I have a 98 W210 300 Diesel and I think I have a wicked air leak in my fuel system.

I recently did a diesel purge and all was fine for a day or so. Then at high speeds Id get a lag in fuel like a flat spot.
This continued until I got home. I ran the throttle up pretty high and I can see the air bubbles in the transparent lines. The strange part about it even though I'm getting horrible gas mileage about 18-20 MPG instead of 28-30 I'm not leaking any fuel out. At low speeds <50mph it is not that noticeable but 60-80 its much more common.

I checked all the fuel lines and even replaced a few but I still have this issue.

-Aside of replacing all the lines and clamps how can I test to see where the leak is?

-How do I do an AIR purge once I think I have isolated the leak?

-Should I get the VITRON lines (since they are tougher than rubber) and the vitron seals for my transparent connectors?

If so where do I get them.


I know if I keep driving it my luck will run out and Ill have more air than fuel in the lines and I dead on the highway?

Thanks for any help.

Chris

 

I am not sure if this is the exact parts for your year and model.
http://www.detali.ru/cat/oem_mb2.asp...SGR=120&SGN=04

I have read that there are O-rings in the Fuel Heater that can leak item #155. You also might want to take a look at the seals that go to item #26 the pre-filter.
In fact whas seals all those fittings that are at the hose ends? The Older models like I drive do not have those.

Also take a look at the top of the Fuel Injection Pump and see if there are any leaks.

Part of the way on the Older models to troubleshoot for air leaks is to get a container of Diesel Fuel and run a longer Fuel Inlet hose to that container and run the Engine from the Fuel in the Container and see what happens. This would bypass everthing to the rear. If you still leaked air it would have to be something forward towards the Fuel Injection Pump.
I am not so sure you could do that with your hose set-up

Here is the complete parts site so you can pic out your model. I was not sure if you had a turbo diesel or just the diesel. The Fuel Hoses and Filters are in the Injection Pump section.
http://www.detali.ru/cat/oem_mb0.asp?TP=1

Also due to atmospheric pressure (14.7 psi at sea level) small leaks sometimes allow air in but the fuel does not leak out. When you run the Vehicle you have a negative pressure from the Fuel Supply Pump inside and the 14.7 psi outside pushing in.