problem after replacing the inlet manifold gasket

[mysst]

I just replaced the inlet manifold gasket in my VX v6 3.8L with aluminum gasket.

after putting it all together and starting the engine I found an "air Leak" coming from the right side of the inlet manifold that can be heard with engine idling problem and both oxygen sensors error code.

I am quite sure I fitted the gaskets in their right place and added sealant in the four corners, also tightened the bolts to 16 NM in their right order.

what could be the problem and how can I fix it ??

could it be because the gasket are metal not plastic like the genuine ones ??

thanks in advance

 

[The1]

the metal vs plastic has nothing to do with the sealing, they both have rubber orings around all the holes. Did you install new rear and front seals and apply the appropriate gasket sealant to the joints? Were all the surfaces cleaned properly? If so and they are on correctly there should be no leaks. Are you also sure the leaking sound isn't from perhaps injector orings or can you see coolant coming out?

 

[Turtl3]

Even tho the gaskets are ali they should still seal. They only thing u can do is take it off again, clean the old sealant off and start again, but instead of only putting sealant in the corners, do the whole surface area instead. Depending on what kind of sealant u r using may make a difference. If u r using something that is quick setting then u need to be quiet hasty getting it all back into position and tightened down. I have seen things put back together too slowly, and as the sealant sets, when the mating surfaces are still being aligned and getting moved around abit to line up bolt holes, it can cause the sealant to ball up and create high spots in the mating surfaces which allows leaks.

 

[mysst]

the metal vs plastic has nothing to do with the sealing, they both have rubber orings around all the holes. Did you install new rear and front seals and apply the appropriate gasket sealant to the joints? Were all the surfaces cleaned properly? If so and they are on correctly there should be no leaks. Are you also sure the leaking sound isn't from perhaps injector orings or can you see coolant coming out?

hi

all surfaces are cleaned as required.
yes new front and rear seals are replaced.
and sealant added to the four corners as instructed.
I didn't do anything with injectors, they have been removed and installed together with the manifold as one piece.
and I can't see any coolant coming out

 

[mysst]

Even tho the gaskets are ali they should still seal. They only thing u can do is take it off again, clean the old sealant off and start again, but instead of only putting sealant in the corners, do the whole surface area instead. Depending on what kind of sealant u r using may make a difference. If u r using something that is quick setting then u need to be quiet hasty getting it all back into position and tightened down. I have seen things put back together too slowly, and as the sealant sets, when the mating surfaces are still being aligned and getting moved around abit to line up bolt holes, it can cause the sealant to ball up and create high spots in the mating surfaces which allows leaks.

well I only used sealant in the four corners.
a friend of mine suggested to add sealant on the whole surfaces like you said.
but is that a right thing to do ??
I haven't seen anyone doing sealant for the whole surfaces.

 

[_R_J_K_]

First thing I'd do is actually determine where the leak is.

Plenty of videos on YouTube about finding vacuum leaks with an aerosol (I use Start Ya' Bastard). You may even find it's coming from the seal between the upper and lower manifolds.

Depending on what and how bad the leak is there is a possibility you can get away with smearing some sealant over the leak. As long as there's no coolant leaking into the intake you might get away with that.

 

[moneypit]

hi

all surfaces are cleaned as required.
yes new front and rear seals are replaced.
and sealant added to the four corners as instructed.
I didn't do anything with injectors, they have been removed and installed together with the manifold as one piece.
and I can't see any coolant coming out

How did you manage to torque the lower manifold in place without separating the upper manifold and injectors away from the lower part? The O rings on the injectors are on the bottom of the injector where they slip into the lower manifold as well as on the top where they go into the fuel rail. A smear of rubber grease is a must so they don't bind and tear the O rings.

I would not smear the intake gasket with sealer, as suggested it should not be needed. I do however, put a light smear of rubber grease on the mateing surface of the manifold to help it slide cleanly over the gasket into position, don't know if it helps, but have done 4 so far and no leaks Also I do run the torque wrench over the bolts a second time, it's surprising that they still pull down that bit more. I also use "aviation" non hardening sealant on the bolts to seal the threads, seems to work well.

There is the vapour line that runs from the bottom of the throttle body and goes through the valley area, then plugs into the valve at the rear of the drivers side head, has that line been installed correctly?

Hope you find the issue without having to rip her apart

 

[Vt v6]

It's rare but redo it again and have the inlet manifold machined, I have heard several times they can warp.

 

[lout]

There is the vacuum line that runs from the bottom of the throttle body and goes through the valley area, then plugs into the valve at the rear of the drivers side head, has that line been installed correctly?

plus 1 for vacuum hose

 

[mysst]

First thing I'd do is actually determine where the leak is.

Plenty of videos on YouTube about finding vacuum leaks with an aerosol (I use Start Ya' Bastard). You may even find it's coming from the seal between the upper and lower manifolds.

Depending on what and how bad the leak is there is a possibility you can get away with smearing some sealant over the leak. As long as there's no coolant leaking into the intake you might get away with that.

all I know is that the air is coming out from the right side.
the sound of the engine won't let me to specify the exact spot