Removing or cleaning the intake manifold, EGR of carbon build up
(ALH engine jetta golf new beetle TDI )
Difficulty: 2/5
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Introduction
The intake manifold must regularly be cleaned of carbon buildup. There is no factory replacement interval, it should just be cleaned when there is significant buildup. This carbon buildup is caused by a number of factors, the EGR gasses mixing with oil mist from the crankcase ventilation (CCV) and soot. Newer cars used finer EGR metering and the new ultra low sulfur fuel reduce the tendency for carbon buildup so just clean as necessary. A thin film or a buildup about 2 millimeters thick is normal and isn't something that needs immediate cleaning. If it's greater than 1 centimeter, I would consider cleaning it, some pictures are at the bottom of the article showing bad clogging. This is also a good time to clean the EGR cooler, the round cylinder behind the intake manifold.
Some people put a EGR block off plate and this will greatly reduce any future carbon buildup in the intake. Disabling or reducing the EGR cycling will increase emissions and could cause a check engine light to appear. For more EGR information, see 1000q: TDI EGR system FAQ.
The problems of excess buildup are causing the anti-shudder valve to stick in the closed position, cutting off air to the engine and resulting in a no-start condition. It is unlikely that it would stick during driving since the anti-shudder valve is only used during engine shut-off with the ignition key. It can also reduce performance and efficiency or send the car into limp mode.
Some people prefer to buy a new intake manifold, some people prefer to clean their old intake manifold because it's much cheaper. A new intake manifold would be cleaner and faster but intake manifolds are just cast metal, there's nothing that can wear out on a used manifold. A pressure washer and brush to clean the intake manifold is suggested that the cleaning process is very dirty. You can also take it to a machine shop for chemical cleaning. I do not recommend bead blasting since improper cleaning can leave tiny particles inside and cause engine damage. Wear old clothes because they will be stained after you clean the intake manifold. And wear gloves and eye protection. There are also chemical cleaners that can clean it while attached to the engine but I do not recommend this. Dealers use to do this until some engines were damaged. In a diesel, the valves are almost touching the pistons due to high compression and if a small piece of dislodged carbon causes a valve to stick, you just damaged the head. You also don't want piece of carbon to break off and potentially go into the turbo so I suggest removing the intake manifold for cleaning. If the cylinder head is really bad then you can remove the head for cleaning too. You will also spill a little coolant if you remove the EGR cooler, check the color of your coolant, do NOT mix green/blue coolant with VW red/purple coolant, refer the article: 1000q: coolant flush for more details.
Parts (click links to compare current prices)
6mm ball end allen wrench or socket
pliers and hose clamp pliers (optional but suggested)
mirror to see the back of the engine
a brush, degreaser, and a power washer if you want to clean the intake
shallow depth EZ outs (pictured below are normal depth EZ outs, these are too
thick to fit in the limited space)
EGR gaskets (egr valve to pipe, at least 2) VW# 069-131-547-D
EGR gasket VW# 038-131-547-A , from tdiparts
EGR gasket o-ring N-905-216-04
intake manifold gaskets VW# 028-129-717-D
, generic
gasket , from tdiparts
new intake manifold (optional) VW# 038-129-713-K
, from tdiparts
new intake manifold bolts (x6 optional) VW# N-904-242-01
, genuine
part , from tdiparts
new EGR (optional) VW #045-131-501-L
, generic
EGR , from tdiparts
Procedure
Remove intercooler output hardpipe-intake manifold hose (outlined in yellow) and air intake-turbo hardpipe intake accordion hose (yellow). (2 band clamps each). Tape over the
exposed pipes so nothing falls in.
Unplug PVC heating element plug (outlined in green above). Disconnect intake manifold change over valve (behind the intake
manifold, 2 allen bolts marked with red circles in pic below). Disconnect anti shudder valve and EGR vacuum lines (purple). Label them so
that they can be easily identified.
Remove turbo intake hard pipe
(pink, behind engine, held by 1 band clamp at turbo and 1 bolt circled in red).
Unbolt 3 bolts holding the EGR cooler down (red circles in below pic). Use a mirror to positively identify them. Disconnect EGR cooler intake (2 allen bolts, marked with green) and outlet (2 allen bolts, marked with green). Remove coolant hoses (3 hoses, marked with blue). The EGR cooler can now be removed. Here are both sides of the EGR cooler.
To finish disconnecting the intake manifold remove the rest of the allen
bolts (6x 6mm allen bolts, in red). These may get stripped so I suggest
pre-soaking in PB Blaster or another penetrating lubricant. Make sure to
tap in the allen bolts to avoid stripping. If they do get stripped, use a
shallow depth EZ out to grip the outside of the allen bolt head. This
gives a greater diameter surface and greater lever arm to turn the stripped
bolt. The EZ outs should be sharp or else they won't bite, if you find
halfway through that it's dull, you can use a dremel to sharpen it. Sears
does not warranty the sharpness of the EZ outs.
Here is another picture that may help you visualize the location of the
bolts. Note that these pictures are thumbnails, click for a larger view.
The exhaust manifold has been removed in the below pics.
Cleaning
The EGR naturally puts exhaust soot into the intake which must be cleaned out. It mixes with oily crankcase vapors from the crankcase ventilation (CCV) and can form a buildup. Do NOT use a chemical dissolver or a vacuum cleaner to suck out the carbon while the intake manifold is still attached to the head. Hard pieces of carbon could fall into the engine and possibly damage the valves or turbo. The intake, EGR, and EGR cooler must be removed from the head for cleaning.
The cylinder head is best cleaned while off the car. If you want to clean the cylinder head while on the engine, I suggest removing the camshaft (follow timing belt removal as spec. in your factory service manual or see 1000q: timing belt removal ALH engine) so that all the valves are closed. You can then use a brush to clean. I would avoid using liquid cleaner just incase it were to leak into the engine and cause hydrolock (engine damage). Make sure to follow up with compressed air to blow out all loose carbon particles.
Below are some pictures showing a moderately clogged intake. This
restriction in air flow hurts engine performance and efficiency. Note that
it doesn't look too bad upstream of the EGR but looking downstream of the EGR shows how clogged it really is. The EGR and the
anti shudder valve (the throttle-like plate used to help shut off the car by
cutting intake air) collect soot
and built up carbon can also jam the anti shudder valve, resulting in a no start
condition. If this happens, just press the lever on the outside of the
valve, connected to the black plastic
vacuum bulb to open the anti shudder valve internally.
Here is another pic by toolnut showing a clogged intake. You have to
look on the downstream side of the EGR to see the really bad clogging.
Obviously you want to make sure it doesn't get to this point. Up to 2 mm
of buildup is normal and I would leave that alone. 1 cm or greater is
where you should consider cleaning the intake.
At this point, you could just buy a new intake manifold because they are not
too expensive. Buying a new manifold will let you immediately change it
and save car down time and you could probably sell yours to someone who wants a
spare as a core. If you want to buy a used one, you should be able to
clean it ahead of time as well. I used a pressure
washer, soaked it in degreaser, scrubbed, and then used the pressure washer again. A hose
will NOT clean it, you need a pressure washer! It
will cause a big mess, so wear clothes you don't mind getting stained.
You can also use chemical cleaners, diesel purge, or soak the manifold in biodiesel. Make
sure to get the internal corners and backside as well. Here is the EGR cleaned - much
better but it will still undergo one more pressure washing. Here you can
see the relationship between the anti shudder valve (black plastic bulb) and the
lever and the "throttle-like plate".
Installation is the reverse of removal. Use all new gaskets on the EGR, EGR cooler, and intake manifold. The metal gaskets could be reused if they are in good shape, the o-rings should be replaced. You may find that your torque wrench will not fit into the limited space behind the cylinder head. Just remember that the cylinder head is aluminum, don't kill the allen screws and don't use threadlocker unless you forgot how difficult they were to remove.
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