Mercruiser 5.7 running hot

[Johnson110]

I started the engine today for the first time this year, It runs like 180 on the muffs, I took the thermostat out still runs hot, pulled the riser off on side was very hot, changed riser gaskets this year on both sides, risers is 3 years old they are mercruiser riser and manifolds, they still look very good, water pump in outdrive was changed last year. Thermostat was changed last year, Could the pump on the engine be bad ? when I first started the engine it would rise to 170 race it up then drop to 150 , now seems to run very hot mostly on the one side, thats the side i pulled the riser all looks good ,

 

[Bondo]

Re: Mercruiser 5.7 running hot

water pump in outdrive was changed last year.

Ayuh,... I'd start there again this year....

 

[Johnson110]

Re: Mercruiser 5.7 running hot

Only been one year since the pump was changed, it is possible for anything else, I see water out the back when running, also I put new flappers in the Y pipe flapper opens out down pipe I believe it is installed properly, any other ideas ?

 

[dubs283]

Re: Mercruiser 5.7 running hot

hose for muffs on full??

have you checked the raw water pump output at the t-stat??

check for blockage in pick-ups, kinked water passage hose at transom, weeds/impeller pieces in oil cooler

 

[Johnson110]

Re: Mercruiser 5.7 running hot

How do you check raw water pump at the t-stat?

 

[dubs283]

Re: Mercruiser 5.7 running hot

How do you check raw water pump at the t-stat?

pull the water supply hose at the t-stat housing and run the engine momentarily and observe the water output

but definitely check all the other items i listed as well

 

[Johnson110]

Re: Mercruiser 5.7 running hot

Thanks I used a better set of flush muffs, temps run about 150 to 163 as per temp gauge, when I race up the engine temps drop down as it should, Only thing now is the stud on the audio engine switch broke off, part runs like 70 dollars from mercruiser! maybe aftermarket one?

 

[dubs283]

Re: Mercruiser 5.7 running hot

what is an audio engine switch??

 

[Johnson110]

Re: Mercruiser 5.7 running hot

There are 2 sensors on the thermostat housing one is for water temp the other is for the alarm that beeps if overheat or low on oil!