Greeting to all, first I want to say thanks to all the posters on here. I've been lurking for quite a while and learned quite a bit of good info.

The truck I have is a 96 310 1500 reg cab short with a nv3500. So these past few days I took the mileage and ended up with 14.9 mpg. I bought this truck new in 96 and it's been a good truck.

Now it's eating coolant and oil so I'm pretty sure the plenum is blown along with the manifold gasket. With the parts on order along with timing change and full tune up, do you think I'll see anything better on the 14.9 mpg or am I risking losing some mpg on it. Right now I'm at 219,000 on the mileage.

What are your thoughts on this?

 

Do you know where the leaking coolant is going? Sounds like you definitely need the plenum repair: https://dodgeforum.com/forum/2nd-gen...um-thread.html

 

Have you checked your oil for milk? Meaning, if coolant is entering the crank case and mixing with the engine oil.

Obviously you know if coolant is missing because the radiator fluid level drops constantly but nothing is on the ground under the truck.

It's important to know if it's in the crank case or just being sucked up by the intake charge.

 

I ordered the plenum off ebay, it should be coming in soon here.

As far as the coolant, I had a mechanic friend of mine say it's probably the manifold gasket. The truck will blow white, smoke when at idle for more that 10 mins. It goes away once I start driving and heat the truck up a little more.

 

Nothing in the oil, I do my own changes. Nothing in the radiator as well.

 

i'd recommend a compression test. it'll prove whether you do or don't have a head gasket problem. if you do, its a lot easier to fix while you have the plenum apart the first (and only) time.

i doubt that your mpg will improve much after the plenum fix. with oversize all-terrain road tires, corrected speedo, driving like grandpa at 55, i've been able to get up to about 16.5. around town was never better than about 15.0

 

an easy quick and free way to slightly increase your MPG is to pull the tailgate off and leave it home. its a GIANT air dam when ur strolling around hauling nothing.

 

incorrect..... mythbusters proved it doesnt work. only thing that give a minor improvement, is removing the tail gate, and putting one of those mesh tail gates on.

by minor improvement.... i mean less than a tenth of a mpg better.

 

TC I'll take that truck off your hands, shame of it to cause you such a problem. When should I come by to pick it up?

 

my trucks jacked up in the rear and stock in the front by pulling off my gate my truck no longer feels like its floating at 65+ and my MPG is up 3 according my OBDII stats. mythbusters is good for ideal situations not in all