Gas mileage has gone terrifically into the dumper 300TE - PeachParts Mercedes-Benz Forum

Saint · #1 10-08-2006, 08:25 PM

Hi guys,
A couple of years ago, I struck a high curb with the driver side of car. This did all kinds of damage..ie..punched a hole in the oil pan, cracked the windshield from an old stone chip, twisted the frame from both sides, ruined the wheel and tire, etc etc.

Finally got all the work done...and I am proud to say that this beauty is back on the road. One of the improvements was replacing the wheels with ML320 wheels. What do you think? I love them. Everytime I see these wheels...I knew I made the right decision. They ROCK!

Anyway,...back on point. I have put about 1000 miles on the car since getting back on the road. BTW...it had sat for roughly 18 months, and remember, it took a heavy jolt throughout the car when that curb was hit. I am getting 12 miles a gallon. The car runs fine, but it takes more pedal to get it going...at least that is the way it feels. The vacuum gauge bears this out as well. I have to give it more gas to get going, and the gauge sits in the red for longer than it needed to before. The car has 170k on it, and before the accident, I was getting around 18-20 miles a gallon.

I am going to start replacing the usual tune up items..but would like any suggestion for things to replace or look for that may be causing the dramatic mileage loss. No fuel leaks that I can tell...performance is normal other than having to give it more pedal to perform normally.

Can I also get a recommendation of spark plugs? Where performance is equivalent to cost. I dont want to overspend on some special plugs when typical bosch plugs will do the job as well.

Thanks folks

whunter · #2 10-08-2006, 08:48 PM

One possible answer.

A heavy impact such as you describe can break the catalyst in the converters, this will cause the converters to plug up.

Try disconnecting the exhaust from the manifold, use binder straps to support it, and take a drive around the block.

If your power/economy return to what was normal, the converters must be replaced.

Have a great day.

cjlipps · #3 10-08-2006, 10:40 PM

Check for dragging brakes. Drive a while and feel for abnormally warm hubs. A dirty, inactive brake system or impact damage could cause the calipers to not retract properly.

t walgamuth · #4 10-09-2006, 05:21 AM

is it smoking black out the exhaust?

it reminds me of what happened with my 280e many years ago. it was the warm up compensator i think.

tom w

lkchris · #5 10-09-2006, 12:59 PM

Of course with larger wheels/tires you are not getting correct speedometer or odometer readings, so your mileage calculations are probably not accurate.

royaiii · #6 10-09-2006, 01:35 PM

You are using truck tires on the car, you will not get the same mpg/braking/handling b/c of your tire combo. On my W124 300E, the size is a 195/65/15. On a side note, I did the same thing to my E320 (running over a curb at 30 mph) without any apparent side effects.

Saint · #7 10-10-2006, 01:33 AM

The exhaust note seems the same. The pressure out of the exhaust is what I get from my other car. I might try disconnecting the manifold if all else fails.

Brakes are fine all around.

No black smoke.

The wheels are from the ml...but the tires are not. ML tires would never fit a small wheel well like this. I am using 205s I believe. The combo I am using, the outside diameter is the same as the wheels I replaced. I checked my speed with a gps, and it is dead on...unlike my truck which is off by 6 mph at 75 mph.

thanks for the tips...I hope to get this figured out soon.

t walgamuth · #8 10-10-2006, 06:31 AM

lets see.

this does not seem like a odometer error thing... too much discrephency for that i think.

tom w