Thermo Valve boost leak advice
Posted: Wed Jul 08, 2026 1:26 pm
I have been chasing boost leaks for a while now. I rebuilt the throttle body (thanks Tom!), replaced some cheap aftermarket Intercooler clamps, and replaced the original ISV hoses.
Now when I pressurize my intake system, I can hear air coming from the thermo valve under the intake. I connected a handheld vacuum pump to the tube that connects to the intake and it holds 18 psi with no leaking. When I connect the pump to the other side of the thermo valve (to the evaporator system side) it does not hold any vacuum. I did this with the engine cold. Do have the lines mixed up or do I need a new thermo valve?
Now when I pressurize my intake system, I can hear air coming from the thermo valve under the intake. I connected a handheld vacuum pump to the tube that connects to the intake and it holds 18 psi with no leaking. When I connect the pump to the other side of the thermo valve (to the evaporator system side) it does not hold any vacuum. I did this with the engine cold. Do have the lines mixed up or do I need a new thermo valve?
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