Exhaust Heat Shield

[ekpolk]

I just noticed another difference between the regular I-4 Camrys and our hybrids. The 2AZ gasser cars have a full heat shield surrounding the exhaust, right from where it exits the block, down to the bottom of the engine room. In the hybrid cars (at least on my hybrid), there's only a little shield between the front of the cat and the radiator/fan and associated stuff. The headers and all exhaust plumbing from the block to the cat are fully exposed. One could, if one were particularly lacking in common sense, get a really bad burn, really fast, were they to touch any of this exposed metal during or right after engine operation.

Anyone know why we get the exposed exhaust, and the I-4 gassers are fully shielded?

[njerald]

Originally Posted by ekpolk

I just noticed another difference between the regular I-4 Camrys and our hybrids. The 2AZ gasser cars have a full heat shield surrounding the exhaust, right from where it exits the block, down to the bottom of the engine room. In the hybrid cars (at least on my hybrid), there's only a little shield between the front of the cat and the radiator/fan and associated stuff. The headers and all exhaust plumbing from the block to the cat are fully exposed. One could, if one were particularly lacking in common sense, get a really bad burn, really fast, were they to touch any of this exposed metal during or right after engine operation.

Anyone know why we get the exposed exhaust, and the I-4 gassers are fully shielded?

The I4s are not all fully shielded. The PZEV engines are unshielded.

The PZEV exhaust manifold is double walled to keep the exhaust temp up and to position the air-fuel ratio sensor in the optimum location.

[tharvey]

Originally Posted by ekpolk

I just noticed another difference between the regular I-4 Camrys and our hybrids. The 2AZ gasser cars have a full heat shield surrounding the exhaust, right from where it exits the block, down to the bottom of the engine room. In the hybrid cars (at least on my hybrid), there's only a little shield between the front of the cat and the radiator/fan and associated stuff. The headers and all exhaust plumbing from the block to the cat are fully exposed. One could, if one were particularly lacking in common sense, get a really bad burn, really fast, were they to touch any of this exposed metal during or right after engine operation.

Anyone know why we get the exposed exhaust, and the I-4 gassers are fully shielded?

Been there and done that and the burn really hurt for several days, trying to change a damaged oil filter on a friend of mines vehicle.

[ekpolk]

Originally Posted by njerald

The I4s are not all fully shielded. The PZEV engines are unshielded.

The PZEV exhaust manifold is double walled to keep the exhaust temp up and to position the air-fuel ratio sensor in the optimum location.

Interesting. I've seen one with the hood up, and a pic of another with the shield. I assumed, mistakenly it appears, that they were all shielded. Thanks for the info.

Of course, this begs the question of why on one car, we have very extensive shielding, with the "burned hand" warning. And then on other cars, there's the hot metal right there exposed. I can see the sensor, but it still looks like it wouldn't be that hard to shield. Oh well, I'm not touching the thing so long as there's any doubt about how hot it is.