Overheating 5.7

[shughes12]

I have a 1988 merc 350 with over heating issues. The boat sat for 7 years. I got it running but it started to overheat! I have changed the Impeller and housing, thermostat, checked water flow, gauge and temp sender and held an IR thermometer to the block beside the sender. Even tried with the leg fully submerged in the lake. What else am I missing??

 

[Scott Danforth]

first, did you try to suck it up from a bucket? if so, you toasted your new impeller

second, how do you know you have water flow?

 

[alldodge]

If you have the belt driven water pump, check the hoses on the pump. Inlet is on the bottom

 

[shughes12]

first, did you try to suck it up from a bucket? if so, you toasted your new impeller

second, how do you know you have water flow?

Never had it running without the intake holes submerged in water.
I took the hose off before the oil cooler, after, and at the tstat

 

[shughes12]

If you have the belt driven water pump, check the hoses on the pump. Inlet is on the bottom

Water flow was good on both ends

 

[nola mike]

Never had it running without the intake holes submerged in water.
I took the hose off before the oil cooler, after, and at the tstat

Intake holes submerged isn't good enough. When you took the hose off, was there flow?

 

[Scott Danforth]

Never had it running without the intake holes submerged in water.
I took the hose off before the oil cooler, after, and at the tstat

you didnt answer the question.

if you attempt to put the outdrive in a bucket, the bucket has to be big enough to get the whole boat in it to submerge the raw water pump far enough for it to prime. not just cover the intake, however get the watter above the pump

otherwise you simply burn up the raw water pump

which is why always use muffs

 

[shughes12]

you didnt answer the question.

if you attempt to put the outdrive in a bucket, the bucket has to be big enough to get the whole boat in it to submerge the raw water pump far enough for it to prime. not just cover the intake, however get the watter above the pump

otherwise you simply burn up the raw water pump

which is why always use muffs

Don't the muffs only cover the intake holes? Either way I used muffs and also had the whole leg fully submerged in the lake

 

[shughes12]

Intake holes submerged isn't good enough. When you took the hose off, was there flow?

Had it with muffs on and also fully submerged in the lake

 

[shughes12]

Intake holes submerged isn't good enough. When you took the hose off, was there flow?

Yes it had strong flow

 

[Scott Danforth]

Don't the muffs only cover the intake holes? Either way I used muffs and also had the whole leg fully submerged in the lake

the muffs cover the intake holes and force water up to the impeller

however if you dont have the hose on full, you can burn the impeller

the water should be spraying out from around the muffs until you start the motor