Evinrude 9.9 Overheating

zslnk

Seaman Apprentice
Joined
Nov 18, 2008
Messages
30
Hello,
I'm fixing an E10RERB (1990's?) for a neighbor that overheated. It wouldn't start/run well after this. Compression was 80/80.

The impeller was changed and the thermostat was melted and changed with new springs and gaskets. I also found the head bolts loose and when re-torqued it ran much better.

To attempt a good repair I removed the head and found the gasket was leaking into the water jacket so I flattened the head (it was warped) and installed a new head gasket.

With a rebuilt water pump, flat head, new gasket and new thermostat parts it starts and runs great but the head still gets over 200F quite quickly in a barrel with a cool water hose feeding it. It's pumping a good stream out the tell-tale until it gets warmer then some exhaust/steam will come from the tell tale but a few RPM over idle puts a good stream again.

This is a fresh water motor with clean water jackets. I'm using an IR thermometer on the head between the plugs and getting 200F PLUS with about 5min of idle and light revs. Could the block be warped causing the new head gasket to leak into the water jacket? I believe its overheating due to combustion gases displacing water in the jacket.
 

rolmops

Vice Admiral
Joined
Feb 24, 2002
Messages
5,419
The compression seems to be low. quite possibly the overheating did a job on the block or the head. 200 degrees is quite hot. My guess is that it will need a rebuild.
 

909

Chief Petty Officer
Joined
Jul 19, 2021
Messages
537
This can be fixed easily. You didn't use an OEM impeller. Just because it pees does not mean its pumping enough water. Steam is always bad. Your thermostat reassembly has issues. You didn't replace the vermitherm or are missing parts. The entire assembly is creates necessary restriction in order to adequately cool the powerhead.
 
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Crosbyman

Vice Admiral
Joined
Nov 5, 2006
Messages
5,433
fix the water flow issue something needs fixing... then just run it... my 9.5 9622a runs fine with 65-70- psi

it is 30 years old and may simply keep going . all depends on what you want if for.
 

zslnk

Seaman Apprentice
Joined
Nov 18, 2008
Messages
30
Compression after the new head gasket is 115/115. Running a bit cooler now (<200F). The bores are good and the head is flat.

As it heats up the tell tale starts to sputter a bit which I interpret as combustion gas filling the water jacket. I also re-torqued the head after a heat cycle.

The impeller and all other parts are OEM.
 
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Crosbyman

Vice Admiral
Joined
Nov 5, 2006
Messages
5,433
recheck thermostat operation and retest watr flow....<200 is to hot !

thermostats open at 140 run a mono line up the pee hole

good to hear psi's went back up to 115
 

zslnk

Seaman Apprentice
Joined
Nov 18, 2008
Messages
30
The thermostat pushes the pin out at ~153f in a pot. Its OEM and new.
ipl.JPG

Thermostat_Parts1.jpg

Thermostat_Assembly1.jpg
 
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Crosbyman

Vice Admiral
Joined
Nov 5, 2006
Messages
5,433
better than 200 if ok look further for water restriction

OEM and Sierra show it as a 143 thermostat but 153 is probably fine but a bit hot
 
Last edited:

909

Chief Petty Officer
Joined
Jul 19, 2021
Messages
537
#41 looks missing.
Double check the OEM impeller, and make sure it's submerged.
If necessary increase the idle rpm via the adjustment screw.
 
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