Fuel System Shot? - PeachParts Mercedes-Benz Forum

shertex · #1 11-18-2010, 06:36 PM

Writing on behalf of my best friend...he may be able to provide me with a fuller description later...but here's my understanding.

He has a 1995 E300 diesel. Had a stalling problem. Replaced fuel filters, problem went away for a few thousand miles, then came back. Told that fuel filter feels "heavier" than it should. Then is told that the most likely cause is a corroded fuel tank and....get this...he needs to replace the ENTIRE fuel system to the tune of $4800 in parts, plus labor (this is the stealership telling him this, of course).

But I'm not getting the logic of it at all. If the fuel tank is corroded, why not, worst case scenario, simply replace the fuel tank and then frequently change the filters until all the crud is purged? Or, better still, just clean the fuel tank. Are they suggesting that somehow corrosion has "infected" the entire system? If that's even possible, is it likely?

So, as it stands, he can replace fuel filters and is fine for a few thousand miles, then problem returns. Oh, one other thing: if he allows the car to warm up for 15 minutes, he doesn't have the problem, even if he would were he not to warm it up.

Thoughts? Suggestions?

He's the one who got me into MB's in the first place...so I want to do whatever I can to get him good advice.

Thanks!

layback40 · #2 11-18-2010, 06:44 PM

has the car been run on WVO ?
The problem is the dealer will not fix things. They just keep replacing stuff till the problem goes away.
The tank needs to come out & be cleaned. The best way is to steam it. I have cleaned tanks by taking them to a factory with a large boiler (cannery) & steaming the tank for a day or 2.
The fuel lines could be blown out with compressed air.
replace filters & keep fingers crossed.

It could be a case of bugs in the tank. Has he cut a filter open?

Hope this helps !

Good Luck

shertex · #3 11-18-2010, 06:45 PM

No...no WVO.

kerry · #4 11-18-2010, 07:27 PM

Why spend $4800 when you can continue to swap out fuel filters? How can a diesel fuel tank corrode? Is it algae? If it were me, long before I spent that kind of money, I'd put an alternate fuel tank in the trunk and run it for a while to see what happens.

layback40 · #5 11-18-2010, 08:54 PM

$4800 is a con job.
Best he go get the car back before they do any damage.
Cut open a filter & post a pic please.

shertex · #6 11-18-2010, 09:56 PM

Here's my friend's description of the situation:

Bought 1995 E300D mid-summer. It had been traded in by the daughter of an elderly woman. I did battle with the used car manager who took it in trade. He wanted to buy it personally. In August the car started stalling after I’d driven it for a 3-4 thousand miles or so. My independent mechanic couldn’t diagnose the problem so I took it to a Benz dealer. They said that they thought a small fragment from a part or hose had made its way down the fuel line near the engine and became an obstacle to fuel flow. They cleaned it and put in a new fuel filter. Car acted fine until mid-November. Same thing stalling after 3-4 thousand miles driven. I took it back to the Benz dealer.

Specifically when this happens it stalls about a half mile down the road, then again another half mile further. Then it doesn’t run as smoothly as one would like but it doesn’t stall again. At times you can feel it slow down as if fuel flow is being ever so slightly impeded however. If I let it warm up (summer or winter) for 15 minutes (no less) it does not stall.

I made several suggestions to the service writer who said he would give them to the mechanic. He had the same person work on it as he did in August (“not all the guys remember how to work on these…”). Among my suggestions were 1) I had heard the biodegradable electrical harness went bad in these almost immediately. I thought it was unlikely to be that but had it been replaced? 2) There was a recall item involving stalling but that had already been done. 3) was there rust in the fuel tank? 4) does the glow plug system only appear to be working but in fact is not?

The mechanic reported back that the rubber seal around at the base of the new (as of August) fuel filter was already deteriorating and that when he removed it the filter seemed abnormally heavy. He now believes that there is rust in the tank (perhaps the elderly woman only filled it up half way and then didn’t use the car). He thinks that the rust it entering the fuel filter and after building up sufficiently it causes the stalling because not enough fuel is getting through to the engine. The service writer advised that my choices were to:

· Sell the car

· Frequently replace the fuel filters for as long as the car will run.

· Replace the entire fuel system the parts of which would alone cost $4,800…plus labor. He didn’t advocate this solution necessarily but it seemed clear that he (and I followed up with the same question to my independent mechanic) believed that in these circumstances that replacing the tank itself would be insufficient. I should have quizzed him further but the thought was that everything leading from the tank to the engine would need to be replaced. Not sure why. Perhaps as a precaution or perhaps the lines themselves can be damaged by rust running through them. Feeling like it is a total loss but not sure.

kerry · #7 11-18-2010, 10:04 PM

Layback is on the money. First question to the mechanic: "What was in the fuel filter when you cut it apart to determine the exact cause?" If the answer starts with, "I didn't cut it apart so. . . .", find another shop.

layback40 · #8 11-18-2010, 10:14 PM

Has the tank strainer been looked at?
My guess is that the filter will either be full of; 1/ rusty water or 2/black gunk. If its 1/ empty the tank & clean as best you can, if its 2/ treat with a bug killer like startron or what ever that stuff is. The fact that he thinks he found a bit of broken down rubber in the line makes me think 2/ . I cant understand these mechs that dont look for the simple things first. Maybe I am just being a Grumpy Old ........

barry123400 · #9 11-18-2010, 10:53 PM

Remove fuel tank and inspect the inside. Have the tank cleaned out or do it yourselves. Try to see what was causing the problem.

If tank will not clean for some reason or you see rust. Get another tank from an auto wrecker and make purchase depend on a clean usable interior condition.

A fuel tank is made of normal steel that is coated inside and out with a layer of lead basically at the time the metal is rolled. In north america it is called tern steel if my memory is right. Possibly the name of the factory the specialty steel originates at.

The interior coating that prevents rust can fail but it is very unusual if it does.. Generally the issue may not be rust but you do not know until you inspect the interior of the tank. For example someone could have intentionally put something in the tank or the rust could have been pumped in.

Try to think a few hundred dollars at worse if you do it yourself. It is pretty certain the injection pump is still good so $4800.00 is hard to understand.

I would for a host of reasons install a fuel pressure gauge in the system permanently as the lift pump might be suspect or the fuel pressure low. Cost about twenty dollars to do this yourselves. After the tank is checked and filters renewed.

If you insist on taking a car or your friend does for all paid for service on a car this old you should have very deep pockets. The sooner one takes on repairs themselves. Overall the more money is saved.

Most required tools pay for themselves or more the first time used. One of the few things in life that I have purchased that have absolutly paid their initial cost many many times over is tools.

The only thing I am certain of from your description is the tank has to be removed and inspected.

shertex · #10 11-19-2010, 05:36 AM

In a situation like this, is it worth experimenting with fuel system cleaning products....I'm thinking especially of Power Service Bio Kleen and/or Clear Diesel....or can contamination be extreme enough that the fuel tank must be removed? Since my friend is not able to do the work himself, I just wondered about utilizing this approach just to see what it might yield.

Parrot of Doom · #11 11-19-2010, 06:09 AM

The easy solution is just to remove the fuel tank and inspect. If its falling to bits, get a new one. They're not expensive.

If things continue to come through the fuel pipes, well, that's why we have fuel filters.

layback40 · #12 11-19-2010, 07:46 AM

shertex,
before you go planning on fixing the problem, please get a blocked filter, cut it open with an angle grinder or hacksaw, post a pic of what you find inside it.
I doubt the mech who has advised you friend knows anything about diesels.

There is a good chance that all you will need to do is remove & clean the strainer, drain the tank, put some clean fresh diesel with bio kleen in the tank & get them to only buy fuel at a station with a high throughput in the future.
We wont know though until we see what is in the filter.

shertex · #13 11-19-2010, 09:01 AM

Quote:

Originally Posted by layback40

shertex,
before you go planning on fixing the problem, please get a blocked filter, cut it open with an angle grinder or hacksaw, post a pic of what you find inside it.
I doubt the mech who has advised you friend knows anything about diesels.

There is a good chance that all you will need to do is remove & clean the strainer, drain the tank, put some clean fresh diesel with bio kleen in the tank & get them to only buy fuel at a station with a high throughput in the future.
We wont know though until we see what is in the filter.

OK....hopefully he still has it, but might not.

And thanks to everyone for their help....looks like my friend's well on his way to a cost-effective solution.

kerry · #14 11-19-2010, 09:49 AM

If he doesn't have a plugged filter, continue driving it until you get one. You need to know what is plugging the filter. There are tons of cases on here of algae plugging filters but very few, if any, of rust plugging filters. If it's algae, the problem is fixable without removing the tank.

hd wood · #15 11-19-2010, 11:20 AM

Story: I just purchased an 84 300D which suffered stalling problems. You could drive 40-50 miles but then needed a tow home. Local shop replaced all kinds of stuff but didn't know the tank had a drain.

I had it towed from Philly and drained he tank. Messy, but not really difficult.
Make sure you get as much of the fuel out as you can before you start and buy one of the plastic mortar pans from Home Depot. $5. If you get the tank down to the point where the light comes on on the cluster you have about 3 gallons left.

My fuel came about fairly nasty, guage was fine and I never even cleaned the screen. The car has never stalled once for me. I wouldn't over think this. Start with the tank. Oh, you can inspect the tank in the car with a small flashlight. If you want me to contact me thru Stormwind Alpacas and the Google. dave