98 TDI hard to start/air in lines

Hello folks, this is my first post here, and I am asking for some help. My name is Gerhard, how do you do?

I have been summoned by my mother to fix her car. Her 98 Jetta has almost 200K miles and it developed some problems. I have a check engine light due to a boost code, can't remember what it is but it doesn't matter right now because the car has a bunch of work that needs to be done. The intake has been closed up to the size of a dime by the EGR valve build up, but I wasn't going to touch that until I could fix the coolant leak down by the water pump. But wasn't going to fix that until I fixed the fuel leak from the injection pump head seal and both the quantity adjuster housing seals.

I fixed the fuel leaks. That was fun. I found all the info on this forum that I needed to get the parts and to finish the job. But I couldn't get the thing to bleed the air out. I eventually succeeded, and with my new VAG COM I set the quantity adjustment, block 2, whatever it was I got it dialed in.

The problem I have is the air bubbles coming through the clear plastic line from the fuel filter to the injection pump. There are lots of bubbles, more air than fuel. What I ended up doing was disconnecting the fuel filter feed line from the tank, and while running a hose from a fuel can to the filter, I had no air bubbles what so ever, the car started and idled great, and I was able to set up the adjustment with VAG COM.

I went back to and connected everything up as it should be and I can't get the engine to start. So what I am asking for here is some good advice as to where I should be looking for the air leaks. All the hoses have 200K miles on them, the T fitting at the fuel filter, all the clamps, everything. There are no visible liquid leaks anywhere.

I plan on replacing the fuel hoses with bulk hose just for the sake of testing for air leaks. Are any of you folks replacing fuel lines just for the sake of mileage? I am becoming somewhat frustrated by this because I need to fix one thing before moving on to another, and the air leak has got me doing a lot of testing without getting solid results.

I inspected the fuel feed line from the tank, plugging one end and applying vacuum to the other and it holds 25" vacuum. I pulled the pickup out of the tank to inspect for debris or clogging and didn't find an obvious fault. My dad is going to get the return line T for the fuel filter just for the sake of the miles on it.

Now, I have read about some folks who have air bubbles in this fuel line while the engine runs without any kind of problems, but I'm not buying it. I know that a diesel engine's starting and driveability's arch nemisis is air in the system.

So if any of you sharp guys have some ideas for me, please share them with me. I will continue to post my results as I continue my tests and hopefully the next time a guy helps his mom with her TDI that won't start, he will have a much easier time fixing it than I am.

I very much appreciate it. I work at a car dealer and when our Dodge Cummins has a hard start and we have exhausted our resources, the STAR center has some hidden information for us. When our Kia's do stupid things and the service information is poorly translated, the Techline comes to the rescue (kind of), and if our Volvos start freaking out with computer jargon and crashes, Volvo Tech Support calls back.

You guys are my VW techline!!

Gerhard

After replacing all the fuel lines, the problem has been reduced dramatically. However, the engine is still producing white smoke, air is still bubbling into the injection pump, and I still have work to do. I will be replacing the o-ring for the valve on the air filter, as I have installed a new valve. I also plan on installing a clear hose onto the fuel pickup unit at the tank to see if my air is coming in from there.

Thanks to those who have helped out. Perhaps when I nail this problem, somebody who is having this same problem can see what I did to fix it.

I had lots of trouble chasing down a big air leak in my fuel system. The tee on the filter makes things difficult because you never know if air is being introduced into the system or is being recirculated. I replaced the fuel filter and the oring on the tee but it made no difference. I finally replaced the fuel filter from and older car, an '86 golf or something like that, that didn't have the tee. The leak went away, and as an added benefit replacement filters are cheaper. Maybe my tee was cracked or something but I really didn't feel like buying a new one.

Do what vanagonjon said.

I replaced my filter with one from an 86 jetta (similar except no T) and spliced the return line together.

I'd bet that stupid T is the source of your air bubbles.

The boost code is probably due to a bad vacuum hose.

The intake can be "cleaned" easily out of the car with a mini torch and compressed air. After cleaning you can slow the buildup by vagcom adaptation or eliminate it with an EGR blockoff plate and ECU chip, unless you can live with the EGR fault code.