Closed cooling system repair

$300boat

Cadet
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Jun 8, 2013
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On the Mercruiser 165 4 cylinder. cooling system leak...Would Radiator Stop Leak work? Would it do any harm to try?
 

Don S

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Re: Closed cooling system repair

NO, that is nothing but a get home type fix.
NEVER was stop leak designed to be a permanent fix. Just temporary till you can fix it right.
 

achris

More fish than mountain goat
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Re: Closed cooling system repair

Where is the system leaking? if it's the exchanger, pull it off and take it to a radiator shop....
 

Bondo

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Re: Closed cooling system repair

On the Mercruiser 165 4 cylinder. cooling system leak...Would Radiator Stop Leak work? Would it do any harm to try?

Ayuh,... Welcome Aboard,... Where, exactly is it leakin',..??
 

stonyloam

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Re: Closed cooling system repair

If it is from the weep hole in the engine waterpump then it is possible that the stop leak would plug the weep hole which would spell DISASTER with a crankcase full of antifreeze and burnt out bearings, and then you would have a $0 boat.
 

$300boat

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Re: Closed cooling system repair

NO, that is nothing but a get home type fix.
NEVER was stop leak designed to be a permanent fix. Just temporary till you can fix it right.
Don, My truck has been leak free for over 50,000 miles after using perm o seal. The boat was free and I was told it leaked coolant and needed a new seal. The permanent fix is more than the boat was worth. If I got a season or two from a bottle of radiator stop leak, I'd be tickled pink.
 

$300boat

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Re: Closed cooling system repair

Where is the system leaking? if it's the exchanger, pull it off and take it to a radiator shop....
I just picked the boat up today. I was told it had a coolant leak. The boat actually came free with the trailer, so I'm hoping to try a low cost solution first. I'll see if I can locate exact leak location in the AM.
 

$300boat

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Jun 8, 2013
Messages
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Re: Closed cooling system repair

Ayuh,... Welcome Aboard,... Where, exactly is it leakin',..??
I just picked the boat up today. I was told it had a coolant leak. The boat actually came free with the trailer, so I'm hoping to try an easy solution first. I'll see if I can locate exact leak location in the AM.
 

achris

More fish than mountain goat
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Messages
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Re: Closed cooling system repair

Don, My truck has been leak free for over 50,000 miles after using perm o seal. The boat was free and I was told it leaked coolant and needed a new seal. The permanent fix is more than the boat was worth. If I got a season or two from a bottle of radiator stop leak, I'd be tickled pink.

You need to understand how the water pump seals on the front of the camshaft work BEFORE you go pouring anything like that into the cooling system on these engines.... It's not a standard engine with a standard cooling system...

As already mentioned. If you plug up that weep hole, good-night Lucy....

Chris.....
 

stonyloam

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Re: Closed cooling system repair

If it is the cam seals, and it sounds like it is it is imperative that that weep hole stay open. Here is how it works: On the 470 engine (yours) the engine waterpump impeller is bolted to the end of the camshaft, and there are two seals that keep the coolant out of the crankcase with the weep hole between. The cooling system is pressurized, just like your truck, and when the seals ware out the front one will begin to leak on the pressure side. When the coolant leaks past the front seal it is no longer under pressure so when it encounters the second seal it is blocked and just leaks out of the weep hole rather than leak into the crankcase and contaminating the oil. If you use stop leak it is possible that it could plug that weep hole and the coolant will remain under pressure and be forced past the second seal into the crankcase and as Chris says "good-night lucy". Here is an article that talks about it: Mercruiser 470 Coolant Leak Now you don't need any of the expensive tools they talk about and if you have the room you don't have to mess with the front engine mount. Matter of fact you don't even need the spedi sleeves (mine was fixed 10 years ago without them and is still holding). Cost you about $100 without the sleeves. Lots of guys here have done it, so help is here. As mentioned before first thing you need to do is replace the impeller in the outdrive.

PS FYI there is nothing more expensive than a "free" boat":facepalm:
 

$300boat

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Messages
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Re: Closed cooling system repair

If it is the cam seals, and it sounds like it is it is imperative that that weep hole stay open. Here is how it works: On the 470 engine (yours) the engine waterpump impeller is bolted to the end of the camshaft, and there are two seals that keep the coolant out of the crankcase with the weep hole between. The cooling system is pressurized, just like your truck, and when the seals ware out the front one will begin to leak on the pressure side. When the coolant leaks past the front seal it is no longer under pressure so when it encounters the second seal it is blocked and just leaks out of the weep hole rather than leak into the crankcase and contaminating the oil. If you use stop leak it is possible that it could plug that weep hole and the coolant will remain under pressure and be forced past the second seal into the crankcase and as Chris says "good-night lucy". Here is an article that talks about it: Mercruiser 470 Coolant Leak Now you don't need any of the expensive tools they talk about and if you have the room you don't have to mess with the front engine mount. Matter of fact you don't even need the spedi sleeves (mine was fixed 10 years ago without them and is still holding). Cost you about $100 without the sleeves. Lots of guys here have done it, so help is here. As mentioned before first thing you need to do is replace the impeller in the outdrive.

PS FYI there is nothing more expensive than a "free" boat":facepalm:
Got It! Thanks so much. I know marine engines are different and would never have tried it without finding out more about the system Your explanation was great. I will read the article and give the fix a try! Thanks again!
 

$300boat

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Joined
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Messages
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Re: Closed cooling system repair

You need to understand how the water pump seals on the front of the camshaft work BEFORE you go pouring anything like that into the cooling system on these engines.... It's not a standard engine with a standard cooling system...

As already mentioned. If you plug up that weep hole, good-night Lucy....

Chris.....
I get it now. That would not be good. Thanks.
 

$300boat

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Re: Closed cooling system repair

As mentioned before first thing you need to do is replace the impeller in the outdrive. - I missed that this was mentioned before. Is it a try it first, or a -you must do it first, before moving on to the seals?
 

achris

More fish than mountain goat
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Re: Closed cooling system repair

Where is the leak from?
 

$300boat

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Re: Closed cooling system repair

Where is the leak from?
Just got the boat yesterday. Bought battery this morning, but having a hard time staring. Just from my garden hose in driveway trying to start, I see what could be coolant (Although it looks brown) coming from outdrive, close to the stern. Also small drips just under the coolant pump housing im engine compartment.
 
Joined
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Re: Closed cooling system repair

Of coarse you shouldn't have coolant exiting the drive. There's a good chance the heat exchanger has a cracked tube from not winterizing properly if you do have coolant out there. Easier to fix than the cam seals.

Confirm the coolant leaking out of the drive, a radiator shop (or plumber if you know one) can solder off the leaking tube and get you back in business.
 
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