Dangerously slow when cold. 1995 E300D - PeachParts Mercedes-Benz Forum

JayK · #1 01-11-2011, 12:14 PM

I searched other cold weather threads, and didn't quite see my problem, so forgive me if this has been beaten to death.

The problem is that I can't go more than about 25 MPH when the car has been sitting and it's in the low 30's. Even after the engine has warmed up to about 60 C the problems persists. It takes about 10 minutes of driving around to be able to go onto the highway or drive up a bridge.

When I do try to go faster, the car lurches back and forth, like it's trying to go but can't. I can't just keep it in 3'rd gear and drive at high revs. In idle, the engine has no problem throwing max revs.

Has anyone experienced this problem in a similar car to mine?

DieselPaul · #2 01-11-2011, 12:41 PM

Sounds like waxing/gelling fuel. Are you using some sort of winter additive or some kerosene? When it goes down to zero I'll put some Kerosene into my tank, but I use a winter additive like the Mac/Napa or Amsoil winter flow improver in every tank.

I had the same problem as you, driving to my fathers house one night I was low on fuel. Filled up on the highway and was out of additive and kerosene. Got to his house, parked the car, and over night it went below zero. The next morning it was a little tough to start, but when I went to drive it, it was definitely MUCH slower until it got all the way up to temp. Put about 15% Kerosene in it that afternoon, parked it overnight again, and no problems.

I'm inclined to believe your fuel is gelling.

Murkybenz · #3 01-11-2011, 12:43 PM

Lurching back and forth like it is trying to go but cannot is classic blocked fuel filters.
I have had this on my 300d om603 and it is a rather odd feeling that the car will not go over a certain speed but drive nice below it.

I dare say it is a Mercedes trait as I have never experienced the lurching in other makes of cars and just find they do not go at all or very hard to start,but the Benz is the opposite and will happily start and run until it hits the revs where there is not enough fuel supply.

BodhiBenz1987 · #4 01-11-2011, 12:52 PM

My 240D had similar behavior when the fuel filters were clogged ... there were a couple times I almost couldn't make it up this one big hill when cold. Had to put it in first and even then crawled up at a pace a snail would laugh at. It was lurching on the highway too. After worrying it might be a slipping clutch or bad injector or something, I just changed the fuel filters and it completely fixed the problem. I also added some Startron to the tank.
In your case it could be a combination of gelling and clogged filters, maybe? I'd change the filters and try an additive as dieselpaul said.

DieselPaul · #5 01-11-2011, 12:52 PM

They could be blocked with gelled fuel.

But probably not a bad idea to change them to just get the wax out of the filters as its not getting any warmer anytime soon.

JayK · #6 01-11-2011, 12:59 PM

The consensus seems to be fuel/filter related. I didn't even think of that. I was suspecting a transmission problem.

One thing I don't understand, if it's fuel, why does it improve with time? How would the fuel get a chance to warm up? I wouldn't think the return fuel would be enough to warm the tank. Or is it just radiation from the block heating up lines and filters?

patbob · #7 01-11-2011, 01:21 PM

Radiation, like you said. Probably just takes that long to melt enough fuel in the filter to get sufficient flow.

Its all about viscosity and pore size. The fuel may not even need to gel completely to cause a flow restriction.

You might also have other issues, like a weak lift pump. In fact, since you're experiencing the problem at only 30F, unless you're running something other than winter D#2, its probably likely. But start with a filter and don't dig in deeper unless that doesn't fix it.not worry about it until summer if that was a sufficient fix.

latitude500 · #8 01-11-2011, 01:26 PM

Mind you I live in Austin Tx, so we don’t have a lot of cold weather in my area of the world. But my understanding of the fuel system is that any unburned fuel returns to the diesel filter and then off it goes to the fuel tank if it’s not needed. So as the engine warms up it sends the warmed up fuel back to the diesel filter. So after some time of driving the warm diesel will melt (some) of the wax inside the diesel filter. So it would be a good idea to put a fuel additive into your tank to help with the cold flow issue you are having.

On another note, I’ve personally installed an in-hose radiator heater to help with start ups in the cold mornings. I know it’s a topic that has been discussed to death on this forum. But if you have a way to plug in your car over night, it would help you with your problem. It would allow the car to be 30-40 degrees warmer right when you start it up. They make electric warmers that heat up the radiator or engine oil too.
Good luck and keep warm.

babymog · #9 01-11-2011, 01:27 PM

There could have been some contamination (grease of some sort?) in the fuel that is causing filter problems, but 30F is not cold enough to gell fuel.

Filter changes are the best first-strike in this, I agree with the above.

The fuel is heated in these cars, by the warm IP, and by the fuel heater that is a water-fuel heat exchanger by the oil filter (in the 602/603, 606 similar?).

Cr from Texas · #10 01-11-2011, 01:30 PM

Quote:

Originally Posted by JayK

The consensus seems to be fuel/filter related. I didn't even think of that. I was suspecting a transmission problem.

One thing I don't understand, if it's fuel, why does it improve with time? How would the fuel get a chance to warm up? I wouldn't think the return fuel would be enough to warm the tank. Or is it just radiation from the block heating up lines and filters?

I actually think the returned fuel would be warmer from being in the engine compartment filters and pressurized by the injection pump. Think about ice road truckers: they're OK as long as they keep the engine running.

I could do the thermodynamic and heat transfer calculations but really don't want to take the time!

SD Blue · #11 01-11-2011, 01:59 PM

Hmmm.............lurching back and forth could be a sign of low transmission fluid as well. This could also give you poor performance even when slightly warmed up.

Have you checked the transmission fluid level? Mine gives these symptoms when only a pint low.

JayK · #12 01-11-2011, 05:16 PM

Quote:

Originally Posted by SD Blue

Hmmm.............lurching back and forth could be a sign of low transmission fluid as well. This could also give you poor performance even when slightly warmed up.

Have you checked the transmission fluid level? Mine gives these symptoms when only a pint low.

Turns out the ATF was about 1/3 l too low; added some. I'll let it cool down for a few hours and see if it's fixed.

retmil46 · #13 01-11-2011, 06:14 PM

Hmmm. Had a similar occurrence with my 87 back Saturday morning. Temps had been down in the high 20's overnight. Started it up and let it idle for about 10 minutes - no problems whatsoever firing it up.

But when I went to back it up, it was like something trying to hold it in place - so much so I looked to make sure I hadn't inadvertently put the parking brake on.

When I started up the road, the tranny was very reluctant to shift - revving up way high trying to go from 1st to 2nd. Engine didn't seem to have any issues with fuel. Same with 2nd to 3rd. When it tried to go from 3rd to 4th, it jumped back and forth between 3rd and 4th about 4 times. I backed off on the pedal and speed, crept up the road at 30 mph. After a mile or so, the tranny started acting normally.

Could be mine is low on fluid as well - has sat fro 2 years while I've been down in TX and only driven occasionally. Plus, from what I've checked since I've been home, the throttle linkage and feedback cable to the tranny are WAY out of adjustment - it exhibited a noticeable flare going from 3rd to 4th last week when in the 60's outside, and vstech and I took it for a test drive.

vpppmg · #14 01-11-2011, 07:32 PM

JayK, I have a '95 E300D as well and am having similar issues, though not as extreme. Thinking it was gelling/waxing problem I've been using DieselKleen as an additive for about a month and it's still persisting. Mine smokes quite a bit while it's going through it's 'warm up', a light blueish white smoke. Does yours smoke more than normal when you accelerate while it's lurching?

Doktor Bert · #15 01-11-2011, 08:09 PM

Gelling/Waxing sounds logical. I don't seem to have that problem, but it is still above 0°F at the moment. Not sure what will happen in sub-zero temps. Cleaning solvent makes a great cold weather additive.