air in the lines 606 turbo - PeachParts Mercedes-Benz Forum

mdisav · #1 02-14-2006, 09:29 AM

I had already changed the spin on the day before and everything was fine. The next day I changed the prefilter and after that it has been hard to start in the morning even nose down and there is air in the lines so it bogs down at higher rpms. Once I drive it around a while it eventually clears out but then the next morning the same thing all over again.

I thought maybe I disturbed the plastic fuel line connected to the prefilter. So I changed all six and it still is the same each day. I already had changed the delivery valve washers and o-rings also. I see no leaks anywhere.

When I rev the car and look at the lines I see the airbubbles appear in the line from the fuel heater in the head to the prefilter.

Is it that challenging to get the air out of the 606? But why would it be fine after driving then in the morning be back and no leaks anywhere?

#2 02-14-2006, 12:34 PM

Follow the air bubbles and they will lead you to the source. Poor starting because of air intrusion seems to be pronounced with a partially filled fuel tank. The air leak is probably from the prefilter O-ring failure. A new one isn't included with prefilter and must be obtained separately.

Chris W. · #3 02-14-2006, 12:49 PM

I agree on the prefilter O ring as a good possibility. As far as observing the source of the bubbles, good luck. I had them (bubbles) on my car and all the lines were showing bubbles. No way I could tell the source.

Rgds,
Chris W.
'95 E300D

mdisav · #4 02-14-2006, 03:00 PM

I have them in all the lines. I did change the 0-ring on the prefilter. When the car shuts down the line coming out of the top of the prefilter develops a air pocket but it always did this before without symptoms. When I start it up this pocket goes away.

mdisav · #5 02-14-2006, 03:01 PM

Chris,
How did you eventually get the air bubbles out?

husk · #6 02-14-2006, 06:07 PM

I had the same problem numerous times with my w210, prior to and before I convertrd to a two tank Svo system... First thing would be to check the fuel filter to make sure the O ring has not worn down and is still sealing the intak diesel line.

mdisav · #7 02-14-2006, 09:26 PM

Husk,
I did replace that o-ring also. I converted to the elsbett single tank system and it worked great for about a week until I changed the prefilter. I am starting to lean toward the shut off valve o-ring or lift pump. Do the shut off valves go bad or do they just need the o-ring replaced.

Also Husk, what did you do to remedy yours?

husk · #8 02-14-2006, 11:42 PM

I replaced all the o rings and lines as you mentioned. That seemed to fix the problem for a little bit, but over time the air kept getting into the system. Here is my post on frybrid.com

http://www.frybrid.com/forum/showthread.php?t=2733&page=1&pp=10

Not sure if you are experiencing the same problems with your single tank system.

Are you sure the prefilter isnt letting in air? Chris gave me some good advice on what to do in the future, it could be your VEG Oil isnt hot enough, and your IP is having a hard time with the veg oil.

mdisav · #9 02-15-2006, 12:18 AM

I do not think it will not work for me to do the modification that Chris suggested because I have a single tank system. I will have no way of fixing the new lines to the shut off valve and lift pump.

mdisav · #10 02-15-2006, 03:13 PM

Has anyone had the fuel heater go bad and suck air into the system. When I shut the car off an air pocket in the line between the prefilter and the fuel heater forms. Is that normal? I know on older cars the prefilter usually has some air in it always. Are these cars suppose to show no air?

michakaveli · #11 02-15-2006, 05:12 PM

Quote:

Originally Posted by mdisav

Has anyone had the fuel heater go bad and suck air into the system. When I shut the car off an air pocket in the line between the prefilter and the fuel heater forms. Is that normal? I know on older cars the prefilter usually has some air in it always. Are these cars suppose to show no air?

I have also noticed this air pocket, but haven't had problems at all when starting. I can't remember if I had this air pocket before. Recently I have had all the fuel lines replaced, I replaced the pre-filter and main filter recently, and the big o-ring for the pre-filter....

mdisav · #12 02-15-2006, 09:20 PM

Well I have decided to bypass the fuel heater and see what happens. It runs fine now but the real test will be in the morning. I have a fuel heater in my Elsbett system that is very efficient so my fuel will still be toasty.

mdisav · #13 02-16-2006, 06:58 PM

Bypassing the fuel heater did not change anything. It still did its usual bogging down this morning. I did not see a lot of air in the lines but it did not start great and it is 50 C. I changed the o-ring at the fuel shut off and that did not do anything either.

I am leaning towards a new lift pump.
Has anyone else needed to replace this item on their 606?

Is there any reason why I would need a whole new fuel shut off valve versus just replacing the o-ring.

What has been the symptom of people needing to replace their fuel heater?

husk · #14 02-16-2006, 08:27 PM

Im pretty sure its your lift pump, the Veg Oil probably has gummed it up, and it is working at a lower capacity.

mdisav · #15 02-16-2006, 11:26 PM

I have only been running vegetable oil for a week. Maybe it is weak to begin with.