There is a leak at where the manifold hooks up with the exhaust pipe that I plan on fixing tomorrow. While I was putting PB on the various bolts and crap in there, I started to wonder about the heat shield on the manifold. What is it supposed to be protecting? Somebody took off the sheild that is supposed to be below it and I am wondering if I could leave this one off as well, I figured the more I can open up the engine bay the better. What do you guys think of leaving the shield off?

Peter,

The way I look at it is that they put it

there for a reason...I guess to protect

the spark plug wires. These wires, I will

assume are already made to withstand much heat.

I just reattached the manifold to the engine and

put the heat shield left off by the PO, it's easy to

put on the guy probably just didn't feel like it.

The shield I am talking about covers where the manifold goes from 4 pipes down to 1 large pipe. It's below the spark plugs which lay across the valve cover anyway. There is nothing near the shield that looks like heat could hurt it. The computer is awefully far forward to be of concern.

Peter B. --

The "heat shield" is actually a shroud used to channel air around the hot exhaust manifold. The intake system, via the air filter housing, air thermostat, and metal hose, channels this preheated air into the engine intake while it warms up—and then, as it gets very hot, begins to mix in some cold outside air.

To be effective, you need to ensure that the metal hose is connected between this shroud and the air filter housing. The hose connects near the oil filter to a 2" diameter nipple on the shroud. Often this hose has long since disappeared.

But be aware that if the hose is intact and the air thermostat has failed (not uncommon) the super-heated air from the exhaust manifold can overheat the AMM, damaging it.

Don Foster (near Cape Cod, MA)

Don--

Good answer. Have you ever wondered about the purpose of the heat shield/warm air intake on the 240 turbo? During a cold start, the warm air would be drawn from the exhaust manifold, run through the turbocharger (where the prudent owner wouldn't compress it too much until the engine is warm) and then cooled in the intercooler. So what's the point of the warm air intake?

I removed the heat shield from my 242 Turbo beacuse of this reason. My car is not intercooled, so the hot air would (and does) help the car warm up faster, but once the engine is warm, it no longer helps. I also did the airbox modification listed on turbobricks.org, and it helps the car breathe better, also avoiding the hot air.

I dunno. Good question.

Why do you ask these questions? Does this belong in the category that includes, "Why is the sky blue?"

(Rayleigh knows, even though he's a scatter brain.)

Maybe so the air will be prewarmed for the turbo, thus helping lubricate it on those extra nippy days.

Maybe so the Turbo Heat Shroud Workers Union of Sveden won't strike.

Maybe to truly confound changing the oil filter.

Don Foster (near Cape Cod, MA)