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Heat riser ???


intimidtr3
02-07-2005, 04:39 PM
I have a 1984 4 dr dually with a 454 auto.I took it to the muffler shop to get exhaust put on it and he told me I needed a new heat riser for my truck to run properly.He wants $150 to put 1 on it and I can't find 1 at the parts store.My questions are:do I need it?What does it do?What is the esaiest way to eliminate it,can I cut the butterfly out and run the vacuum somewhere else?Any help would be appreciated.Thanks.

abaird
02-07-2005, 04:44 PM
$150!!!???
I think the heat riser is just the tube that runs from the intake tube to the exhaust manifold. the one on my 1986 fell off. If that tube is all you need it should cost 50 cents.

intimidtr3
02-07-2005, 04:49 PM
It is a cast iron piece that goes between the manifole and the exhaust pipe.It has a buttrfly on it and is ran by a vacuum thing(I don't know what it is called).I have never had a problem with 1 before that I know of.

abaird
02-07-2005, 04:54 PM
hmmm...the one on my 86 wasn't cast iron, it was really thin tin. But the part on the intake tube where it connected is still there, is that the butterfly?

broughy84
02-07-2005, 05:32 PM
the one on my 88 is real flimsy. It's like a flexpipe....real cheap.

Is the truck running alright without it?

The only purpose of a heat riser is to help with cold starts. It transfers heat off the exhaust manifold to the intake so that it will suck some warm air at first to help with combustion during those early morning >40 degree starts.

intimidtr3
02-07-2005, 06:45 PM
It does not go to the intake. It is a cast iron piece that bolts to the right manifold exhaust where the exhaust pipe itself hooks up. The pipe that you are talking about comes off the top of the manifold and goes to the air breather, that pipe is fine.

J-Ri
02-07-2005, 09:30 PM
The part you are referring to controls the valve that everyone else is talking about.

What I would do in your situation is disconnect the vacuum line that goes to the part on the exhaust. Plug the hose and zip-tie or duct tape it near the valve on the intake. During the summer just leave it off, you don't need it then. On a really cold winter day, just hook that line up directly to the intake valve.

abaird
02-07-2005, 10:14 PM
the one on my 88 is real flimsy. It's like a flexpipe....real cheap.

Is the truck running alright without it?

The only purpose of a heat riser is to help with cold starts. It transfers heat off the exhaust manifold to the intake so that it will suck some warm air at first to help with combustion during those early morning >40 degree starts.

If you were asking me if it is running alright without the flexpiupe, I don't really know. The truck doesn't ever want to start when cold anyway, but when it eventually does it seems to idle fine without the felxpipe. My 86 is probably missing all that stuff that he meant, its amazing it runs at all.

broughy84
02-08-2005, 12:50 PM
lol

J-Ri
02-09-2005, 12:43 AM
Yea, those heat risers stop working so good once they get old and rusty. Don't exchange much heat across the rust. Mine was installed and working when I bought my truck, removing it didn't make much of a difference. Sometimes on really cold days, quick WOT will make it almost die even after running for almost an hour.

JohnnyR17
02-09-2005, 12:51 AM
A heat riser that is stuck CLOSED will give you problems and cause your truck to run poorly.

Yes, you can take it off and cut the butterfly out.

You will need to have the heat riser in place or fabricate a spacer of some sort. Without the riser your y-pipe will leak where it mates to the exhaust manifold.

Fireplug
02-09-2005, 10:34 AM
The cast iron part that mount between the exhaust manifold and the exhaust pipe is called a Butterfly Valve and has a counterbalance weight and a vacuum line on it. It is used to help heat up the system for emissions. When they go bad most time they rust in the closed position. When closed the exhaust is blocked from flowing down the pipe and that will cause all kinds of driveabilty problems + burnt exhaust valves. Most peope wire tie the dam thing open and never think about it again.
The heat riser/stove pipe runs fron the exhaust manifold to the air cleaner and is used to warm the cold air going into the carb/or throttle body. It is a metal pipe on some trucks or a carboard type tube on others.
150 bucks for the butterfly valve is about right but I would not do it just force it open and tie it open and forget it.
I dont say that to often to just Mickey Mouse something but for that part I would.

JohnnyR17
02-09-2005, 06:15 PM
Well put Fireplug.
You said it better than I did!

J-Ri
02-10-2005, 02:27 PM
...but I would not do it just force it open and tie it open and forget it....

Don't completely forget about it, or the wire you tied it with will rust, break lose, and the valve will fall shut. Took about a year for that to happen on mine, but crawling underneath them once a year is much better than paying $150

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