yamaha f60 2007 overheating at idle, cools once has revs ???

[lembo]

hi lads got a little kevlacat with twin f60 yamahas.
recently had a full major service. impellors, thermostats, all the stuff got done.
now one of the motors is running hot at idle. it has alarmed a few times.
as soon as I put some revs on it it cools to the same running temp as other motor. (have both connected to my garmin sounder so can track temps)
ive changed over the thermostats to see if the problem changed motors but problem still remains. after abit of research it sounded like a pressure relief valve or poppet valve. but apparently my motor doesn't have one of these valves.
the tell tail is pumping but at a slightly lesser flow then the good motor.
on the hot motor the anodes got done at the service (good motor got done previous service)
Im thinking maybe something has loosened up and restricted flow somewhere. I will start pulling things apart to see if things are clogged.
anyone had similar problems or can help me out with something to look at?
any help would be appreciated.
motors have 650 hours and when running at anything higher then idle temps are exact same and no problem ???

[Aussie123]

Less tell tail and increasing revs to cool the engine sounds like a crook impellor.
Did you get the old parts back from the mechanic that did the service because it sounds like it was not done or you may be just unlucky to get a crook new impellor fitted.

[lembo]

didn't get old parts but he serviced it at my house and I saw him replace it so was definaely done. it first overheated on a recent trip. I pulled the leg off and checked out the impellor it looked all good. it was a whole kit replacement so housing was done too. it all seemed visually good. don't know if its possible to look good and not work ? its brand new so not hardened or anything. its got me stuffed im just hoping some of the mighty boating brains on here will help. maybe il buy a new impellor and install and worse case il just have myself a spare .

[chris69]

To me it sounds like water is not getting up to the powerhead until theres a few revs on is there a blockage somewere,or you have a faulty thermistate.

[Fed]

Did you remove the impeller to check the key?

[lembo]

im thinking possible blockage, maybe something loosened up when anodes were replaced, and clogged up. yeah I checked whole impellor, all visually looked good. no sings of it slipping on shaft or anything. I swapped thermostats with the other motor that doesn't overheat and it done nothing. still ran hot. I might just have to start pulling apart whole cooling system and checking it for blockages and things. I will do another impeller too. Just to be sure. start the process of elimination. it doesn't take many revs to cool it down.

[MyWay]

before you pull a part i would call mechanic who service to have look 1st

[Bremic]

Swap the bottom part of the leg over - gearbox bit - see which motor does it then, will tell you if the problem is with the water pump.

[Rip it up]

Sounds stupid. But check the water intake screen. I've had a f60 get sand granules wedged into the screen blocking 80% of the little holes.
Next I'd try to take the hose off the tell tale jet from inside the cowling. Just to confirm the jet is not clogged with grit.

Couple of simple things that I've had to do before.


Damo's dodgy boat building factory.

[lembo]

anyone wanna swap for some twin 90 suzukis

[lembo]

I feel that the tell tale is pumping a bit less not from a blockage in the tell tale pipework but just because the whole thing is lacking pressure at idle. it picks up with flow once revs increase.
I think I might swap legs and see if the problem tranfers to other motor , at least that will tell me its in the leg or block.
yeah the strainer is clear and the tell tale( parts I can get to so far) are clear. I might start pulling more things apart tomorrow. there looks to be a whole plate you can pull off which will hopefully give me access to water jackets.
but im thinking maybe the impeller is a beez dick out or not sitting right/miss aligned and it only suffers at its lowest reves and as soon as it spins faster its enough to overcome the slight miss alignment and pumps enough to keep cool.
thanks for your ideas guys. its keeping me thinking.
il let you know how I go.

[Fed]

Spun the bush inside the impeller? Might not be very obvious with taking a real hard look at it.

[Spaniard_King]

Impellor housing has melted causing a deformity behind the cup.. sucking air.. full pump kit required..

[Marchy001]

Hope like hell it's not the case but 2002-2005 f225's did similar.

They melted exhaust castings which mixed hot gas with water causing overheat at idle. Or something like that anyway.

I repeat I hope it's not the case with the f60.

[Noelm]

Hope like hell it's not the case but 2002-2005 f225's did similar.

They melted exhaust castings which mixed hot gas with water causing overheat at idle. Or something like that anyway.

I repeat I hope it's not the case with the f60.

No, those motors didn't melt anything, the exhaust had/has a corrosion issue, Spaniardking is on the money, as usual.