MPG and a bad overflow valve

[wernergerman]

Can a bad overflow valve cause poor MPG?

My current calculated mileage is 12,5 MPG,no smoke,seams enough power,but I’m new to Dodgeland,and have none to compare with due to the facts mentioned in my signature. I’ve checked the fuel lines,looks to be dry and OK.

Mine is a 97 auto,4. 10 gears,4X4,What MPG have I to expect?

Thanks for your input.

 

[The patriot]

12. 5 seems kind of low. Really depends on the type of driving you do, and the driver.

I dont know if the overflow would do it, but you should check your timing. I'd "clean out" the catalitic converter. This will kill MPG's when it's clogged too.

"Winter grade" fuel will hurt it also. I run straight #2 through the winter, I get 20 regularly. Our trucks are similar, but I have the 5 speed. Last month I ran 3 tanks of winter grade fuel through the truck. I lost 3 MPG's.

BTW, I have not replaced the overflow valve on mine yet. Pull the spring out (be careful of parts falling!!) the spring should be . 550" long I think? Someone correct me here if I'm wrong.....

Eric

 

[Cooker]

4. 10's seem to be much garder on fuel than 3. 54's, and an auto is hard on fuel than a 5 speed. I'd say the comination you have is about 3 MPG less than a manual truck with 3. 54's



If you are running 80MPH down the expressway with 4. 10's I'd say your MPG's are about right.



As mentioned winter fuel is worse and a plugged kitty can really affect fuel economy.



What size tire do you have? This will have an affect on your cruising RPM's.



I'd say you might be a little low (I think you'd be around 14-15 combined and 16-17 on the highway), but it really depends on your driving.



It must be a little difficult to get parts where you are at

 

[pwknapp]

Shoot, mine has a 5sp and 4. 10's, I wish I could get 16-17 highway. Any speeds over 60-65 really kill the mileage. 13. 9-14. 5 seem to be the norm at 70mph with 235/85/16 tires and a flatbed. Ain't got enough hangin' to run it at 80 for a whole tank. Turning 2450 rpm at 70.

 

[sewman]

The last ticket I got he said I was doin 84 I guess them tires do make a difference.

Bob- 5spd & 4. 10

 

[wernergerman]

I have 245 75 16 stock tires

Hope someday in future to get a set of 255 85 16,but they are in USA,he he,

It certainly is a problem to get any part here,but I manage to do my best and use parts from other vechicles,russian usually,make myself.

My truck was totalled in USA and now it looks like new,have got all the front replaced,front axle recovered,turned the tube in differential housing,it now steers straight. I know I’m stupid,but the sound of mr. Cummins is worth the efforts,and I like the glances I get when I arrive in my Goat!

Werner

 

[Deezul1]

When my overflow valve went bad I couldnt get over 65 mph floored pulling my 6000lb travel trailer but running empty it still got 21 hiway and 17. 5 city. Remove your overflow valve and measure the spring, it should be . 500 long. If it is shorter stretch it to . 550 and reinstall it. If that solves your problem get a new valve from Piers Diesel, best price by far.