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Old 26 July 2019, 19:01   #1
Country: Ireland
Town: Mallow
Make: Avon Seasport 4.65
Length: 4m +
Engine: Mariner 60hp
Join Date: Aug 2014
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Some crap lodged in engine cooling circuit

I am convinced there is some stuff floating around in the cooling circuit of my mariner 60. It did get to overheating a few times but I have always managed to free it up fairly easily. Would the head gasket need to come off it and be replaced if I wanted to see what's inside or is there an easier way of getting rid of whatever is inside?

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Old 27 July 2019, 01:41   #2
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Hang fire before diving into removing the cylinder head just yet.

Elaborate more on the overheating. Does engine have a good tell-tale, is it used predominantly in salt water? What's the current servicing routine like (when was impeller last changed) and any maintenance after a trip such as flushing?

Sure you can strip out the head, but it comes with a degree of risk. The bolts will be invariably seized depending on the age of the engine. You need new bolts when refitting, a head gasket, and there's a torque sequence to do it properly.

First thing I'd do is remove the thermostat. These do fail. You'll need a gasket when you replace it anyway. That will give you a good idea of any salt build up.

I'd also run the engine with Salt Away or vinegar solution in a tub, and see what that does. You can use nylon strimmer line into the tell tale for any obstructions. If you're doing the cylinder head, then do the water jacket too.

Get some pictures up.

Is that with or without VAT?
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Old 27 July 2019, 01:49   #3
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It sounds like your problem is definitely inside the head? Some people have found their tell tale / pee pipe gets a bit clogged up - and it can be cleared with some still plastic passed up the inside.

Ultimately the only way to see whats happening inside the water passages is to take the head off. Some people have success flushing through with salt away or even just descaling with something like vinegar or citric acid in the water (make sure you thoroughly flush with fresh water afterwards), which will dissolve any easily removable limescale. If its really bad though the limescale will be in places where the flow doesn't get to easily and therefore flushing will not reach. If its got that bad - removing the head may not be a bad idea as there are probably internal anodes that are overdue inspection/replacement.

The other "common" obstruction is bits of broken impeller if you've had an impeller failure. They don't dissolve so need the head to come off if you can't wash them out.
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Old 27 July 2019, 05:11   #4
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Originally Posted by Poly View Post
It sounds like your problem is definitely inside the head?

A bit harsh
Rule#2: Never argue with an idiot. He'll drag you down to his level & then beat you with experience.
Rule#3: Tha' can't educate pork.
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Old 27 July 2019, 13:21   #5
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Is there not an anode in the block you could have a look at first removing head bolts could be another problem if you shear one
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Old 28 July 2019, 11:13   #6
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If water pump is doing its homework right, remove thermo and air flush with a compressor set to 30 PSI the internal thermo hole.

If that motor has high hours use on salt water, no matter if it was flushed with fresh water afterwords will definitely have collected salt layers on all cooling water paths. If wanting the motor to work as when new will need to remove the entire power head from base, remove thermo (s), cylinder head (s) exhaust cover (s) if having more than one, squirt pure vinegar on all water paths, let penetrate and mechanically scrape to immaculate perfection all water paths locates on cylinder head and internal crankcase as well. Poke with a plastic cannula alll water holes located under crankcase (4) Will need to order new head, exhaust, thermo and base gaskets.

There's always the risk that may broke any of the cylinder head, exhaust bolts when removing them, specially if both head gaskets were not torqued to their fact specs soon after break in period ended or when have changed new gaskets, salt water may have made its way in through gaskets and seized any of the mentioned bolts.

Now the dilemma is : keep boating overheating if the compressed air, flushing did nothing or make a full water path preventive maintenance risking breaking any bolt that can be removed latter at a machine shop ? Check pics for understanding..

Happy Boating
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