"Carteret or bust" OR "Is the engine meant boil"

[Steve_D]

"Carteret or bust" OR "Is the engine meant boil\"

Had a problem with an overheating engine yesterday - bit of and ar*e when you only have one. We were on route to Carteret from St PP when the alarm went off south of Sark. We waited for the engine to cool down then limped in to the Greve de la Ville and used one of the moorings while we went off for lunch.

a bit of experimenting found that if we kept the revs down to about 2k it was ok, so we limped home at 6.5 knots.

We checked there was nothing around the water intakes, the pump and impellers are new this season so should be ok. Anyone any ideas what it might be? Merc 4.3l with alpha leg.

I have a suspicion that my mate sprayed over the anodes while antifouling the leg, I have now cleaned them off but was wondering if there might be some corrosion in the water intakes because of this, does this sound feasable?

Grateful for any suggestions.

Steve D

<hr width=100% size=1>Now I've got to think of another sig....

 

[ArthurWood]

Re: \"Carteret or bust\" OR \"Is the engine meant boil\"

I would still check the impeller condition, and also the heat exchanger for blockage.

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[BarryH]

Re: \"Carteret or bust\" OR \"Is the engine meant boil\"

I thought the Merc 4.3 was raw water cooled? Unless of course it got the freshwater system added as an option. Don't know.
Anyway if its raw water cooled, check for any blockages in the system ie is water getting round and out the exhaust. If its a closed system also check that for blockages and/or water loss. One area where those engines suffer is the risers. Take'em off and see if the waterways are getting blocked with corrosion.

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[chippie]

Re: \"Carteret or bust\" OR \"Is the engine meant boil\"

We had a similar problem on a mate's boat.,it turned out to be the 'radiator'cap.
What do you callit when its not on a radiator? Pressure cap?

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[Steve_D]

Re: \"Carteret or bust\" OR \"Is the engine meant boil\"

You're right enough it is raw water cooled. I reckon its corrosion in the system, must remember to give my mate a slap and make him write out one hundred times "I must not spray paint the anodes"

Ta

Steve D

<hr width=100% size=1>Now I've got to think of another sig....

 

[Steve_D]

Thermostatic valve thingy

Apparently it was stuck half open - or half closed? anyway the engine was running slightly cool on tickover and hot above 2000 revs.

It was replaced a couple of days ago and I went out for a run for an hour or so this evening at various speeds and the temp stayed below 180 on the guage, apparently the valve opens at 165 so 170 - 180 sounds about right for the engine temp.

Thanks for folks comments, they'll give me some ideas if I get the same alarm again.

Ta

Steve D

<hr width=100% size=1>Now I've got to think of another sig....

 

[ArthurWood]

Re: Thermostatic valve thingy

Seems a bit hot to me. My 7.4l and 3.7l are set for 147F, tho they run at 165F when Gulf temp is 85F. The 147F temp is according to the manuals.

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[Steve_D]

Re: Thermostatic valve thingy

165 was according to the engineer chappie I seem to recall seeing something similar on the web when I was looking for some clues as to what was wrong.

IIRC the warning was along the lines of "don't use a non-marine version of the valve thingy as they are set at 185 whereas the marine one was 165".

I will get my hands on the manual for a look

Thanks

Steve D

<hr width=100% size=1>Mmmmm maybe not....

 

[Steve_D]

Re: Thermostatic valve thingy (followup)

I found the quote that I was looking for it is on a "ask the expert" site in Canada the relevant bit of the article quotes the following.

"I am assuming you replaced the thermostat with the MerCruiser replacement part and not the automotive equivalent. The automotive thermostat opens at about 195 degrees while the marine unit opens at 165 degrees."

( http://www.powerboating.com/pbc17-5/ask17-5.html )

<hr width=100% size=1>Mmmmm maybe not....

 

[ArthurWood]

Re: Thermostatic valve thingy (followup)

Well, if that's what it says, who am I to argue?

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