I have a '94 F350 SC 2WD 460 Auto that needs some work. It has 122k miles with a Jasper engine replacement at 113k miles. Rebuilt E4OD just after engine replacement. This is a very clean truck that was a toy hauler most of it's life.

Issues are:

1. Fading brake pedal. No fluid loss or leaking. Possible bad MC?

2. Sporadic miss/stumble after warm. I have replaced almost every sensor, distributor, plugs, wires, cap, etc. I removed the PCM for inspection. The blue capacitors don't look nearly as bad as some I've seen. I'm planning on having it reworked once I have time. The only trouble code I get is 311, which makes sense since the air pump is deleted. More time will be spent here after I get the brakes worked out.

3. Dual fuel tank switch broke loose inside instrument cluster. Looks like it was repaired once before.

I'm sure there will be other things, but these are the priority for now.

Working on the brakes first. I removed the rear wheels to inspect the brakes since I haven't done so since I got the truck. I got to this point and need to clarify if I need a BFH to break the drums loose or a wrench to remove the axle shaft. Both drums are stuck solid.

Axle code is D5 which tells me this is a 10.25 Sterling w/4.10 gears.

Any input is appreciated.

John

 

To remove the drums take an AIR HAMMER with about a 6" LONG 3/8 POINT TAPER PUNCH and punch in between each lug and then if the brakes are backed off the drum should come off.

 

Cool, I'll give that a try. Thanks for the input. Any idea about the fading pedal?

John

 

Perform brake master cylinder diagnosis test. Refer to brake master cylinder diagnosis chart.

 

Well thanks for the tip subford. After less than one lap around each set of lugs, both drums popped loose. It's really amazing how strong a bond there is between very small amounts of contact. I put a light coat of anti-seize compound on the face and edge of the hub where the drum contacts it.

After some clean up and inspection, I found that the guide clip for the self adjusting cable had fallen out and was wedged behind the shoe on the passenger's side. The star wheel had a few teeth that were worn and it was turned out less than half of the driver's side.

So I bought a self adjuster kit and installed the new clip and star wheel.

Everything else was clean and dry, shoes are still more than 50%.

Wheels and lug nuts are on, just have to adjust the shoes and then see if the pedal has changed at all. Stay tuned.

Thanks again for the input, it was a big help.

John

 

So I got the rear brakes adjusted and test drove it. The pedal was better but still not right, still too much travel.

So I decided to check the brake booster push rod to see if there was an issue there. It was out of adjustment by almost 3/16" of an inch.

After proper adjustment, bolted the MC back on and took another ride.

The pedal feels like normal brakes again. Not nearly as much travel and less effort required to stop.

There is still pedal fade when running but is it much slower now. So still something to chase down

Is there an easy way to test the booster and check valve for issues?

And is there a link to the MC diagnosis chart anyone can share?

Thanks for any input.

John

 

So I discovered a new symptom last night driving home from a jobsite.

While driving through a snow storm, I switched the control from heat to defrost and had sporadic defrost, then nothing, then good defrost. If I switched to mix it would pretty much stay consistent.

This morning I had the truck idling outside with the control set on defrost and realized after a couple of minutes that I could here the A/C trying to cycle.

I figure that there is a vacuum leak somewhere in that part of the system. Probably the white vac. line that goes through the firewall.

Does anyone have a thread or pics of the best way to approach replacing that line and any others that are involved?

BTW, the brakes seem a lot better and the pedal has almost no fade now.

I have replaced all the vac. lines under the hood which helped driveability a little, but it seems that there is more to chase out.

Any input is appreciated.

Thanks,

John

 

A vacuum leak will not stop the heater fan from blowing to defrost.
It is the other way around, if you have a vacuum leak it will always blow to defrost.

The diagram below is for a 1996 but a 1994 is the same.\:


/

 

I think that I found the wacky heat-A/C issue.

I did a bunch of testing and chasing of the vacuum lines.

All the lines in the engine bay and inside the cab check out fine-no leaks.

All of the valves/actuators check out fine as well.

Last thing that I checked was the selector switch. It was so brittle that pieces broke off as I was trying to disconnect it.

So I'm hoping that's the problem. Ordered one from Rockauto, waiting for it to arrive.

**I do have another issue that I forgot to list at the start of this thread**:

Cold starts in the winter months result in no power steering until the truck runs for a few minutes. If I turn the wheel immediately after starting, I get power assist turning right if I force it a little Left turn is more sluggish.

The truck is parked inside my unheated shop. If I let it run for 3-5 minutes without moving the wheel, it will have power assist without any issues.

The pump whines in the winter but not so much in warm weather.

Time for a system flush?

Or should I do the van pump upgrade?

Any input is appreciated.

Thanks,

John

 

Thanks for the diagram, it was a huge help in chasing things down.

John

 

You could try a fluid flush, that kind of issue can be a bit hard to diagnose though, as it could be a box or a pump problem. The fact that one direction turns better than the other makes me lean towards box.

 

I got the new selector switch installed. It solved the wacky heat/defrost/AC issue.

The intermittent stumble/hesitation is still there when the truck is warmed up.

I'm going to pull the PCM and send it here:

Ecu Repair Now, automotive circuit board testing and repair

They said for $200 maximum they said they would test it and replace anything necessary.

So my plan is to take the PCM out of my other truck and put it in this one while they fix it.

My question is:

**Will a '95 F350 460 E4OD 4x4 work in a '94 F350 460 E4OD 2WD?**

I'm also figuring that swapping them will tell me if the PCM is the problem or something else if the truck runs the same.

Now back to the power steering.

I started the truck today in a cold shop after sitting for three days.

There was no power assist in either direction. I let the truck run for about a minute and try again to find it had power assist in both directions without any forceful effort.

As I stated before, the pump whines in the cold after start up, but not in the summer months.

**So could it be airlocked or can it actually freeze?**

Any input is appreciated.

John

 

Yes, the other ECU will work just fine. Also, don't bother with ECURepairNow, another member just recently had very bad luck with them. Just get a reman from Autozone - it will cost about the same or even less.

 

Thanks for the confirmation on the PCMs.

Any more input on ECURepairnow?

I actually found them on this forum with good reviews.

When I talked with them, they sounded knowledgeable and professional.

As I've said before, this truck is super clean. So I'm hesitant to give up what looks like a pristine PCM to receive an unknown rebuild.

Thanks for the input/opinions. Please keep them coming.

John

 

Here's the thread where I found ECURepairNow:

https://www.ford-trucks.com/forums/1...o-buy-pcm.html

My PCM doesn't look nearly as bad as the pics subford posted. You can just see a little discoloration around the bases of the capacitors.

I'll take pics when I pull mine back out.

Thanks for any input.

John