Losing my mind over a clogged heat riser pipe!

[crvc]

I believe I still have the manifold from my '67 bug's original engine. I can trade or sell it if you're interested.

crvc

[Ghia Finland]

Some guys are lucky enough to be able to get wire or similar objects thru the blocked heat riser.

I ended up opening both bends next to the straight part. The tube was fully blocked with rock hard material. It's possible to drill thru this stuff with metal drill. Conreate drillbits will not cut thru. You end up creating a lot of heat, but not much else. If you open both bends you can actually see into the pipe and be able to determine what is good enough for you.

Wire with bend ends was not able to cut this stuff. The only thing I did't try was to use oxy/ acetylen to burn the rest of the stuff away. This might have worked, since opening both bends makes it possible to to actually get the flame and heat inside of the tube.

This rock hard stuff exists only in the straight centeripe that is in contact with the intake manifold. That leads to the question why? As soon as you start the car, evaporating gas starts to cool the pipe. Water in the exhaust gases is a result of burning. Put the cooling and water together and there will be some condensation in the center part. These water droplets attract carbon deposits and sludge starts to form. As the motor runs longer pipe is well heated and it's temperature is above condenstation, and the pipe remains dry. Also, if you just briefly run the motor the center tube does not have time to warm up and some moisture will be left inside. That will cause rusting.

So the stuff inside is mixture of rust and carbon. If you have ill runing engine you may also get oil mixed into this mess. If the pipe is well oiled from inside it will protect it from rusting and therefore it maybe possible to poke thru with wires etc.

[notsnarb]

[Todd66]

I had the same problem with one of my 66 when I bought it. The whole thing was absolutely packed with carbon. I tried everything mentioned above and more. I made some progress. I finally decided my time was worth something and bought a new one. I wish I would have just done that sooner. Some may call me a quiter, but as was once said "If at first you don't succeed, quit. There is no reason to make a damn fool out of yourself."

[beetleman217]

I since have combated two other heat risers which I was able to unclog with the steel cable and drill trick. So the clogging varies greatly from engine to engine. The one I had to drill - I'm still convinced there was no other way as in that case it was rock hard.

And just an update for all the skeptics - the liquid weld patch is still holding up nicely, two years later now!
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If all else fails, stop using all else

1977 Westfalia
1961 Beetle

[oggelbe2011]

I cleaned a few out with a coat hanger and a drill, then a final reem out with a larger wire cable...messy but it worked. Also used the liquid weld method to plug the holes. 4 years on now and no problems with the epoxy patches.

[Tim Donahoe]

I once owned a bug that had two threaded plugs where the PO had drilled out the pipe at the bends. He actually tapped and threaded the heat riser holes he'd made.

Maybe he figured he'd have to do the job again and wanted easy access.

Tim

[wcfvw69]

My 67 bug manifold was clogged solid as well. I did what most have done. Bought some cable at Lowe's cut the cable at an angle and inserted it into my drill that I ran backwards so it doesn't unwind the cable. I used penetrating oil as a lubricant and it seemed to also help in cutting thru the carbon/rust. As mentioned, it does take time and patience to get thru all the crap but the results are worth it.
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[ChrisRheinschild]

I have a rebuilt 1500 that I am going to assemble. I blew air in the heat riser. Nothing!!! Darn!!! I tried 5 others and they were all plugged. No problem. A throttle cable in my drill. No luck or whatever. Next a clutch cable - nope. Tried OxyClean. It bubbled and went down. Added more, it bubbled and went down. Topped them off and closed up. I would put the rest of the solution down in the morning. The remaining solution in the "red solo cup" had turned to water and cement. This meant I had added a cement layer on top of my carbon plug.

I still had 2 manifold that were not usable. No problems - only solutions!!!!

Fired up the gas grill with 3 of the 5 burners on high. 4 hours at 600 degrees. I removed one with pliers and hosed it. The aluminum stayed warm

Back to the bench vice and ball peen hammer. I stood it on end and hammered the aluminum. A rain of carbon came out. A lot. I reversed the manifold and repeated the process. More carbon. I tried the air and had a very slight flow. More banging and more carbon. More air flow. One more time and great air flow. Next the clutch cable on the drill. Nice. I spread the cable ends and polished it from both ends. More air and just carbon dust this time.

By now the other manifold had cooled. No water hose this time. I repeated the process. Hammer, reverse, hammer, air three times. Great flow. Polished with the clutch cable. I am happy.

The side benefit of this process is all the grease and old paint are gone. Clean the flakes with Scotch Brite, primer, grey paint and DONE!

I hopes this works for you.

[dcheek]

I'm curious. There is a procedure in the Muir book that has you heat the carbon with a torch and then run pure oxygen through the riser. Has anybody tried this? Sounds dangerous!

Dave
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1961 Bug
1965 Bug
1966 Sunroof Bug
1966 Westy
1976 914 2.0
1989 911 Carrera
1981 Diesel Rabbit Pick Up
1982 Diesel Vanagon
2014 Golf (last year German mfr for NA)
2019 Jetta Gli, 35th Anniversary Edition, 6 speed

[KTPhil]

[dcheek]

[BWD]