Just bought a 1985 F350 6.9L Diesel - List of questions... - Diesel Forum

Danspeed1 · 11-12-2009, 09:56 PM

So I just bought an 85 Ford F350 6.9L Diesel Pickup today. I ALWAYS wanted a Diesel pickup, but I found myself always buying gasoline cars instead... i guess for fear of the unknown. The truck I bought is in fairly good condition and i think I got a steal on it (from what my friends tell me). But as you can imagine its far from perfect. Here's the short list of concerns. If any of you can ease my mind, or at least steer me in the right direction if the something needs to be fixed, I would appreciate it.

First thing I noticed is that all the gauges work, but in particular the oil pressure gauge reads low. In fact, at idle its like its not even working. At first I thought it was not working. It was not until I drove it at around 30MPH that I noticed it move to the normal (center) area on the gauge. But as soon as I stopped it went back down to low again. Is this normal for these trucks or am i having an oil pressure issue? Or maybe the gauge is bad? Truck runs like a top. Friends agree, its one of the smoothest running old diesels they have heard. Is there any reason for concern?

Second question... When driving the truck its pretty smooth, but it makes a worying sound/wheel bearing sound. Seems like its coming out of the front. Its pretty loud, and changes with the speed of the vehicle. Thought at first it was the massive tires, but now I am wondering if it is actually a wheel bearing sound. Are these trucks noisy or is this a problem?

Where should I begin with the maintenance? I have been told replace the fuel filter ASAP, oil change, trans fluid change, differential fluid/transfer case fluid, AND REPLACE THE GLOW PLUGS? What else?

Thanks for the input,

Dan

Matt0987 · 11-12-2009, 10:14 PM

On the second question about the sound. Rotate the tires and see what happens. I have had the "bearing" sound on a couple of 4x4s and found that when I rotated the tires the sound went away. I have to guess that it was because the rear tires were square and the fronts had become cupped.

Regarding the oil pressure there are a few things that it might be. I would suggest that you give the truck a good service. Change the oil and filter. As long as you are at it change the fuel filter(s). Lube the front end and the other zerts. Change the tranny, diff, and T/C fluids. Make records of the service work. Milage of the service, oil change tire rotation, etc. Even if you were told that it was recently done.

One thing about many diesel owners is that we like to maintain our vehicles. We like to know them.

Oh, and the batteries. Low, old, batteries are death to starter motors on those engines.

I was very pleased with my 83 6.9. It lacked the computers of today. The parts, like the injectors, were easily accessable. Not under the valve covers like todays engines. The water seperator was on the firewall and easilly accessible. The fuel filter was up on top and easy to access. AND, it is still running strong for my nephew, today.

Matt0987 · 11-12-2009, 10:17 PM

Oh yes, the glow plugs, too. They are easy to access and not too expensive.

And, as a thought, a major lack of oil will effect the oil pressure. Make sure there is plenty in the engine. But then, if you do the maintanance you will know that.

Matt0987 · 11-12-2009, 10:21 PM

You might want to put together a signature that indicates the miledge of the truck, some of the particulars like if it is a 4x4 or a 2x4, if it has a lift, along with other modifications that it has, where you are located -the weather and altitude does effect how a vehicle runs-, and perhaps a picture of the truck.

chuckster57 · 11-12-2009, 10:23 PM

The 6.9 and 7.3 L IDI engines depend on VOLUME not pressure for oil lubrication. Normal fully warm is about 12 PSI @ idle and about 30-40 @ cruising speed. The dash gauges are not very accurate and they read a particular reading based on a "range"..If you want to know the real pressure then you will need a good aftermarket gauge. I have an electric but a mechanical would work too. Readings will depend on oil weight and relative wear on the rotating assembly.

I would pull the front wheels and inspect/probably clean & repack the bearings. Take a good look at the race on the spindle for excessive wear and pay attention to the installation instructions ( torque).

Danspeed1 · 11-12-2009, 10:29 PM

Hey,

Thanks a lot for the tips. I am pretty confident I can tackle everything you mentioned myself. However, things like the water separator.... have no idea what that is... where can I learn more about these trucks/engines? Not really even sure what type of oil to put in.

Thanks again...

P.S

Its a slightly lifted 85 Ford F350 6.9L Diesel 4x4 short bed, non-turbo. I am located in New York. Weather is like 38-45 right now... should be in the 60's next week, and probably drop back into the 30's the week after. Weather is odd this year. Truck starts up first shot, no hesitation what so ever, so far, from dead cold.

Dan

chuckster57 · 11-12-2009, 10:35 PM

If it has the factory original water seperator then it is located on the firewall If I remember right. I use DELO 400 15W/40..You can use any DIESEL rated oil and some members in your neck of the woods use a lighter weight in the winter, your choice.

The water seperator is just what it says..keeps the water out of the fuel, diesels don't react well to it...Some one with the original set up should chime in with the exact spot of the water sep.

Matt0987 · 11-12-2009, 10:37 PM

On my 83 the water seperator was on the firewall on the driver's side in the engine compartment. There was a ring on the bottom that you pulled down to open the valve. The water and/or fuel, ran down a tube to just under the cab. There you can easily catch it and dispose of it. At about 150K miles I had to change it and installed a Racor because of the unavailablity of an OEM unit.

Matt0987 · 11-12-2009, 10:49 PM

As a side note, I would also recommend that you use a fuel additive. Your engine was built when real diesel was available. Since then we have gone through Low Sulfer Diesel LSD and now Ultra Low Sulfer Diesel ULSD. A good fuel additive adds lubricants that replace the one removed from today's fuels. I used Stanadyne in my 6.9 back in the day. I use it now in my current diesels. See my signature for which ones I drive. The additive does make a difference in how they run and, I believe, lasts. You can feel that the engine runs smoother and quieter. "They" say that the additives help the o-rings last longer, too.

Danspeed1 · 11-12-2009, 10:51 PM

Guys,... Thanks a lot for the tips... I am totally stoked about working on this truck and driving it.

Forgot to mention, It has 130K on it, BUT, it also had a plow attached. I plan to use it as a local driver... Pulling around "stuff," and plowing my road. Its actually in really good condition. Not what you would picture a "plow" truck to be.

I will post pictures in a couple days....

Keep the tips comin!

Dan

Danspeed1 · 11-12-2009, 10:54 PM

Quote:

Originally Posted by Matt0987

As a side note, I would also recommend that you use a fuel additive. Your engine was built when real diesel was available. Since then we have gone through Low Sulfer Diesel LSD and now Ultra Low Sulfer Diesel ULSD. A good fuel additive adds lubricants that replace the one removed from today's fuels. I used Stanadyne in my 6.9 back in the day. I use it now in my current diesels. See my signature for which ones I drive. The additive does make a difference in how they run and, I believe, lasts. You can feel that the engine runs smoother and quieter. "They" say that the additives help the o-rings last longer, too.

Can I get the fuel additive at my local parts store (AUTOZONE/ADVANCE)?

How do these motors react to sea foam. Thinking about running a little in the oil before I change it?

Dan

Matt0987 · 11-12-2009, 11:07 PM

You can get "a" fuel additive from them. You will ned to Google Stanadyne for a local distributor. or, go to Stanadyne's website.

Diesel Fuel Additives - Stanadyne

CDX825 · 11-13-2009, 01:48 AM

Don't do the sea foam thing! Its fine in a gas motor but I would never recommend it in a diesel.

The truck holds 10 quarts of oil and the oil is supposed to be checked when its hot. Allot of people make this mistake and overfill these engines.

If you have the room you can run the powerstroke oil filter. It holds an extra quart and filters better. Your truck being 4x4 may not have the room for it though so you would have to check.

If your trucks starting good when cold I would say don't worry about replacing the glow plugs. But if you do decide to do so or when the time comes only use Motorcraft glow plugs. Most of the other plugs tend to swell up and break off when removing them. Autolite is the worst when it comes to this.

As far as the oil pressure goes its probably the sending unit or connection on it. Mine was doing the same so I put in a real gauge and all is well.

For an additive I run a half quart of ATF per tank of fuel and it seems to help quite a bit. Two Stroke oil also works quite nicely. The main concern adding a lubricant to the fuel because the new diesel fuel lacks it.

Hope this helps some! Welcome to the forum!

Matt0987 · 11-13-2009, 02:07 AM

Never put ATF or 2 stroke oil into modern engines. Even your 85. Use a real aditive. It only takes a few onces per tank and it is designed for use as an additive. Stanadyne makes diesel fuel pumps and the like. They know what they are doing.

They also make a product that kills off microbs in the fuel. It is a good idea to use it every couple of years. There are several companies that make it. And, yes, Stanadyne makes one also.

chuckster57 · 11-13-2009, 10:10 AM

Quote:

Originally Posted by CDX825

Don't do the sea foam thing! Its fine in a gas motor but I would never recommend it in a diesel.

I have drained the fuel filter and filled it with Seafoam twice and it helped clean the IP and injectors.
I woudln't use it as a fuel additive cause of the cost. I use P/S Diesel Kleen ( silver bottle) from Wally world with every fill up. I have also read of members putting seafoam in the oil about 100 miles before an oil change.