4.3 mercuiser overheating

[vernonbluewater]

Cruising @ 30 mph ran at 175 degrees. Apparently should be 160. Has aftermarket closed cooling system with heat exchanger . Exhaust risers still raw water cooled. When slowing down from cruise to 5 mph alarm would come on - a touch of throttle would turn alarm off.Replaced impeller, (looked fine no wear) replaced thermostat to 140 degrees ( turns out already had 140 in it, replaced anyways )- now runs hot on hose , 200 degreees instead of 175 before. I made it worse. Any suggestions would be appreciated. Really wondering why I bought a boat, nothing but aggravation. Thought I would be enjoying with family instead of fixing ALL the time. Boat mechanic says could be exhaust risers clogged. Oh yeah, I checked heat exchanger clean & clear.1993 4.3 mercruiser 4bbl . Question - if running on hose, how does impeller suck in water if not in drive?

 

[HT32BSX115]

Re: 4.3 mercuiser overheating

Howdy,

It appears that you may have something (impeller fragments or other debris) clogging the raw water path to or from the engine.


If it ran 175 all the time that might be ok. My 454 runs about 170-180 on the gage all the time.

Regards,


Rick

 

[Bt Doctur]

Re: 4.3 mercuiser overheating

Should have used the complete kit ,not just the impeller.Torn gaskets, bad base plate,loose SS cup,leaking water pocket cover.

 

[vernonbluewater]

Re: 4.3 mercuiser overheating

Hi Bt Doctur, Forgot to mention I did use the impeller kit with all that you mentioned