The following is a primer on what to look for in a used Ford truck or van, powered by the 1983 to 1987 6.9 and 1987 to 1994 7.3 IDI (Non-Powerstroke) engine.
Obviously any vehicle purchase should include an inspection for the obvious signs of trouble. Leaks, squeaks, obvious damage, bad smells, and the like should all be investigated to ascertain their origin and if they are a concern. Driveability, road noise, tracking and other such things are all part of the assessment of a vehicles worth and desireability. This discussion is meant to cover the specialized things one must look for on an IDI powered truck, and is not meant to exclude any of the normal things mentioned or not mentioned above. It is up to the prospective new owner to do what is possible to identify early on, any issues that may affect the longevity of the vehicle and satisfaction of the purchase. Make sure the truck you are looking at is an IDI powered truck! Many people mistake a Powerstroke engine for an IDI or the other way around. IDI's are characterized by a beefy V-8 engine with a forward mounted rotary injection pump with individual steel lines radiating outward to individual injection nozzles at each cylinder. It may or may not be turbocharged, and the turbo, if so equipped, may be in one of 3 different locations, depending on the Factory, or aftermarket turbo installed. A Powerstroke looks like a chunk of plastic with a lot of wires attached.
Things to look for on both engines -
Normal cruising should be light haze to no smoke
Lugging should be brown or black
Normal acceleration should be light haze to dark smoke*.
Against compression should be no visible smoke
* If the previous owner has turned up the injection pump, you may have significant black smoke on acceleration. This is normal. However, for a factory calibration, you should see little or no smoke. Also the injection pump timing may be off. It would be appropriate to have the truck timed once you purchase it, to ensure best performance.
The truck should run strong. Unless the truck is extremely heavy, it should feel like it has a lot of pep. Don't expect it to burn rubber and throw you back in your seat though. This is a diesel and not a gas engine. Observe the smoke, and listen for any noises. A properly maintained IDI sounds like a sewing machine with an attitude!
Things specific to the 6.9LD.
Block casting........INTERNATIONAL HARVESTER DIESEL ENGINES
6.9L and 7.3L Core Identification
6.9L Old Style Block
Block Casting Number:
On left side of block (beneath oil cooler) 1805440C1
Note: Some 440 blocks are truly new style and must be visually inspected by raised donut around the block heater, frost plug (right rear). Old style below serial number 173828.
Visual Identification: *No counter bored area for block heater
*No defined area on side of block for dip stick
*Thickness of cast iron around block heater 3/8" (.375")
Head Bolts: *7/16, 12 point socket is used to torque head bolts
*Block tapped with 7/16-14 for head bolts
6.9L New Style Block
Block Casting Number: 1807996C1 Note: Some new style blocks have casting
number 440. Above serial number 173828.
Visual Identification: *Has counterbored area for block heater
*Very defined relief area cast in side of block for dip stick tube.
*Thickness of cast iron around block heater 15/32" (.470")
*Latest style (not all new style 6.9) has ribs around head bolts, rear two on left side go from head gasket surface to pan rail - same as 7.3
Head Bolts: *Same as old style 6.9
7.3L Block
Block Casting Number: 1809000 C1
Visual Identification: *Same as 6.9L new style block
*Head bolt ribs on side of block extend from pan rail to head gasket surface or rear two head bolts left side
Head Bolts: *1/2" - 12 point socket is used to torque head bolts
*Block tapped with 1/2 - 13 for head bolts
Things specific to the 7.3LD.
Obviously any vehicle purchase should include an inspection for the obvious signs of trouble. Leaks, squeaks, obvious damage, bad smells, and the like should all be investigated to ascertain their origin and if they are a concern. Driveability, road noise, tracking and other such things are all part of the assessment of a vehicles worth and desireability. This discussion is meant to cover the specialized things one must look for on an IDI powered truck, and is not meant to exclude any of the normal things mentioned or not mentioned above. It is up to the prospective new owner to do what is possible to identify early on, any issues that may affect the longevity of the vehicle and satisfaction of the purchase. Make sure the truck you are looking at is an IDI powered truck! Many people mistake a Powerstroke engine for an IDI or the other way around. IDI's are characterized by a beefy V-8 engine with a forward mounted rotary injection pump with individual steel lines radiating outward to individual injection nozzles at each cylinder. It may or may not be turbocharged, and the turbo, if so equipped, may be in one of 3 different locations, depending on the Factory, or aftermarket turbo installed. A Powerstroke looks like a chunk of plastic with a lot of wires attached.
Things to look for on both engines -
- Condition of the oil.
- Condition of the coolant.
- Condition of the glow plugs.
- Condition of of the fuel system
- Hard starts
- Electrical.
- Road test
Normal cruising should be light haze to no smoke
Lugging should be brown or black
Normal acceleration should be light haze to dark smoke*.
Against compression should be no visible smoke
* If the previous owner has turned up the injection pump, you may have significant black smoke on acceleration. This is normal. However, for a factory calibration, you should see little or no smoke. Also the injection pump timing may be off. It would be appropriate to have the truck timed once you purchase it, to ensure best performance.
The truck should run strong. Unless the truck is extremely heavy, it should feel like it has a lot of pep. Don't expect it to burn rubber and throw you back in your seat though. This is a diesel and not a gas engine. Observe the smoke, and listen for any noises. A properly maintained IDI sounds like a sewing machine with an attitude!
Things specific to the 6.9LD.
- Headgasket problems
- Glow plugs.
- Block cracking.
Block casting........INTERNATIONAL HARVESTER DIESEL ENGINES
6.9L and 7.3L Core Identification
6.9L Old Style Block
Block Casting Number:
On left side of block (beneath oil cooler) 1805440C1
Note: Some 440 blocks are truly new style and must be visually inspected by raised donut around the block heater, frost plug (right rear). Old style below serial number 173828.
Visual Identification: *No counter bored area for block heater
*No defined area on side of block for dip stick
*Thickness of cast iron around block heater 3/8" (.375")
Head Bolts: *7/16, 12 point socket is used to torque head bolts
*Block tapped with 7/16-14 for head bolts
6.9L New Style Block
Block Casting Number: 1807996C1 Note: Some new style blocks have casting
number 440. Above serial number 173828.
Visual Identification: *Has counterbored area for block heater
*Very defined relief area cast in side of block for dip stick tube.
*Thickness of cast iron around block heater 15/32" (.470")
*Latest style (not all new style 6.9) has ribs around head bolts, rear two on left side go from head gasket surface to pan rail - same as 7.3
Head Bolts: *Same as old style 6.9
7.3L Block
Block Casting Number: 1809000 C1
Visual Identification: *Same as 6.9L new style block
*Head bolt ribs on side of block extend from pan rail to head gasket surface or rear two head bolts left side
Head Bolts: *1/2" - 12 point socket is used to torque head bolts
*Block tapped with 1/2 - 13 for head bolts
- Trans and clutch.
Things specific to the 7.3LD.
- Cavitation.
- Serpentine belt.
- Transmission
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