Mercruiser Bravo 3 5.0L MPI not warming up

[bengaltiger14]

Hello everyone. As my title suggests, I have a 2005 Sea Ray with 5.0L MPI Bravo 3. For the past year, I have had a problem with the engine not heating up. In the middle of the Summer, the engine temp would rise to maybe 115 degrees. I verified the operation of the thermostat and even replaced it even though it test good. I did, however, replace the impeller and after idling in the water for 10 minutes, the engine got very hot and actually set off the high temperature alarm. Both the digital and analog gauges indicated high temperature as expected. I fixed this problem.

I can touch the engine manifolds with my hands after hours of operation and it does not feel very warm. It feels like about what the gauges are indicating. Any other ideas or suggestions?

 

[achris]

Re: Mercruiser Bravo 3 5.0L MPI not warming up

The manifolds should be cool to the touch, that's normal. You need to verify that the engine is genuinely not warming up, with an IR gun, then check with a scan tool or diagnostic software what the ECU is seeing.

Chris.....

 

[bengaltiger14]

Re: Mercruiser Bravo 3 5.0L MPI not warming up

I will try to get my hands on an IR gun but I can put my hands most anywhere near the engine and not feel much heat being generated.

 

[Bondo]

Re: Mercruiser Bravo 3 5.0L MPI not warming up

I will try to get my hands on an IR gun but I can put my hands most anywhere near the engine and not feel much heat being generated.

Ayuh,...... Welcome Aboard,... The T-stat Housin', right where it meets the intake is where ya oughta be Checkin',...

 

[tpenfield]

Re: Mercruiser Bravo 3 5.0L MPI not warming up

Did the impeller installation get resolved? Does the engine get up to temp or at least rise under load versus idling?

Got some pics of the thermostat housing area?

Is this an 'open' system (raw water cooled) or is it a closed system (heat exchanger, etc) ?

 

[alldodge]

Re: Mercruiser Bravo 3 5.0L MPI not warming up

. For the past year, I have had a problem with the engine not heating up. In the middle of the Summer, the engine temp would rise to maybe 115 degrees. I verified the operation of the thermostat and even replaced it even though it test good.

Is the boat new to you? If it is not and it heated up fine prior to the past year then disregard:
When you replaced the thermostat where all the parts there? Not knowing your serial number and, have a look here and see if they all parts were accountable, and installed correctly.
http://www.mercruiserparts.com/Show...0&bdesc=Thermostat+and+Housing(7+Point+Drain)

 

[bengaltiger14]

Re: Mercruiser Bravo 3 5.0L MPI not warming up

To answer everyone's questions:

The impeller issue did get resolved and the temperature will rise under load but only to around 115 degrees. It is an open system and I'm not 100% sure if it heated up fine prior as I was new to boating and did not pay any attention. Also, all the required parts were there and intact.

Today, I believe I may have found the problem. I disassembled the T-stat housing and found that the thermostat was not sitting flush with the gasket on the insides. There was maybe a 1/4" offset that is allowing water through. I purchased a new housing and lower housing gasket and reassembled. I will not know for sure if this solves the problem until I actually run it. I will keep you updated.