Manifold Heat Shield question

1998 2.4L Tacoma and the heat shield over the exhaust manifold is cracked from the center bolt hole to the edge near the head and there is a second crack at the rear margin of the shield.

The cracks have me thinking about the manifold - Cracked cast manifolds are apparently also common.
- Do all cast manifolds eventually crack or only a small %? (truck has 115,000 miles)
- Is there anyway to minimize the risk of a crack forming in the manifold?

Are the 2.4L and 2.7L heat shields the same?

Thanks,
Shawn

 

I have the same question but not sure because you started out talking about a crack in the heat shield? If your heat shield is cracked, why not just replace or repair the heat shield somehow? The exhaust manifold is more serious, of course and requires a new manifold. I will post separately because I am not sure if our questions are related or not. I have 1998 Tacoma 2WD with 2RZ.

 

My wife had a 96 which needed the exhaust manifold at around 150k. In fairness we live in Massachusetts so we do have rust.

 

My heat shield had cracks at every bolt. Got noisy so it's gone. Had another shield less used and had identical cracks. Running without it. Found exhaust leak at y pipe.lol

 

I was wondering if cracking in the heat shield is an indicator that the manifold is likely to crack soon. If so, I would start looking for the 2000+ steel tube manifold. If not, I'd just replace the heat shield.

Thanks for all the replies.

Shawn