justs last week i bought a 1984 f-250 6.9 deisel w/137,000mi. It starts very good runs very nice. I dont know anything about diesels. but i cant tell any problems w/the way it runs, all seems fine but it just has not enouigh power without a load pulling a medium hill about 3/4 mile by the time i hit the top i loose probably 7-10 mph with my foot on the floor and yesterday i was pulling my 14 ft. trailer with 3 4-wheelers on it and it really struggled but seemed to be running fine as i was pulling the hills i looked back and seen no smoke. I dont know if that is something good or bad but it might be a clue of something.
I am just dissapointed. it seemed that any gas motor would have pulled the hills better than that. Mabey there is nothing wrong and these motors are not strong and you could help me with some performance tips or mabey there is something wrong or something to look for and you could help.
friends tell me it should really blow black smoke when pulling hills or when im really getting into in but i seen none. hope ya'all can help thanks

 

Wondering how old the fuel filter is? Might try this first and we'll go from there. Also try a diesel fuel additive as these engines most likely don't like the new Ultra low sulfur diesel which is coming out as we speak. There is very little lubricant in the fuel and these engines was designed to run on high sulfur for lubrication.

Myself - I use B5 biodiesel which is excellent. I've used it for 7 years in my farm equipment and have had no problems and even a power increase.

 

The 6.9 was not a big HP motor, 175 is the number.

But it will pull just about anything you hook to it, just not fast.
Also it will keep pulling it for a very long time, 300,000+ miles is not uncommon with proper maintence.

You will not be the first person there, but you will always get there no matter what is hooked to the back.

There are several things you can do to make it run better, but if you really want to get power the only option is a turbo.

 

does previously posted discription of power seem right to you? I mean it is to the floor and loosing power the whole way. Just seemed weak to me. I have owned a 1999 6.5 turbo and there is no comparison. I was not overly impressed with the 6.5 either but this is way less. if this is what to expect that is fine but it is a dissapointment

 

What transmission do you have - an E4OD doesn't like to be in Overdrive while pulling any kind of a load uphill. If your intake and exhaust are stock this will be even more true. I have a heavy old camper I haul around, mountain area, Just get it out of overdrive so the rev's are up to 2500, 2800, and the truck will maintain and keep pulling. I've added a 4" ram air mod, got rid of the soup bowl in the intake, and added a three inch exhaust, including a 3" y pipe. Along with rebuilt injectors and IP the trucks performance has been significantly improved. I have a set of headers coming, which I e-mailed a guy who actually has put a set on his truck, and claims performance is nearly as good as a turbo charger, but with no performance lag, less expensive-no moving parts, and figures his fuel economy improved by 6 mpg. I will be sure to let you know how this works out- sure wish there was a way to figure out horse power without putting it on a dyno?? where would you find one of those??

 

A additonal thought, I had about 150,000 miles on mine, wouldn't see any black smoke ever. I figure my IP was getting tired, so I put a new rebuild on. That made a huge differance in my power, now when pulling a hill I see a slight black trail behid me with much better power.

 

thanks a bunch for your input. I believe i will get going on that 3" exhaust and I feel pritty stupid but im not sure what an IP is. Also I asked advanced auto and they said that there is no air intake improvments available other than a K&n air filter. I know very little if anything about diesels any more input would be appreciated.
Anyways does my discription of its power seem about par for it or do you think something may be lacking. I havent tryed it since new fuel filter and come fuel additive.
Oh my truck does not have overdrive

 

need to cut soup bowl out of air intake this does seem to improve much and go to daves air ram intake works real good i myself made mine where it scoops air under the front bumper works real good also incresed fuel a flat and half this is only after i nstalled pyro on the beast i pull a small bobcat up and down a 6% grade 12 miles long about 4 times aweek and at 60 is no prob sometimes even faster but just have to watch the gages cause this az heat will really play hell with any type of engine

 

Custom, these 6.9 IDI's are not fast but will take a beating! I have the same truck as you and have done some inexpensive mods to get more ooomph...first these engines love air and I have played with lots of different combos-Dave's S. has the best for ram air [see his photo gallery]....2nd is exhaust, I have dual 3inch exhaust [big difference in throttle responce], but if you thinking of going turbo-go single 4inch...3rd, turning up your IP [injection pump], while I haven't done this, I do have the timing advanced...4th is maitenace, I change my fuel filter every 10,000 kilometers,use a fuel additive every fill, oil change-every 5000 kms. These 4 are fairly cheap...the exhaust being the most expensive [but worth every penny]...for any real power your going to have to get a turbo!! I have propane injection, while it doesn't increase power all that much, it helps with milage while pulling a load...there might be some simple reasons your IDI is not running right [IP & or injectors needs replacing]. There's high performance IP's, stage 1 injectors, intercooler, etc, etc if you want to throw some money at it. Custom you have come to the right place for advice, there is a ton of knowledge on this site...use it, I only wish I would have found this site earlier, it would have saved me a lot of trial & error! lol

 

You should never see heavy black smoke behind you. If you do, then you need to cut back the fuel as all you are doing is wasting fuel and potentialy overheating your exhaust valves and exhaust system.

Light smoke is ok. Read the articals on this web site, they are very good. Purchase and install an exaust pyrometer BEFORE changing from a stock condition and that will give you a baseline of what you can saftly do with your paticular truck / load combo.

These are very expensive engines to rebuild ~ they wil last a long time in stock trim or mildly modified form, less durability if modified with no thought as to exhaust temps.

David

 

Custom, when you compare a turbo diesel to a NA engine you are comparing apples to oranges.
Look at it this way.
At sea level air pressure is 14 PSI.
A natural aspirated motor has 14 pounds of air pressure pushing into the combustion chamber.
Now you have a turbo that is increasing the pressure by 7 PSI.
Now the combustion chamber is getting 150% of the air it was as a NA motor.
So with an increase in fuel delivery you can instantly increase the power out of the engine by 50%.
So that took the 175 HP engine and turned it into 262.5 HP engine.
87 HP is a huge increase in power on a diesel.

 

Yah, I agree with everything bcford said, especially the exhaust being the most bang for the buck in terms of performance. I'm pretty happy with mine so far, But the reason I am avoiding the turbo is the life of then engine issue, seems turbo leads to head gasket cracked blocks etc, issues. This is my reason for going to try headers. If you put 4" of air in the top, add fuel, reason says the less power it takes to drive the expanded volume of comusted air out of the engine, the more you can put to the ground.

 

thanks all very much. I believe I am giong to work on getting more air to the engine and opening the exhaust. Im not looking for a super power house just some more power which i feel it needs to do me justice.
Thanks again