Coolant leak - intake manifold?

Trying to sort out a coolant leak on a 5VZ-FE with 280k miles. Head gaskets were replaced 30k ago.

I'm getting coolant in the exhaust, rough startup. Pressurizing the cooling system leads to coolant in cyl 6. But both compression test and leak-down test on cyl 6 don't show a leak. I'm starting to wonder if coolant is getting through the intake manifold gasket. I replaced it a year ago (could have done something wrong, though). Could there be a crack in the intake manifold that is leaking coolant into the cyl? Could there be a crack in the head that isn't showing up with a leakdown test?

 

Easiest way to go about this I would say is pressurize the cooling system and look around cylinder 6 with a camera down the plug hole.

I've only worked on the 3vz-e which did have coolant through the intake. I don't know about this engine. If you have brass frost plugs on the intake then yes coolant flows through it. If memory serves from the 3vz, the coolant hoses enter the intake from the rear passenger side of the intake.

If it's pressurizing the coolant system though, it's almost certainly a head issue. If the intake manifold was compromised it wouldn't have pressure in it ever beyond atmospheric.

Who changed the head gasket? Maybe a little bit of old material was missed during cleaning. Heads most likely don't need machining unless the engine overheat but proper cleaning is paramount

 

^^^ agreed, there are many very good probe cameras on Amazon for under $100, high resolution and can be submerged. Make sure that it has a light on the end too.

 

Thanks. I’ll do that. A shop changed the head gasket, so I trust them. I did overheat for a minute or two about a year ago when I didn’t burp the cooling system before taking it for a test drive. Even a short overheating could have been enough to crack/warp the heads, yeah?

 

Potentially but not guaranteed... I would still go through the process of diag-ing it again though so you know for sure. I'm not a fan of going parts canon. That gets expensive very quickly and sometimes causes more problems in the proccess