TheSamba.com :: View topic - Muffler -> Heat riser question.

Thu Oct 29, 2009 10:44 pm

I was about to put on my muffler when I noticed that the holes that attach to the heat riser don't go through to the exhaust at all. Since I just put a lot of effort into trying to unplug my heat riser, and ended up giving up and buying a new one, I'm guessing it's not supposed to be that way. They just end where they're attached to the pipe. This is wrong, right? Should I just drill some holes through?

Thu Oct 29, 2009 10:59 pm

This isn't an aftermarket set of headers is it? They like to block off the heat risers so you get a colder fuel charge. The result is a little more power at a cost of lessened driveability and poorer fuel mileage.

Thu Oct 29, 2009 11:05 pm

Most likely that is an aftermarket set of headers or exhaust. They need to be drilled out. Some people like cold manifolds or don't have a manifold that will cover that area while others want manifold heat so that they don't get icing in it. You can always block them off again with a piece of tin can in between if they are too hot in summer. Just drill them out with small holes no bigger than the holes in the gaskets, maybe about 1/2 the size. Drill a pilot hole first and go to slightly larger drill bits as that may be weld material, uneven and hard. Both sides have to be drilled as the pulses between cylinders are what push the exhaust through.

Thu Oct 29, 2009 11:06 pm

Ok.......we've established you do have a freakin' digi cam after your last 20 question thread.....

http://www.thesamba.com/vw/forum/viewtopic.php?p=4158429&highlight=#4158429

Post a fukkin' pic if you want a quick answer. Is that really so hard?

Thu Oct 29, 2009 11:07 pm

I don't know what's up with it, the bus came with it. I just rebuilt my engine and was putting it all together when I noticed. I've been driving it for years like that. I'm way more into milage and drivability than power, but I can see the PO being the kind of guy that would do something like that...

*edit* pics:

Thu Oct 29, 2009 11:11 pm

Uvula wrote: So I can just drill through it, right?

I suggest drilling all the way thru it......

Thu Oct 29, 2009 11:34 pm

SGKent wrote: You can always block them off again with a piece of tin can in between if they are too hot in summer. Just drill them out with small holes no bigger than the holes in the gaskets, maybe about 1/2 the size. Drill a pilot hole first and go to slightly larger drill bits as that may be weld material, uneven and hard. Both sides have to be drilled as the pulses between cylinders are what push the exhaust through.

Thanks, this is what I'll do. How would I know if it was too hot? I was under the impression that a clogged heat riser could cause overheating. If I have it drilled through, it should be okay in the summer, so long as I'm not in a really hot climate right?

Thu Oct 29, 2009 11:39 pm

the hole to the exhaust (arrow) already looks open. Blow compressed air into it on both sides and see if it goes into the exhaust. If it doesn't you need to drill through the pipe under the hole into the exhaust. Before you do however, the screw/bolt hole on the right needs to be drilled and tapped or it will leak. It requires two bolts to keep it from leaking. You may want to consider replacing that exhaust. If you are going for the stock look get a stock exhaust for your year. If you are going for performance get a set of headers like you have but be sure that both bolt holes are there. I am concerned that the right bolt hole won't hold and it will leak.

Also ignore 73Kombi. That is how his mother dealt with him when he was high on meds.

Thu Oct 29, 2009 11:47 pm

when you put everything back together use some red silicone sealer - just a little even on the donuts and it will help seal it for a long time. That bolt hole on the right looks like trouble from the photo view. I think there is weld that has slopped into the slot the bolt needs to go into.

Thu Oct 29, 2009 11:53 pm

SGKent wrote: the hole to the exhaust (arrow) already looks open. Blow compressed air into it on both sides and see if it goes into the exhaust. If it doesn't you need to drill through the pipe under the hole into the exhaust. Before you do however, the screw/bolt hole on the right needs to be drilled and tapped or it will leak. It requires two bolts to keep it from leaking. You may want to consider replacing that exhaust. If you are going for the stock look get a stock exhaust for your year. If you are going for performance get a set of headers like you have but be sure that both bolt holes are there. I am concerned that the right bolt hole won't hold and it will leak.

The hole is definately not open, the shiny part in the hole in the picture is the outside of the pipe where I scratched it with a screwdriver to make sure it was solid. About the bolt hole, is it supposed to be round? the one on the other side looks just like that too, I was under the impression it was supposed to be that way. Unfortunately I am under some pretty heavy time constraints right now, and need to be driving this bus to california in two days to make a job interview, so I really can't afford to wait around for any more parts to come in the mail.

*Edit* Here are some better pictures of the bolt holes...

The same side:

The other side:

I really really need to get to california! would it be better to drive the bus with these possibly leaking, or just leave them plugged up like they have been for the last six years I have been driving this bus?

Fri Oct 30, 2009 7:25 am

Just drill the holes and call it done.
Aftermarket headers like that frequently arn't drilled through because a lot of people that put on a header also have dual carbs. Dual carb manifolds don't have heat risers. But your single carb manifold with heat risers needs to have the header holes drilled so it gets exhaust flow.

Use new gaskets and get new bolts, flat washers, and nuts. Usually it is difficult to get the flanges lined up to get them bolted together. Use a punch or a phillips head screwdriver down thru the holes to pry and get them lined up. Also you might need to leave the intake manifold loose until you get it all lined up.

P.S. Ignore all that stuff about tin cans, being too hot, tapping a bolt hole and all that. The slot is there so that you can get it bolted together.