2000 Jetta won't start due to air in the lines

K

Keysd402

Active member
Joined
Jul 28, 2020
Location
Central square ny
TDI
2005 Passat tdi
I have a 2000 Jetta TDI ALH 5 speed, I've been having this issue since I bought it. I keep seeing air seep back to the clear line from the injection pump. I've replaced all the seals in the pump put a new fuel filter in it I've bleed the system and the injectors at least 10 times. I'm stumped on what to look at next. Any help is appreciated. Thank you.

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Steve Addy

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
Not the correct forum but fuel problems for the ALH Mk4 will be similar.

The Mk4 filter thermo-T can have a faulty o-ring that can allow air into the lines. The o-ring on the B4/Mk3 cars is part of the filter so it gets changed every time you replace the filter. On the Mk4 cars the T has the o-ring so it never gets changed.

It would be my starting point to replace the o-ring on the thermo-t and see if that doesn't resolve the problem.

If that doesn't do it then start with the connections at the filter itself and verify sound clamping force. If that still doesn't resolve the problem move on down the line to the next place where hoses / clamps are present.

Finally, if that doesn't do it go to the tank and check your connections at the sending unit and / or the one-way valves too.

Hope you find it, annoying to have these problems, I know too well!!

Steve
 
K

Keysd402

Active member
Joined
Jul 28, 2020
Location
Central square ny
TDI
2005 Passat tdi
Steve Addy said:
Not the correct forum but fuel problems for the ALH Mk4 will be similar.

The Mk4 filter thermo-T can have a faulty o-ring that can allow air into the lines. The o-ring on the B4/Mk3 cars is part of the filter so it gets changed every time you replace the filter. On the Mk4 cars the T has the o-ring so it never gets changed.

It would be my starting point to replace the o-ring on the thermo-t and see if that doesn't resolve the problem.

If that doesn't do it then start with the connections at the filter itself and verify sound clamping force. If that still doesn't resolve the problem move on down the line to the next place where hoses / clamps are present.

Finally, if that doesn't do it go to the tank and check your connections at the sending unit and / or the one-way valves too.

Hope you find it, annoying to have these problems, I know too well!!

Steve
Click to expand...
I replaced the thermostatic tee this morning and rebled the system and I'm still getting air bubbles in the clear line.

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S

super1

Veteran Member
Joined
Apr 19, 2010
Location
NY
TDI
none
Keysd402 said:
I replaced the thermostatic tee this morning and rebled the system and I'm still getting air bubbles in the clear line.

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Click to expand...

How’s your return lines in between the injectors?


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K

Keysd402

Active member
Joined
Jul 28, 2020
Location
Central square ny
TDI
2005 Passat tdi
super1 said:
How’s your return lines in between the injectors?


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Click to expand...
I was actually just testing those, it looks like my return line going back to the injection pump has a small leak. looks like that's my issue. Thank you all for the help.

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AndyBees

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
The return lines send fuel back to the tank via the filter. If the Thermostatic Tee is operating correctly, all fuel will go back to the tank during the hot summer months.

There is "pressure" on the return hoses from the injectors to the return pipe out of the IP, including the return pipe out of the IP. So, those hoses/pipes will leak fuel rather than pickup air.

My 2000 Jetta (son owns it now) has always had a small amount of air in the clear line. The ALH in my Vanagon has air in the clear line. I installed new hose back to the tank and it still has a trickle of air occasionally. It has the old MK1 screw-on style filter, so no T.

Anyway, you'll just need to keep looking... until you find where the air is getting in.
 
PakProtector

PakProtector

Veteran Member
Joined
Jan 5, 2014
Location
AnnArbor, MI
TDI
Mk.4's and the Cummins
I went through this with my son's 2000. It has been fixed since we drilled out and defeated the check valve in the tank pick-up.
cheers,
Douglas
 
K

Keysd402

Active member
Joined
Jul 28, 2020
Location
Central square ny
TDI
2005 Passat tdi
PakProtector said:
I went through this with my son's 2000. It has been fixed since we drilled out and defeated the check valve in the tank pick-up.
cheers,
Douglas
Click to expand...
Would replacing the whole pickup fix this issue? my buddy has an oem one from his old tdi he said he'd give me if I needed it.

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