Suzi 175 overheat at idle

[Goochi]

Hi,

My Sizi 175 4st is intermittently but regularly giving an overheat alarm at idle. I get this in the water not just with muffs. Can do it at the boat ramp sitting at idle or when reducing to idle after cruising. Haven't have a problem when the revs are raised.

Things I've done.
1. Replaced impeller. Didn't change the housing (i'm not a pro mechanic however the housing looked ok)
2. Replaced thermostat (The old one fell apart when inspecting it) and flushed water backwards thru the system.
3. Removed the anodes in the water galleries and flushed them as well (with the lower leg removed, about 2 spoons of sand came out)
4. Inspected water pressure relief valve near top of leg. Looks OK however I don't know how firm the spring should feel.

Things I've noticed.
1. On Muffs when the alarm come on the water coming out of the exhaust(prop) is still cold. Therefore water is not passing thru the block - hence overheat.
2. When I had the Thermostat out and ran the motor at idle very little water made it to the thermo housing...not sure if this is normal. I expected that plenty of water would be pumped there all the time.

I've thought about replacing the pressure relief valve - but I'm just guessing now. Also considered if the impeller housing is leaking water.

Has anyone had a similar issue or a good idea what is causing this?

Cheers.

[Chimo]

Perhaps the galleries through the block have blockage or at least some narrowing.

Might pay to take it to a qualified mechanic who may need to pull it down.

Similar issue happened to a friend and after stuffing around for months pulling it down and cleaning the galleries was what was needed.

Remember "BOAT" Bring out another thousand. Spending $s is just part of the deal...............

Cheers
Chimo

[Aussie123]

It could be the wear plate in the impeller housing.
You may need a full water pump kit.

[Noelm]

Sure sounds like the poppet valve to me (pressure relief valve I think Suzuki call it) the tell tale water being cold does not mean it's not circulating through the motor.

[Flex]

I had an issue after getting a f60 yamaha serviced.
Woukd over heat at idle but temps would be fine under way.
If it was a blockage you would assume it'd overheat while up and running.
My issue was a dodgy impeller out of the box. Pulled the leg of to check it twice and looked totally fine. I couldn't see anything wrong with it. Replaced it with another and fixed the issue.

Popper valve as suggested sound like another.

Best way to tell is pull your leg off. Hook hose direct to your intake pipe thus bypassing impeller. Run motor and See if it over heats.

[Goochi]

Thanks Flex,

I'll give that a try.

[scottar]

Not sure if the zuk's cooling functions the same, but with the rudes the poppit / pressure relief valve will cause over cooling at idle if it is faulty - opens to bypass the thermos to supply more water when running at rpm. If the thermostat isn't opening or the passage it sits in is restricted (did they make sure they got all of the bits out from the old one?) it could cause that issue. Could also be as suggested with lack of water due to impeller or housing.