Hey kids,

Just replaced my exhaust flange donut on the passenger side of my 2004 Jimmy. Was ticking for a few months or so and was slowly getting worse.

The new donut seemed to be smaller in diameter than the old one. Didn't seem too concerned as I just figured the design was a bit different.

Seemed to be made of a more soft material than the old one, which was rock hard (probably due to age).

Anyways, replaced the gasket and bolted her up tight. Seemed to seal up and didn't move when tightening.

Start the car, and the ticking is LOUDER than before. However, once the engine runs a bit and warms up, ticking is completely gone (never went away before, but was a bit quieter).

Now, I haven't been able to run it up to proper operating temperatures because I have some steering work I'm in the middle of, but someone mentioned to me that the new donut needs to be heated up by the exhaust running at normal temp, where it will expand to fill the gaps, then it will harden a bit, preventing the leaks. They said the reason it leaks right now at first is because I haven't done that.

Also, it never specified which way was up. I figured it didn't matter, as the donut was symmetrical, but there was s metal flange coming out of one side. I figured this was just to help keep it aligned when tightening the bolts.

Now, is this true for those who have done the job? Seems like the science behind it COULD work, but also, doesn't make sense at the same time. Looking to hear from others who have done this job.

 

Did the old donut look like it had been leaking when you pulled it out? I'm thinking you might have a cracked manifold or a leak between the manifold and the head.