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Discussion Starter #1
Hey there, I have a boosted Duratec and I'm having issues with the coolant system, the pressure is getting so high the coolant tank cap can't hold it (tried 5 new different caps) and leaks everytime I floor it.
I think I have a bad head gasket, cylinder pressure is going into the coolant system.
Engine is built and running 18psi (ARP head studs, K1 rods, Supertech pistons, Cosworth IM, GT2871R turbo)
Anyone experienced this?

Cheers
 

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Sure sounds like you blew a head gasket. Happened to me on the turbo lima 2.3 in my xr4ti. Cooling system was extra pressurized But I had the chocolate milk coolant too so it was obvious.There are kits to detect carbon monoxide in cooling system I hear.
 

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Discussion Starter #4
Sounds like your lifting the head , change the HG , you have to TQ the ARP head studs 6-8 times

Is your tuner turning off the KS ?

Tom
6-8 times? :oops:
Is it necessary heat cycles between each retighten?
Didn't know that ARP needs to be torqued 6 to 8 times. I followed their instructions, ARP lubricant and three equal steps to 60 ftlbs.

KS is on always.
 

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There is part of your problem ,78 Lambda =11.5 Air fuel and its WAY to lean

I shoot for .73/.74 Lambda or 10.8 Air Fuel ,

Anything over .77 Lambda or 11.3 A/F I tell my Customers to let off

Difference between 10.8 and 11.2 Air Fuel in HP/TQ is minimal , it just isnt worth running it lean as you can see

Tom
 

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Sounds like you blew a gasket because you're running too lean of a mixture. Only way you would have built pressure on cooling system is if exhaust fumes are leaking into it. You can test by watching for bubbles in reservoir or actually test for CO emmisions coming out of bubbles with dye tests. If you got emmisions coming from radiator it's 99.9% gasket.
 
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