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Hi everyone!
The snow has finally melted from the yard, so the annual troubleshooting session can begin once more.
This spring’s theme is to figure out where the huge amount of steam during cold starts is coming from.
The amount of vapour is so extreme that I don’t dare leave the car running anywhere public as within a five‑meter radius a thick cloud forms, and you can’t even see out of the car through it.
As far as I understand, it has to be steam, because I drained almost seven litres of yellowish water from the middle muffler. The vapour has no sweet smell or taste like coolant normally does. I also did a head‑gasket leak test with the colour‑changing fluid just to be sure, and it didn’t show a positive result.
Now to the core of the story, with some background.
When I bought the car, the wastegate actuator arm had been disconnected so the wastegate was stuck open. After reinstalling it, everything worked as it should. Encouraged by that, and being a young driver back then, I installed a manual boost controller and raised the boost close to 1 bar. Then, at some point, the boost dropped again, and I couldn’t find the cause no matter what I checked. Last year it finally turned out the catalytic converter had collapsed and created a massive blockage, so there simply wasn’t enough gas flow to spin the turbo.
Now the speculation begins, because I can’t say what caused what.
The turbine housing was cracked into three pieces.
The exhaust manifold gaskets were in shreds, as was the gasket between the manifold and the turbo.
Not knowing any better at that moment, I replaced all of those gaskets and installed a new turbo with an intact turbine housing.
Of course that didn’t fix the issue, but I kept driving and wondering where my boost pressure was disappearing.
It’s also worth noting that this steaming only began after installing the new turbo. I don’t remember how much it steamed back then, but it definitely wasn’t as dramatic as it is now.
This week I removed the new turbo and the exhaust manifold again because I really wanted to get this sorted before summer weather arrives, but even now the cause isn’t completely clear.
In the photos you can see a chalk‑like white residue on the turbine housing surface that has leaked through the sealing surface.
There is also some of this white deposit on the turbine itself, and all the way on the backside of the exhaust manifold. But I don’t think I see any of it in the exhaust ports of the cylinder head?
When I removed the turbo, I suspected an internal coolant leak in the CHRA, but I couldn’t see any obvious signs of it, and blowing air through the water channels with soapy water didn’t make any bubbles.
At this point I’m no longer sure whether this white residue is burned coolant, or something caused by running rich/lean.
Continuing that thought, could this vapour simply be the result of combustion itself?
In one of the pictures the turbo-to-manifold gasket is completely destroyed. That normally leads to incorrect oxygen sensor readings, which then affect fueling. But could this much vapour really come from just that?
I know the exhaust system no longer has water pooled inside it because I’ve painted and modified it outside the car.
I have brand new manifold gaskets and a turbo fitting kit on the way, so even if the real issue doesn’t reveal itself this time, at least I’ll be satisfied that nothing is leaking before the catalytic converter. ;D
Huge thanks for any help and advice, and I’m really looking forward to your replies!
The snow has finally melted from the yard, so the annual troubleshooting session can begin once more.
This spring’s theme is to figure out where the huge amount of steam during cold starts is coming from.
The amount of vapour is so extreme that I don’t dare leave the car running anywhere public as within a five‑meter radius a thick cloud forms, and you can’t even see out of the car through it.
As far as I understand, it has to be steam, because I drained almost seven litres of yellowish water from the middle muffler. The vapour has no sweet smell or taste like coolant normally does. I also did a head‑gasket leak test with the colour‑changing fluid just to be sure, and it didn’t show a positive result.
Now to the core of the story, with some background.
When I bought the car, the wastegate actuator arm had been disconnected so the wastegate was stuck open. After reinstalling it, everything worked as it should. Encouraged by that, and being a young driver back then, I installed a manual boost controller and raised the boost close to 1 bar. Then, at some point, the boost dropped again, and I couldn’t find the cause no matter what I checked. Last year it finally turned out the catalytic converter had collapsed and created a massive blockage, so there simply wasn’t enough gas flow to spin the turbo.
Now the speculation begins, because I can’t say what caused what.
The turbine housing was cracked into three pieces.
The exhaust manifold gaskets were in shreds, as was the gasket between the manifold and the turbo.
Not knowing any better at that moment, I replaced all of those gaskets and installed a new turbo with an intact turbine housing.
Of course that didn’t fix the issue, but I kept driving and wondering where my boost pressure was disappearing.
It’s also worth noting that this steaming only began after installing the new turbo. I don’t remember how much it steamed back then, but it definitely wasn’t as dramatic as it is now.
This week I removed the new turbo and the exhaust manifold again because I really wanted to get this sorted before summer weather arrives, but even now the cause isn’t completely clear.
In the photos you can see a chalk‑like white residue on the turbine housing surface that has leaked through the sealing surface.
There is also some of this white deposit on the turbine itself, and all the way on the backside of the exhaust manifold. But I don’t think I see any of it in the exhaust ports of the cylinder head?
When I removed the turbo, I suspected an internal coolant leak in the CHRA, but I couldn’t see any obvious signs of it, and blowing air through the water channels with soapy water didn’t make any bubbles.
At this point I’m no longer sure whether this white residue is burned coolant, or something caused by running rich/lean.
Continuing that thought, could this vapour simply be the result of combustion itself?
In one of the pictures the turbo-to-manifold gasket is completely destroyed. That normally leads to incorrect oxygen sensor readings, which then affect fueling. But could this much vapour really come from just that?
I know the exhaust system no longer has water pooled inside it because I’ve painted and modified it outside the car.
I have brand new manifold gaskets and a turbo fitting kit on the way, so even if the real issue doesn’t reveal itself this time, at least I’ll be satisfied that nothing is leaking before the catalytic converter. ;D
Huge thanks for any help and advice, and I’m really looking forward to your replies!
