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post #186 of (permalink) Old 07-05-2017, 06:28 AM
GregSef
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Join Date: Jul 2008
Location: Huntington, New York
Posts: 950
Garage
My 2 cents:

If a liner has turned or popped up even a little with liner o-rings that have been in the engine for any length of time you have to replace that O-ring. The O rings harden and take on all the imperfections that they seat on. Change its seating position and they don't seal. Any time they are disturbed its over.

I had to pull a motor and change the O-rings the day before a race weekend to learn this.

Its way to easy to revolve a motor while you are breaking it down. So now the minute a head comes off the hold downs go on. If your not sure which liners moved then they all should be changed.

Also in my experience most of my head gasket issues on V6 motors were about leaking combustion pressure into the coolant system (3000 PSI) not with coolant (15 PSI ) into the crankcase. When I wound up with the dreaded milkshake in the crankcase it was almost always the liner seals. Of course it can and does happen that a head gasket fails and leaks coolant into the crankcase but that is usually very obvious and not a subtle indication at the fire ring. Coolant laying on top of a piston when you open a motor means nothing since it leaks out when you pull the head. Steam cleaning of a combustion chamber from a leak is an indication of a big enough water leak to get some water in the crankcase.

Greg

1972 Berlina Vintage Racer, 1987 Milano Platinum (LeMons Car), 1982 GTV6 EP Race Car, 1974 GTV Vintage Race Car, 2012 VW GTI stage II, 1966 Corvette Coupe 327-350, 2007 Triumph T100 Bonneville. Dearly departed: 1971 Fiat 124 Spider, 1983 Saab 900 Turbo, 2004 Saab 9-3 Aero, 1995 BMW 540i Sport, 2014 Audi A4 (swamped)

Last edited by GregSef; 07-05-2017 at 07:57 AM. Reason: clarity
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