is a sending unit which reads the temp...and sends that to your gauge.
The other is the overtemp alarm sender which will activate the audible signal to warn of an overheat situation.

These gauges are NOT spot on accurate(they're actually ammeters). They're designed to give a close approximation.

Trust the readings from your IR...they'll be within a couple of degrees.

My gauge will read 200...but 1/2 from the actual sender will read 170. As a matter of fact...except the exhaust manifold, there's no place on the cylinder head/block which reads over 180 usually.

Remember, as lake water temps rise...so to will your operating temps. My well water stands around 58 degrees, and the motor runs around 130/140 on muffs. When I hit the lake...where the surface water temp is 80, and I'm running at high power settings...175/180 is more common. I do take my IR with me just to "spot check".

 

[HasseEd]

Re: Is my Mercruiser 4.3 running hot ??

One is a sending unit which reads the temp...and sends that to your gauge.
The other is the overtemp alarm sender which will activate the audible signal to warn of an overheat situation.

These gauges are NOT spot on accurate(they're actually ammeters). They're designed to give a close approximation.

Trust the readings from your IR...they'll be within a couple of degrees.

My gauge will read 200...but 1/2 from the actual sender will read 170. As a matter of fact...except the exhaust manifold, there's no place on the cylinder head/block which reads over 180 usually.

Remember, as lake water temps rise...so to will your operating temps. My well water stands around 58 degrees, and the motor runs around 130/140 on muffs. When I hit the lake...where the surface water temp is 80, and I'm running at high power settings...175/180 is more common. I do take my IR with me just to "spot check".

Now I have checked with my IR on the intake where the temp sender is and engine temp goes from "140-149 F" at most and gauge shows "158-172" while running on 1000 RPm for about 15 minutes. I also checked the sender at 149 F and I got 140 ohms.What does this readings says ?
/H