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  #1  
Old 11-19-2012, 06:31 AM
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Location: Los Angeles
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87300td getting terrible fuel mileage

It's not the most scientific but using the old gallons divided by miles driven method I seem to be only getting about 21-22 mpg. I don't know if it would contribute to the problem but I've had very very bad glow plugs in the car until this week when I changed them. As my temp runs well below the mid point unless I'm PUSHING it, it's been suggested that perhaps the thermostat is stuck open and not allowing the car to get up to a temp that will facilitate full burn. But otherwise the car seems to run REALLY well, strong pull, not too much smoke. I have correct sized tires that are up to pressure. I guess it could be anything but any other big suspect reasons for bad fuel economy?

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  #2  
Old 11-19-2012, 07:06 AM
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Calipers dragging, alignment out, alda too rich, air filter dirty, fuel filter dirty, too much junk in the trunk... bad fuel, cheap winter fuel...
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #3  
Old 11-19-2012, 08:12 AM
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85 300D 4spd+tow+h4
 
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Leaking return lines?
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1991 300D Nearly Perfect
1994 E320 Cabriolet
1995 E320 Touring
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  #4  
Old 11-19-2012, 08:24 AM
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Quote:
Originally Posted by winmutt View Post
Leaking return lines?
I recently got awful mileage on my e300d, my fuel/air filters etc were all in order and on investigation the end cap on the last injector was cracked & leaking... the fuel was dribbling down the end of the block. You can lose a surprising amount with this or leaking return lines.

Engine temp should be around 80 btw, climbing to mid-point or 90 when working harder.
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1983 230E W123 M102
1994 E300D S124 OM606 (x2)
1967 250SE W108 M129
1972 280se 3.5 W108 M116
1980 280SE W116 M110
1980 350SE W116 M116
1992 300E W124 M103
1994 E280 W124 M104
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  #5  
Old 11-21-2012, 07:06 AM
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Yeah it hangs around 60-70 when at full temp. Either the gauge is inaccurate or I think my thermostat is stuck open.
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  #6  
Old 11-21-2012, 08:58 AM
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Hmmmm....20-25 seems about right to me, but there are many variables, as previously mentioned.

In comparison, my 1978 300SD gets 25 on the average and a high of 27 with the lowest ever recorded fuel economy of 22 mpg, and that was running the A/C at over 90mph.

My fuel economy remains unchanged whether I was running the old 60C or the 80C version....Robert
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1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership
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  #7  
Old 11-21-2012, 09:19 AM
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one of my TD's gets around 24 average, and one gets around 30 average... the 30 is lower miles on the clock, and nearly stock. the 24 is rebuilt engine, with #22 head, and no cat or alda... FUN to drive, but it gets old pouring a black cloud on the cars behind me... driving that with a feather touch on the pedal eliminates the cloud, but then the trans shifts poorly... it's a toss up.
my 30mpg wagon has recently dropped mileage significantly due to leaking Delivery valves, so I ordered a set and the wrench... *I"M TIRED OF A PUDDLE OF FUEL EVERY MORNING!
lets just say, the engine block under the IP is PRISTINE! zero traces of any dirt on there!!!
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #8  
Old 11-21-2012, 09:20 AM
vstech's Avatar
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OP, I don't know where you live, but if you are on winter fuel there is a significant power loss from that, and couple that with your lower engine temp due to the thermostat problem, and I can see that combining to lower you mileage. FIX THE THERMOSTAT!
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #9  
Old 11-21-2012, 10:59 AM
JamesDean's Avatar
Electrical Engineer
 
Join Date: Apr 2005
Location: NE Ohio
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Quote:
Originally Posted by vstech View Post
OP, I don't know where you live, but if you are on winter fuel there is a significant power loss from that, and couple that with your lower engine temp due to the thermostat problem, and I can see that combining to lower you mileage. FIX THE THERMOSTAT!
I'm currently averaging 34 in my 300D 2.5... Is that on par with winter diesel economy numbers? When we go back to "normal" diesel can I expect fuel econ to improve?
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Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #10  
Old 11-21-2012, 11:23 AM
vstech's Avatar
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yup. likely it'll bump you up to 36or more if you are getting 34 with winter mix. you must drive very economically.
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #11  
Old 11-21-2012, 11:34 AM
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Electrical Engineer
 
Join Date: Apr 2005
Location: NE Ohio
Posts: 5,034
Quote:
Originally Posted by vstech View Post
yup. likely it'll bump you up to 36or more if you are getting 34 with winter mix. you must drive very economically.
I got 39 on my return trip when I bought the car.. pure highway 165 miles, 60-65mph no cruise control..

My driving is purely highway (commute is 65 miles each way) so its usually at 70-75mph, partial cruise control. I drive the 190E around town mostly...or thats the plan anyway.

__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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