Well, you guys were right - the stumbling problems seems to be a blocked heat riser tube. After running the engine to full operating temps, the tube is just barely warm (I have been told it should be hot enough to burn your finger on touch). Does anyone have any advice or experiences in cleaning/reaming this sucker out? I would prefer not having to drop the engine, as the car has an auto-stick with lots of ATF & associated connections. I have removed the muffler ,and am working the heat riser tubes from under the car. I have used cables on a drill, carb cleaner, penetrating fluid, and have even considered easy-off oven cleaner. The problem is that the tube is blocked in the middle (a.k.a. The "D" section). The first 14 inches, or so, coming in from either side is open. Trying to get that spray chemical up and into the center is difficult. Compressed air shot into one side does not exit the other. I'm getting no-where, quick. Does anyone know the inside dimensions of the "D" section? Would a cable coming in from the one of the riser tube ends possible hang-up on the area where the round tube changes to the "D' tube, or is that junction smooth? I have read some of the ideas for cable reaming on different VW websites. I was hoping that someone in this forum could shed some light, experiences, ideas on conquering this problem. Thanks, Rich
Help/advice cleaning blocked heat riser
Jan 26, 2004
Last reply: 3 years ago
10 Replies
The tube is just that: a tube. The center section is a casting which is there merely to transfer heat to the manifold. If you can't take the thing out, hammer blows to the heat tube will often break up the carbon inside. You prob don't want to use the oxy-acetylene torch in the engine bay...
Speedy Jim
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Get a used clutch cable. Cut a short (half the tube at most) lenght and put it in a variable speed, reversible drill. Start feeding the cable from one end while you turn the cable slowly in reverse (forward will untwist the cable).
Hiya Richard,
Eduardo has the ticket! The "cable in the drill" does work. But let me tell you............you really need to remove the manifold and the tubes to do this effectively. I know that's a pain (I have an AS also) but it's the BEST way to get the job done.
Mike
1970 AS BugIf not too bad, an un-furled wire coat hanger will work.
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" ..... I ain't no bandleader!!"
Richard,
Use a clutch cable(old/new, doesnt matter). Measure about halfway through the riser tube with it and then cut the cable at that point. Measure from the end that has the threaded section. What you want to do is chuck the threaded end in a reversible drill and use the cable as a 'roto-rooter' to clear out the tube. I would feed it in as far as possible, reverse the drill to un-furl the cable a little, and then reverse again to cut through the crap. I had to periodically stop and tap all the debris out before cutting again.
I had to do this job on my 74 super(which has TWO pre-heat tubes, twice the fun!). It does work but it will take some time. I removed the intake manifold to do mine, it's just too much trouble to try and do it in the car.
Chris
in article EXARb.20272$ snipped-for-privacy@news4.srv.hcvlny.cv.net, Ilambert at snipped-for-privacy@optonline.net wrote on 1/27/04 1:43 PM:
No can do. Engine has to come out first, in order to get manifold off.
-Rich
Well that's a bunch of crap. I just did it not to long ago.
check out J Henry's page for this problem...
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How did you do it without dropping the engine?
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