Captain_Kaboom

It's mounted to the passenger side exhaust manifold, and has a line to thermostat housing. Also appears to have a rod that connects to something lower on the exhaust manifold that pulls up and down a piece of metal.

A big smiley face to whoever can tell me what this thing is, and why it sounds like a tinkering hammer when my car is cold. Can I remove it? Can I fix it? I dunno, but someone please tell me what it is!

Thanks!

Paul L

Heat riser control valve.

Captain_Kaboom

Hum what does it do?

MikeC

When your engine is cold it blocks the exhaust coming out of that sides cylinders and forces it through the exhaust crossover in the intake manifold and out the other bank of cylinders exhaust manifold. The result is faster warm up times.

Captain_Kaboom

Cool! Thanks guys. Chilton's just told me that I need a new actuator. Fun fun!

Thanks all,
Kaboom

gmcclurg

I disconnected mine when I went to duals. Haven't missed it at all and haven't noticed any significantly long warm up problems, but I don't drive much in the winter.

Paul L

They are very expensive. But I picked up a unit in the C3 Parts area of this Forum for a good price.

carlmb

There are spacers available to replace this component. Looks like the heat riser with no guts. Think I got mine from ZIP.

killain

Keep in mind it's part of the emissions system. Getting rid of it might be against the law where you live. It's also a federal law I believe and has a penalty? :cuss

Captain_Kaboom

I just bought a replacement on ebay for $22 bucks, so I think I may just replace it. If I disconnect it- it just stays in the open position? I didn't want to pull it and have it close off half my exhaust.

How does this effect a true dual setup?

Paul L

Yes, default (no vacuum) position is open. On true dual exhaust systems the passenger side provides the warm-up on its own. In pre-cat con days that side was actually called the cold side because the exhaust exiting the muffler was "cold" until the heat riser opened. Over time the relative lack of heat for those short periods led to a less efficient vaporization of acidic liquids in the muffler. And typically the passenger side muffler would fail before the driver's side. Trivia of the day ;) .