So this is my new tow vehicle.




It is a 1991 D-350 Dually, Intercooled Turbocharged, O/D Auto.

It has some issues.

1. There is a knock at start up that quiets down. It also seems to get louder at random times. Or I just loose it in the normal diesel rumble.
2. The A/C doesn't work.
3. The Message Center doesn't work.
4. The odometer stopped working at 142,000. So the mileage is unknown.
5. The valve covers are trying to impersonate the Exxon Valdeze
6. The dash is busted into several hundred pieces.
7. The trans appears to be over filled by quite a bit.
8. The engine temp gauge barely moves past the first tick. I'm guessing it should run a bit warmer after a full hour of driving.
9. The front springs are fully reinforced with blocks of rubber. AKA spring helpers.
10. (This space reserved for future findings )

For the knock I'll try to get a video posted up if I can get the sound to come out good enough. And, ask for help then.

I'm living in the deep south so the A/C is a must. I don't think the push buttons on the ventilation controls are doing anything. For example if I push defrost no air comes out of the top vents. So when I push A/C the compressor is not engaging. I just filled the system with 134 as a previous owner already converted it. Reading the owners manual, yes it came with one, there is supposed to be some sort of sight glass. I cannot find a part in the engine bay with any type of sight glass. I suspect this thing was once part of the A/C system:

• Solved - trans cooler - Yes? No? If yes, will the A/C work with out it? If not what is it and do I need it?
• How can I make the compressor engage to test the A/C system?
• How do I test and fix the ventilation push buttons?

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• What year trucks can I find a replacement dash from?

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Reading the owners manual I read about a water/fuel separator that should be drained. I don't seem to see it on the non-exhaust side of the engine like the book shows.

• Am I just blind?

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• Where is the fuel filter?
• Is there a shop manual I can buy that covers this truck?

I paid $3500 for it and I might have paid too much

Thanks for any help provided in advance!


PS. I think I'll try to keep all the request for help I'll be posting to this one thread. We'll see if it works.

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3 Mar 11
Click the link to hear the knock:
http://www.youtube.com/watch?v=pRaPgM4c_3k
I am embarrassed to say, but I didn't hear the knock before I bought it.

• So what is causing the knock?

 

That thing in the first pic is a heat exchanger for the trans fluid, it warms up the fluid for faster and better performance, + it also cools it down to what ever the coolant temp is, or try's to anyhow.

the fuel filter is half way down the block right against it on the driver side, there should be a couple wire conectors going to it for the water in fuel sensor and fuel heater.

Dar

 

The sight glass you mentioned is on top of the dryer which is hanging off the passenger fender right behind the air filter box. Don't know how to tell if the refrigerant is any good or not. Hopefully someone with some HVAC knowledge can chime in on this soon.

The fuel filter/water separator is on the driver's side of the engine. In your last picture, it's roughly right below the intake tube. Tucked up behind the throttle linkage bracket and hugging the block.

 

Nice looking truck! I love single cab duallies, they're my favourites.

As Jimbo said, the sight glass is on top of the dryer/accumulator tank. But, it's not going to be much use if the compressor isn't cycling. There's a myriad of reasons why that's happening, but you said the systems been converted to R134a. Do you know if any of the hardware was changed also? The hoses/tubes, orifice tube, accumulator/dryer all need to be changed too.

 

A trans cooler, I never would have thought that.

Then I guess the truck has what an aftermarket cooler tucked up and behind the grill. The additional temp gauge in the cab doesn't work and one of the heat probes in the transmission lines is broken. Maybe one of these days I can fix that too. But, right now this gauge is not a priority.

Thanks for the complement!
Ok there is no sight glass on top of my dryer/accumulator tank.
I do not know if the system was changed over to 134a the correct way. And, I agree the right way would to be change out all the parts you list. But, I should be able to test the compressor, even an R12 compressor right? Both systems work on the same principle. Any help with getting the a/c system working without me just tossing parts at it would be great.

 

yOUR as blind as i am, i think , i'v never found my sight glass ,,,yet. @2x on the truck , the 2- rowes are my favorite,,, welcome!!!!

 

Check the relay's on driver;s side by hood hinge 1 of them control's A/C

 

Is a relay present on a non i/c by chance? My a/c quit working a while ago and I don't think it's because I lost the charge.

 

just jumper the compresser of with a hot wire while the engine is running. Also it wont kick on by itself if it freon is low.

 

About the knock, does it come and go with engine cold and warm or just cold? On the video it sounds like it goes away as the oil pressure builds up, normal for a cold engine but not a warm engine. Do You run any fuel additive? I would recommend a good dose of 2 stroke oil (like the outboard at walmart) and power service white bottle on a regular basis to loosen it up a bit.

 

It is very noticable at start up. Then goes away. When just reving the engine you can hear it too. I can pick it out on the video, of course I know what I'm listening for :P

I just bought the truck and I did not add any fuel additives. I'll put a pint of 2 cycle in next fill.

 

I'm pretty sure the compressor should have 12 volts any time the key is on. The ground circuit is what controls the A/C clutch. The ground signal originates from the temp control/ mode control buttons. At least this is how my "early" 91 is. 91.5s may work differently.

 

Welcome.

The A/C controls in the dash could very well be bad, They're vacuum buttons and could be leaking. The ones in the 93 take forever like when you push defrost it takes a full 10 seconds for it to switch over.

The knock COULD be a cracked flex plate?

You can run jumper wires into the A/C compressor, One gets 12v and another gets ground. I just use a little battery box . This will turn the Compressor on and at least tell you if it's blowing cold air and is charged. If it works good then it could be the low pressure switch on the firewall passenger side or could be the controls in the dash like you said.

 

Welcome and Congrats!

From the photos that you provided I noticed your battery wiring has quite a few connections to the hot lead.

It would be beneficial to use an idea like the power distribution deal that the previous owner of my truck did (albeit it still needs improvement). You may want to add a few relays to the mix so that not everything has always on power. I am guessing this is where some of your electrical problems are coming from.

Take a look at your fuse box, I bet there are quite a few taps there. You will need to sort this mess out to make sure that it isn't a short or such that may be causing your message center not to work. Check where there wires are going through the firewall and make sure there is a grommet there protecting the wires from rubbing on metal.

Also take a look at the Copper soldered connections to the positive terminal of my battery. Pay particular attention to the battery terminal connectors. This way you only loose the Battery terminal connectors when they break and you don't have a huge mess of wires.

Looking at your negative terminal on your battery, I am taking a guess that you may need to add more grounds from the firewall to the block, chassis, radiator etc. These trucks usually don't have enough ground.

I see a few loose unprotected wire running around in your truck. It would be great if you could get some of that black accordion style split flex tubing for electrical protection and put some around those wires.

I am excited that you have your new truck! These first gens are awesome.

 

If it is a loud knock that goes away as soon as oil pressure built up, I might worry a little bit. Does it go away when it warms up? How much have you driven it? How does the oil look? Could it be a really loose rocker?