Changing Fuel Filter on 116/107

[Styria]

This is one task which I particularly dislike, the reason being that there appears to be no means of shutting off the fuel supply whilst one is disconnecting the various hoses and fittings that are part of the fuel filter arrangement.

As much as I try to avoid spillage, I invariably finish up with petrol all over my arm up to the armpit, and this is despite the fact that I know what is going to happen. By the time you try and force a plug to stop the flow of petrol, you've lost about half a liter - it really gushes down as the hose diameter is quite large.

Has anyone experienced the same problem, or am I just being stupid or unknowing in how to shut off the supply of petrol ? If there is no means of shutting off the supply, I would really consider this to be a design deficiency hardly appropriate from a company like Mercedes Benz. Regards Styria

 

[BAR]

Well this is not something I have ever attempted on the Merc myself, but I have done ths many times when in my youth and playing with the rally car.

At that time I used to clamp the fuel line off using a pair of Vise Grip pliers.

Maybe the same technique can be used on Mercs.

 

[AAB]

Styria,

Many many moons ago, I removed the tank of my 74, 450SEL to give it a clean out, & being the brilliant man that I am, I made up a tap that would screw into the base of the tank,so that in future, I could turn off the tap & do whatever was required without petrol spillage.

As described recently, I had to remove the tank to get at the nuts that held in my rear suspension spheres. ( once again, why the hell did the tank need to come out to get at the nuts !! )

Would you believe that I could not get the tank out because my famous tap was in the way, & I had to remove the tap to get the tank out & get a minor bath of petrol as well.

No tap there any more, but I believe that crimping the fuel line works.

Regards,

Alex

 

[Styria]

Hi AAB, I obviously agree with you as far as the clamping is concerned - it is quite easy, but frankly I am not game enough to do so and there is no way I would want to attempt to do do it.

As you would know, it is quite a large hose, and it is supplied as one unit with the fitting that's screwed into the bottom of the tank. It is expensive, and perhaps time consuming to get hold of to buy new from the dealer - and difficult to remove should the hose part become fractured or start leaking - plus, you'd just about need a new assembly and one would have to drain the tank. It is just one of those jobs one can do without., and it'd be all in the name of just changing the fuel filter. Less than brilliant. In your opinion, other than clamping, is there any other way ? BTW, thanks for your response. Regards Styria

 

[WGB]

I use a pair of hose pipe clamps which are for sale at most autoshops for a few dollars only.

I have used these on my cars in the past but would be careful with someone else's car with possible perishing hoses - as you are Styria.

On my own car I would rather put on new hoses for safety - so the clamps would be safe to use but a customer might take some convincing.

Bill

 

[Styria]

I use a pair of hose pipe clamps which are for sale at most autoshops for a few dollars only.

I have used these on my cars in the past but would be careful with someone else's car with possible perishing hoses - as you are Styria.

On my own car I would rather put on new hoses for safety - so the clamps would be safe to use but a customer might take some convincing.

Bill

Hi Bill, quite frankly, I need some convincing as well - those hoses are very stiff and not easy to handle, It's quite a while since I have checked on the price, but from memory it could be close to the $150.00 mark. Personally Bill, what do you think of the way everything is designed - I still reckon that MB could have done a lot better. Regards Styria

 

[WGB]

Changing the Filter and/or accumulator is not a lot of fun and the threat of spillage and subsequent fire risk is dangerous.

I always leave my car on the hoist overnight so everything is stone cold and I make sure the battery is disconnected.

The real risk is all the cars with terminal rot in the fuel lines - and that includes the rubber connection pieces that attach to the chassis mounted steel pressure and return lines.

Bill

 

[s class]

styria, I know what you mean about getting the fuel up to your armpits....

The filter is located after (in terms of flow) the fuel pump. The inlet (pump) side of the filter is the where the majority of the fuel flows out - the outlet side goes to the high pressure lines to the engine, which don't contain much fuel.

In my experience of changing filters, the amount of fuel that is released through the pump seems to depend on the condition of the pump. Some 7 or 8 years ago I fitted a new pump plus non-return valve to the 280SE, and at subsequent filter changes found almost no fuel coming out. The pump has served well for 200 000km further, and in fact needs replacing again, and has now worn to the point that it allows fuel to fairly gush out when the filter is changed.

I would also avoid clamping the main fuel line - they are usually very crusty. The last one I bought at the dealer here cost only about $35 I think. (yes, the main fat hose with the crimped on fitting that screws into the gauze at the bottom of the tank.

 

[TJ 450]

I was able to source the main feed hose for $30 at a local supplier. The brand was Cohline. The genuine part was $80 from the dealer and was the same brand.

That is a messy job, even moreso is changing the pump.

Tim

 

[carl888]

Golly, I think this is my first post! I have just replaced every hose I can find on the 280 SE. According to the service information with the car, the fuel lines within the engine bay were replaced in 1992. The hoses from the tank to the pump have never been changed. (Car is March 1974). The job is actually really easy, I completed it last night, and split no petrol.

The first thing to do is to reduce the pressure in the lines. Just start the car with the fuel pump fuse removed. Next, clamp the line from the tank to the pump. I use one of these, made by Girling:




Then just drain the tank, I used a 20 liter drum, (Yes, there was less than 20 liters in there!) simply open the clamp and drain away. Helps if you have a hoist I admit as you can just lower the car onto the drum.

You can see the old hose here, notice the frayed outer weave:




I had to call on some odd tools to remove the line and the strainer:

line: 3/8" drive 19mm crowfoot socket with 3/8" "S" extension and

strainer: 46mm 3/4" drive socket with 3/4" to 1/2" adapter (3/4" drive extension is too thick to clear the driveshaft):




So, out they come:






The new bits, strainer was $51, hose $30, from the dealer (Ignore the throttle rose joint):




The new bits installed:




Lets do the other hoses around the pump too, and throw on a new fuel filter (Don't confuse the fuel filter and fuel strainer, the strainer is in the tank, the filter is by the pump):




Lets do the return line and vapour lines as well opposite the pump:




Gosh, glad I did, here is the return line:






The new ones installed, with new clamps:




Now we are on a roll, lets do the engine bay...the reason? Although the hoses were replaced in the 1992 and the car had done a measly 7,000 kms in that time, the hoses were hard, and in places, cracked. Be warned if you have a D-Jet car, check them!

Pressure regulator:




D-Jet rail (before and after):









Have fun!

Carl.

 

[Lukas]

Hi Carl,

Thanks for the pics and welcome to TopKlasse.

For all: I wouldn't be happy to clamp my fuel lines (or any automotive hoses), as you can damage perished ones (which as Bill rightly says you should replace anyway), but also because you can induce weak points in the hose wall which can be the source of leaks later on.

I'd side with Carl in draining the tank - either drive it a lot first, or siphon it out of the petrol flap, and then drain the rest from under the car. That way you also have an empty tank that you can slosh some fuel around in to see how much goo and crunchy bits are in the bottom.

Alternative - tip the car onto it's left side? Not all the way , but if there was only a little fuel in the tank, a 20 degree slope might help?

 

[carl888]

Thanks for the welcome Lukas. I wouldn't clamp any hoses either! That's why the hose was replaced. Can't see any reason you would not replace it myself, especially for $30.

I was amazed how clean the tank was inside, it really was spotless. Had I known, I would never have replaced the tank strainer, it looked like new, but since I had one, may as well put it in.

Regards,

Carl.

 

[Styria]

Hi Carl, that's a great and comprehensive write-up. I notice that some items and fittings on your car are different to the K-Jet Cars - obviously under the bonnet, but even the fuel pump is different.

Just changing the filter and/or the pressure accumulator are the items that cause most of the problems fuel spillage wise. As Bill and others have/have not said that clamping was the correct and easiest method, I still think that the design as per standard is poorly executed as really there should be a tap that would enable one to shut-off the fuel supply. I changed both items yesterday, and boy, did I cop a soaking even though I knew what could be in store, and I had plugs ready to block off the lines.

For some time now before starting when hot or cold, I have held the ignition key in the turned-on position to build up fuel pressure and fuel supply to facilitate easier starting. I have previously made reference to the replacement of those items, and it just took time to get around to carry out the job. Right now, it would appear that this work has been successful, but I've not driven the car for any distance or length of time. BTW, I cannot stress highly enough the necessity to change the filter on a regular basis - in my view, at least once per annum. Quite frankly, I do not know how fuel reached the fuel distributor under the bonnet - the filter was absolutely blocked and the pump must have been working overtime to try and cope with the almost total blockage.

Carl, I am also interested in the source of hoses and cllamps you fitted - straight from the dealers ? I know the strainer and large hose are geniune, but what of the smaller ones and clamps ? Also addressing Tim in WA, the items you bought are the same as Carl's, but I take it yours were after market items on account of the price difference ? Anyway, thanks to everyone for their input. Regards Styria

 

[TJ 450]

Hi Styria,

Yes, I purchased a Cohline feed hose, Bosch fuel pump and filter from an OEM supplier here in Perth for the 6.9, at very reasonable prices.

I have a genuine feed hose on the 450 that was purchased from the dealer that was somewhat more expensive, but had the MB insignia. A the end of the day, they are basically the same, but for a Concours vehicle the latter would be preferable.

Tim

 

[carl888]

Hi Styria,

The strainer and hose I bought from local dealer, Mercedes-Benz of Melbourne, they were $50 and $31 respectively. Whilst I know the dealers often come in for a bit of flak, I have an excellent relationship with the people there and mostly the pricing is very competitive, but more importantly, they have it on the shelf. For example, the tank to pump hose was $1 more than what Tim paid.

The hose (Both the rubber and braided) and the clamps came from Wuerth. I like their clamps particularly. Whilst I have strayed from the original Mercedes-Benz clamps, the Wuerth ones are superior, they are just made from a slightly heavier gauge steel and the clamping mechanism is stiffer.

The fuel filter came directly from Bosch.

Regards,

Carl.

 

[Styria]

Just an update and further comment. There is no doubt that the hose clips from Wurth are of excellent quality, although I have seen another type, although different, from the same supplier, i.e. Wurth. The superior feature of these clamps when compared with those from TRIDENT is that the Wurth units do not cut into the rubber.

BTW, I didn't know that one could buy from Bosch direct - that's the filter I am talking about. Thanks for the info.

As previously posted, I replaced both filter and accumulator. The accumulator I used was second hand, albeit it looked practically brand new. It is the one with the two Inlets/Outlets. The late model 116s as well as the 126s have a single Inlet/Outlet fitting. If you buy genuine (heaven forbid, the single unit type retails for about $750.00 - so beware. Anyway, I have found that the car is easier to start now, whether hot or cold, and perhaps, possibly, Gleaming Beauty now has a liitle extra oomph in the acceleration stakes - mind you, you cannot really be sure. Main thing is, better starting and at least a fuel filter that is not almost completely blocked. Regards Styria