How to Replace the Exhaust System on a 75 to 78 VW Bus
Consider what kind of exhaust you have. , Inspect the existing system., Place cardboard under rear of vehicle where you will be working., Remove the old system., Now that the old system is gone, take a good look at your heater boxes., Look at the...
Step-by-Step Guide
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Step 1: Consider what kind of exhaust you have.
Look over your stock system.
Is it in good shape or maybe needs something simple, like replacing a hanger or tailpipe? Either leave it alone or do minor repairs.
If it is stock, what you have is better than anything on the market., You might be able to do the work without jack stands or ramps.
The cardboard will keep any crud that comes off the old system from getting on your driveway while protecting the new system from getting scratched up – scratches through the paint can make it rust faster., This may be as simple as removing the bolts at the flanges, then removing the hangar bolts and lowering it to the ground.
Some penetrating lubricant on the nuts may help loosen them up.
A number of areas are a bit difficult to get to with the old system in place, so don’t be afraid to cut the soon-to-be discarded pipes to make getting at bolt faces easier.
Make sure the old exhaust is supported as you unbolt it to keep it from torquing the heat exchangers or anything else it may be attached to., Are they in good condition with no dents, major rust or other serious defects? If they are, then go ahead with the installation.
But if your boxes are damaged, then replace them with a model that is compatible with replacement stock exhausts and use that exhaust configuration instead., Make sure they are smooth and flat.
Crud can build up on the heater box side, especially if there were exhaust leaks through the old gaskets.
Also, hold the replacement system in place to make sure the flanges are at least close to meeting up.
A quarter inch offset is fine, but some of the kits being mass produced are coming out with flanges that are not even close.
These need to be sent back.
For minor defects in the mating surfaces of the flanges, either smooth them out yourself or take them to a machine shop and have them do it.
Smooth surfaces are essential to preventing exhaust leaks.,, Don’t worry if they don’t meet exactly.
If they come up short, take two garden shovels, placed the handles in the new exhaust system intake pipes and pry outward to make up some of the difference.
They may still not align exactly, but should be close enough that you can place a big screwdriver through the exhaust flange, gasket and heat exchanger flange bolt hole and use it to gently leverage everything into place long enough to get the first bolt on that side.
Then add the rest of the bolts through the flanges on both sides, hand tightening each., Now tighten the bolts the rest of the way down.
The new exhaust should be secure to the heat exchangers.
Now, tighten up any bolts for the hangers.
Some of these are designed to allow some movement in the system, so don’t over-tighten any of those., Visually inspect the installation and wiggle the new exhaust to make sure it is not loose from the heat exchangers anywhere.
With the van in neutral, the parking brake on and the wheels blocked, crank the engine and let run for a few minutes.
Before the engine gets too hot, feel around where the flanges meet.
If you have any leaks, you should be able to feel the exhaust blowing through them.
Bolts may need to be tightened up at the flanges to compress the gaskets right.
If that does not work, take the new system off and make sure again that the gaskets and mating surfaces are aligned right and smooth, with no defects.
Again, sometimes you might have to use two gaskets to get a good seal with aftermarket exhaust systems., Exhaust systems heat and cool, plus they vibrate.
This can loosen bolts and fasteners.
It is a good idea to check that everything stays tight.
After a week, it is a good idea to go over most areas like this every month or so to make sure nothing has come loose.
It also does not hurt to keep an ear on your motor.
Given the distinctive sound of the VW air-cooled engine, it’s usually easy to ear if you have even a relatively minor exhaust leak. -
Step 2: Inspect the existing system.
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Step 3: Place cardboard under rear of vehicle where you will be working.
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Step 4: Remove the old system.
-
Step 5: Now that the old system is gone
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Step 6: take a good look at your heater boxes.
-
Step 7: Look at the flange surfaces for the heater boxes and the new exhaust system.
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Step 8: While supporting the new exhaust in place
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Step 9: on the end opposite the tail pipe
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Step 10: put the first bolt
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Step 11: with washers
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Step 12: through the exhaust flange
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Step 13: gasket – or two if necessary – and through the heater box flange and hand tighten.
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Step 14: On the opposite end of the system
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Step 15: behind the tail pipe
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Step 16: try to get the holes to line up.
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Step 17: Tighten everything up.
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Step 18: Check your work.
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Step 19: Reinspect everything a day later and then a week later.
Detailed Guide
Look over your stock system.
Is it in good shape or maybe needs something simple, like replacing a hanger or tailpipe? Either leave it alone or do minor repairs.
If it is stock, what you have is better than anything on the market., You might be able to do the work without jack stands or ramps.
The cardboard will keep any crud that comes off the old system from getting on your driveway while protecting the new system from getting scratched up – scratches through the paint can make it rust faster., This may be as simple as removing the bolts at the flanges, then removing the hangar bolts and lowering it to the ground.
Some penetrating lubricant on the nuts may help loosen them up.
A number of areas are a bit difficult to get to with the old system in place, so don’t be afraid to cut the soon-to-be discarded pipes to make getting at bolt faces easier.
Make sure the old exhaust is supported as you unbolt it to keep it from torquing the heat exchangers or anything else it may be attached to., Are they in good condition with no dents, major rust or other serious defects? If they are, then go ahead with the installation.
But if your boxes are damaged, then replace them with a model that is compatible with replacement stock exhausts and use that exhaust configuration instead., Make sure they are smooth and flat.
Crud can build up on the heater box side, especially if there were exhaust leaks through the old gaskets.
Also, hold the replacement system in place to make sure the flanges are at least close to meeting up.
A quarter inch offset is fine, but some of the kits being mass produced are coming out with flanges that are not even close.
These need to be sent back.
For minor defects in the mating surfaces of the flanges, either smooth them out yourself or take them to a machine shop and have them do it.
Smooth surfaces are essential to preventing exhaust leaks.,, Don’t worry if they don’t meet exactly.
If they come up short, take two garden shovels, placed the handles in the new exhaust system intake pipes and pry outward to make up some of the difference.
They may still not align exactly, but should be close enough that you can place a big screwdriver through the exhaust flange, gasket and heat exchanger flange bolt hole and use it to gently leverage everything into place long enough to get the first bolt on that side.
Then add the rest of the bolts through the flanges on both sides, hand tightening each., Now tighten the bolts the rest of the way down.
The new exhaust should be secure to the heat exchangers.
Now, tighten up any bolts for the hangers.
Some of these are designed to allow some movement in the system, so don’t over-tighten any of those., Visually inspect the installation and wiggle the new exhaust to make sure it is not loose from the heat exchangers anywhere.
With the van in neutral, the parking brake on and the wheels blocked, crank the engine and let run for a few minutes.
Before the engine gets too hot, feel around where the flanges meet.
If you have any leaks, you should be able to feel the exhaust blowing through them.
Bolts may need to be tightened up at the flanges to compress the gaskets right.
If that does not work, take the new system off and make sure again that the gaskets and mating surfaces are aligned right and smooth, with no defects.
Again, sometimes you might have to use two gaskets to get a good seal with aftermarket exhaust systems., Exhaust systems heat and cool, plus they vibrate.
This can loosen bolts and fasteners.
It is a good idea to check that everything stays tight.
After a week, it is a good idea to go over most areas like this every month or so to make sure nothing has come loose.
It also does not hurt to keep an ear on your motor.
Given the distinctive sound of the VW air-cooled engine, it’s usually easy to ear if you have even a relatively minor exhaust leak.
About the Author
Helen Burns
Brings years of experience writing about crafts and related subjects.
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