TheSamba.com :: View topic - 40HP Heat Risers

Sun Jul 27, 2008 5:03 pm

Hey All,

I need some help here. I've search and read all there is on cleaning the heat risers on a 40 HP intake manifold. I tried clearing mine with the carb clean and clutch cable technique but was unsuccessful ( I think). The center section is still clogged. If totally cleaned out I should be able to blow compressed air in one side and feel it through the other side right? It's one pipe right? Judging from the length of cable that fits into each side, mine are now cleared up to where they meet the center section but they won't go any further (believe me I've tried)...so I'm wondering if the heat riser pipes are actually two separate pipes and the cast center section is actually solid?

To confuse me more, I purchased a "rebuilt" intake manifold from a reputable VW parts supplier that is supposed to have the heat risers cleaned but I can't get compressed air through that one either. So, what gives?...does the pipe go all the way through?

Sun Jul 27, 2008 5:49 pm

The heat risers on my '65 is one piece - I can blow compressed though them. I also have two spare manifolds that I can blow air through them as well.

Keep diggin' :P

Sun Jul 27, 2008 6:01 pm

That's what I thought...thanks so much for the confirmation. I'll send the rebuilt unit back. Guess I'll try the boiling water in the oven thing on my original.

Sun Jul 27, 2008 6:16 pm

They are one piece of pipe. The hot air goes in on the passenger side, out the other side, then out the tailpipe.

There have been several threads about different ways to clean them out, just depends on what you have to work with.

I've had pretty good success with the old clutch cable method, but it takes forever, and you never really get it all out. :roll:

Sun Jul 27, 2008 6:18 pm

Cleaning the heat risers is a major PITA! Not something I want to try to do again, ever...

I tried (emphasis on "tried") to clean the heat riser from my 40hp. Tried soaking in carb cleaner, heating up with a torch, cable in the drill, and smacking it with a hammer. Carbon started to dislodge while hammering, but in the end I ended up cracking the cast aluminum (not good). I ended up buying another one which wasn't clogged.

Since the manifold was ruined, I cut off one of the heat risers. It was so tightly packed with carbon, I didn't see how any of the prescribed ways would clean it out. The heat riser tube also squishes into a 'D' shape which makes cleaning with the cable even harder.

Save yourself anymore grief and buy an unclogged one. I bought mine for $30 and then found out another Samba member sells them for around $15. I can't remember the name, so try a WTB ad instead.

Good Luck...

Sun Jul 27, 2008 6:58 pm

Yeah...I've gone through 3 big can of carb cleaner soaking for days and spent a total of 3+ hours with the wire & drill. Progress stopped when I hit the center section...probably where the pipe makes the D shape. I'm reluctant to try the torch and hammer technique because I don't want to crack the casting but it's probably my next move...I've got nothing to loose at this point. I'd try the oxy-acytelyene trick but I don't own a set-up. So, the search is on for a clean used one again. Thanks guys.

Sun Jul 27, 2008 7:28 pm

Don't give up hope on the torch method. Go to Home Depot and rent one for a couple of hours. Here is how it is done:

http://www.thesamba.com/vw/forum/viewtopic.php?t=257399&highlight=solid+rocket+booster

Mon Jul 28, 2008 9:12 am

Here is how I cleaned one years ago. It was off a 1200 and was totally clogged with carbon

I took an old lawn mower cable (the kind with the spiral metal outer sleeve) and bend a 1/4" to 3/8" hook on the one end of the inner wire. I put the other end in a drill and used this as a flexible "drill" to bore through the carbon. I toook less than 5 minutes. The cable is flexible enough to go from one end of the riser to the other.

Mon Jul 28, 2008 9:58 am

Another way is to drill a hole at the outside of the bend in the riser and then clean it out without having to contend with getting the cable through the bend. Then weld up the hole again after you are done. Mine was done that way.