I recall in one of your earlier videos you had put a lower temp thermostat in your car. I have a M104 and tried a 79 degree thermostat. Gas mileage tanked. I’ve since switched back to the stock 87, refilled the fan clutch, and added some redline water wetter to the coolant. Overheating is solved and my fuel economy is back to 19-20 city and almost 30 highway.
I could understand during the winter time with a lower thermostat causing issues, but here in Temecula summers are brutal and this car was just not designed for hot climates, so many complaints on the net for the M103-104 running to hot, now the car has the 75c thermostat and temp is at the 85c mark, idling for a few minutes almost to the 90c mark, that 194F so, I think the 75c thermostat is fine for summers here, winter I switch back to 87c. Lats winter we ran the 87c stat and poor MPG still bad. Also I tested my duty cycle yesterday and its not reading right, unadjustable, so I'm thinking the EHA went bad again, crazy systems. That could be a reason for poor MPG, it adjusts the mixture a little.
I have a 1989 300 CE that I just solved the “poor gas mileage” issue on. I was getting 12 mpg instead of the 18 to 22 that I should have been getting. I smoke tested the intake and I had a massive vacuum leak in the rubber boot under the KE air flow meter. Upon replacing, I am up to 21 mpg.
It had a slight (but annoying) hesitation off the line upon the initial press of the gas pedal. At idle, once warm, it also fought slightly for a steady idle. It liked to surge and then back off in about a one second cycle between 650 and 700 rpm. Idled steady until it hit 80 Celsius however. Both these symptoms were very subtle and others who drove the car thought it was “fine”. I knew with only 12mpg fuel economy, there must be a fairly serious issue. That is about 40% worse than even the lowest acceptable mileage for a properly functioning M103. Upon fixing the vacuum leak I had to re-adjust the lambda. The car is new to me, and whoever worked on it previously, had set the lambda down to 28% to attempt to compensate rather than fix the vacuum leak. Smoke tester cost me about $120 on Amazon. There are not many single items that can cause such dramatically poor gas mileage, but a vacuum leak is one of them and it is easy to eliminate, or confirm with the smoke test.
I’ll ask my neighbor Rick the mechanic if he can borrow one from work, still with vacuum leaks I would have bad running condition, the recent emissions test showed the engine is running very very clean , bad vacuum would have showed up.
Yes, hard to believe you could pass emissions with a substantial vacuum leak. It is perplexing how gas mileage could be so poor with just a bad lambda adjustment, or O2 sensor, or EGR. To my knowledge, you would need to have many small things wrong to equal 12 mpg fuel economy. I don’t disagree that it is unlikely in your case, but I would eliminate it nonetheless having already made the repairs that you have. I am a novice and it only took me 1/2 hour to do including set up of a new smoke tester. I also found I had small (likely inconsequential) leaks in several of the fuel injector “O” rings and seals as well.
Wow😮😮😮😮, a very very nice looking old Mercedes. Very clean engine bay. Pls let us know more details. 1st owner from new?. Miles done in this car. More on expensive repairs. Type of repairs over the past 5 years. How much you paid for it. What it is worth now. MPG looks like very poor. Bought a W211 one year ago with 163hp. Need some work on it. Itchy to change the part of the MB Tex to tartan fabric. Over here a much much older W124 260E cost as much as a pre 2006 W211. Happy motoring!.
Maybe, good idea, I replaced thermostat last summer with a 78c due to very hot temperatures here and car was running to hot, will put stock 87c back in for winter.
I recall in one of your earlier videos you had put a lower temp thermostat in your car. I have a M104 and tried a 79 degree thermostat. Gas mileage tanked.
I’ve since switched back to the stock 87, refilled the fan clutch, and added some redline water wetter to the coolant. Overheating is solved and my fuel economy is back to 19-20 city and almost 30 highway.
I could understand during the winter time with a lower thermostat causing issues, but here in Temecula summers are brutal and this car was just not designed for hot climates, so many complaints on the net for the M103-104 running to hot, now the car has the 75c thermostat and temp is at the 85c mark, idling for a few minutes almost to the 90c mark, that 194F so, I think the 75c thermostat is fine for summers here, winter I switch back to 87c.
Lats winter we ran the 87c stat and poor MPG still bad.
Also I tested my duty cycle yesterday and its not reading right, unadjustable, so I'm thinking the EHA went bad again, crazy systems.
That could be a reason for poor MPG, it adjusts the mixture a little.
I have a 1989 300 CE that I just solved the “poor gas mileage” issue on. I was getting 12 mpg instead of the 18 to 22 that I should have been getting. I smoke tested the intake and I had a massive vacuum leak in the rubber boot under the KE air flow meter. Upon replacing, I am up to 21 mpg.
Good , but I would think the car would run kinda bad with a massive vacuum leak, did it? ours runs great.
It had a slight (but annoying) hesitation off the line upon the initial press of the gas pedal. At idle, once warm, it also fought slightly for a steady idle. It liked to surge and then back off in about a one second cycle between 650 and 700 rpm. Idled steady until it hit 80 Celsius however. Both these symptoms were very subtle and others who drove the car thought it was “fine”. I knew with only 12mpg fuel economy, there must be a fairly serious issue. That is about 40% worse than even the lowest acceptable mileage for a properly functioning M103. Upon fixing the vacuum leak I had to re-adjust the lambda. The car is new to me, and whoever worked on it previously, had set the lambda down to 28% to attempt to compensate rather than fix the vacuum leak. Smoke tester cost me about $120 on Amazon. There are not many single items that can cause such dramatically poor gas mileage, but a vacuum leak is one of them and it is easy to eliminate, or confirm with the smoke test.
I’ll ask my neighbor Rick the mechanic if he can borrow one from work, still with vacuum leaks I would have bad running condition, the recent emissions test showed the engine is running very very clean , bad vacuum would have showed up.
Yes, hard to believe you could pass emissions with a substantial vacuum leak. It is perplexing how gas mileage could be so poor with just a bad lambda adjustment, or O2 sensor, or EGR. To my knowledge, you would need to have many small things wrong to equal 12 mpg fuel economy. I don’t disagree that it is unlikely in your case, but I would eliminate it nonetheless having already made the repairs that you have. I am a novice and it only took me 1/2 hour to do including set up of a new smoke tester. I also found I had small (likely inconsequential) leaks in several of the fuel injector “O” rings and seals as well.
Wow😮😮😮😮, a very very nice looking old Mercedes. Very clean engine bay. Pls let us know more details. 1st owner from new?. Miles done in this car. More on expensive repairs. Type of repairs over the past 5 years. How much you paid for it. What it is worth now. MPG looks like very poor.
Bought a W211 one year ago with 163hp. Need some work on it. Itchy to change the part of the MB Tex to tartan fabric. Over here a much much older W124 260E cost as much as a pre 2006 W211.
Happy motoring!.
great car man!, what kind of fue do you put on one of these? thank you
Is the mileage reading correct? Wouldn't be the first time the counter is slow due to age and needs greasing
If every cylinder is firing on too rich a fuel-air mixture, of say more than 20%, would it not quickly blacken up the spark plugs?.
It would and it would have failed emissions tests 2 months ago, I’m going to replace 02 sensor next, that may help a lot.
Hello
I have the same car , and it shakes when I stop or idle ,what it could be please .
Thank you
I love you vidéos
Check motor and transmission mounts.
What will be w124 260e fuel consumption
A little better but these cars are heavy, built like a tank, so not the best mpg.
Check those strut mounts guy!
Hello
Watertemp to low.
👀 germany
Nice car.
Maybe, good idea, I replaced thermostat last summer with a 78c due to very hot temperatures here and car was running to hot, will put stock 87c back in for winter.
❤❤⚘⚘😍😍