2017 Mazda cx9 2.5t burning coolant

Joined
Mar 9, 2012
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Hey everyone we have a conundrum and wanted to see if someone more knowledgeable than myself had any ideas. The car will intermittently run rough and it burns through coolant supposedly it had used about 4 gallons in 2 weeks. When you coolant pressure test it the pressure does not hold and it will smoke like a freight train once started after doing the pressure test. Crazy thing is with a boriscope in the cylinders we cannot see any coolant and any of the charge pipes for the turbo I can't see coolant there as well. As much as it smokes out of the exhaust when pressure tested and then started up after the pressure test is performed you would think we would see coolant somewhere. Does anyone have any ideas or possible causes of this issue?
 
Joined
Jul 30, 2003
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GA
Pressure test then boroscope before you burn it all out. Hope you don't hydro lock it.
 

JRed

Site Donor 2021
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Coolant could be pushing through a crack or casting defect on the exhaust side of the head and either pooling in the exhaust manifold or making its way into the hot side of the turbo/catalytic converter/exhaust/etc.

Less likely but the EGR cooler is worth checking. Could have an internal leak that's introducing coolant into the EGR circuit.
 
Joined
Jul 7, 2014
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@PimTac, what model years does this problem affect? I think the 2.5T has been standard on the CX-9 since MY 2017.

When did Mazda get it sorted out? (I'm assuming that the revised head and exhaust-manifold gasket are used on all new ones after a certain date.)
 
Joined
Mar 4, 2017
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...
@PimTac, what model years does this problem affect? I think the 2.5T has been standard on the CX-9 since MY 2017.

When did Mazda get it sorted out? (I'm assuming that the revised head and exhaust-manifold gasket are used on all new ones after a certain date.)


It goes from 2016 to 2020. The TSB gets specific on later model years with VIN numbers.

2016 was the first year for the SkyActiv CX-9.
 
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