Exhaust Leak Repair: Causes & Solutions

Hi,

While I don't have a TDI, but a Fiat Multijet, I don't think that makes a difference when it comes to this problem.

My air conditioning compressor was faulty, and I removed it along with a friend who is a mechanic and sent it in for repair. While doing so, we noticed that a stud bolt had broken off the exhaust manifold on the first cylinder. You could also clearly see the smoke during a cold start. When the engine was warm, it sealed itself, and no smell was detectable. In retrospect, I should have just left it as it was.

So, we disassembled everything, sent the manifold to be resurfaced, and reassembled it all with new gaskets. However, there is no gasket between the manifold and the turbo.

The fact is, it smells like exhaust fumes when it's idling. There's no smoke or whistling, so it's just a very minor leak. Unfortunately, I have a very sensitive sense of smell, which is driving me crazy. And it's definitely not healthy.

I got a particle measurement device from the chimney sweep and used it to check the exhaust system. The device is detecting emissions right between the turbocharger and the exhaust manifold, and also slightly from the fourth cylinder.

Is there a heat-resistant sealant that can be used for this?

dokky wrote:

Is there a heat-resistant sealant that can be used for this sealing job?

No. Either the sealing surfaces (even under the influence of heat) are uneven, or there are fine cracks in the material.

I suspect hairline cracks, but there's nothing visible. I've cleaned everything thoroughly, and the DPF has already regenerated several times. It smells fine when the car is stationary, but it stinks during regeneration. However, even after 2000 km, there are no signs of soot or residue. I'm not going to replace any parts just based on suspicion.

Since it smells like exhaust fumes coming from before the catalytic converter, the issue likely lies with the exhaust manifold, the turbocharger, or the connection between the two.

Also, consider exhaust coolers and their associated piping as well.

Hi,

We've checked all of this multiple times, and everything has also received new seals.
You can only smell it inside the vehicle when the car is stationary. However, exhaust fumes are not healthy either.

Tomorrow, we'll try lifting it again. Yesterday, when we were cleaning the DPF, it smelled really bad.

Have you ever held something against the exhaust pipe to try and locate/listen for the leak?
The engine should, of course, be running .

Hi,

No hissing, nothing. We've also already tested the system by running it at full power multiple times.

I've already borrowed a sensitive exhaust gas analyzer from the chimney sweep, and I'm going to use it to check the system later.

Just to put it simply: Are the injectors sealed? Exhaust gases could also be escaping from there, which you would be able to smell.

You could test it there with a mild mixture of water and a squirt of dish soap, sprayed from a pump spray bottle. Where it starts to foam...

Hi,

"Back then, I tested the engine with a measuring device and sprayed it with leak detection spray. The injector bore seals are tight. When assembled, there's a strong smell coming from the first cylinder, while the rest of the engine bay smells neutral. Because there's a cover around it, anything can rise up from below."

After having my Punto inspected today, I've lost interest in my Bravo, and since an oil change is due in 1000 km, it can stink for another month.

"My guess is that the exhaust manifold shifted again after being adjusted, or there's a hairline crack in the turbo. There's no soot visible anywhere. So, I'm going to disassemble everything, put it on the lift, and have my friend, who's a chimney sweep, run diagnostics on the system again using his measuring equipment."

The leak has been found.

Crack in the turbocharger housing. This is going to be an expensive repair...

Thank you for the feedback!