High Temp alarm - anyhting to worry about

[2iar]

Hi all Ausfishers,

I managed to get out yesterday for the first time since January ::). Ran across the bay and spent a couple of hours at Curtin pulling in undersize squire and sweetlip and what I think was a Batfish of 3-4 kg - good fight but disappointing that it wasn't something more suited to the table. I then moved round to Smith Reef but conditions weren't great for my little boat and I headed back to Bribie. A bit of an unproductive day in terms of take-home catch but an enjoyable day none the less.

After a bit of a slog through a choppy northern bay, the Passage was comparatively flat, so as I believe is beneficial for the motor, I gave the Suzuki DF70 some WOT time on the way to the boat ramp. I'd had it serviced quite recently and managed to hit 6000 rpm - I think its previous PB was 5800. Anyway after a few minutes of top speed, I got a temp alarm and brought her back to neutral. The tell tale was still pumping strongly and I didn't want to turn it off in case it wouldn't start again - I think it's got "limp-mode" if I'd had to crawl the rest of the way to the ramp. However, after a minute or so of idling, the alarm cleared and I returned to the ramp uneventfully at normal speed.

Do you think I've got anything to worry about? Did I just give her too much stick? Is the above common? Is there any likelihood of damage?

Your opinions would be appreciated.

Good luck,
Mike

[peterbo3]

It may be a wise move to take it back the tech who did the service. He can download the overheat details & possibly check what caused the alarm to go off. WOT is where the engine gets hottest & if an impeller vane has split or lost a tip the water pump may provide enough flow at lower revs to keep the engine cool but at WOT there may be an issue.
Although you have recently had it serviced a faulty impeller out of the box is rare but can happen

[Spaniard_King]

Definately worth checking,

possible causes: Thermostat stuck not allowing full flow of water when needed most.

Blockage in the outlet side of the cooling system (hence a good tel tale showing good water supply)

[midcoast learner]

I had the same problem last Christmas.Alarm went off ,stopped and let it idle for a couple of minutes alarm stopped .Water flow was good.Did it a couple of times on the way home . Each time i stopped let it idle.(It is an 88 V4 110 hp Johnson).Took it the mechanic and turned out to be a faulty sensor in the head.Once replaced has been fine since.

[2iar]

Thanks folks, I appreciate you taking the time to answer. Is there any likelihood I've caused some damage or has the motor been smart enough to alarm and throttle down?

[Jarrah Jack]

You should be OK. The motor didn't seize or anything like it. No steam coming from under the cowl. I've had worse with no apparent damage. Good motors those DF 70's.

I'll be interested to read what the mechanic reckons.

[MTAQ/BTAQ]

I have a DF70, it doesnt overheat but I was confused when the oil light began to flash, thought I had a problem but "when all else fails then read the destructions", it simply meant it needed a 100 hour service. Thank goodness.