Hi guys, I just bought my first diesel truck. I have had a diesel VW now for about 2 years so I am kinda new to the diesel scene. My truck is a 93 F-250 with 178k. It has a five speed trany. Here is the history that I know about: New batteries, New fluids, oil, brake fluid, coolant, gear oil. New filters, glow plugs, and injectors. Glow plugs are Motorcraft brand. New radiator and water pump. Things that need replaced: Rear right hand brake cylinder, front brake pads, center support bearing for the drive shaft, radiator overflow tank, power stearing pump leaks.

The truck does not like to start when the engine is cold. The "wait to start" light only stays on for about 4-5 seconds, if I try to cycle them a second time the light goes out right away. If I give it a little bit of throttle while tring to start it seems help a little.

It clunks when shifting gears. Drive shaft universals are tight but the center bearing support has a lot of slop.

The brake pedal is hard and brakeing is poor until the engin has run for a while. No brake lights are on.

Emerg. brake works sort of. It needs adjusting because if the grade is too steep it won't hold.

Other then these few items the truck runs great and is in awsome shape I am the second owner. It has never pulled a fifth wheel. The previous owner was an Amsoil dealer and took very good care of it.

Any help with these few issues that I have would be greatly appreciated.

 

I would check and make sure that if all the GPs are new, that they are all hooked up and there are no shorts. And the throttle does help it start, even the owners manual will tell you to hold the peddle half way down in temps above 50 and all the way below 50.

2. The clunk could be worn U-joints, combined with a wore yolk in the rearend

3. The brakes are hard because the vacuum pump is going out (its right below the altenator)

4. The E-brake just probably needs adjustment.

5. I would ask the P.O. if he knows anything about SCA and cavitation.

 

You've prolly got a Glow Plug or two burned out. Th WTS light should light for a good 15-20 secs in the AM.

Does the brake light, light when You turn the ignition on? You might have a vacuum pump going out.

Prolly need to replace the brake shoes. Might try adjusting them. See if that helps

 

The gp harness is attatched to all gps and appears to be in good shape. The gps are supposedly new. The brake light does come on when the key is turned on and goes out like it should. I was leaning towards a vacuum pump too. You guys will have to forgive me, I'm new to the forum lingo, what is the P.O. and SCA? What is the easiest way to test the glow plugs?

 

P.O. previous owner

SCA (Supplemental Coolant Addtive) they prevent cavitation from happening which cause tiny microscopic holes in the cylindar walls.

To test GP's take a test light and attach one end to the hot on the battery and then individually test each GP, if the test light comes on, then its a good GP, if its a bad GP it won't glow


http://www.oilburners.net/articles/cavitationartic.html

 

Welcome to the IDI forum.

PO- Previous Owner
SCA- Supplemental Coolant Additive- Put into the coolant to maintain the chemical levels for engine protection. Diesel engines (specifically the 7.3) are prone to cavitation. This can lead to pin holes in the cylinder walls that can cause engine failure.

Jason

 

Dang it, Hoffman I didn't even realize that your new here, so as Jason said

Welcome to the IDI section of FTE

 

Cavitation is a localized low pressure zone that forms adjacent to the outer wall of the cylinder. It is caused by by the flexing of the cylinder wall due to the high cylinder pressures experienced in diesel engine ignition. Gasoline engines don't typically get this failure mode due to lower cylinder pressures during ignition. Basically what happens is the cylinder wall quickly expands due to ignition then returns to its original geometry. This expansion of the cylinder wall is more pronounced as you increase the demand for power. Bascially when you increase your demand for power you are pumping more fuel into the cylinder. If you have a turbo charged unit you are also increasing air charge. This increase in fuel and air causes a more violent ignition which further increases cylinder pressures and thus increases the flexing of the cylinder wall. This fast cylinder wall movement causes a low pressure zone to be created in the coolant adjacent to the cylinder wall. When this pressure zone drops below the vapor pressure point (temperature, coolant ratio, and additive dependant) a vapor bubble is formed. When this low pressure zone returns to a high pressure zone, the vapor bubble collapses, causing an implosion, or pitting phenomena on the cylinder wall (like hitting the surface with a microscopic ball peen hammer). If left unchecked, it will eventually eat all the way through the cylinder wall.

Stolen from thedieselstop.com

 

The glow plug issue can be caused by a bad "water temputure senser" it tells the relay how cold/warm the engine is. The colder the engine, the longer the glow plugs have to stay on. We have the very same problem with our 87 E350 6.9 diesel and were pretty sure it's the "water temp senser".

 

WOW, thanks for the info on cavitation. I will try to call the P.O. and find out if he put SCA in the coolant. He didn't say anything about it. Great article by the way. GP testing appears to be the same as it is on my VW. If the gps are ok could I have a problem with the controler? I thought I read somewhere on this forum about the controlers having grounding problems?

 

Do you guys know where I can get a shop manual? The Chilton manual that I bought isn't worth the paper its printed on. Where is the coolant temp sensor that the controler is using to determin glow time? The P.O. did say something about he thought the temp sending unit was going bad because the temp guage reads lower then what He thought it should. If he had'nt said anything I wouldn't have thought anything about it because it looks fine to me. What other inputs does the controler look at? Fuel temp?

 

Sadly the only shop manual I have ever found for an IDI is well, here.

 

The temp sensor that he is referring to is for the glow plug circuit and is different from the sender for the gauge.

I have a set of factory manuals for my '93. Very informative about diagnostics and repair of all systems on your truck. I paid under $100 for the complete set off of Ebay a few years ago.

Jason

 

Where is the temp sender for the gp's I thought they were just resistance controlled.

 

try books4cars.com