Hey guys I'm new to this forum. Well I've had a 1987 volvo 240 for a few years now and just today looked online and saw that most people get around 20-25 mpg and the government estimated mpg is 22 combined. Well I get on average 16-17.5, highest being 19 a couple times and lowest being around 14. I've had SO much done to this car since I bought it I can't even list it all, but I'm guessing there must still be things that could be replaced which are affecting my gas mileage. Anyone have any ideas on how to boost my numbers?

 

our 87 240, which we've flogged since new, and now has about 400K miles on it (odometer died at 250K about 10 years ago), gets a fairly consistent 25mpg on mixed town/county driving. on long road trips I've seen 27mpg, and even flogging it hard around the county here rarely goes much below 25mpg.

I'll admit, since the odometer broke, we don't track mileage, other than on long trips where I can get the mileage from google or whatever.

 

Change your fuel filter. ($15 and an hour)
Running some fuel system cleaner won't hurt either.

 

May I ask what kind of weather you are driving in? Reason being is I bought my 240 around winter and wondered why my gas mileage was so low. Then I realized duh, the weather . Im not saying you're making the same mistake I am, but just checking .

 

whats funny is that I actually get my better gas mileage in the winter since I dont have AC on or windows down ( I live in florida ). I'll look into the fuel filter but I think that might have been done.

But I just got a spark of memory, and recall that one time my friends dad drove my car and said something about my car not shifting passed either 2nd or 3rd (cant remember which). It just kind of went in one ear and out the other, but now that I think about it, could I be getting terrible mpg's cus im cruising on the highway at such high rpms? If such is the case, what would be the cause of this issue?

 

The fuel filter is a regular maintenance item.
It should be replaced every 25,000 miles or so.

 

a 240 should be somewhere around 3000rpm at legal freeway speeds. if you're running ~5000 rpm in 2nd, or ~4000 rpm in 3rd, yeah, that would guzzle gas.

cruising steady in 'D' at freeway speeds, push the button on the shifter and the yellow "UP" arrow on the dash should light and the RPMs should go up significantly. push the OD button again, the light should go out, and the rpms should drop back down to around 3000 rpm (at about 60mph)


If this issn't happening, then yes, something is wrong with your overdrive. there's the button, a relay in the circuit, an actuator solenoid on the transmission, then there's the mechanical OD inside the AW70 transmission. if the light goes on/off but the RPMs don't change, then its probably mechanical. if the light doesn't go on, then it may well be electrical.

 

I'm constantly surprised by how many people calculate fuel mileage by thinking they can, say, go from 3/4 of a tank to 1/2 a tank and after noting miles driven, divide the tank capacity by 4 and then do the math. It's important to note that fuel gauges are not particularly accurate. Fill the car to the brim, note mileage. Drive car a good distance and top off the tank again, noting mileage. It's the only way to get an accurate assessment. I'd also suspect that people professing mileage in the high 20's and low 30's are 1. Lying 2. mistaken 3. running extremely lean 4. have modified their vehicles. Pick one or more from the list. The Volvo 240 was never designed and built as an economy car. It is heavy (lots of redundant safety stuff) and purposely under tuned to provide long life. Actual mileage new is dictated by transmission and rear end ratios. The 91 240 sedan w/ automatic had epa estimates of 18 local, 20 combined, 23 highway. The manual does a bit better at 19 local, 21 combined and 26 highway. That's brand new! Properly inflated tires are a must as is an accurate, functional O2 sensor.
While I am certain there are some modified Volvos getting better mileage, I am equally certain there are those that, operating a 114 horsepower car have precious little to brag about. If you can't brag about mph, brag about mpg, right?

 

Most of the driving I do with my 240 is city driving and I only average about 17-18 MPG with a 5 speed (same MPG as my Mustang with twice the number of cylinders). My 850 is a couple hundred pounds heavier and gets better mileage (about 22 city 27 hwy). I have to agree with Swift, although these cars are 4 pots, they're not that fuel efficient.

 

Keep in mind, Volvo had intended 1984 to be the last year for the 240. For each year after that, the 240 was on thin ice. The luke warm sales of the 740/760's kept the 240 kicking many more years, eventually outliving the 7 series by a year! Old school technology but old school reliability. The 850 is an engineering marvel, faster, more fuel efficient. Not nearly so simple to work on and maintain.

 

Pierce! I think your solving my problem! My OD has always been broken on the car, it's practically ALWAYS on. If it's off and I push the button, the light comes on and it stays on for however long it wants, no matter how many times I push the button, and it eventually turns off by itself in days/weeks, but then turns on again by itself out of nowhere all the time. I'd say on average it's on 95% of the time I'm driving. So now I'm pretty sure that would be the main culprit. How can I go about troubleshooting to find the exact malfunction?

And to Swift, that's exactly how I do it as my gas guage has always been broken. I fill to the brim, then every 200 miles on the odometer i fill again, and have calculated my mpg's every time since Ive had it.

 

when the light is lit, the OD is disabled so the car stays in 3rd rather than going into OD aka 4th, assuming everything is working properly. your symptoms seem like it could be the OD relay. the button goes to this relay, which also gets an input from the tranny indicating its in 3rd, and in turn sends the power to the solenoid in the transmission that activates the OD. afaik, its not actually a relay, its an electronics module.

on an 87 240 I believe the overdrive relay is up behind the center of the dashboard somewhere, but frankly, I forget. the diagrams show it as a large relay, mounted on its side, with the connector end pointing to the left, held in a clip. its volvo p/n 3523804 I think. sadly, 240's have the relays scattered all over haphazardly, on the 740 and later cars they were mostly centralized in a single relay panel, makes life much simpler.

 

The overdrive relay in auto 240's is behind the center vents. You will see it to the left when you remove the glove box.

 

typo alert, relay connector pointing to the RIGHT, duh! ;-/

 

Okay guys I don't know much about cars at all, so could you please explain what I need to do in leimans terms? lol thank you

 

Step 1) Find a good Volvo mechanic

Step 2) Fork up a fair amount of cash.

 

ooo

how much you think it'll cost? more than the money id save in gas over a couple years?

 

I'd imagine an experienced volvo mechanic could diagnose your OD problem in an hour. if its an electrical problem, it would likely be fixed on the spot (that OD relay is a $40 part, for instance). if its a mechanical problem in the transmission, then it could be expensive.

 

I was going to say your problem was using A/C, that the usage of the a/c was causing lower mileage. 18-19 in the city with the a/c on doesn't seem that bad to me for this car, depending on your hypermile skills. but OD not working is something your going to want to get fixed first.

 

my 240's A/C has been broken for 20 years, hah, it never worked that good when new. but, my city/town/county mileage was always around 22-23mpg, while highway mileage was typically 25mpg when leadfooting it, and I got a high of 27mpg on a long run where i just stuck it at 65 in cruise control all the way up US101 from Anaheim to Santa Cruz.


oh.. all my cars (and motorcycle) seem to get about 10% less mileage on this crappy e10 gas we get now. the MTBE crud before that was much the same. and my numbers above are from back when my odometer worked (it died at 250K about 10 years ago, car now has about 400k estimated).l