Fuel Filter Change

[J. Huber]

Hello. Kind of a basic, maintenance item question. Very shortly, I am going to crawl under and change my main fuel filter. Its been a couple years -- I figure it can't hurt. (Unless I drop the wrench in my eye or something...) Anyway, I recall last time that it was quite a balancing act getting the rubber o-ring to stay in place while I screwed the canister back on. Anyone have a tip or trick for this? Also, how often do these rubber rings need to be replaced. I don't think the filter came with the ring (like the oil filters do.) Thanks.

James
63 230SL

[glcg123]

I find it easier and cleaner to change the filter from the top. Loosen the centre top bolt on the filter housing. Then, with the other had holding the cannister continue to remove the bolt. Once off you should be able to maneuver it out from the top.

I then look underneath and remove the o-ring with a screwdriver. I have never had a proble with the o-ring not fitting but if it falls out I would hold it in place with some vaseline. Reverse the procedure to install the new cartridge.

I change my filter yearly even though I have had the system flushed and the tank cleaned/relined. I only drive it 4 months of the year but any bit of moisture sitting in there over winter can cause some corrosion in the lines. It is a small price to pay for peace of mind. I have found the OEM filter from MB to be less expensive than from a retailer such as NAPA. Not sure why. It just may be where I live.

George

1965 230SL

[J. Huber]

Ahh. Good idea George. I'll try it from above -- and if need be, try the vaseline trick. Thanks.



James
63 230SL

[ja17]

Hello,

If your car has factory power steering, changing the filter from the top is more difficult. I also use George's tip on holding the o-ring in place. Changing it every time is not needed but not a bad idea. the seal does not come with the original filter. Some owners remove the entire canister and do the filter change on the workbench.

Two persons is easiest. One guy to fasten or un-fasten the bolt with a long extension and socket from above, while the second guy below gets a bath and keeps everything lined up!

Joe Alexander
Blacklick, Ohio

[graphic66]

I use a product called Sylglide. It is made just to lubricate rubber like O- rings. Regular petroleum based lubes can break down rubber with time. A tube of this stuff comes in real handy and will last almost a lifetime.

[J. Huber]

Hi Joe. Fortunately mine does not have PS. Well, here's an update -- tried it from the top. Came out very easily. First, the good news. My filter was kind of dark and there were a few pieces of crud in the canister. I guess thats good because it means the filter was working. Now, the bad. My rubber o-ring is shot!! And, I don't have a spare. So I am going to try the local import place -- is this anything really specific to MB -- if so, anybody have the quickest way to get one?

Lesson 1. Always plan for this. Have a spare seal handy.

James
63 230SL

[66andBlue]

Hi James,
which rubber O-ring is it, #39 or #42 in my picture in this topic: http://sl113.org/forums/index.php?topic=2589 ?
It may be difficult finding a correct #39.
The filter kit (000180 0009) from M-B comes with all the necessary small parts.

Alfred
1966 blue 230SL automatic

[glcg123]

The local MB dealer might have this O-ring. If not take the damaged O-ring and cannister to a place that rebuilds hydraulic cylinders. They usually stock every size and type seal imaginable. Last year the O-ring on the rad overflow tank of a friend's Olds Alero split. He stopped driving the car when the engine light came on due to a non-pressurized cooling system. It was boilng like crazy. As the car was near a hydraulic repair shop we went in and had the seal matched in about 5 minutes. Cost $.90. The dealer would have sold him a new cap with seal for about $16.00 plus they were a fair distance away.

Good luck.

George

1965 230SL

[ja17]

James,

The Mercedes dealer will have most parts the next day for you with no shipping charge.

Joe Alexander
Blacklick, Ohio

[J. Huber]

Thanks all. Since I don't have a MB Dealer (well, anywhere closeby), I tried our local German supply house. He ordered me one for pick-up tomorrow. $2.99. I can live with a two-day turn-around. I was just fearing that I'd have to order one from our 113 parts places -- reliable but a minimum one week usually. It's Springtime -- time to get some drivin' in this weekend!

PS Alfred -- you obviously thought I meant oil not fuel. But thanks for the input. I could probably use one of those too!

James
63 230SL

[TheEngineer]

May I suggest to test the o-ring for resistance to gasoline: There are many rubber compounds and your friendly dealer maybe doesn't know. I would buy two o-rings, install one and put the other into a jar with gas. If it swells after a few days, you know you have the wrong compound. I do that with hoses that are sold to me. Funny how that works. Also, I seem to recall that you can connect a pressure gage on the downstream side of the filter. If it shows low pressure, the filter needs replacing.

[J. Huber]

Good advice Engineer. However, in this case, I saw him look up the part in the Mercedes book, so I think I am getting the real McCoy. I only asked for one -- so lets hope so.

PS While I am waiting on the seal, isn't there another fuel screen somewhere that might need checking/cleaning?

James
63 230SL

[Naj ✝︎]

Hello, James,
 

quote:PS While I am waiting on the seal, isn't there another fuel screen somewhere that might need checking/cleaning?

Its one of these 'Pagoda' things....

"If there's rust on the outside, there's plenty more inside"

If you have sediment in the filter bowl, there will be more in the electric fuel pump screen.......and the tank screen??? :?:

Sorry, I am wearing my Devils Advocate Hat today.

naj

68 280SL

[J. Huber]

Naj. Are these things the average Joe or Jim can crawl under and check?

James
63 230SL

[Naj ✝︎]

Hi, James,

 

quote:Are these things the average Joe or Jim can crawl under and check?

Yes, I think so.
May be best to take the fuel pump off the car and do it on the bench (or kitchen table when the dragon is out!!)
Have a looksy here:
http://index.php?topic=3601

The tank screen is part of the drain plug. You can run the fuel down till after the red light has come on and then you may have about 2+ gallons left. You can suck the tank dry by connecting a line to the elecrtic pump outlet and drain into a safe container. You will need a tubular socket where the outer hex fits into the drain plug. I think its 22mm on the outside but ...its been a long time since I did it. (Have a look at ja17's tank tour. He made a wrench with a bolt...)
Easy enough???
naj
68 280SL

[rwmastel]

quote:Originally posted by J. Huber

Anyway, I recall last time that it was quite a balancing act getting the rubber o-ring to stay in place while I screwed the canister back on.

James,
Make sure you don't have TWO seals in there!

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[J. Huber]

Thanks Rodd. Only one -- I know because I got under and looked to see if any crud from old seal was stuck in the groove. I could imagine two would cause some problems.

BTW, I decided to crawl under the fuel pump -- to see what that filter is all about. It took me about 45 mins just to get the shield off! (well not really off, just loose -- since a fuel hose runs through it) Didn't help that the only 10mm socket I have is stripped out. Or that that darn vertical spare is in my way! No wonder they did away with it.

Anyway, I can see how things work -- but I decided not to unhook any fuel lines. My tank was FULL! So I am going to run things down to reserve -- and if I get brave, I'll disconnect and check the pump filter and tank screen...

Related questions: if I unhook the inlet line, gas will pour out right? And then will I then remove the plug in tank? Or would you do it the other way around? And do I have to "bleed" anything when I put things back together? (I have no idea how).

James
63 230SL

[George Davis]

Hi James,

if you unhook any of the gas lines, gas will pour out unless the tank is empty or nearly so.  Any gas in the lines will leak out, of course.

And yes, some bleeding may be necessary when all is reconnected.  If there is air in the pump, it won't pump anything, it just spins the air around.  After refilling the tank, I'd suggest loosening the outlet hose and pulling it off enough to allow the air and a few drops of gas to leak out before trying to fire it up.

George Davis
'69 280 SL Euro manual

[hands_aus]

quote:Originally posted by J. Huber

Related questions: if I unhook the inlet line, gas will pour out right? And then will I then remove the plug in tank? Or would you do it the other way around? And do I have to "bleed" anything when I put things back together? (I have no idea how).

James
63 230SL

James,
If the inlet hose to the pump is in reasonable condition with no cracks in the rubber, you might be able to clamp the hose near the tank. That will minimize the amount of fuel you will lose.
Surprisingly you will not lose much at all.

When I replaced my rebuilt pump, the pump ran for a short while before the system was fully primed.

If you don't want to remove the pump from the mountings, you could try cleaning the inlet filter screen by using an artists brush and keep dipping it in fuel to remove the crud (what an appropriate word).
Doing it that way is tedious given the position you will be in, however it may be even worse removing the pump from the mountings.
One of the square shafted mounting bolts on my car had rusted on the thread and the nut kept on turning on the shaft of the bolt.
I had to grind the bolt away which made it a slightly bigger job.

If you do decide to replace the fuel line, it is important that there is no sag in the line from the tank to the pump inlet fitting.
This allows the fuel to be gravity fed even if the pump is not working.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Ricardo]

James
A little word of caution from my experience....my old style pump had been replaced by the previous owner with a new style. When I tried to remove the large cup/nut that holds the pump filter screen, I couldn't get it to turn. It seemed like I was going to tear the pump off it's mountings, so I ended up removing the pump and putting in my large vice. It was still a real bear to loosen, to the point I thought I was going to damage something, before it finally came loose. The pump still looked like new and I doubt that the screen had been removed previously, as the pump had been recently installed when I bought the car. Maybe I just had a really stuck one, but if you have problems getting your's loose, you might be wise to remove the pump...not that hard actually.
Oh and thanks for the words of support a couple of weeks back, I didn't reply as I was at Dan's for a week, giving him a hand, but....it's always nice to find someone in your corner  

[Naj ✝︎]

 

quote:When I tried to remove the large cup/nut that holds the pump filter screen, I couldn't get it to turn. It seemed like I was going to tear the pump off it's mountings, so I ended up removing the pump and putting in my large vice. It was still a real bear to loosen, to the point I thought I was going to damage something, before it finally came loose. The pump still looked like new and I doubt that the screen had been removed previously, as the pump had been recently installed when I bought the car. Maybe I just had a really stuck one, but if you have problems getting your's loose, you might be wise to remove the pump...not that hard actually.

 

quote:Hello,

These fittings can be removed easily with an air impact gun on or off the car. It is especially difficult to remove it anyway else, especially when in the car.

Caution: avoid using an electric impact because of danger of fire from the electric motor and gasoline.

Joe Alexander
Blacklick, Ohio

naj

68 280SL

[Ricardo]

Naj
I guess I should have followed the link....like most things it's all been discussed before and I apparently posted a similar comment two years ago. :?