Hoses and filters
 

Alec300SD, it sounds like you are describing the earlier filter. Mine has no number on it and epc.net does not show a part number for my filter head.


I have a screw on filter with an "O" ring, picture attached.


I will check or replace the secondary filter now and fill it either with fuel or with diesel purge. I will also replace the fuel lines with 7mm (search: IAP Performance AC133107 Fuel Hose (7.0 x 2.5mm; 1 Meter; Made in Germany for VW Beetle)


Funola, you said; Assuming you've replaced the leaking return lines, maybe the act of replacing the secondary filter started your problems?


I don't know since I replaced return lines, clear lines and filters.

If the car was running perfectly before you did any kind of parts replacement, then whatever you did is suspect.

IIRC, if the center bolt of the filter housing takes a 24 mm wrench, it is the later style and it needs 2 rubber o-rings and no copper washer. If it takes a 22 mm wrench, it is the earlier style and it needs a copper washer only, no rubber o-rings. That copper washer is not a common size thus hard to find unless from the dealer if still available. Someone found a replacement home plumbing fiber washer that supposedly works. You'll have to search for it.

If you had installed the short clear line before replacing any of the fuel system parts, and saw that there was no bubbles in the clear line, then install the first part, start the engine and look at the clear line before replacing the next part, you'd know if you had installed the parts correctly.

Next time you work on your fuel system, remember to install the clear line first.

REPLY TO FUNOLA
 

If you remember, you suggested adding the clear line between the filter and cigar hose. As I said in my prior post, I am not understanding how you are using this short clear line to diagnose anything. My hunch, many posts ago, was if bubbles were coming to the secondary filter via the clear line attached to the overflow valve, they would logically exit the cigar hose. Now, that I put the clear hose in the chain, it confirms my thinking about where the bubbles go; it is back to the fuel tank.


I also have not opened the 24mm nut on top of the secondary fuel filter, and have no reason to assume it is the problem. What's is it for any way? I ask, as I said in my prior post, I have a screw on filter.


In the beginning the car stopped running. I have somewhat of a vacuum leak from the door openers, and at times, I would drive somewhere, exit the car with key, and let it run. It would sooner or later stop. I changed the two fuel filters, and I could not get it started. After getting it towed home, I did a diesel purge, as I said early on in this thread, and the engine was running fine, EXCEPT AS I NOTED, the idle was a little rough, something new. LOL

The big bolt in the top of the fuel filter housing is what you loosen to remove the fuel filter. If you just spun the fuel filter on, it's probably loose! The filter doesn't "spin on" (or "spin off" for that matter), you hold it in place and snug down the bolt on top! The idea being to prevent making a mess and sloshing fuel everywhere.

The idea behind the clear hose is to use it as a diagnostic tool. Before you remove anything, install the clear hose and make sure you have a solid column of fuel going back to the tank. Do your work, purge the system and make sure it's still a solid column of fuel without any air in it.

You can have air circulation problems without actually sending air through the injection pump. There is a bleed hole in top of the secondary fuel filter housing that will return small amounts of air to the tank. The clear line serves as an early warning.

You may not think it important that the air is going to the tank, but it's coming from somewhere and it's passing through the injection system. After it goes to the tank, it expands and puts the tank under pressure. Wait until your tank vent clogs and you'll understand why it's important.

Screw on filter? Where did you get your filter change procedure from?

rickmay,

You don't have a screw on filter head, you have a fuel filter head with a hollow bolt in the center that needs to be sealed on two surfaces against the filter head.

The filter head part number is visible on the left side of your photo but I can't quite make out the actual number.
If it reads 6150920208 you need two o-rings just like the one in the second photo on post 2 of my Fuel filter upgrade thread.

If it reads 6150920108 you need a crush washer and one o-ring.

Replacing the secondary filter without renewing the hollow bolt seals can give rise to the air incursion symptoms you are having.

This is correct. I was incorrect when I said crush washer and no o-ring.

VERY INTERESTING
 

With regard to where I learned about changing filters on my 83, 240D, it looked like a spin on filter and worked fine the first two times 5 years ago.


My filter head is the 615 092 02 08 part number. Attached is a photo of the 24mm hollow bolt with the two lovely "O" rings. I know there will be some that are critical about the way these look, so I just ordered four each, and will clean the bolt and install the rings this weekend.


BTW, do these need replacing with each filter change? Responses seem to say that they should be replaced each time.

Wow, those O-rings are wasted! It's a good idea, but not critical to replace them with each change. Obviously don't let them go as long as the ones you show in the photo...

You need to spank yourself like you said. :D

Funola
 

I would rather find some younger lovely to do that for me. :eek:


As for my mechanical ability, I know enough to build my own house, and cars are somewhat new to me. When one of the best Mercedes (dealer) mechanics admitted that he would have to get "the book" out to service my car, I thought to myself...... I can read too.


Never done before until I bought this car;

rear brakes, fixed transmission control switches on the valve cover, replaced the nylon shifter bushings for the trans from inside of the car, switches, master brake cylinder, valve adjustment and a whole bunch more (and I am still living to brag about it) :rolleyes::rolleyes::rolleyes::rolleyes::rolleyes:

BUBBLES, tiny bubbles
 

I am still getting bubbles.....drat.


I have tried
two primer pumps
put the old overflow valve back in
fuel lines replaced with 7mm fuel line, all connections tight and unmovable and dried with toilet paper as suggested. No apparent fuel leaks.


The car is running a little better (I assume the 7mm hose and clamps tightened) with less noise despite the bubbles. Since this was a Florida car, I am pretty sure there are no pinholes in the rear to front metal lines, particularly since no bubbles are coming thru the primary filter. I cannot check these lines under current circumstances.


Since I see no bubbles coming from the fuel tank, and the two clear lines coming from the top of the IP are under pressure (they should leak fuel, as opposed to letting air in), it seems the only place where air can get in is the flare fitting on the left side of the lift pump or maybe the lift pump gasket is leaking. This is the suction side of the lift pump where air is more likely to be introduced. I only mention the gasket as the lift pump runs in pulses (it seems), with pressure the gasket should not let air in, it seems, but what about after a pulse. Seems logical, but after all, I am the cretin that thought I had a screw on filter.


What also doesn't compute with me is that I see the bubbles coming thru the clear line coming from the overflow valve (engine side) and no bubbles coming from the IP thru the forward clear line that runs to the secondary filter.


^&%$#(*&%%&%&^$#%#&^&^%%%(&^%%&%&^%*&^%
nada more to say at this hour.

From your current description it sounds like an air leak at the overflow valve.
Did you replace both aluminum crush washers of the banjo bolt for the overflow valve?
If you did, maybe you need to snug the overflow valve a bit more.
Counterhold the barbed end of the clear fuel line with your thumb so the line doesn't rotate when you apply more torque to furrther crush the washers.

Active air incursion is not always visible at idle,.
If you increase the rpms you may see air in the line going from the secondary fuel filter to the IP.
Did you replace the copper crush washer under the primer pump?