Glyn M Ruck

I agree but for years the car division was a status symbol & the truck division made all the money. Schrempp changed that.

pcy

Please don't jump to the conclusion that E85 is what caused the premature failure of the pump. Many factors could've contributed to the pump failure - bad pump to start at the assembly, overheating the pump (on a long journey running the car with less than 1/4 of tank of fuel while the pump has been running for hours), etc.

I am not pretending to know the cause for the pump failure. We have no evidence to declare that E85 caused the pump failure :-)

pcy

I am reading this thread very keenly because I also have '07 C280 4matic with 68K miles. When I looked for the fuel filter under the car, it wasn't there. Eventually, I found out that my fuel filter is integrated as part of the fuep pump, similar to John's car. I may be next in line to replace the pump...

John, have you started opening the pump? Here is a picture of the top of the fuel pump ring nut on my car. Please look at the red arrow I drew, it's pointing to the nut that's part of the 'hose-clamp-looking' thing. I think we should be able to remove that ring nut by loosening that nut on the clamp.

johnand

May have to do some surgery on the old pump and take a look. Not sure if I will stop using E85 just because of this.

I am just frustrated, as the car was supposed to go to the body shop today, not with this it probably won't make it there until next week

johnand

As I just posted, I will disassemble the pump and see what is up. I do drive 80-90% highway, and do regularly run the car to empty (Reserve fuel level).

PCY, in my fuel filter thread I posted the WIS document for fuel pump replacement. They did indeed change the caps to a band clamp that you loosen the nut on the clamp to remove. Beats the hell out of buying the $150 tool. I still haven't cracked it open, as I am ordering the pump today, and will wait until I have the pump. I will put together a write-up with pics. I hope yours holds up, and mine was just a bad one.

Though, I find myself a little lucky with this, as the pump had one last run to get my car home. Reading the post Glyn pointed out, and others I read, could have been worse and failed while in traffic

LILBENZ230

I wasn't jumping to any conclusions, we're all just discussing. Honestly, though, does anyone ACTUALLY believe that the car has a 16.4 gallon gas tank and you're not to use more than 12 or you're going to burn out the fuel pump? I get so tired of hearing that nonsense. I've ran my car to 0-miles remaining literally countless times and have never had a problem on any car I have owned. Hell in high school I drove 40,000 miles in a Honda Accord that I can't remember ever having more than 1/4 of a tank. The thing I was worrying about burning out was the light in the dash that illuminated the low fuel light, not the fuel pump. A manufacturer would have to be incredibly stupid to design something so flawed that it is ruined if used as intended.

mskembo

I don't think it has to do with burning out the fuel pump necessarily, my understanding was that it's more a case of passing more contaminates through the fuel pump. I've had this issue in the past with older (less thoughtfully engineered) vehicles. Remember that all the crap that accumulates in the fuel tank typically settles at the bottom of the tank, so running your tank to empty increases the amount of debris that is sucked up by your fuel pump. I think this is where the majority of the damage comes from. Just my 12 cents.

LILBENZ230

How would the fuel pump not always be pulling fuel from the bottom? If contaminants sit on the bottom of the tank it wouldn't matter if it were almost empty or completely full. I'm not being sarcastic, I really am interested to know how the fuel pump wouldn't always be pumping from the bottom in order to use the tank's full capacity.

mskembo

This is just my understanding, and I'm open to being corrected. Modern fuel pumps have either, a floating pickup that allows it to pickup from the upper part of the fuel tank, or a switched assembly that has a long pickup tube and a short pickup tube. The long pickup is used in normal operation, and when it is time for reserved fuel a switch is thrown allowing the deeper fuel to be accessed.

This is a simple picture, but it shows a fuel petcock from a motorcycle that has a Reserve option.


You can see what I mean by a long and short tube. A petcock without the reserve option looks like the one below.



I'm sure someone will speak up if I'm not correct here.

LILBENZ230

I wouldn't have known that, though it makes sense. Still, I have never had the idea in my head that it was negligent to drive my car through the full range it provides. I never get fuel before the light, and a lot of the times I will drive till there is 0 range remaining. I have never had issues. It should be noted that even with 0 miles remaining there is still ~1.1 gallons in the car per my experience.

mskembo

LOL, that's probably why you haven't had an issue! I had a Chevy years back that never got below half a tank for the first 100k or so, then got laid off and things got really tight. Long story short, I started putting in $5 at a time (back when that was more than a gallon of gas) and less than a month later the fuel pump went out. The mechanic who fixed it was the one that explained it to me. However the build up that hadn't been touched in the first 100k was probably the problem more than my just draining down to the bottom of the tank.

johnand

Do I believe it? Not really, just what I have heard for a long time in the auto industry. My 1991 Sentra with a known suspect in-tank pump (There was 2 revised part numbers), has 214,000 miles on the original pump, and it was my commuter car for over 15 years, and it was driven the same as my C230, and always run until the gas light came on. In fact, the gas light bulb burned out at one point several years ago. My 1998 Jeep Grand Cherokee is driven the same way, and is just shy of 200,000 miles on the original pump.

mskembo

That's PRICELESS! Like I said, not an expert, just passing on the (dis)information that I've been given.

johnand

I would believe pulling the crap from the bottom of the tank may kill a fuel pump, MUCH more than I would the less than 1/4 tank thing.

johnand

Just ordered the pump and a new seal (Just in case), for $231 with overnight shipping from parts.com 20 minutes later I got a shipping notice from them

Probably will wait until the weekend to tackle it, as I have a lot of work this week.

Glyn M Ruck

Running tanks low should not be a concern from an overheating perspective. These pumps will go a long way bone dry & that never happens - the car would not run.

What kills most FI pumps on Benz & many other vehicles is that the pump is before the filter & runs flooded. So it sees any dirt in your tank before it's taken out by the filter. The most common failure mode on these pumps is metallic debris like rust sticking to the pump motor magnets & seizing the pump when build up becomes too great. This problem goes right back to old W123's

I'm not saying E85 caused this - it is one possible contributing factor. Alcohol causes corrosion in mild steel tanks & pipes. It also has a habit of loosening up dirt in storage facilities etc. I believe that all alcohol fuel facilities should be fitted with 1 micron nominal, 3 micron absolute - 75 beta ratio polishing filters before discharging fuel into a car's tank.

Something I instituted in SA on all filling station pumps of ours that dispensed alcohol laced fuels. That stopped the crap.

Carsy

Prevention may be better than the cure.

I have owned a diesel car for 16 years & for that time I have always kept a clean white rag in a plastic bag in my boot to wipe the fuel pump nozzle before inserting it in the car filler orifice !!. Call it **** but you would not believe the crap that is wiped off .

In my previous car I was able to open a drain plug at the btm of the tank which I did yearly to flush out a litre of fuel & some deposits & water.

I have yet to find a drain plug on the W204.

LILBENZ230

It's most likely due to the fact that that sort of extreme just isn't necessary. You should absolutely take care of something as expensive as a car.. however, they are not as fragile or delicate as they seem. I hate to use it again as an example since Trey gets butthurt, but my ex's 200,000 mile Camry never had any problems after 200k miles of driving full to empty (sometimes completely dry), never a fuel filter change, etc.

mskembo

Interesting point. Every piston powered airplane in the world has fuel checks at the lowest point of the tank, and before every flight you take a sample out to make sure there isn't water or other contaminates in the tank. Why haven't auto manufacturers started doing this?

Edit: I'm talking about airplanes from the mid 40's on, not just new ones.

LILBENZ230

Because it would be quite inconvenient to be dressed in business clothes crawling under your Mercedes to take a sample of fuel before leaving for work each morning.

Carsy

Also every ship engine , power plant & refinery have drains at the bottom of their fuel oil & lube oil tanks to purge the contaminants & water.

Surely, the cleaner you keep your fuel the less wear will be experienced by the equipment supplying it to your combustion chamber.

I think that you should drain your MB fuel tank every Sunday before Mass.

Glyn M Ruck

Yep - The auto manufacturers see no safety issue - the car is not going to fall out of the sky with resultant liability, & it's a cost issue. In the early alcohol fuel days in SA BMW fitted a sensor & dash light that showed free water or a phase separation in the fuel tank. The BMW board just about developed a hernia over the $5 on-cost of fitting such a device.

When you look at the expensive EECS (Evaporative Emissions Control System) systems fitted to our cars because it is legislated in Europe - a simple drain plug that could be checked at every service would be a good idea. Crap builds up in cars fuel tanks - period. We, the oil industry slowly dispense our tanks & pipelines to you the customer rust flake by rust flake.

My old Alfas all had a fuel pressure regulator fitted standard ex works with a large glass bowl & a quick release clamp. You could immediately see crap or water coming through from the tank & do something about it.

In today's world the auto manufacturers don't care if you get stuck at the roadside. They are quite happy to sell expensive spare parts & content that this is unlikely to be a problem under warranty. Every 5 bucks saved per unit is more profit.

LILBENZ230

I don't disagree with that. If the car's on a lift at every service and you could drain a little from the bottom, that would be a good idea.

pcy

johnand

Pump arrived today!

On last question: Should I disconnect the battery before replacing the pump? Normally the answer would be yes, but I am deathly afraid of frying the SAM when reconnecting the battery that others have experienced.