Possibility of carbon getting into cylinder head when removing intake manifold?

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sfierz

Veteran Member
Joined
Jan 21, 2001
Location
Rockford, Illinois
TDI
1996 Tornado Red Passat
Hey guys, some of you may remember my aborted attempt to remove the intake manifold on my B4. Two pesky allen bolts were the culprit, and I haven't yet revisited that maintenence until the weather gets a little warmer. Plus, I will need a new turbo inlet pipe, too, which is about $130-150. However, this car is just not getting enough air, It runs OK and pretty clean for the most part, but the MAF readings on Vag-com were in the 300 range, not 900 where it is supposed to be. My concern now is that if I remove the intake, could carbon crud drop down into the cylinder head, necessitating removal of the head? That would be bad. In some ways, I am tempted to let a trusted and experienced mechanic do it even though I believe I can handle this job once I get the two stripped bolts out. How likely is it that carbon will get in the cylinder head, and is there any way that can be prevented or taken care of (i.e. shop vac) if it does happen?
 
thebigarniedog

thebigarniedog

Master of the Obvious
Joined
Oct 14, 2007
Location
Fail Command (Central Ohio)
TDI
1998 Jetta tdi
sfierz said:
Hey guys, some of you may remember my aborted attempt to remove the intake manifold on my B4. Two pesky allen bolts were the culprit, and I haven't yet revisited that maintenence until the weather gets a little warmer. Plus, I will need a new turbo inlet pipe, too, which is about $130-150. However, this car is just not getting enough air, It runs OK and pretty clean for the most part, but the MAF readings on Vag-com were in the 300 range, not 900 where it is supposed to be. My concern now is that if I remove the intake, could carbon crud drop down into the cylinder head, necessitating removal of the head? That would be bad. In some ways, I am tempted to let a trusted and experienced mechanic do it even though I believe I can handle this job once I get the two stripped bolts out. How likely is it that carbon will get in the cylinder head, and is there any way that can be prevented or taken care of (i.e. shop vac) if it does happen?
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Post the prior link. Unless you have come to grips as to "why" your prior attempt failed (i.e. learned from your prior shortcomings) you might be better off letting someone else do this for you before you do something worse. It is not meant as a slam, please do not take it that way. Some people just can't get laid in a whorehouse with a fistfull of fifties on a slow night --- it just is the way it is. Good luck.
 
S

sfierz

Veteran Member
Joined
Jan 21, 2001
Location
Rockford, Illinois
TDI
1996 Tornado Red Passat
I can post a link to the other post, but I aborted mainly because of two stubborn allen bolts. I didn't have the correct tools to get them out, even though I used what people suggested. I also didn't feel like dropping $150 for the inlet pipe when I could epoxy the old one and put it back in. Once the old one comes out again, I'm pretty sure it will be replacement time, since the old one was so brittle. Right now, I am concerned about getting carbon into the cylinder head, and not having the proper tools to deal with it. Then it would be my bad. However, I am no newbie mechanic, and have done quite a few successful repairs on this car, and I know that I can certainly work smarter and with more care than most mechanics, including ones who regularly wrench on TDI's.
 
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DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
This is not usually a problem, but yours sounds pretty bad.

I would supply air from a low pressure regulator to the glow plug hole on the cylinder with an open inlet valve. Air blows the trash out continuously.

This works for cleaning the inlet ports on the head as well. Just move from one cylinder to the next, rotating the engine until air blows out the hole to be cleaned.

I use a compression testing fitting with the schrader valve removed to supply the air.
 
twentyeight

twentyeight

Veteran Member
Joined
Jul 14, 2009
Location
Phoenix, AZ
TDI
1Z & ALH
I've successfully cleaned the ports on two B4s using a smallish vacuum. Rotate the engine so that the intake valves are closed on the cylinder you're working on (You'll probably have to remove the valve cover to be able to tell where the engine is at). I also used some compressed air while the vacuum was running.

The compressed air in a glow plug port trick sounds fantastic as well, though you'd have to have the valves somewhat open for that to work…

Won't small bits of carbon that make it into the cylinder just burn up anyway?
 
The Turtle

The Turtle

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Joined
Jul 24, 2006
Location
rural Maryland
TDI
1996 B4 Passat wagon, SpeedTuning chip, 360,000+ miles, 1996 B4V, 306,000 miles on original engine
The reason the crud is in the intake right now is because it didn't make it into the cylinder when it was tiny crud, so now it's all stuck together. It's goopy enough that the odds of stuff getting into the head just by removing the intake are not high. It's much more likely that you'd dislodge stuff when actually cleaning the intake ports in the head (which will have crud in them, too) but as above, a shop-vac with a little tiny crevice tool while you work helps a great deal.
 
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PaJames

Veteran Member
Joined
Apr 17, 2005
Location
Milford Pa.18337
TDI
96 passat TDI wagon
Bring the motor to TDC, all valves will be closed. remove intake, clean it out and do a good job.

Take a shop vac and carefully get down to the intake posrts on the head. Anything loose will be removed by the shopvac.

PaJames
 
TDeanI

TDeanI

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Joined
Oct 14, 2007
Location
Bremerton WA
TDI
'97 Passat TDI Wagon w/ 286K mi.
If in doubt afterward, just make sure you can rotate the engine two complete revolutions by hand, then you are good. You are only worried about huge pieces getting in there, although it is possible I guess to mess up the turbo with a chunk that falls in there and gets blown out on the exhaust stroke on startup, but the turbo wouldn't really be spinning at initial startup, and it would get burned up quick enough if it was big enough to keep the turbo from spinning.

I carefully reached in the intake ports and blocked them with a piece of rag before breaking off the encrusted pieces blocking the ports with my fingers. Now I wish I would have done the air trick and did a more thorough job of cleaning, but with my luck the glow plug would have broke off.
 
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