Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 10-11-2014, 06:52 PM
Registered User
 
Join Date: May 2014
Posts: 122
1987 300D Sedan MPG Issues

Ok, only when I baby this car and don't use my a/c I can get about 27 mpg.

By baby I mean travel the speed limit only at about 75 mph.

I haven't checked the emission "rat's nest" on this car so I assume it's working as designed.

If it weren't working as designed could that cause some MPG issues?

On my '93 it kept my turbo from working so I did the wastegate mod and EGR delete to get the turbo to work.

From what I've seen there is a lot of oil in the intake but I guess there's no way around that without some modifications.

What kind of mods could help that?

As it stands now I use/burn about a quart every 1-1.5K miles.

Reply With Quote
  #2  
Old 10-11-2014, 07:09 PM
Quahog's Avatar
likes plumb bows
 
Join Date: Nov 2010
Location: Portsmouth, RI
Posts: 633
w/those driving habits, take that 27 mpg & be happy

do look into that oil consumption- seems a little excessive.

carry a couple of quarts of your favorite flavor in the trunk & check levels @ every fill-up. you don't want to run dry.

you are either burning it, leaking it or a combination of the two.
__________________
1991 300D

Reply With Quote
  #3  
Old 10-11-2014, 07:36 PM
jake12tech's Avatar
Registered User
 
Join Date: Nov 2011
Location: Philadelphia, PA
Posts: 2,878
Got 32MPG with an automatic '87 300D driving at 65 without any AC. So maybe a little less for you at 75, but that does seem a little low to me. Yes, do check those oil leak(s). Too much.
__________________
Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k
Reply With Quote
  #4  
Old 10-11-2014, 07:40 PM
Registered User
 
Join Date: Mar 2014
Location: Philly
Posts: 492
FWIW- I get 22-24 around town and 27-29 on the Hiway same situation of the oil consumption and oily intake. I was hoping for better mpg but thats pretty dead on mpg going by the original sticker info I read somewhere on the 124perfomance website. Non modded engine.
Reply With Quote
  #5  
Old 10-11-2014, 07:45 PM
Wodnek's Avatar
Vintage Mercedes Junkie
 
Join Date: Jun 2004
Location: Southeast Wisconsin
Posts: 1,661
Pushing 75 with the air on gets me 24 with my 87 300D. I never saw 30, but I got close keeping it at 65 with the air off.

Now my wife's 95 E300D, We see 30-37, air on or off, doesn't seem to hurt the mileage.

My 87 300 TD, (now my daughter's) we have seen 31 if you keep it below 70.
Bottom line, take your 27 to the bank, unless you want to slow down.
__________________
1959 Gravely LI, 1963 Gravely L8, 1973 Gravely C12
1982 380SL
1978 450 SEL 6.9 euro restoration at 63% and climbing
1987 300 D
2005 CDI European Delivery
2006 CDI Handed down to daughter
2007 GL CDI. Wifes

Reply With Quote
  #6  
Old 10-11-2014, 07:48 PM
bsmuwk's Avatar
124.051
 
Join Date: Jan 2009
Location: IL / WI
Posts: 1,013
Wouldn't even call that MPG an issue.

I've always seen about 27-28 going 70 in my 603 powered beasts- AC made no difference.
__________________
Allen Kroliczek
Oak Grove Autosport | Oak Grove Autosport
01 G500, 82 300TD, quite a few more.....
Reply With Quote
  #7  
Old 10-11-2014, 08:44 PM
Registered User
 
Join Date: May 2005
Location: Deer Creek, IL
Posts: 63
I get a very consistent 29-31 mpg with mostly 55-65 mph driving and some in town. Lowest I have ever seen was 28 mpg. These cars are turning what, 3200 rpm or so at 75 mph? I have a feeling fuel consumption rises significantly on these engines above 3k rpm.

Also, my engine only leaks/burns about 1 qt. per oil change which is about every 8k miles. Very impressive oil control on these engines.
__________________


1985 190D 5 speed - bone stock, 300k+ miles SOLD
1986 300E factory 5 speed - black on black
1987 300D- ALDA removed, timing advanced a bit, R129 rear springs, cabrio front springs, 17" Metris steelies, 250k miles
1997 Dodge Ram 3500 Cummins

Last edited by CatDieselPower; 10-11-2014 at 09:08 PM.
Reply With Quote
  #8  
Old 10-11-2014, 11:34 PM
Registered User
 
Join Date: Sep 2007
Location: Calgary Alberta Canada
Posts: 1,924
Oil in the intake could be blow by a catch can would help.
Reply With Quote
  #9  
Old 10-12-2014, 12:33 AM
Registered User
 
Join Date: Aug 2010
Location: Sacramento, CA
Posts: 3,115
At 70 mph, one gets ~30% poorer mileage than at 55 mph. That was the rational for the national 55 mph interstate speed limit during in the 1970's "gas crisis". The cars then had more air drag so probably a lesser effect for a 1987, but not much. If you want really great mileage, follow a tall semi-truck, but I find that only practical at 65 mph or less. In our 2002 minivan, that increases our instantaneous mileage reading from 24 to 33 mpg (if no cross-wind).
Reply With Quote
  #10  
Old 10-17-2014, 08:55 PM
Registered User
 
Join Date: May 2014
Posts: 122
OK, that all makes sense.

I just can't get over the claims hypermilers make...like 35mpg in a W123 for example.

I love the cruise and sometimes I will only get 24 when traveling in extreme West Texas going at least 90mph.

These cars do just fine on the high end of the speedo. :-)
Reply With Quote
  #11  
Old 10-17-2014, 09:31 PM
Registered User
 
Join Date: Jun 2004
Location: West of Ft. Worth. TX
Posts: 4,186
First, don't believe the claims of the hyper-milers. They may reach those mpg's if there are extenuating circumstances, such as mostly downhill, but not as a general rule.

Could that oil in the intake be due to turbo seals starting to weep?

(BTW, going 90mph in west Texas will cause the state troopers to pass you. Just to show you they can. I'll never forget being passed by a Porsche in the middle of the night, near Monahans, and I'm willing to bet it was hovering near 200.)

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 08:33 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page