6.9 diesel questions

[okumaguru]

I recently traded for a 1988 F-250 4X4. The truck came out factory with a 7.3 but it had problems so they put a 6.9 diesel in it. They were in the process of installing a new front timing seal in it when the guys dad had a heart attack so that is how I traded for it.
I have heard lots of complaints about the 6.9's especially with automatics behind them(which is what mine has) and 3.55 gears not having any power.
My questions are would this most likely be computerized or not and will it be gutless compared to a 95 F150 4X4 with a 5.0 automatic? Are there ways to increase the power without having to "mortgage the farm"? Also, what kind of fuel mileage should be expected?
I would appreciate any opinions.
Thanks
Tim

 

[greywynd]

None of the Ford (International) diesel's were computerized until the 7.3 powerstroke. As to increasing performance, unless you're willing to do some major stuff, not much you can do. (Not like you can add a chip or anything.) There are guys that would know how to turn up the injection pump possibly, but the guys that really know the stuff that can do that, are few and far between.

Personally, I've always heard issues with the 6.9's, but not much with the 7.3 (I have one of them, no issues at 260K kilometres.) The only issues I've heard of witht he 6.9's though are the occasional head gasket.

Which tranny in it? Mine's got the C6, would have to check the rear end ratio. These aren't get up and go trucks, but they will carry pull a big load all the same, just don't expect to get there fast!

 

[Steve Frazier]

The biggest problem with the 6.9s was cavitation in the coolant system. Just make sure you do a coolant test with every oil change and add coolant supplement if needed.

My fire department has an old pre-Powerstroke 7.3 F-350 as a brush truck and it's gutless. There's quite a bit of torque to get you rolling, but once you are it just runs out. You won't win any drag races with it, that's for sure.

Banks used to offer a turbo kit for these engines, I don't know if they are still available or not.

 

[okumaguru]

I would much prefer to drop a big truck engine into it and have a real truck but I really don't have any way to persuade the misses that it would be a good idea. Right now I'm driving 35 miles to work in a 2 wheel drive Ranger. I HATE it!!!!!!!! It has no power etc. I would like to be able to drive a full sized 4X4 that doesn't break the bank on fuel. I also pull a trailer from time to time. I can't decide if I should put the time into getting this one running. I only get around 20 MPG on the ranger. I could loose a few miles per gallon to be driving a 4X4 but not a lot.
Any idea what kind of mileage the 6.9's got. Mine has an automatic transmission but I don't know exactly which one. I wish it had a stick. I would have already got it on the road.
Thanks
Tim

 

[okumaguru]

cavitation??

How do you test the coolant system? Do you mean test the antifreeze? I'm afraid I'm new to the Ford diesels. I do know the VW diesels had a problem with the coolant system. The water sometimes wouldn't get to the water pump if you allowed it to completely empty so you would have to add water, quickly increase and decrease the throttle, then add more water.
Something like that???:beatsme

 

[will_gurt]

How do you test the coolant system? Do you mean test the antifreeze? I'm afraid I'm new to the Ford diesels. I do know the VW diesels had a problem with the coolant system. The water sometimes wouldn't get to the water pump if you allowed it to completely empty so you would have to add water, quickly increase and decrease the throttle, then add more water.
Something like that???:beatsme

It is called a Litmus test. The test consists of dipping a strip of treated paper into the coolant and then matching the color up to the color scale to see what the level is. You then add a additive (Name ecsapes my mind) to bring the coolant back into check. It measures the acids that build up over time in the cooling system. Kind of like testing the PH level in the swimming pool. The cavitation spoken about here can result in cylinder walls cracking from the bubbles breaking open. What the cavitation does is pit the cylinder walls until they crack them.

 

[okumaguru]

Litmus test

Is this something I can purchase at OReillys? Is this something I should check or is it something I'm better off having checked by someone who knows what they are doing. It doesn't have any coolant in it currently. Is there some way of checking it without dissassembling or filling with antifreeze. The radiator is in the bed of the truck. I don't think they ever started this engine in the body actually.
I think I have heard of that check before but I've never checked it. I had a VW Rabbit diesel and my VW mechanic was telling me there was something he checked when he replaced the head gasket to tell if it had carbon or something in the cooling system, probably the same thing.
Thanks
Tim

 

[Steve Frazier]

It's a paper test like mentioned, you just dip the test paper in the radiator and read the colors. Any well stocked parts store should have them or be able to get them for you. Then if needed you add the coolant supplement that restores the ph, adds lubricants for the pump and adjusts the additives to prevent cavitation.

If I remember right, a guy I worked with that had the same engine/transmission combo got 18mpg around town and close to 25mpg on trips.

If you want the optimum engine in there, look for the Cummins 5.9B series. These things can make all kinds of power, get very good fuel mileage and will outlast the truck. If you do a Google search, you will find several companies that sell conversion kits for them.

 

[mag6000]

You can get the test strip kit and coolant additive at your Ford or International truck dealer. I prefer the International dealer myself as they're prices are generally much less. When my truck still had the 6.9 I would do the test once a year. I'm now running a 5.9 Cummins in this same truck and life is much better.

BTW, if you want to do a ton reading on cavitation, test kits and coolant additive, check out thedieselstop.com or oilburners.net. Each has a very active 6.9 and 7.3 idi section.

 

[okumaguru]

I just signed up today for the diesel stop and posted a similar post. I will go check out the oil burner site right now, hadn't heard of it.
Thanks
Tim

 

[TRACKHOE71]

try going on www.thedieselstop.com its a site decitated to ford pickups and deisel engines.

 

[capt_met]

the 6.9 isn't a bad engine. not going to win any races but will get you there. the cavitation issue isn't as bad with the 6.9 as it was with the 7.3 but you stll need to keep an eye on it. you might check out oilburners.com. the guys over there are a little over the top on the old idi's but they know their stuff. there are things you can do to bring up the performance. turn up the fuel, add a turbo. before doing any of this you would probably want to add some gauges to keep a better eye on what the engine is doing.
good luck,

 

[okumaguru]

I just signed up for oilburners. I haven't posted anything yet. I think, based on what I have gotten here and on the dieselstop I will probably start working on it next week weather permitting.
Thanks to everyone and I'll keep everyone posted as I go.
Thanks
Tim

 

[will_gurt]

tell if it had carbon or something in the cooling system, probably the same thing.
Thanks
Tim

Exxactly, it test for Nitrates in the coolant.

 

[RonG]

That DieselStop.com site has recently changed hands,just in the last few days and the new owners have trashed it.It used to be a daily stop for me but not anymore.It is a shame too as it was one of the classier boards.I am not a Ford fan by any means but there were some resources over there that were second to none for good solid info.Gonefishen had to be the best Detroit guy there is and was very generous with his time.There were others and they will be missed.Ron G

 

[Steve Frazier]

I used to be a daily reader over there too, but there were some changes made several years ago that discouraged me, it was right after they had to do the name change. There's a picture of my truck there someplace when I went to one of the gatherings here in upstate NY.

 

[Serv]

I had a mid 80's single cab 4x4 with a 6.9L diesel in it. I took care of the gutlessness with a used ATS turbo setup that a friend sold me for around 1,500 bucks complete with a boost gauge and pyrometer. I wasted no time installing it.

This setup really woke the truck up. The power was comparable to those mid 90's 5.7L GM half ton pickups. :usa


http://www.jhdiesel.com/ats.htm

 

[John C.]

I've got an 84 6.9 in a 3/4 ton 4x2 automatic that has worked real well. It currently has 150,000 miles and hasn't seen regular use in a couple of years.

I've had trouble with the glow plugs and the old switch controller. The switch goes bad and will hold the glow plugs on for too long and burn them up quick. I'm on the third switch in two years. The latest one won't work if the coolant temperature is over 45 degrees F. I'm going to put in a button to run the thing manually.

Most people that I know that had one of these have lost a fuel pump. I've been told it's because they ran the fuel tanks dry before switching. I've never let mine run out so maybe that's why I haven't had the problem yet. Fuel pumps are real expensive compared to tune ups in a gas engine.

As stated previously, this engine doesn't have much snort. I get about 21 miles per gallon on the highway with it and 17 in town. I only have to carry a load once in while so I don't really care about the power. I've had service trucks with 7.3 power and while the engines lasted a long time for the weight they were carrying I felt I needed more power. The power stroke engine is where, in my opinion, they first started to become more than a toy.

 

[okumaguru]

Sincerely appreciate everything

I truly appreciate all of the suggestions and thoughts. I am going to start working on it next week, weather permitting. I can't afford a turbo right now but knowing it could help will be an incentive. I'm sure everyone will be hearing from me from time to time. My only diesel experience to date is on a VW Rabbit. Oodles of torque on the lower end but that's all it had, and 45-50 mpg didn't hurt either. The biggest problem I had with the Rabbit was no matter what I wanted to do to it, it was still UGLY!!! I apologize to die hard VW lovers but I'm afraid it just didn't do it for me. I bought it for $100.00, drove it for about 4 years, then traded it for the truck we have been discussing.
Thanks to everyone again.
Tim

 

[Jeff D.]

Okumaguru, I owned a '87 Ford 3/4ton with the 6.9L and a C6 tranny, and have also driven for employment a vehicle with a 6.9L. My father also had 6.9L's in a couple of his trucks.

I agree with the rest here, they are underpowered, atleast HP and acceleration wise. They will get the job done though, and once you're rolling do pull reasonably well. They just don't give good acceleration.

My Dad had one that went down due to cavitation erosion, or pitting through the cylinder walls into the combustion chamber. We didn't know or understand about that particular problem with the 6.9's at the time. With the testing and additon of SCA's(supplemental coolant additives) to keep the nitrite levels high enough, that should never be an issue. FWIW, it had over 200k miles at that time, so still not too shabby for an '85!!

I've also heard the addition of a turbo can make a big difference in performance, but also that these engines already have a relatively high compression ratio, due to being naturally aspirated, and therefore can't handle much of an increase in manifold pressure without very close monitoring of combustion temps.

One other thing I noticed on the ones I've owned and run is they go through alot of oil. Almost like a Detroit 2cycle would. I was adding a gallon every two days to the one I ran for work, although that was working it hard for 8hrs a day and running it on the governor much of the time.

If I had a choice I'd pick a 5.9LCummins fisrt, but an older 7.3 or 6.9 would be my second choice, and definately before Chevy's 6.5L's.

Good luck with it!!