Got this '86 SS u see...beautiful she is, but sometimes it seems it's only body panel deep...anyway, on to my problem.

The exhaust heat valve supplying the vacuum to my EGR has rusted off the exhaust pipe. Is it necessary to mount a new valve on the pipe and if so, how would u do it?
If it isn't necessary, can I just cap off the vacuum?
And finally, if I do cap off the vacuum, will my engine run as if it were out of tune?

Okay, one more question...when I went out looking to replace my thermal (ported) vacuum switch, I found 'bout six of 'em. They all look alike, with the exception of one that has a small filter looking thingy under the bottom port. Does it matter, which TVS I replace if they all match up to my car?

Thanks....Dominoe

 

You're skirting the rules regarding topics needing to be 3rd gen related, but since they aren't specific to Monte's, I'll let it slide (this time. . .).

The valve helps prevent fuel pooling in the intake plenum when the engine isn't fully warmed. I haven't been running one since 2001. It doesn't change the tune to cap off the vacuum feeding it.

You need the proper thermal vacuum switch for the function. Figure out what it's called by tracing it on the vacuum diagram decal under your hood, and ask for that one at the parts store. If your decal is missing, you can check the FAQ forum for what the f-body diagrams look like. But, if you ask someone to post a Monte diagram, you've crossed the line . . .

 

Thanks for the input, five7kid...still new to my Monte...didn't realize it fell into the 4th Generation class...

Dominoe

 

Your Monte Carlo isn't a 4th gen.

But it's also not a 3rd gen F-body. Which means, it's not suitable subject matter for this board.

But since the mod was kind enough not to lock or delete your post, I'll help you out.

First off, the thing on the exhaust pipe that you can see isn't a "valve", it's a diaphragm. And, it doesn't "supply vacuum to the EGR". It is not connected with the EGR in any way whatsoever, except to the extent that it's on the exhaust system, and the EGR recirculates exhaust gas back into the intake.

There is however a valve INSIDE the exhaust, that the diaphragm that you can see, actuates. The diaphragm is not replaceable, but the whole little "sandwich" thing that contains the valve and that the diaphragm bolts to, is. Last time I needed one I got it at NAPA. You take off the 2 nuts that hold the Y-pipe to the manifold, and it goes between them. Its official "name" is "EFE valve", or sometimes "heat riser valve". It forces the right-bank exhaust to go up over the top of the engine, through the intake manifold under the carb, and out through the left exhaust manifold, when the engine is cold; it helps it to warm up faster.

It definitely does matter which one of those thermal vacuum switches you get. The deal is that they each do something different at different temperatures. Some open when they get hot, some close. And of course, they have different thread sizes. There are actually 2 that I know of that do the right thing; which is, open when cold, close when hot, and that fit the hole that thing goes in. The right one depends on whether you have the L69 (VIN code G) or the base model LG4 (VIN code H). They're all supposed to have a filter; which all that it does, is to keep dirt from getting into the system whenever the valve opens and lets the vacuum escape (i.e. lets outside air into the system). It falls out alot before it makes it to the buyer.

EGR is something completely else, not connected with any of this in any way.