Mercruiser Exhaust Manifold too hot??

[redfiveshoe]

I have a SeaRay 176 w/ Mercruiser 3.0. I have been concerned about the operating temp. While on the lake , i took a temp gun and shot different parts of the motor. I got 170-180 everywhere except for the exhaust manifold. It was 200-205 up front and 195-200 near the back. Should i be concerned about this?
The boat seems to run around 175 anyway, according to the gauge. I recently had alot replaced thinking that it was running too hot. The thermostat, gauge, water recirulation pump, are all new. I also had it checked for any leaks and everything was good. The impeller has less than 30 hours on it (1.5 years) and the boat holds steady at 175, it doesn't rise at higher rpms. If it was the impeller, wouldnt the temp be rising at higher rpms?

Is the motor temp a problem? Manifold temp a problem? IF so, what could it be?

 

[Volphin]

Re: Mercruiser Exhaust Manifold too hot??

Your manifold will run hotter as it is handling all the exhaust gasses. How old is the manifold? Is this a new condition? Has it ever been pulled and inspected for blockages?

 

[Bt Doctur]

Re: Mercruiser Exhaust Manifold too hot??

Unless this 3.0 is FWC you should be running at 140-145. Impeller is due for replacement. also check for a 140 deg. thermostat

 

[alldodge]

Re: Mercruiser Exhaust Manifold too hot??

Not knowing what year your motor is or serial number of your engine? Serial number 0L341000 and above went to 160 degrees

Also check your timing
1? BTDC Serial number break: 0L096999 and below
1? ATDC Serial number break: 0L097000 - 0L0340999
2? ATDC Serial number break: 0L341000 and above.

 

[Bondo]

Re: Mercruiser Exhaust Manifold too hot??

I have a SeaRay 176 w/ Mercruiser 3.0. I have been concerned about the operating temp. While on the lake , i took a temp gun and shot different parts of the motor. I got 170-180 everywhere except for the exhaust manifold. It was 200-205 up front and 195-200 near the back. Should i be concerned about this?
The boat seems to run around 175 anyway, according to the gauge. I recently had alot replaced thinking that it was running too hot. The thermostat, gauge, water recirulation pump, are all new. I also had it checked for any leaks and everything was good. The impeller has less than 30 hours on it (1.5 years) and the boat holds steady at 175, it doesn't rise at higher rpms. If it was the impeller, wouldnt the temp be rising at higher rpms?

Is the motor temp a problem? Manifold temp a problem? IF so, what could it be?

Ayuh,.... Welcome Aboard,..... Is this a Saltwater boat,..??

While yer impeller ain't got alotta hours on it,...
It's Still the 1st place to look, in Any overheat situation,...

 

[redfiveshoe]

Re: Mercruiser Exhaust Manifold too hot??

It is a 2003 with less than 150 hours. As far as i know, the manifold is the original and has never been removed. It has never been in salt water. It is an OM serial number, so i assume 160 is OK.
With the temp gun, everything checks out between 160-175 except for the exhaust manifold. Even the riser is only around 115.
The thermostat was replaced with OEm parts.

When hooked to the ears, it seems to have warm water coming out of the back. Warm, but not hot to the touch

 

[1ruralmailman]

Re: Mercruiser Exhaust Manifold too hot??

that would kinda make sense when hooked to the ears the water from a hose in under pressure,so it could help it cool the manifolds,unlike in the water were it would depend on the impeller to get the water inside the motor to cool it.

 

[redfiveshoe]

Re: Mercruiser Exhaust Manifold too hot??

I ordered the impeller kit today. We'll give it a shot.