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Suzuki DF90 overheats at idle

draig

New member
Hi Fellas

The root cause of


Hi Fellas

The root cause of this one is proving a tricky one to track down. Would appreciate any help / Advice I can get on this.
Suzuki DF90 (2003) low hours (<200) 90% fresh water use.
Never had a problem with this motor before - it's been great.
Been stored in garage all winter - unused for 5 months. (now summer down here New Zealand in January).
Changed oil and plugs. Took it to the local tech to get the impellor changed (suzuki part). First time used the boat it goes great (just the same) but after it's warmed up and you put it in neutral and let it idle for a few minutes it sets off the overheat alarm. Restart and cruise and it's good again. Back to idle and > overheat!!! This has continued for the last 4 uses.
So check:
Peeing ok - seems to be a good steady stream even at idle although a little reduced in force.
Thermostat opening - opens at about 60C but just a little bit.
Visually checked the temperature sensors on the head and exhaust manifold and they seem intact - I will measure the resistance on them next to ensure that is within spec.
I have a workshop manual but it does not really help in diagnosing the root cause on this problem.
A ECU dump would help as it would tell me the temp of each sensor when the alarm is triggered but the tech does not have one and the nearest is a 5 hour drive away!
How best check that I don't have restricted water flow through the system - I assume the pilot jet peeing just tells me the water pump is pumping - looking at the cooling water route chart I figure you could still have a restriction upstream and the pilot would not be affected.
Starting to tear what little hair I have out over this one - Local tech not making much progress either - Any pointers fellas?

Thanks in a advance for your help.

Draig
 
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