#21  
Old 05-23-2020, 09:19 AM
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ZeGermanHam ZeGermanHam is offline
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Quote:
Originally Posted by steve25 View Post
I had just such a leak in my daily driver Subaru.
It was a head gasket and a very very small leak into a cylinder.

My coolant over the course of 5 days of a 74 mile round trip to work and back would go down by a little over 1/4 of a gallon, just enough to use up the reserve in my overflow tank.

It never steamed or smelled out the tail pipe either atleast at hot idle.

I got lucky and 3/4s of a tube of the Brass and Aluminum powder fixed it.
Subaru head gasket failure every 100k miles seems to be the rule rather than the exception, which has been my experience with my Impreza. That said, I would never recommend using the mechanic-in-a-can sealants. They do a number on the coolant passages, radiator, and the heater core. And yes, I know Subaru dealers used it.

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  #22  
Old 05-24-2020, 05:40 AM
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Well so far( 25K miles or so) it's done the job and the motor is running cooler and in reaction to that the fan does not come on as much at stop lights and at idle.

I have no problem with the metalic powder I used and have used it many times before, in fact In new cars on the line GM put 2 tablets of the stuff in every car's cooling system as a precaution!

It's the ciramic type liquid head gasket sealers that can clog up a cooling system darn fast if you have not fully flushed it out first.

Oh, and by the way my Sabaru's had 175K on it be fore the issue started and it was due to a slight but short overhead session from a pin hole leak in the middle of the lower hose.

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  #23  
Old 05-25-2020, 12:05 PM
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Cometic gaskets require a very smooth finish to the deck and head. (RA 50 or better. If you do not have it you can get head gasket leaks from them. I have seen this.

  #24  
Old 05-27-2020, 09:36 AM
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Quote:
Originally Posted by JSPONT View Post
Cometic gaskets require a very smooth finish to the deck and head. (RA 50 or better. If you do not have it you can get head gasket leaks from them. I have seen this.
I think we have a winner!
The block & heads were prepped around 20 years ago when Felpro & copper gaskets were the only gaskets around.

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  #25  
Old 06-01-2020, 04:50 PM
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Originally Posted by Speargun View Post
I think we have a winner!
The block & heads were prepped around 20 years ago when Felpro & copper gaskets were the only gaskets around.
You might get away with different gaskets, but I would check the heads and cylinder walls while it is apart

  #26  
Old 06-01-2020, 05:50 PM
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Gonna jump on the head gasket/cracked head bandwagon.

Had nearly those exact symptoms with my '73 'bird when a head gasket blew. No steam clouds out the exhaust or milky oil, just all the coolant would disappear after driving it.

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  #27  
Old 11-11-2020, 06:16 PM
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***UPDATE***

I finally got around to pulling the heads off and it looks like compression may have been sneaking past the Cometics between the cylinders.
I rotated the crank and also discovered that #5 cylinder has a small crack in it so it's time to 'throw it in the gutter & go find another.'

Now I'm waiting on my machinist to finish up a '67 block with splayed caps so I can start a new build.

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  #28  
Old 11-11-2020, 09:02 PM
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Who does your machine work?

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  #29  
Old 11-11-2020, 11:41 PM
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Yes, pull the plugs. The cylinder(s) with the leaks will squeeky clean. You should have a trail of white smoke out of the exhaust too. If it leaks compression , it generally leaks under vacuum too and sucks coolant into the cylinder.

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  #30  
Old 03-05-2021, 01:07 AM
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Use hylomar M for sealant.

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  #31  
Old 03-05-2021, 01:45 PM
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Just an additional note, make sure gasket bore size is not smaller than combustion chamber!
Common error when selecting Cometics. Cataloging references bore size 😬.

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