Main fuel filter leaking on top. Am I missing something?
 

Hey, all, the 83 300SD I've been working on seems to have fuel leaking onto the top of the main screw on filter. I didn't pull the bolt when I changed the filter, but is there supposed to be a washer or seal under the top bolt? I re-tightened it, but there is still a little fuel coming from someplace and setting on top of the filter housing (head). The filter is a new one I installed, and I don't remember if was leaking when I got it or not. Can't find an exploded view of this. Does anybody have any idea what might be the cause of the leak? Thanks.

If this is the copper ring on the banjo connection above the secondary spin on filter - then you are advised to replace it. However I'd just take it apart - clean it up - and see if it will reseal. If it is bent / distorted change it. Don't over tighten the nut.

Be sure to replace the rubber "O" rings on the big banjo bolt too.

And if the banjo bolt has two o-rings, it does not need the copper washer...

Where can we get these o-rings and/or copper washers? Ideally, I'd like to get viton o-rings as I'll be running biodiesel in my 300SD.

Wouldn't that have been in the new filter box? I've got spare copper and steel rings everywhere from my oil changes. Since I didn't pull that bolt, I didn't check under it. The filter has it's own seal. Never had this problem with my 300d. (The one in question is a turbo, but I don't think that makes any difference on the fuel line. Anybody got any manual pics? I'm looking for my cd on these things. As usual, it's hiding under all of that other "real important" clutter.:o

Many auto parts stores have a whole set of drawers full of copper crush washers in various sizes. Depending on how well-stocked they are you might have to convert from metric to the next biggest inch-based size, but the exact dimensions of these washers are rarely critical.

I had the same problem with my 300 SD. Been a good while back and my memory is a bit fuzzy on particulars, but --- best I can recall the washers that came with the filter did not fit the bolt. I made one from some spare gasket material and all has been well for a long while (long enough for me to forget details). At any rate, it was easy.

Change those O rings
 

Go to your local auto parts store or Harbor Freight and get a metric selection box of O rings. Changing the O rings each time you change the fuel filter is a good thing. The copper ring goes under the head of the bolt... (Belt and suspenders)

The same goes for any place you have any O rings. Remove and replace the hard old rings with new ones. It's just a good practice.

Pete

The filter does not come with the crush washer, as this is for the old style banjo bolt.

I have used a #30 cap thread gasket I purchased from the local hardware store.

83 should not have any o-rings on the fuel filter bolt... just an aluminum crush washer.
what's the part # on the filter base? if it ends in 01 it's just got the crush washer. standard oil filter copper ones will work, the plastic ones may even work, not totally sure though.

You might want to reconsider that notion.

Copper washers are the way to go..........they seal better.

The red arrow is pointing to the "02", as you see there are two "O" rings on the banjo bolt.

A filter head with an "01" will need a crush washer. One like the one in the pic is still on my old 240, its made of a composite material.

You are the Man toomany...

I don`t know what year MB switched to the 2 "O" rings and eliminated the aluminum washer. but I do know 84 and 85 use only the 2 "O" rings.

I just ordered some "O" rings from Allpartsexpress, part# MBZ005942 36¢ ea. couldn`t locate the aluminum washer.

Fastlane lists a "hollow bolt seal ring" part# W0133-1644383 for 27¢.
They also list "seal ring Aluminum" part# W0133-1644391. there are 2 different pictures with the same Part# with 2 different price. 22¢ and 14¢ :confused:

The oil pan copper washer is listed as 12MM. that would be way too small to fit.

I upgraded our 240D to the later style filter head to make life simpler. ;)


Charlie

Ahhhh... Thanks tmmbz, that helps a ton. (Not that everyone elses comments didn't). I guess I'm one of those visual types. I love to read, I am very capable of discussion, but Show Me an image, and it's done. Charlie, I may have failed to mention earlier but this is an 83sd. I crosschecked the filter before I put it on (had a new extra for my 81 300d), and I just spun the old one off and put the new one on. There were no gaskets or or seals in the box with it (It's an OEM Bosch), so I just snugged it up, then when I noticed fuel on top of it, I tightened the nut a hair. Didn't even think about gaskets since there were none in the box. It probably didn't even need new filters, but i thought since I had them, it would be worth a shot, since I had no idea what was wrong with it when I got it. But thanks for the info. I was initially just looking for a diagram or exploded view so I would know what was supposed to be in there. Thanks guys. I'll go out and check this.

Thanks Army, ^ those "O" rings get brittle over time and fail to seal.

Great info!! I just went out and looked on my 85 300SD that has had a persistent leak on top of the filter and it has the "02" # and a crush washer! My 84 300TD has had the same problem and I am gonna check it tomorrow (already soaking wet from the heavy rain) and see if I have some o rings in stock to fix this nagging problem. Diesel is too damn expensive these days to be rust proofing the engine compartment with it. :eek: Thanks for the effort! -Scott

Showme, I know you have an SD, but it is still a 617.95x engine like the 300D`s and like the 240D`s with the 616.xxx engine. they all use the same filters. If you have the number "01" cast in the filter head, you use an aluminum washer under the bolt. if you have the number "2", no washer under the head, but use 2 "O" rings on the bolt shaft.

When I mentioned my 240D, I had up graded it to the "02" filter head.

If I remember corectly, the filter head that uses the washer, has one "O" ring on the bolt shaft.

10Fords, you might be leaking because you are using the washer. It may be keeping the "O" rings on the bolt shaft from seating all the way into their seat. In other words it might be keeping the bolt too high. just a thought.

Charlie

That makes sense and was my thought also. But it would seem that the washer would seal even if the o rings didn't? Either way- if it doesn't leak who cares why it works!:D

Using a metal seal that is not appropriate could cause the lower o-ring to be out of its proper position, in which case there could be an internal leak from the dirty side of the filter element to the clean side. In other words, some fuel could be bypassing the filter element entirely.

That is exactly true.

The new filters do not come with any type of extra seals/washers like come in most of the German oil filters.

The "O" rings probably don`t get changed because most people don`t have extras on hand and or I`ll get some and do it next time which never happens. also I know when I change mine, I loosen the bolt, then just spin off the filter, spin on the new one, tighten the bolt w/o removing the bolt. then the "O" rings end up being on for a loooong time and suddenly it is leaking. I know I went through this in the begining before I fully understood how it all worked.

These leaky fuel filter threads seem to come up a couple times a year.

Charlie

Any suggestions for a stuck bolt? I'm afraid to just stick a breaker bar on it and pull for fear of snapping the hollow banjo bolt.

As you are going to replace the spin off fuel filter try going retro and use a chain wrench to treat it like a spin on / off engine oil filter.

That bolt is supposed to be simply snugged so it doesn't leak.

You have to get it off, so proceed as you see fit.

The threaded section is stout.

Yikes:eek: I am going to fix it right now!:eek:

Yeah, I'll try that first. I'm not optimistic, though, because it'll be much harder to get a good purchase on the filter than it will be on the bolt.

The previous Mercedes I had, I didn't know about the bolt and heaved on the filter for like 20 minutes trying to get it to spin. Finally I undid the bolt and it came right off. ;)

Thanks, good to know it's sturdy.

I think I'll put a breaker bar on it and then tap the bar with a mallet, to see if I can coax it loose that way. (Poor man's impact wrench!) I seem to break fewer fasteners that way than if I use a cheater bar and just heave on them.

Isn't the filter the only thing that the bolt is actually attached to? I mean, once you spin the filter loose, the bolt is able to move too, right?

The hole in the filter head in a smooth bore, and the bolt just sits in it. the filter screws onto the bolt, and the bolt is snugged up to keep the filter tightened to the sealing face of the filter head.

when removing the filter, loosen the bolt and then unscrew the filter, drop it down and lift it out. the bolt is then held in the hole by the friction fit of the "O" ring.

Charlie

I agree it is sturdy - however I remember a thread not so long ago where an indy was telling a forum member that the bolts nearly always snap off when he does them up!

Sounds like too many folks are unaware of how to go about installing a fuel filter on these cars.

Knowledge is power.

Yeeah, I've always thought these were about the easiest fuel filters that I've ever had to change. I changed the one on my 81 300D 4 times in the 4 years we've had it, including when we first bought it as a "just in case" move. I've never had one leak, though. And since this car was just given to me, and I have driven it maybe a mile total, I don't know if it had been leaking before or not, but with a new filter and an extra nudge on the top bolt, I didn't want to go any further without asking the forum their thoughts. As usual, it's raining\sleeting out today, and about 37*, so I'll probably hold off for nicer weather to get under the hood. I've got the turbo drain tube's o-rings, gasket and lower grommet for replacement, and a new check valve for the now non-existant breather oil tube's entry point in the pan housing, but I'm not getting out there and getting my butt soaked and a spring head cold just to get it in a day or two sooner. Also going to pull the vac pump back off and replace what I believe is the bad check valve so it will shut off (put the 81's in there and put it's good one in mine). The main thing is this- you all have answered my question about what's supposed to be under the head of that bolt, and also what o-rings should be on the banjo bolt, so mission accomplished on my end of this whole post! Thangyouvurrymuuuch..:rockstar:

Took the copper washer off my 85 300SD yesterday, put it back together and presto! No more leakage! Thanks again for the great info. You guys rule!

Checked mine and the housing has a one one it, which tells me it should have a crush washer and either no 0-ring or a single 0-ring on the bolt. I'm a little confused about what washer type to use, since I've heard composite, copper, aluminum and steel. They must all work since everyone that has recommended them believe that's the choice to make. I'm going over to the local NAPA store and see what I can find. Anybody got any specific ID\OD\thickness specs in case there is no washer to go by? If not, I'll just get what's closest. (Also, 0-ring thickness, size if you've know it?)

Okay, yes, you should have a crush washer. The composite one I have in the pic, I bought from the hardware store, so it's an SAE measurement.
As follows: 3/4 (19.05mm) x 7/8 (22.22mm) x 1/16 (1.5mm).

The rubber "O" ring is 11 x 15 x 2mm.

Any malleable http://dictionary.reference.com/browse/malleable crush washer will work, as that's what is needed to conform to the uneven machining on the fuel filter head to ensure a seal.

thanks! Just went over to NAPA and they were useless. I'm going to Ace Hardware tomorrow. Of course, while I had everything opened up and I was at the parts store, it started raining, so I turned the old washer upside down (it's aluminum and in pretty bad shape) and put it back together till tomorrow. This "little" side job is turning into a PITA. Thanks, tmmbz, I do appreciate that standard measurement. It will be a big help, then I'm done with this fuel leak! :)

You're welcome, tell the hardware guy it's a #30 Cap Thread Gasket, he'll know where it is. The new ones are plastic, (don't know if they'll work) I think I have the last composite ones here in central VA.

A hardware store, not a home center (Lowe's, Home Depot etc.).

Will do. Yeah, our old Mueller's Hardware is one of those 'real' hardware stores that's been bought out by Ace, but they still carry everything, (although now that it's an Ace franchise, it's all Chinese and foreign crap, although they have conveniently left everything priced as if Americans were paid to make it. The local saying is ACE hardware- All Chinese Everything! I've actually had things that I bought a couple of years ago, and still have it unopened, and take it back to find that all the ones on the rack look exactly the same, but are now made in China. Many times. I ask them, "Hey, what about my slave labor discount?! They just cringe). If that doesn't work, maybe the Fastenal that's 7 miles away in Farmington will have them. Anyway, thanks very much!

Let me clarify that when I say "foreign crap", I mean the 3rd world countries with cheap labor and low quality control that corporations are getting rich off of, not European. Or Canadian. (Mexico is included with the former, though.)

So if I do snap it off, the broken piece will come out with the filter?

That's reassuring. I wasn't so much worried about having to find another banjo bolt as I was about having to try to drill and tap the broken one out of the housing.

Hope to get a chance to tackle this this weekend. I've been too busy to work on cars the last couple weeks.

Are you refering to what Army said in post#31 about snapping off the large main bolt that secures the filter to the head?

If you are snapping them, then you are tightening it down way too much. It only needs to be snugged up.
Just lay off the wheaties that morning :rolleyes:.

Have you ever used a spin-on oil filter? well the fuel filter needs to be about that tight.

Charlie

X2 on the wheaties - they're a bloody menace.

Maybe he has a 10' extension handle on his breaker bar like me :D

Yes, I know. My problem is someone *else* tightened it really tight and I'm afraid of snapping it trying to get it loose.

It needs to come off, so take precautions, such as have another handy, or at least know where to get one.

It is done! NAPA had nothing that would work. My hardware store didn't have anything, and didn't even know what a #30 cap thread gasket was. Then on to Fastenal, who I thought would have everything ever created. Nothing remotely close! I then tried Tractor Supply, The Family Center (another local farm supply store), and a Butler Plumbing Supply Store. (He told me that O'Reilly's new store has helped him out a lot! {What's this world coming to when a major plumbing supply warehouse has to depend on a chain franchise auto parts store?!}) So I broke down and called AutoZone, and the kid found the copper washer assortment and, after measuring the parts, there was one 3/4"ID that was a tad over 1mm thick, by my metric tape I took with me. SO! After a long search and acquiring a package of copper washers I'll probably never use (only one was the size I need), the job is done, and there seems to be no fuel leaking from the top of the filter. :D Of course, there is a large 5' area on the asphalt out front from the time I've had the filter off and on. :( But it doesn't matter. I'm just glad it's good. Summary here, as much as I despise Auto Zone, they actually had what no one else had, could find or in some cases, comprehend. Whoever mentioned Autozone early on, I tip my hat and apologize for doubting you. Thanks everybody.

Glad to hear things worked out.

I'm surprised no one knows what a #30 cap thread gasket is, my local hardware store folks point me right to it.

I agree, what's the world coming to?

An O'Reilly's is going up here, right beside Advance Auto, just down the street from an Auto Zone.

Mine came apart just fine once I put a breaker bar on it...it was overtightened, but not ridiculously so. I just couldn't get a good purchase on it with the wrench I was using before.

What do you guys do with the diesel in the filter? Seems like pouring it back into the tank just means any crud in it will end up in the new filter, but pouring it down the drain is a decided no-no...

I pour mine into my tractor...